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Patrick Turner
 
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Miles O'Neal wrote:

On Mon, 23 Feb 2004 18:28:13 +1100, Patrick Turner wrote:

Not quite. In a SE Class A amp, you typically get just under 50%, but
45% is very easy to get.


45% is very optimistic, and represents the practical limit for class A
efficiency.
Most tetrode/pentode amps are 35%.


Mayeb big tubes are winpy; I mostly
play with 6BQ5s and 6V6s. I have
*never* had a problem getting more
than 40% out of a Class A amp.


OK, but that is at only one value of load.
At all other values of load, you just won't get the 40%.




And Push-pull Class A gets you just a little better than double what
you'd get with an equiv- alent SE design design of one tube, so you run
right about 50%.


Very seldom.
The amp doing 50% plate efficiency is usually operating with considerable
class AB. the max efficiency of class B with tubes is around 66% only.


RCA disagres with you; it's not just me.


I suggest you take a peak at RDH4.




...with a few extra AB watts to make it to about 30 at onset of
clipping. Such operation is substantially class A.

This is where you are wrong. An amp is biased for one *and only one*
class of operation under its normal operating conditions.


No, most amps with enough bias current will operate as pure class A amps
with an appropriate minumum load to alow this to occur. Below this load,
they are class AB, and above that min load, the power is all class A


NO. BY DEFINITION (yes, I am shouting
in hopes it will get your attention)
am amp is biased for a given operating
class under a certain set of conditions.
If you bias it as Class A for a certain
set of conditions (which certainly includes
the load), then within those conditions,
it is Class A. If any of the conditions
change, then you have to refigure things
for that set of conditions. And if it
comes up Class AB, then it *is* Class AB.
Not "Class A except..."


I agree with you, no need to shout to get my attention.
You repeated what I said.


...
Now a Class AB amp will operate similarly to a Class A amp until the
signal starts reaching cutoff, but that doesn't mean the amp is Class A
until that point.


I think your'e the one who has it wrong. One could have a class AB amp,
each tube is operating in class A at low voltage/current swings.
One can prove this easily. Set up a PP amp with 6L6 and Ea = 400v, and
bias at 30 mA.
use about a 5k a-a load.
measure the current into the CT on the OPT. there is a region of operation
where the current input stays constant, hence the power input is constant,
and the amp *must* be working in class A. As soon as one tube begins to
cut off while the other carries on, its class AB, and the power input
starts to rise, indicating class AB.


It *does not matter* that at lower signal
levels both tubes conduct 360 degrees.
What matters is that within the operational
parameters of the circuit, at some point
each tube conducts less than 360 degrees,
then the amp is not biased class A.


There is a transition from 360 d to less than 360,
which means it goes from class A to AB....
its not a sudden transition, especially in triode PP amps.....



Class of operation is not what the amp is
doing at any given moment, which is how
you are treating it. This is a common
misconception, and we've beaten it to
death in the past.


Oh.
Well, I don't plan to convert all the ppl all the time.
I know class A operation when I see it, and class AB operation.




If a PP amp is biased so
that you ever reach cutoff before clipping, it's not Class A.


But the cut off isn't linear in many tubes, and in amps which are

regarded

So what?

And for the record, lots of amps "regarded"
as Class A - are not Class A.

as class A, there is still a slight increase in power input near clipping,
because the current cut off in one tube is less than the current increase
in the other.


Again, so what? The Class of operation is
not defined by total current consumption.
It's defined by what goes on within the
individual tubes, considering the system
as a whole.


I have described what I know to be class A.
Its when each tube in a PP circuit has less than 5% thd in its signal *current*.

Once 5% is exceeded, usually its then running class AB.




If the wave forms of the cathode currents are examined its
plain to see that in a class A amp, each output tube has quite a lot of 2H
distortion current, but not actual complete current cut off.


I'm not sure why this is relevant...


Its *very relevant*.



...
Most guitar amps are PP mainly class B in their output stages.

Wrong! Most of them are Class AB, not Class B.


I think you misunderstand.
Most guitar amps display full cut off of the tube *current* for most of
the cycle at clipping with a sine wave.


The operating classes have to be defined
as cutoff before clipping occurs. Otherwise
they make no sense.


Before cut off, its class A.
After cut off, and before clipping, its class AB, simple.



If the amp is set up for class AB, the AB power max is about 21 watts of
which 5 could be class A, and the remaining 16 is B, because after 5
watts, the tubes start to cut off during the cycle. Connect a CRO to a
cathode resistor, and you will see what happens.


There you go again. Basic electronics theory.
An amp is biased for 1, and only 1, class of
operation under its operating parameters. It
may *act* the same as a Class A amp up until
a certain point, but it either *is* or *is not*
Class A. If it exhibits the characteristics
of Class AB at any point, then it *is* Class
AB. That's how things are *defined*.


I can't win.




... Very few
*pure* class A PP output stages are ever used, and *extremely* few
single ended class A output stages.

The former is obviosuly correct, but
as to the latter ... there are more and more of these every day.


Not much use of SE musicians amps.


Nope. The Fender Champ is still a
hugely popular amp. SE Gibson Skylarks
and Kalamazoos are still used a lot.
Check out the AX84 site. Note the
UniValve and BiValve. As I said,
SE amps are (re)gaining popularity
for a variety of reasons.


I have yet to service an SE muso amp made recently.



The SE amp is a gutless wonder to many musos.


Irrelevant to this discussion.


Nope, because musos like to have enough power,
and PP is the cheapest easiest way to power.



...
And who said they would take that? I haven't seen anyone talking about
a 600W Class A SVT!


Well if some of the hype about some of the sturdier 6550 brands are to
believed, you'd think there is some magical quality, some special ability
for the tube to exceed the ratings, but there is no magic in the ratings.
Perhaps the cathode emisions under stress do vary over time somewhat
earlier with russian tubes.


All I was asking was why you were arguing that
5x bit as if someone had said they would take
that.

I have not noticed falling emissions with russian tubes, but then we
havn't had time to evaluate this. Maybe in 30 years, some grey haired old
bugger will hark back to his youth in 2004, and try to tell folks that
2004 tubes are so much better than 2034 tubes. There will be only 3
samples left in the world of mint GE 6550 in 2034, and arguments will rage
that perhaps they are chinese fakes....


8^)

...
That's not the point. You were talking about how bad it was to run an 8
ohm amp into 1 ohm or less, and claimed lower impedances were worse than
high. So I just went up the same amount you went down (8-4-2-1 vs
8-16-32-64). I can guarantee that if you try that load, your tube
amp will fry, fry, fry. The closer you get to an open load, the worse
off a tube amp is.


Any tube amp should be able to be used without a load up to when the
voltage swing reaches the peak value of the supply voltage. To make sure
the swing is limited to stop arcing. diodes from anodes to 0V can be
added, as seen in the schematic at

http://www.turneraudio.com.au/htmlwe...00ulabmono.htm


They're running those tubes extremely gently
compared to any guitar amp!

There are three diodes in series to limit the negative swing of the anode
voltages...


You just destroyed the sound of the tube guitar amp!
I *hate* the sound of diodes in plate circuits. And
I am not alone! The distortion turns to crap.


There is no measurable distortion due to the diodes being in the circuit.
The reverse diode currents are extremely small.
The overload character of the amp with a speaker connected shows that
the clipped wave form has a peak voltage value less than the
value of the supply voltage.
The diodes *only* conduct when the anode peak voltage swing exceeds
the value of the plate supply, ie, when an anode voltage goes *negative*, which
afaik, never occurs when a load is connected and when over driven to the point
where
the output wave is basically a square wave.



The only reason preventing full output signal voltages with no load in
tube amps

is appalling design methods, ie, bean counters, ie, the humans failing to
take enough responsibility for their constructions.


Nonsense. There are plenty of fried *good*
amps around from running with no load.


The only way to fry an amp is to have too much current and voltage
across the tubes, and I have never ever seen any tubes come to grief
when accidentally used with no load, although I have seen
arcs start from the high voltages generated, which should be limited..




...
The shorting jack is there to prevent the amp from ever seeing an open
circuit, or no load, when it may indeed misbehave by oscillation and die
from its poor design.
Its very unlikely anyone will use the amp with no speaker connected.
Nobody likes playing music at a gig in silence.


Speakers get unplugged all the time.
People switch speakers with amps plugged
in, pull cords for various reasons, trip,
knock things over, etc. Speakers blow.
It happens all the time, and flyback
effect kills lots of amps.


I know several musos who have me service all their gear.
I ahve never had one with trouble from a shorted output,
or an open output.
Tube amps normally cope with the temporary abuse you speak of.



All my amps can be used with or without a load, no worries. accidental
signals taken up to clipping with no load does *zero* damage.


Good for you. Put diodes in all your plate
circuits, or just run them all at very
low power?


With a load, the peak voltage anode swing is always less than the value of the
supply
voltage.
Diodes do not limit maximum power in any way.
With diodes connected, there is no measurable increase in thd!


With 12 tubes in my amps, I get away with separate RC cathode bias for
each tube, in my case with 15 watt x 500 ohms with 1,000 uF per tube
cathode.
All the worry about biasing 12 tubes properly does not exist, since auto
bias sets itself very reliably. The tubes get it easy in my amps, and i
hope they last, and last, and last......


Well, there's my answer. Yeah, if you baby
it, it'll be fine. I'd hate to see what you'd
try to do building a drag racer. "No, really!
We'll put five engines in it, and never rev it
past 2000RPM. It'll last forever!" 8^P


I think drag racing lacks something.
The cars can't go round corners.
Its like body building, its all vanity.
Ever see a body builder win a 1 mile race?

So, horses for courses.

Patrick Turner.



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  #82   Report Post  
Rich Koerner
 
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Thank You Miles!!!!!!!!!!!!!!!!!!!!!!!!!!!




Miles O'Neal wrote:

snip to get to the important stuff


NO. BY DEFINITION (yes, I am shouting
in hopes it will get your attention)



Yeah, You have to do that sometimes.

Then there is the 50 gallon drum I keep in the back yard with a 2x4 soaking in it 24/7.

That's there so when I have to smack someone's head, to get their brain cells jump
started, I don't break the 2x4.




Class of operation is not what the amp is
doing at any given moment, which is how
you are treating it. This is a common
misconception, and we've beaten it to
death in the past.



THANK YOU MILES!!!!!!!!!!!!!!!!!!!!!!




Again, so what? The Class of operation is
not defined by total current consumption.
It's defined by what goes on within the
individual tubes, considering the system
as a whole.



This is the proper view to have.







If the amp is set up for class AB, the AB power max is about 21 watts of
which 5 could be class A, and the remaining 16 is B, because after 5
watts, the tubes start to cut off during the cycle. Connect a CRO to a
cathode resistor, and you will see what happens.


There you go again. Basic electronics theory.
An amp is biased for 1, and only 1, class of
operation under its operating parameters. It
may *act* the same as a Class A amp up until
a certain point, but it either *is* or *is not*
Class A. If it exhibits the characteristics
of Class AB at any point, then it *is* Class
AB. That's how things are *defined*.


You want to borrow my 2x4!!!!!!




... Very few
*pure* class A PP output stages are ever used, and *extremely* few
single ended class A output stages.

The former is obviosuly correct, but
as to the latter ... there are more and more of these every day.


Not much use of SE musicians amps.


Nope. The Fender Champ is still a
hugely popular amp. SE Gibson Skylarks
and Kalamazoos are still used a lot.
Check out the AX84 site. Note the
UniValve and BiValve. As I said,
SE amps are (re)gaining popularity
for a variety of reasons.



LOL, as the two sonic worlds collide in their ideals of sonic reproduction.

Both worlds are not without there surreal views on reality.

However, if given a choice which of the two is more grounded, I'll be found on the stage
playing my ass off creating the REAL Deal!!!!!!!!!!!!!!!!!!

With my tube too!!!!!!!!!!!!




And who said they would take that? I haven't seen anyone talking about
a 600W Class A SVT!



Because, it's not practical!!!!!!!!!!!!!!!!!!

Brute power from tubes from the low end boys, has all the highs and harmonics of the
guitar, yet all the fat fat low end on the floor soft as a pillow humming your body
cells. Nothing like AB for the POWER.

Besides, who'd carry a 600W class A SVT anyway.

Not to mention the energy cost for the silence it produces, between the notes
played!!!!!!!!!





That's not the point. You were talking about how bad it was to run an 8
ohm amp into 1 ohm or less, and claimed lower impedances were worse than
high. So I just went up the same amount you went down (8-4-2-1 vs
8-16-32-64). I can guarantee that if you try that load, your tube
amp will fry, fry, fry. The closer you get to an open load, the worse
off a tube amp is.


Any tube amp should be able to be used without a load up to when the
voltage swing reaches the peak value of the supply voltage. To make sure
the swing is limited to stop arcing. diodes from anodes to 0V can be
added, as seen in the schematic at


****sssssssssssssssssssst, over here.

Can you get on another page for a second.

ANY AMP!!!!

You said ANY AMP!!!!!!!!!!!!!!!!

Horse Hockey!!!!!!!!!!!!!!!!!

USER ERROR, USER ERROR!!!!!!!!!!!!!!!!!!!!!!!

Give me a break!!!!!!

Must be a liberal!!!!!!

Let's write a law to protect amps from *users* in error.


http://www.turneraudio.com.au/htmlwe...00ulabmono.htm


They're running those tubes extremely gently
compared to any guitar amp!




If we designed EVERYTHING to survive IDIOTS, and BABY TUBES as suggested,!!!!!!!!!!!!!!!!!

The 1967 Corvette Big Block would be the wife's car to go shopping, never exceeding 15
miles per hour, because of the clamping diodes on the gas pedal for fear she will over rev
the engine missing a shift while her foot has the gas pedal on the floor.

God forbid, the engine should ever be hurt or stressed in anyway!!!!!!



sigh


I can't believe we are even having this dialog!!!!!!!!!!!!!!!!!!!

This is at opposite ends of the spectrum, and the 6550 is the link!!!!!!!!!!!!!!!!

This is freaking insane!!!!!!!!!!!!!!!!!!!

Miles, you got there ahead of me, so I'm letting you run with this one.

What a waste of potential horsepower!!!!!!!!!!!!!!!!

The hell, turning 6550's into sleeping wimps, and bragging about it too.

Run them *******s in AB, and MOVE some freaking air Damn It!!!!!!!!!!!!!!!!!

Oopsie, I almost slipped my grip!!!!!!!!!!!!!!

Sorry Miles, I promise to control myself, and leave quietly.



There are three diodes in series to limit the negative swing of the anode
voltages...


You just destroyed the sound of the tube guitar amp!
I *hate* the sound of diodes in plate circuits. And
I am not alone! The distortion turns to crap.



Not to mention, there is no chance of *Angel Hair* on the sound of the guitar!!!!!!!!

Sterile tone, is guaranteed.


Damn, Miles, I'm sorry.

I promise, I'm leaving now!!!!!!




With 12 tubes in my amps, I get away with separate RC cathode bias for
each tube, in my case with 15 watt x 500 ohms with 1,000 uF per tube
cathode.
All the worry about biasing 12 tubes properly does not exist, since auto
bias sets itself very reliably. The tubes get it easy in my amps, and i
hope they last, and last, and last......


Well, there's my answer. Yeah, if you baby
it, it'll be fine. I'd hate to see what you'd
try to do building a drag racer. "No, really!
We'll put five engines in it, and never rev it
past 2000RPM. It'll last forever!" 8^P



SWEET!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


Regards,

Rich Koerner,
Time Electronics.
http://www.timeelect.com

Specialists in Live Sound FOH Engineering,
Music & Studio Production,
Vintage Instruments, and Tube Amplifiers
  #83   Report Post  
Rich Koerner
 
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Miles O'Neal wrote:


Can we even *get* a set of curves???????????




Coming up!!!!!

http://timeelect.com/images/6550ap1.gif
http://timeelect.com/images/6550ap2.gif
http://timeelect.com/images/6550ap3.gif
http://timeelect.com/images/6550ap4.gif
http://timeelect.com/images/6550ap5.gif
http://timeelect.com/images/6550ap6.gif
http://timeelect.com/images/6550ap7.gif
http://timeelect.com/images/6550ap8.gif







Regards,

Rich Koerner,
Time Electronics.
http://www.timeelect.com

Specialists in Live Sound FOH Engineering,
Music & Studio Production,
Vintage Instruments, and Tube Amplifiers
  #84   Report Post  
James Angelo Ruggieri, P.E.
 
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So you are telling me that you have no basis to conclude these other
tubes
are so bad.


Did I say that? Please read on...


Yes you did by deferring to experts - implying that you did not know. On the
other hand - you could have cited accepted industry documents, references,
or publications --but you did not. Had you offered some reasonable
scientific basis for your opinions - then it was possible you could have
swayed me.

This thread was posted to alt.guitar.amps. Are you also a musician? How

many
different tubes have YOU experimented with in a Marshall 2204? What style

of
guitar do you play? How many different guitar amps do you own? What are

your
tube choices and why?


But it manifested in alt.rec.audio.tubes. Yes, I am a musician, I play the
guitar - however, not as much as I used to. I also don't own as many guitar
amps as I used to, and I'm not familiar with the Marshall 2204 - however, I
suspect it to be similar to the characteristic Marshall line of tube amps
that prevailed in the sixties - a rot gut simple and cheap push pull audio
amplifier with intentionally substantive distortion characteristics when
subject to overdrive.
When selecting tubes for these inherently imprecise devices, I use the
following criteria:

Does the tube fit into its octal socket
Will the tube perform without denigration within the given design parameters
of the amplifier
Are the tube elements loose such as to short out when the amp is subject to
expected shock and vibration

I find it humorous that so much is made of the fine characteristics among
tubes when the application is so rough - that is, the discussions seems to
be addressing the detailed characteristics of a Formula 1 racing tire as
applied to a garbage truck. Not that I am identifying these cadence
amplifiers as "garbage" and I much prefer the sound of Stratocaster through
a rot gut Marshall than through a Polytone - however, I believe that there
is much subjectivity, rhetoric, and yes - histrionics introduced into these
discussions.

I don't care what the data sheets say, I don't care what the curves look

like.
I sometimes can't keep the grid and screen straight in my mind. What I

care
about what they SOUND like in my gear, and how long they will perform.


I also don't care too much what the data sheets say owing to the fact that
the QC and reproducibility of manufacturer among the subject tubes to be
more consistent than the application of being used in inherently and
intentionally imprecise instruments.

Don't assume that I'm some yahoo just because you don't know me or because

you
have a different perspective on tubes.


I don't know where you got this from - I simply asked you for the basis of
your opinions. But you admit that your basis to be subjective --which is OK

So you are telling me that distortion is desirable and important to

you -
well - isn't distortion (a non-linear characteristic) a feature normally
inherent with poor tubes or poor circuits?


I thought you knew Marshalls, Sun, Fender, Ampeg...


But I do - as explained above. I also know that their desirable qualities
are owed in large measure to their imprecise performance.

I can tell you that it produces a better sounding
midrange distortion in my Marshall and most of my other equipment. I've

tried
many, I've had others swap tubes so I judge them blind. I prefer Mullards

with
a slight preference for the long plates.


Then - you will admit that perhaps your Mullard with the long plate may not
sound so good in another Marshall amp.

Is that why NOS GE's cost so much? NOS Tung Sols? Telefunken? Mullard?

Bugle
Boy? Or do you believe that it is just non "experts" that don't know any
better, and we'd all be better off with Sovteks or Chinese?


I guess the answer here is the use of the NOS - indicating scarcity. As you
know the audiophile and music business is the playing ground for some of the
most intense marketing hype and appeal to subjectivity. From Monster Cable
to all sorts of nonsense. Of course, antiques typically commands high prices
because they are scarce. The scarcity, together with the subjective hype
will result in increased prices. But, and I'm sure you will agree, that to
say that my grandmother's old Singer sewing machine will perform better than
a newer machine is a bit off - no matter how many self-made tekkies weigh in
on the matter.

I'd just like to see some scientific data to support the opinions.

Regards

Jim




JAMES RUGGIERI
"Jim Anable" wrote in message
...
"James Angelo Ruggieri, P.E." wrote:

I'll leave the specifics to the "experts."


So you are telling me that you have no basis to conclude these other

tubes
are so bad.


Did I say that? Please read on...

What experts?


I don't speak for others, they will chime in if they want to. Among them

are
musicians, owners of amp companies, experienced amp techs...

I consider myself an expert and it is my opinion that these other tubes

are
fine.


This thread was posted to alt.guitar.amps. Are you also a musician? How

many
different tubes have YOU experimented with in a Marshall 2204? What style

of
guitar do you play? How many different guitar amps do you own? What are

your
tube choices and why?

If you can't answer those questions, you're "expertise" means squat to me.
Don't assume that I'm some yahoo just because you don't know me or because

you
have a different perspective on tubes. Hi-fi people with have one

perspective.
Engineers may have another. Musicians, yet another, based on EXPERIENCE

and
personal tastes on TONE.

I don't care what the data sheets say, I don't care what the curves look

like.
I sometimes can't keep the grid and screen straight in my mind. What I

care
about what they SOUND like in my gear, and how long they will perform.

The current offerings of many types of tubes are NOT "fine" with me.

Isn't this issue a point of contention across the industry?


I have
used the 6550 for years in guitar amp applications -- applications

that
could
be considered "abuse" by hi-fi standards, which may be why I can

detect
the
difference in quality and life and you can't. I have spoken with

others
who
share my opinions, some of whom might be better able to explain the
"specifics."


But I too was tempered in tube use as applied to cadence amplifiers:
Marshalls, Sun, Fender, Ampeg and so on. Yes, it is an abusive

environment.
I wasn't speaking from a HiFi perspective - and I'm uncertain how you

can
imply that my perspective to be HiFi based - however, I also believe

that
you also cannot tell me what the difference is - aside from physical
vibration, etc issues.

I have an ear. I can hear the difference in how different tubes

distort.
Distortion characteristics are important to guitar players. Hi-fi

uses
just
want clean, and they don't make the same sorts of demands on the

tubes.

So you are telling me that distortion is desirable and important to

you -
well - isn't distortion (a non-linear characteristic) a feature normally
inherent with poor tubes or poor circuits?


I thought you knew Marshalls, Sun, Fender, Ampeg...

I'm not about to give you the history of distortion in guitar amps, but

what YOU
may only consider to be "inherent with poor tubes or poor circuits" is

desirable
to MANY guitarists. In a sentence, it may have started with limitations

of
early guitar amps, but now it is an art form.

What kind off distortion do you
speak of?


I was speaking of power tube distortion. However, I also have opinions on
preamp tubes. I currently have a 1958 production 17 mm plate Mullard

ECC83 in
the gain position of my 2204. I can tell you that it produces a better

sounding
midrange distortion in my Marshall and most of my other equipment. I've

tried
many, I've had others swap tubes so I judge them blind. I prefer Mullards

with
a slight preference for the long plates.

With respect to power tube distortion, my Marshall has a relatively low
impedance on the plates. Drive the power tubes hard, they distort.

Different
tubes sound different when they distort. There IS a sonic difference

between
brands. GE 6550A gives high output with solid low frequency response in a
2204. When they distort, they have a "metal" (harsher) sounding

distortion, as
opposed to the "bluesier" (rounder, with earlier break up) sounding

EL34's.
That's how they act in my amps, and that's what I care about. They also

last
longer than current production tubes.

But you're the EXPERT, and you know Marshalls, so I shouldn't have to tell

you
that.

WE have an incentive to buy, but is the increased cost and difficulty

worth it
to manufacturers that have no problem selling what they make now???

Initial
setup costs would be nothing to sneeze at.


And what are those setup costs? Do you know? Didn't Adam Smith say a
contestable market will invite new players - and is there not incentive

for
new players to provide "non-turd" tubes? I'll tell you why there are no

more
GE 6550's - its because the current manufacturers can provide a similar
product at competitive prices.


Is that why NOS GE's cost so much? NOS Tung Sols? Telefunken? Mullard?

Bugle
Boy? Or do you believe that it is just non "experts" that don't know any
better, and we'd all be better off with Sovteks or Chinese?

They have considerably lower variable costs
than we do here in the US, and can thus offer the same tubes


Do the majority of "experts" consider the current offerings to be "the

same
tubes" as GE 6550A?

at a cheaper
price. As Smith also noted - price is entirely subjective, and the GE

folks
knew that they would have incurred excess marketing costs in order to
mislead folks into believing that that their tubes were so much better

than
the next guy's - as a means of justifying the much larger expenses. By

the
way - do you know who owns GE?


That'd be the shareholders.



  #85   Report Post  
James Angelo Ruggieri, P.E.
 
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I have an ear. I can hear the difference in how different tubes
distort.
Distortion characteristics are important to guitar players. Hi-fi uses

just
want clean, and they don't make the same sorts of demands on the tubes.


So you are telling me that distortion is desirable and important to you -


Tell me that you are joking ?

No -- I'm very serious. On the one hand folks embrace the distortion
characteristics of cadence amplifiers -- while on the other hand they are
addressing tube parameters and performance that serve to reduce distortion.
Seems to be a disconnect to me.

Wouldn't you characterize, lets say, a Marshall amp an example
of poor circuits? By audio REPRODUCTION enthusiast standards,
I would say so. But the audiophile standards have little currency
as regards the needs and desires of musicians using the distortion to
PRODUCE
music. A different endeavor entirely from listening to music.


If you are a HiFi enthusiast, I suspect that to you, the idea that the
massive distortion
of relatively unstable circuits running tubes above their design limits,
is a desirable effect may seem odd. But millions of music fans would
disagree
as the distorted guitar amp has been one of the more widely recognized
sounds
used in music for the last 60 years.


Although I have designed and built both HiFi and Cadence devices, I cut my
teeth on Cadence devices, and I can appreciate and discern the performance
requirements for both. I'm uncertain if the Marshall designer(s) intended
the distortion characteristics inherent in their amps - or if it was an
unintended consequence, and the design was driven by economics. I suspect
the latter - given the period of time the general design was developed. I
love the sound of a Marshall for a guitar - and much prefer that "sound"
than say piping my guitar through a Crown DC 300, for instance. However, I
would also not pipe my CD player through a Marshall, unless I wanted to
annoy my neighbors.

I simply believe that the prevailing notions being conveyed in this forum to
dismiss Chinese and Soviet Tubes as "junk" or "polished turds" to be
unfounded nonsense - perhaps rooted in either racist or protectionists bias.
In either case, an element of ignorance seems to be present. If someone is
going to call something junk - I'd like to know why - and so far, no one has
offered anything scientifically reproducible.

Regards



--
JAMES RUGGIERI
"Steve Eaton" wrote in message
...

"James Angelo Ruggieri, P.E." wrote in message
news:TBy_b.1221$Ri6.2@lakeread04...
I'll leave the specifics to the "experts."


I have an ear. I can hear the difference in how different tubes

distort.
Distortion characteristics are important to guitar players. Hi-fi

uses
just
want clean, and they don't make the same sorts of demands on the

tubes.

So you are telling me that distortion is desirable and important to

you -

Tell me that you are joking ?


well - isn't distortion (a non-linear characteristic) a feature normally
inherent with poor tubes or poor circuits?


Wouldn't you characterize, lets say, a Marshall amp an example
of poor circuits? By audio REPRODUCTION enthusiast standards,
I would say so. But the audiophile standards have little currency
as regards the needs and desires of musicians using the distortion to
PRODUCE
music. A different endeavor entirely from listening to music.

No, I wouldn't say that distortion is only to be found using poor tubes.
Any tube will distort if you desire it to. I would call a tube poor if the
characteristic sound of the distortion it produces is not musical to my
ears.
And I CAN hear both objective and subjective differences of the distortion
components of different tube types and brands. Some I like better than
others.

Most of my guitar amps use 6L6 type power tubes so I am most familiar
with those. In this case, just for example, every set of Sylvania's that I
have had sound similar to each other and different from let's say Sovteks.
And in every case they sound better. But that is not to say that all the
current tubes
are junk. I think that the cheap Shuguang 6L6 sounds very close to
those old Sylvanias

If you are a HiFi enthusiast, I suspect that to you, the idea that the
massive distortion
of relatively unstable circuits running tubes above their design limits,
is a desirable effect may seem odd. But millions of music fans would
disagree
as the distorted guitar amp has been one of the more widely recognized
sounds
used in music for the last 60 years.

I can understand why an audiophile might not like that sound, but I don't
understand
how an audiophile, who would certainly hear the subtle differences in the
sounds of tube types and brands when the tube is running clean, could

doubt
that there are even more exagerateded differences that can be heard when a
tube
is clipping.





What kind off distortion do you
speak of?


Harmonic distortion for the most part I would suspect.




.






  #86   Report Post  
James Angelo Ruggieri, P.E.
 
Posts: n/a
Default

and the price of GE6550A has gone far too higgh to be worth buying,
at over US $400 for a matched quad, ( which in my experience
means little, because they don't stay matched ).

And further - "matched" on a production jig often does not mean "matched"
in your amp!



--
JAMES RUGGIERI
"Patrick Turner" wrote in message
...

Look, NONE of the import 6550's have what GE did to theirs. After all,

THEY raised the
standards for what was commonly thought of as a 6550 here in the states.

The import
companies have THEIR *Versions* of what they THINK a 6550 should be.

Published families of curves for each should represent EACH of these

6550's, and SHOW
exactly what the electrical differences ARE!!!!

There is this mistaken notion that all 6550's SHOULD *BE* the same!!!!!!


(snip some interesting info about "polished turds", et all)

I did a search on the GE6550A.
It appears that the 16 pcs I bought in 1996 are GE6550A, the good sort of

tube
you are raving about.

I looked at

http://www.tubeworld.com/6550.html

and the price of GE6550A has gone far too higgh to be worth buying,
at over US $400 for a matched quad, ( which in my experience
means little, because they don't stay matched ).

I couldn't place my hands on the spec sheets for the GE6550A,
to compare it with other versions to confirm your claims
about these tubes superior ratings.

perahps you could be so kind as to post to the group the
list of maximum design ratings of the GE6550A,
and others that you regard as inferior.

Patrick Turner.



  #87   Report Post  
Patrick Turner
 
Posts: n/a
Default



Rich Koerner wrote:

Miles O'Neal wrote:

Can we even *get* a set of curves???????????


Coming up!!!!!

http://timeelect.com/images/6550ap1.gif
http://timeelect.com/images/6550ap2.gif
http://timeelect.com/images/6550ap3.gif
http://timeelect.com/images/6550ap4.gif
http://timeelect.com/images/6550ap5.gif
http://timeelect.com/images/6550ap6.gif
http://timeelect.com/images/6550ap7.gif
http://timeelect.com/images/6550ap8.gif

Regards,

Rich Koerner,
Time Electronics.
http://www.timeelect.com


Thanks for the set of curves.
The only one which wouldn't dowload properly was no 8.

They refresh my memory, and I must say there is nothing particularly
new to learn that I can tell from the last time I saw these specs.

I also cannot see that the specs convey any greater ability when
compared to
the EH6550 that the russians make.

A word about the russian 6550.

There seem to have been 4 versions of the 6550 coming from russia.
there was the Sovtek red lettered 6550, with parallel glass bottle,
similar in shape
to the GE 6550.
Then there was the Sovtek KT88, with a small coke bottle shape,
and then the EH6550, and EHKT88, with a larger coke bottle shape,
similar to MOV KT88.
These last three appear to have exactly the same looking electrode
structure within, and all the samples I have measured at random
had the same Ra, Gm and U.
The Gm is slightly less than GE, and Ra slightly higher.
The engineer at EH said they have altered the tube a little,
and apparently the grid is slightly larger dia, which explains the
lower Gm and higher Ra.
It makes mass production easier.
But he refused to answer my questions as to why there seem to be
the same internals to tubes labelled 6550, and KT88.
Methinks it because of modern marketing, where
they sell more output tubes if they have all the types available, and
since
the KT88 is so close to 6550, then they might as well use the same
rationalised
electrode structure, because users will never figure out why this is so,
and not
care about any difference between the old KT88and 6550 which may have
been in favour of either.

That is how I see the situation with russian 6550/KT88.
I have never used or compared Svetlana 6550/KT88 myself,
but I did supply a pair of Svet 6550 in a mono Leak 60
to a guy who has used as a foldback amp without any trouble for the last
6 years.

I could be wrong about EH, since I have never toured the factory daily
for a week or two recently.

I have serviced amps using Sovtek KT88 which are now 5 years
old, and used daily for a few hours.
These are idling at about 400v x 55 mA in Quad II very modified amps,
and running in triode.
When I measured the tubes this week during their latest service,
the maximum power level had not detectably moved downwards,
and the gettering still appears as bright as it should be after 5 yrs,
and there is little grid current at idle.
I think they are ageing just as well or better than the GE tubes I also
have
used and witnessed.

The curves you have tendered so kindly to us all do not contain info
wherin it is explained how to get 175 watts from a pair.
I figured one would have to use AB2, and an 800 v value for Ea,
and an RL about 5.3k a-a.
Just what conditions allow 560 watts from a sixpack?
If thast's the claimed max output power, then allowing for transformer
losses of
10%, the output power at the anodes at clipping would be 616 watts.
Is this the maximum possible with 40 dB of over drive, ie, max square
wave po?

But since it is possible to get 125 watts ( sine wave, at clipping )
from a pair of EL34,
I guess it would be possible to get 175 watts from 6550.

I prefer the mode of operation mentioned at
http://timeelect.com/images/6550ap3.gif
where Ea = 400v, Eg2 = 310v, and
Po = 40 watts, with only 0.7% thd into a 5 k load,
with plate current for the two tubes
starting at 170mA, and rising to 185mA at clipping.
This means each tube is idling at 34 watts plate dissipation,
and at clipping the input power is 74 watts, and since
output power is 40 watts, efficiency is 54%,
so because the efficiency is over the class A maximum of about 40%,
the test amp is a class AB amp with 5k as the load.
If the rated load was say 8k, po would be less, and perhaps 34 watts,
and the amp would then be class A nearly up to clipping, because
efficiency
woukld be about 45%.
The GE 6550A when used in UL gives about 34 watts of pure class A
into 8k and 53 watts of AB into 5k, as seen in this schematic at
http://www.turneraudio.com.au/htmlwe...0ulabinteg.htm
Notice that I used Ea = 515v.
A picture of the amp is at
http://www.turneraudio.com.au/htmlwe...Integrated.htm
This amp has Sovtek KT88, but it'd do *exactly* the same thing with
EH6550/KT88.

I seem to remeber the KT88 originally had a higher screen rating, which
meant
you could run UL with up to 600v.
Leak made a 60 watt mono amp which used 6550/KT88 which made 65 watts
into 4.5k in UL with 50% UL taps.

From what I know, the only way to relatively safely get more power from
any 6550/KT88
is to use a high Ea between 600v and 800v, and keep Eg2 down at
no more than 440v, and drive it class AB1 into a high value load as I
mentioned in other posts.

One Mr Jute in another thread about 6SL7 and milspec BS rated tubes at
r.a.t.
said he thinks 6550 and KT88 are poor tubes if you want real music, and
my answer to this
generic criticism of his is that KT88/6550 are not inherently bad,
and the sound you get depends how the tubes are used.
To me, using such tubes to get 100 watts or more from a pair
negates what I set out to do.
If I made such power from a such a parsimonius amount of glassware,
I would fail to conform to my idea of measuring well enough
to have any chance at conforming to my standard where the amp both
measures well and sounds quite glorious.

The guitarist who likes folks to feel the chest heave, and see the walls
sway
may well like to do all that with a minimum of tubes, and expensive ones
at that,
but it is a case of false economy, imho.
The distortion he puts up with, and enjoys, ranges up from a percent
at low levels to perhaps 50%.

Is there a difference in an amp sound where you have a pair driven into
overload to make 150 watts sounds any different to a quad of tubes using
a lower B+,
but making the same over driven 150 watts, and with the same
% over drive, ie, the samilar wave form?

Methinks the quad of tubes might last longer than the single pair
flogged harder.

I am of a frame of mind where I would never be attracted to any venue
where
people are trying to make their guitar amps work a bit.
At 17, I was, and the power used by a 3 peice band and singer maybe only
ever totalled
300 watts, for a typical large local community hall.
They often used the same one big amp, and nothing was driven much into
clipping.
But now power is cheaper than ever before, and bands tend to
try to headbang their way through the night, and the sound levels are 20
dB over where
they were when I was 17.
The musos keep the audiologists in work.
I was strollin down town here the other night, and 4 young turks between
16 and 18
all drressed in black with chains were strivin to entertain 100 strong
crowd
with their rumblings and snortings, and dismally they showed not any
talent to be able to sing or play a tune. But they could be heard
several blocks away.
They had so much gear, so much power, so much volume, so much
"attitude",
and nothing else. Its a shame that most who start like this will be deaf

and poor by the time they realise they have to learn to
play, and learn music, and how to sing, before they would ever get the
break that would give them a decent income.

I am far more concerned about the sound of the first 5 watts.

So, are the russian cathodes fragile? do they "go soft"
sooner than the GE us made cathodes?

Where is the evidence that russian grids and screens can't take as much
dissipation
compared to the nos us made tubes?

What is causing the alegedly inferior russian tubes to wilt under the
pressure
which the GE tubes are supposed to be able to take?

Patrick Turner.








Specialists in Live Sound FOH Engineering,
Music & Studio Production,
Vintage Instruments, and Tube Amplifiers


  #88   Report Post  
kyser
 
Posts: n/a
Default

"James Angelo Ruggieri, P.E." wrote in message
news:mLH_b.1328$Ri6.387@lakeread04...

I'm uncertain if the Marshall designer(s) intended the distortion

characteristics inherent in their amps - or if it was an unintended
consequence, and the design was driven by economics. I suspect the latter -
given the period of time the general design was developed.

AFAIK, the intention of Jim Marshall, and Ken Bran (the designer) in early
1962 was to build a more powerful version of the original Fender Bassman
amp, given both the high price of imported US gear in the UK at the time,
and the concurrent demand by local groups (eg Clapton, Beck, Pete Townshend)
for louder amplification than the existing VOX AC30s, Selmers etc.

Mimicking Fender, they initially chose 5880s and 6L6s for the output tubes,
then KT66s (which gave more power and distinctive distortion) from January
1964 to December 1965 as the US tubes became hard to get) , and finally the
cheaper and far more available EL34s from early 1966, as the supply of KT66s
also dried up.

The amp (soon designated the JTM45) was an immediate success when demo'ed in
Marshall's London music shop, and achieved instant fame and fortune when
used (and overdriven with a Gibson Les Paul) by Clapton on the John Mayall
Bluesbreakers "Beano" album.

The rest is history .....


  #89   Report Post  
Patrick Turner
 
Posts: n/a
Default



"James Angelo Ruggieri, P.E." wrote:

and the price of GE6550A has gone far too higgh to be worth buying,
at over US $400 for a matched quad, ( which in my experience
means little, because they don't stay matched ).

And further - "matched" on a production jig often does not mean "matched"
in your amp!


I might add that matched does not mean matched for
Gm right across the operation range.
This means that in an AB amp, which most PP amps are,
the there is quite a bit of difference in the transfer curve
for the top half of the wave compared with the bottom half, since
each tube only does its own half of the wave.
The result is lots of 2H in PP in a PP amp.
Musos should really like this trait with unmatched tubes.

But purist hi-fi ppl might find that the thd of the PP amps they own could have
up to 12 dB less thd if only the tubes were matched for Gm, and not
just for a given bias current for the same grid bias voltage.

The use of adjustable signal drive to the output grids allows an owner to
reduce 2H distortion in PP amps to a minimum if he wishes.
Many PP amps, even class A types, where the maximum of cancelling of
2H distortion occurs, could have their thd further reduced by deliberately
trimming the drive voltages to the PP grids.
Unfortunately, a CRO and distortion analyser is needed to do this, and when
tubes are
renewed, the old setting is wrong, and the thd may be worse.
So equal drive voltages to each op grid is what most folks settle for.
But in fact, users of stereo amps may find that
one channel makes 3 times the thd of the other.
I guess that providing thd is below 0.2 % at 10 watts no matter
what the lack of matching is, then the music isn't spoiled.
Trimming is sometimes hard to do; it is in the Quad II amp.
In a pair of these I serviced this week, thd at 5 watts was able to be reduced
about 10 dB max by simply swapping the EF86 and KT66
around for lowest thd.
Amps with an LTP driver stage are easier to deal with.

Patrick Turner.



--
JAMES RUGGIERI
"Patrick Turner" wrote in message
...

Look, NONE of the import 6550's have what GE did to theirs. After all,

THEY raised the
standards for what was commonly thought of as a 6550 here in the states.

The import
companies have THEIR *Versions* of what they THINK a 6550 should be.

Published families of curves for each should represent EACH of these

6550's, and SHOW
exactly what the electrical differences ARE!!!!

There is this mistaken notion that all 6550's SHOULD *BE* the same!!!!!!


(snip some interesting info about "polished turds", et all)

I did a search on the GE6550A.
It appears that the 16 pcs I bought in 1996 are GE6550A, the good sort of

tube
you are raving about.

I looked at

http://www.tubeworld.com/6550.html

and the price of GE6550A has gone far too higgh to be worth buying,
at over US $400 for a matched quad, ( which in my experience
means little, because they don't stay matched ).

I couldn't place my hands on the spec sheets for the GE6550A,
to compare it with other versions to confirm your claims
about these tubes superior ratings.

perahps you could be so kind as to post to the group the
list of maximum design ratings of the GE6550A,
and others that you regard as inferior.

Patrick Turner.


  #90   Report Post  
James Angelo Ruggieri, P.E.
 
Posts: n/a
Default

Thanks for the background and history!


--
JAMES RUGGIERI
"kyser" wrote in message
...
"James Angelo Ruggieri, P.E." wrote in message
news:mLH_b.1328$Ri6.387@lakeread04...

I'm uncertain if the Marshall designer(s) intended the distortion

characteristics inherent in their amps - or if it was an unintended
consequence, and the design was driven by economics. I suspect the

latter -
given the period of time the general design was developed.

AFAIK, the intention of Jim Marshall, and Ken Bran (the designer) in early
1962 was to build a more powerful version of the original Fender Bassman
amp, given both the high price of imported US gear in the UK at the time,
and the concurrent demand by local groups (eg Clapton, Beck, Pete

Townshend)
for louder amplification than the existing VOX AC30s, Selmers etc.

Mimicking Fender, they initially chose 5880s and 6L6s for the output

tubes,
then KT66s (which gave more power and distinctive distortion) from January
1964 to December 1965 as the US tubes became hard to get) , and finally

the
cheaper and far more available EL34s from early 1966, as the supply of

KT66s
also dried up.

The amp (soon designated the JTM45) was an immediate success when demo'ed

in
Marshall's London music shop, and achieved instant fame and fortune when
used (and overdriven with a Gibson Les Paul) by Clapton on the John Mayall
Bluesbreakers "Beano" album.

The rest is history .....






  #91   Report Post  
James Angelo Ruggieri, P.E.
 
Posts: n/a
Default

Where is the evidence that russian grids and screens can't take as much dissipation
compared to the nos us made tubes?

What is causing the alegedly inferior russian tubes to wilt under the pressure
which the GE tubes are supposed to be able to take?

Doesn't seem to be any real evidence






--
JAMES RUGGIERI
"Patrick Turner" wrote in message ...

Rich Koerner wrote:

Miles O'Neal wrote:
Can we even *get* a set of curves???????????


Coming up!!!!!

http://timeelect.com/images/6550ap1.gif
http://timeelect.com/images/6550ap2.gif
http://timeelect.com/images/6550ap3.gif
http://timeelect.com/images/6550ap4.gif
http://timeelect.com/images/6550ap5.gif
http://timeelect.com/images/6550ap6.gif
http://timeelect.com/images/6550ap7.gif
http://timeelect.com/images/6550ap8.gif

Regards,

Rich Koerner,
Time Electronics.
http://www.timeelect.com

Thanks for the set of curves.
The only one which wouldn't dowload properly was no 8.
They refresh my memory, and I must say there is nothing particularly
new to learn that I can tell from the last time I saw these specs.

I also cannot see that the specs convey any greater ability when compared to
the EH6550 that the russians make.

A word about the russian 6550.

There seem to have been 4 versions of the 6550 coming from russia.
there was the Sovtek red lettered 6550, with parallel glass bottle, similar in shape
to the GE 6550.
Then there was the Sovtek KT88, with a small coke bottle shape,
and then the EH6550, and EHKT88, with a larger coke bottle shape,
similar to MOV KT88.
These last three appear to have exactly the same looking electrode
structure within, and all the samples I have measured at random
had the same Ra, Gm and U.
The Gm is slightly less than GE, and Ra slightly higher.
The engineer at EH said they have altered the tube a little,
and apparently the grid is slightly larger dia, which explains the
lower Gm and higher Ra.
It makes mass production easier.
But he refused to answer my questions as to why there seem to be
the same internals to tubes labelled 6550, and KT88.
Methinks it because of modern marketing, where
they sell more output tubes if they have all the types available, and since
the KT88 is so close to 6550, then they might as well use the same rationalised
electrode structure, because users will never figure out why this is so, and not
care about any difference between the old KT88and 6550 which may have been in favour of either.

That is how I see the situation with russian 6550/KT88.
I have never used or compared Svetlana 6550/KT88 myself,
but I did supply a pair of Svet 6550 in a mono Leak 60
to a guy who has used as a foldback amp without any trouble for the last 6 years.

I could be wrong about EH, since I have never toured the factory daily
for a week or two recently.

I have serviced amps using Sovtek KT88 which are now 5 years
old, and used daily for a few hours.
These are idling at about 400v x 55 mA in Quad II very modified amps,
and running in triode.
When I measured the tubes this week during their latest service,
the maximum power level had not detectably moved downwards,
and the gettering still appears as bright as it should be after 5 yrs,
and there is little grid current at idle.
I think they are ageing just as well or better than the GE tubes I also have
used and witnessed.

The curves you have tendered so kindly to us all do not contain info
wherin it is explained how to get 175 watts from a pair.
I figured one would have to use AB2, and an 800 v value for Ea,
and an RL about 5.3k a-a.
Just what conditions allow 560 watts from a sixpack?
If thast's the claimed max output power, then allowing for transformer losses of
10%, the output power at the anodes at clipping would be 616 watts.
Is this the maximum possible with 40 dB of over drive, ie, max square wave po?

But since it is possible to get 125 watts ( sine wave, at clipping ) from a pair of EL34,
I guess it would be possible to get 175 watts from 6550.

I prefer the mode of operation mentioned at
http://timeelect.com/images/6550ap3.gif
where Ea = 400v, Eg2 = 310v, and
Po = 40 watts, with only 0.7% thd into a 5 k load,
with plate current for the two tubes
starting at 170mA, and rising to 185mA at clipping.
This means each tube is idling at 34 watts plate dissipation,
and at clipping the input power is 74 watts, and since
output power is 40 watts, efficiency is 54%,
so because the efficiency is over the class A maximum of about 40%,
the test amp is a class AB amp with 5k as the load.
If the rated load was say 8k, po would be less, and perhaps 34 watts,
and the amp would then be class A nearly up to clipping, because efficiency
woukld be about 45%.
The GE 6550A when used in UL gives about 34 watts of pure class A
into 8k and 53 watts of AB into 5k, as seen in this schematic at
http://www.turneraudio.com.au/htmlwe...0ulabinteg.htm
Notice that I used Ea = 515v.
A picture of the amp is at
http://www.turneraudio.com.au/htmlwe...Integrated.htm
This amp has Sovtek KT88, but it'd do *exactly* the same thing with EH6550/KT88.

I seem to remeber the KT88 originally had a higher screen rating, which meant
you could run UL with up to 600v.
Leak made a 60 watt mono amp which used 6550/KT88 which made 65 watts
into 4.5k in UL with 50% UL taps.

From what I know, the only way to relatively safely get more power from any 6550/KT88
is to use a high Ea between 600v and 800v, and keep Eg2 down at
no more than 440v, and drive it class AB1 into a high value load as I mentioned in other posts.

One Mr Jute in another thread about 6SL7 and milspec BS rated tubes at r.a.t.
said he thinks 6550 and KT88 are poor tubes if you want real music, and my answer to this
generic criticism of his is that KT88/6550 are not inherently bad,
and the sound you get depends how the tubes are used.
To me, using such tubes to get 100 watts or more from a pair
negates what I set out to do.
If I made such power from a such a parsimonius amount of glassware,
I would fail to conform to my idea of measuring well enough
to have any chance at conforming to my standard where the amp both measures well and sounds quite glorious.

The guitarist who likes folks to feel the chest heave, and see the walls sway
may well like to do all that with a minimum of tubes, and expensive ones at that,
but it is a case of false economy, imho.
The distortion he puts up with, and enjoys, ranges up from a percent
at low levels to perhaps 50%.

Is there a difference in an amp sound where you have a pair driven into
overload to make 150 watts sounds any different to a quad of tubes using a lower B+,
but making the same over driven 150 watts, and with the same
% over drive, ie, the samilar wave form?

Methinks the quad of tubes might last longer than the single pair flogged harder.

I am of a frame of mind where I would never be attracted to any venue where
people are trying to make their guitar amps work a bit.
At 17, I was, and the power used by a 3 peice band and singer maybe only ever totalled
300 watts, for a typical large local community hall.
They often used the same one big amp, and nothing was driven much into clipping.
But now power is cheaper than ever before, and bands tend to
try to headbang their way through the night, and the sound levels are 20 dB over where
they were when I was 17.
The musos keep the audiologists in work.
I was strollin down town here the other night, and 4 young turks between 16 and 18
all drressed in black with chains were strivin to entertain 100 strong crowd
with their rumblings and snortings, and dismally they showed not any talent to be able to sing or play a tune. But they could be heard several blocks away.
They had so much gear, so much power, so much volume, so much "attitude",
and nothing else. Its a shame that most who start like this will be deaf
and poor by the time they realise they have to learn to
play, and learn music, and how to sing, before they would ever get the
break that would give them a decent income.

I am far more concerned about the sound of the first 5 watts.

So, are the russian cathodes fragile? do they "go soft"
sooner than the GE us made cathodes?

Where is the evidence that russian grids and screens can't take as much dissipation
compared to the nos us made tubes?

What is causing the alegedly inferior russian tubes to wilt under the pressure
which the GE tubes are supposed to be able to take?

Patrick Turner.







Specialists in Live Sound FOH Engineering,
Music & Studio Production,
Vintage Instruments, and Tube Amplifiers

  #92   Report Post  
James Angelo Ruggieri, P.E.
 
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And still yet further - this matching issue seems to be all the more fluff
in the cadence arena - where distortion is embraced with the utmost
affection



--
JAMES RUGGIERI
"Patrick Turner" wrote in message
...


"James Angelo Ruggieri, P.E." wrote:

and the price of GE6550A has gone far too higgh to be worth buying,
at over US $400 for a matched quad, ( which in my experience
means little, because they don't stay matched ).

And further - "matched" on a production jig often does not mean

"matched"
in your amp!


I might add that matched does not mean matched for
Gm right across the operation range.
This means that in an AB amp, which most PP amps are,
the there is quite a bit of difference in the transfer curve
for the top half of the wave compared with the bottom half, since
each tube only does its own half of the wave.
The result is lots of 2H in PP in a PP amp.
Musos should really like this trait with unmatched tubes.

But purist hi-fi ppl might find that the thd of the PP amps they own could

have
up to 12 dB less thd if only the tubes were matched for Gm, and not
just for a given bias current for the same grid bias voltage.

The use of adjustable signal drive to the output grids allows an owner to
reduce 2H distortion in PP amps to a minimum if he wishes.
Many PP amps, even class A types, where the maximum of cancelling of
2H distortion occurs, could have their thd further reduced by deliberately
trimming the drive voltages to the PP grids.
Unfortunately, a CRO and distortion analyser is needed to do this, and

when
tubes are
renewed, the old setting is wrong, and the thd may be worse.
So equal drive voltages to each op grid is what most folks settle for.
But in fact, users of stereo amps may find that
one channel makes 3 times the thd of the other.
I guess that providing thd is below 0.2 % at 10 watts no matter
what the lack of matching is, then the music isn't spoiled.
Trimming is sometimes hard to do; it is in the Quad II amp.
In a pair of these I serviced this week, thd at 5 watts was able to be

reduced
about 10 dB max by simply swapping the EF86 and KT66
around for lowest thd.
Amps with an LTP driver stage are easier to deal with.

Patrick Turner.



--
JAMES RUGGIERI
"Patrick Turner" wrote in message
...

Look, NONE of the import 6550's have what GE did to theirs. After

all,
THEY raised the
standards for what was commonly thought of as a 6550 here in the

states.
The import
companies have THEIR *Versions* of what they THINK a 6550 should be.

Published families of curves for each should represent EACH of these

6550's, and SHOW
exactly what the electrical differences ARE!!!!

There is this mistaken notion that all 6550's SHOULD *BE* the

same!!!!!!

(snip some interesting info about "polished turds", et all)

I did a search on the GE6550A.
It appears that the 16 pcs I bought in 1996 are GE6550A, the good sort

of
tube
you are raving about.

I looked at

http://www.tubeworld.com/6550.html

and the price of GE6550A has gone far too higgh to be worth buying,
at over US $400 for a matched quad, ( which in my experience
means little, because they don't stay matched ).

I couldn't place my hands on the spec sheets for the GE6550A,
to compare it with other versions to confirm your claims
about these tubes superior ratings.

perahps you could be so kind as to post to the group the
list of maximum design ratings of the GE6550A,
and others that you regard as inferior.

Patrick Turner.




  #93   Report Post  
RonSonic
 
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On Tue, 24 Feb 2004 03:30:29 -0500, Rich Koerner wrote:

Thank You Miles!!!!!!!!!!!!!!!!!!!!!!!!!!!




Miles O'Neal wrote:

snip to get to the important stuff


NO. BY DEFINITION (yes, I am shouting
in hopes it will get your attention)



Yeah, You have to do that sometimes.

Then there is the 50 gallon drum I keep in the back yard with a 2x4 soaking in it 24/7.

That's there so when I have to smack someone's head, to get their brain cells jump
started, I don't break the 2x4.


Ahh, the Patented Koerner Klue-Stick (tm).

Ron

  #94   Report Post  
Miles O'Neal
 
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On Tue, 24 Feb 2004 17:42:34 +1100, Patrick Turner wrote:


RCA disagres with you; it's not just me.


I suggest you take a peak at RDH4.


I spend quite a lot of time in Radiotron,
thanks very much.

NO. BY DEFINITION (yes, I am shouting in hopes it will get your
attention)
am amp is biased for a given operating class under a certain set of
conditions. If you bias it as Class A for a certain set of conditions
(which certainly includes the load), then within those conditions, it is
Class A. If any of the conditions change, then you have to refigure
things for that set of conditions. And if it comes up Class AB, then it
*is* Class AB. Not "Class A except..."


I agree with you, no need to shout to get my attention. You repeated what
I said.


It's not at all what you said.

A given amp is one thing or the other.
It's Class A, or it's Class AB, or
whatever class you design it for.

But you have consistently said it's
Class A until this point, then it's
Class AB.

Those are *not* the same things.

I hadn't noticed the cross-posting,
or I'd have had a better idea where
you are coming from, and not gone
into some of the things the way I
did, as our worlds don't overlap
as much as some folks think.


There is a transition from 360 d to less than 360, which means it goes
from class A to AB.... its not a sudden transition, especially in triode
PP amps.....


That's why I got frustrated enough to
shout. You really don't seem to be
listening.

I explicitly stated that a Class AB
amp operates with its tubes conducting
360 degrees until the signal reaches a
certain point. But it's *still* a Class
AB amp, even at those low signal levels.

You could speak of it as "operating in
a Class A manner" or something. But it's
*not* Class A up to some point. By
definition. Neither you nor I get to
change those definitions. Not unless
we achieve a much higher level of
importance in the EE world. 8^)

Class of operation is not what the amp is doing at any given moment,
which is how you are treating it. This is a common misconception, and
we've beaten it to death in the past.


Oh.
Well, I don't plan to convert all the ppl all the time. I know class A
operation when I see it, and class AB operation.


But the behavior at low signal level is
not the class of operation!!!!!!!!

You seem to be defining the class of operation
by the behavior you see *at a given moment*,
when it's properly defined by the worst (or best,
depending on your viewpoint 8^) case scenario,
by what it does at the edge of its parameters.

....
Again, so what? The Class of operation is not defined by total current
consumption. It's defined by what goes on within the individual tubes,
considering the system as a whole.


I have described what I know to be class A. Its when each tube in a PP
circuit has less than 5% thd in its signal *current*.

Once 5% is exceeded, usually its then running class AB.


This is a wonderful theory, and probably helps
you do all sorts of cool stuff. But it's not
the way class of operation is defined, so it's
horrible communication.

If the wave forms of the cathode currents are examined its plain to
see that in a class A amp, each output tube has quite a lot of 2H
distortion current, but not actual complete current cut off.


I'm not sure why this is relevant...


Its *very relevant*.


Feel free to explain. But don't forget to
tie it into the accepted definitions, OK?


The operating classes have to be defined as cutoff before clipping
occurs. Otherwise they make no sense.


Before cut off, its class A.
After cut off, and before clipping, its class AB, simple.


You keep repeating this in various forms, but
*it's still wrong*.

If it can go into cutoff before clipping
within the design parameters of the amp,
it's Class AB, *period*. The fact that
it behaves as if it were Class A up until
that point is irrelevant.

A spy may operate as if s/he is a loyal
citizen. But s/he's still a spy. S/he's
not a loyal citizen between the times
s/he's reporting home. S/he's only a loyal
citizen if s/he *never* reports back to
the foreign government. Applying your
definitions, s/he's a loyal citizen
most of the time, because s/he isn't
actually sending reports to the foreign
power at that moment.

If the amp is set up for class AB, the AB power max is about 21 watts
of which 5 could be class A, and the remaining 16 is B, because after
5 watts, the tubes start to cut off during the cycle. Connect a CRO to
a cathode resistor, and you will see what happens.


There you go again. Basic electronics theory. An amp is biased for 1,
and only 1, class of operation under its operating parameters. It may
*act* the same as a Class A amp up until a certain point, but it either
*is* or *is not* Class A. If it exhibits the characteristics of Class
AB at any point, then it *is* Class AB. That's how things are
*defined*.


I can't win.


Not if you keep trying to make up the
rules as you go, no, you can't!

Look...

I don't think the operating class definitions
are that useful in the real world. The way
you think is the way I would *like* to think.
But it's technically invalid.

So as I said, feel free to use some other
terminology. "Operates like Class A until
cutoff" or something. Otherwise you just
perpetuate the confusion.
....

Nope. The Fender Champ is still a
hugely popular amp. SE Gibson Skylarks and Kalamazoos are still used a
lot.
Check out the AX84 site. Note the
UniValve and BiValve. As I said,
SE amps are (re)gaining popularity
for a variety of reasons.


I have yet to service an SE muso amp made recently.


That's fine. The more recent ones haven't
needed much service, by all accounts. And
they don't tend to get as much abuse as the
big amps, since they're more suited to home
and studio use, or very small venues. But
they're around, and growing.

I don't see much in the way of triode-based
stereo gear, but that doesn't change the fact
that it's there, popular, and wonderful at
what it does.

OTOH, I mostly work on smaller amps (30W and
under), and about half the amps I see are SE!


The SE amp is a gutless wonder to many musos.


Irrelevant to this discussion.


Nope, because musos like to have enough power, and PP is the cheapest
easiest way to power.


See above. Not everything is about raw
power. Your bias (sic) is showing!

....
There is no measurable distortion due to the diodes being in the circuit.
The reverse diode currents are extremely small. The overload character of
the amp with a speaker connected shows that the clipped wave form has a
peak voltage value less than the value of the supply voltage.
The diodes *only* conduct when the anode peak voltage swing exceeds the
value of the plate supply, ie, when an anode voltage goes *negative*,
which afaik, never occurs when a load is connected and when over driven to
the point where
the output wave is basically a square wave.


I'll look into that some more. Thanks.


....
The only way to fry an amp is to have too much current and voltage across
the tubes, and I have never ever seen any tubes come to grief when
accidentally used with no load, although I have seen arcs start from the
high voltages generated, which should be limited..


Fried sockets, fried OTs, which can lead to
fried tubes. I *have* seen these, and heard
of lots more. But the amp dies whether the
tubes die or not.
....
I know several musos who have me service all their gear. I ahve never had
one with trouble from a shorted output, or an open output.
Tube amps normally cope with the temporary abuse you speak of.


Most of them do, most of the time.
It's still not a good idea.

The only amps I've seen die from shorted
outputs were SS amps. But it's suboptimal
for tube amps as well. Just not as bad
as an open. I'm sure that running
a tube amp flat out into a short for a
prolonged period would eat the tubes.
But I have seen amps die almost instantly
from an open, esp. when being run hard.

All my amps can be used with or without a load, no worries. accidental
signals taken up to clipping with no load does *zero* damage.


Good for you. Put diodes in all your plate circuits, or just run them
all at very low power?


With a load, the peak voltage anode swing is always less than the value of
the supply
voltage.
Diodes do not limit maximum power in any way. With diodes connected, there
is no measurable increase in thd!


There are other forms of distortion... 8^/
Perhaps they don't matter as much in your
world, but they do have an impact in the
guitar amp world.

....
I think drag racing lacks something.
The cars can't go round corners.
Its like body building, its all vanity. Ever see a body builder win a 1
mile race?


It is what it is. [shrug]

And a guitar amp is what it is, and a
stereo hifi amp is what it is. Lugging
a 6 tube head around would be bad enough.
I can't imagine lugging a 12x6550 head
around.

I don't have my newer RCA handy. How
much heater current does that puppy pull?


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  #95   Report Post  
Miles O'Neal
 
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On Tue, 24 Feb 2004 09:06:24 -0500, James Angelo Ruggieri, P.E. wrote:

Where is the evidence that russian grids and screens can't take as much
dissipation compared to the nos us made tubes?

What is causing the alegedly inferior russian tubes to wilt under the
pressure which the GE tubes are supposed to be able to take?

Doesn't seem to be any real evidence


Did you even read what Rich said
earlier? The GE6550A was engineered
to be much more robust than the 6550
(note lack of "A" suffix). Just as
the 6L6GC is much more robust than a
6L6, 6L6G, or 6L6GB.

I've yet to hear of anyone claiming
to replicate the 6550A. They all just
say (AFAICT) 6550. I have owned several
amps that needed 6L6GCs If you dropped
a 6L6 or 6L6GB in my Peavey Heritage
(130W from four tubes, running either
550 or 575V on the plates, I forget
which), how long do you think they
would last?

I suppose it's possible that there
are some, somewhere, that could take
it, but that's hardly the norm.


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  #96   Report Post  
James Angelo Ruggieri, P.E.
 
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Did you even read what Rich said
earlier? The GE6550A was engineered
to be much more robust than the 6550
(note lack of "A" suffix). Just as
the 6L6GC is much more robust than a
6L6, 6L6G, or 6L6GB


Yeah - I read what everybody had to say. What does "more robust" mean and
how was this determined. Also, how does this assertion map to the Russian
tubes? Everyone I speak to, and personal experience shows the Russian tubes
to be as good if not better than the GE's. Now if you have something
specific in mind, then identify what the shortcomings are in these "foreign"
tubes.

--
JAMES RUGGIERI
"Miles O'Neal" wrote in message
news
On Tue, 24 Feb 2004 09:06:24 -0500, James Angelo Ruggieri, P.E. wrote:

Where is the evidence that russian grids and screens can't take as much
dissipation compared to the nos us made tubes?

What is causing the alegedly inferior russian tubes to wilt under the
pressure which the GE tubes are supposed to be able to take?

Doesn't seem to be any real evidence


Did you even read what Rich said
earlier? The GE6550A was engineered
to be much more robust than the 6550
(note lack of "A" suffix). Just as
the 6L6GC is much more robust than a
6L6, 6L6G, or 6L6GB.

I've yet to hear of anyone claiming
to replicate the 6550A. They all just
say (AFAICT) 6550. I have owned several
amps that needed 6L6GCs If you dropped
a 6L6 or 6L6GB in my Peavey Heritage
(130W from four tubes, running either
550 or 575V on the plates, I forget
which), how long do you think they
would last?

I suppose it's possible that there
are some, somewhere, that could take
it, but that's hardly the norm.


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  #97   Report Post  
Peter Völpel
 
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Patrick Turner schrieb:

I have described what I know to be class A.
Its when each tube in a PP circuit has less than 5% thd in its signal *current*.

Once 5% is exceeded, usually its then running class AB.


An amplifier is class A when it is biased for class A
and always conducts therefore 360 degrees.
There is no level where it transits to class AB.
An amplifier biased for AB is still no class A, even the
tubes conduct 360 degrees up to a certain level.

Peter
  #98   Report Post  
James Angelo Ruggieri, P.E.
 
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Design meets luck,
and a star is born.

Aye - well said - as in most accomplishments

--
JAMES RUGGIERI
"Miles O'Neal" wrote in message
news
On Tue, 24 Feb 2004 23:43:19 +1000, kyser wrote:

"James Angelo Ruggieri, P.E." wrote in message
news:mLH_b.1328$Ri6.387@lakeread04...

I'm uncertain if the Marshall designer(s) intended the distortion

characteristics inherent in their amps - or if it was an unintended
consequence, and the design was driven by economics. I suspect the

latter
- given the period of time the general design was developed.

AFAIK, the intention of Jim Marshall, and Ken Bran (the designer) in

early
1962 was to build a more powerful version of the original Fender Bassman
amp...


Right.

By all accounts, Mr. Fender didn't originally
plan for distorted sounds. But they took off,
and he grudgingly accepted that. (Many of his
engineers did not, and after Leo left the company,
they drastically cleaned up the sound, annoying
many, many customers).

Jim Marshall, OTOH, wanted to duplicate the Bassman
sound, then listened to the musicians, some of whom
wanted distortion and some of whom didn't. So he
was intentionally including some.

But some of the sound *did* come from the parts
available in the price range. Design meets luck,
and a star is born.


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  #99   Report Post  
Miles O'Neal
 
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I'll have to reply to Rich and Patrick
here, since the original posts haven't
showed up...

JAMES RUGGIERI
"Patrick Turner" wrote in message ...

Rich Koerner wrote:

Miles O'Neal wrote:
Can we even *get* a set of curves???????????


Coming up!!!!!

http://timeelect.com/images/6550ap1.gif

No, Rich. I meant for the EH and other
current production tubes!


The curves you have tendered so kindly to us all do not contain info
wherin it is explained how to get 175 watts from a pair.

....
But since it is possible to get 125 watts ( sine wave, at clipping ) from a pair of EL34,
I guess it would be possible to get 175 watts from 6550.

I'm with you - this would make me a wee bit nervous.
But it makes sense.


....
One Mr Jute in another thread about 6SL7 and milspec BS rated tubes at r.a.t.
said he thinks 6550 and KT88 are poor tubes if you want real music, and my answer to this
generic criticism of his is that KT88/6550 are not inherently bad,
and the sound you get depends how the tubes are used.

Most tubes can sound good in the right
application. Some are more robust than
others.

I don't think Mr. Jute has many followers
in AGA. 8^)

...
The guitarist who likes folks to feel the chest heave, and see the walls sway
may well like to do all that with a minimum of tubes, and expensive ones at that,
but it is a case of false economy, imho.
The distortion he puts up with, and enjoys, ranges up from a percent
at low levels to perhaps 50%.

If it sounds right, and it feels
right, and the guitarist can afford
it, who is to say it's a false
economy? (Although at some point,
the guitarist had better find
someone to start producing 6550As
again. 8^)

Is there a difference in an amp sound where you have a pair driven into
overload to make 150 watts sounds any different to a quad of tubes using a lower B+,
but making the same over driven 150 watts, and with the same
% over drive, ie, the samilar wave form?

Normally, yes, because you're operating in a different
portion of the tube's range.

I can get the same power from a 6BQ5 at 250V
or 300V. At 300V, I can get incredible clean
tones, but it's harder to get pleasing musical
distortion (I know, an oxymoron in the hifi
world). At 250V, it's easy to get the distortion
tones I want, but the clean isn't as nice.

Methinks the quad of tubes might last longer than the single pair
flogged harder.

Undoubtedly. But for a gigging musician, there's
the minor problem of carrying the amp around,
nevermind having to keep spare tubes.

I am of a frame of mind where I would never be attracted to any venue where
people are trying to make their guitar amps work a bit.

That's fine, but a lot of folks are!


I am far more concerned about the sound of the first 5 watts.

Understandable. But that won't go very far with
a bass amp on stage, esp. with a drummer!

-Miles


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  #100   Report Post  
Miles O'Neal
 
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On Tue, 24 Feb 2004 23:43:19 +1000, kyser wrote:

"James Angelo Ruggieri, P.E." wrote in message
news:mLH_b.1328$Ri6.387@lakeread04...

I'm uncertain if the Marshall designer(s) intended the distortion

characteristics inherent in their amps - or if it was an unintended
consequence, and the design was driven by economics. I suspect the latter
- given the period of time the general design was developed.

AFAIK, the intention of Jim Marshall, and Ken Bran (the designer) in early
1962 was to build a more powerful version of the original Fender Bassman
amp...


Right.

By all accounts, Mr. Fender didn't originally
plan for distorted sounds. But they took off,
and he grudgingly accepted that. (Many of his
engineers did not, and after Leo left the company,
they drastically cleaned up the sound, annoying
many, many customers).

Jim Marshall, OTOH, wanted to duplicate the Bassman
sound, then listened to the musicians, some of whom
wanted distortion and some of whom didn't. So he
was intentionally including some.

But some of the sound *did* come from the parts
available in the price range. Design meets luck,
and a star is born.


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  #101   Report Post  
Miles O'Neal
 
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On Wed, 25 Feb 2004 00:53:24 +1100, Patrick Turner wrote:

"James Angelo Ruggieri, P.E." wrote:

and the price of GE6550A has gone far too higgh to be worth buying, at
over US $400 for a matched quad, ( which in my experience means little,
because they don't stay matched ).

And further - "matched" on a production jig often does not mean
"matched" in your amp!


I might add that matched does not mean matched for Gm right across the
operation range.


Buying matched tubes from someone whose
matching techniques you don't know is a
crapshoot.

They need to be matched at the correct
operating parameters, or as close as
possible.

Matches sets on ebay? If I was going to
buy those, I'd want to get several sets
and send them off to Lord Valve or
someone for real matching. (In fact,
I once bought tubes from a friend, who
bought them on enay but didn't like
them in his amp, and sent them off to
LV. The "matching" was way off as
delivered from ebay via my friend...


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  #102   Report Post  
Miles O'Neal
 
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On Tue, 24 Feb 2004 12:09:05 -0500, James Angelo Ruggieri, P.E. wrote:

Did you even read what Rich said
earlier? The GE6550A was engineered
to be much more robust than the 6550
(note lack of "A" suffix). Just as
the 6L6GC is much more robust than a
6L6, 6L6G, or 6L6GB


Yeah - I read what everybody had to say. What does "more robust" mean and
how was this determined. Also, how does this assertion map to the Russian
tubes? Everyone I speak to, and personal experience shows the Russian
tubes to be as good if not better than the GE's. Now if you have
something specific in mind, then identify what the shortcomings are in
these "foreign" tubes.


Rich has detailed it. If not in this discussion,
then before. He also published the GE6550A
specs, for comparison with the old 6550 specs.
I have no experience with either, perosnally.
Nor do I have a problem, per se, with "foreign"
tubes, as you call them. I mostly deal with
smaller amps, and while I love the good NOS
tubes, on a daily basis, I work with JJs,
Sovteks, EH, and a variety of other, modern
tubes - which are all so far from either current
or former so-called "Communist" countries. [1]
I really like some of them. I have amps in
which mothing can touch a Raytheon 6BQ5 of all
things, and another in which I have yet to
find anything that sounds as good as a pair
of EH EL84s. No idea if the EH will hold up
like the Raytheons (they run hard for years and
years), but they're certainly easier to find,
and they sound better in that amp. I have
another SE amp I thought the Raytheon would be
the ticket for, but the JJ rules. And seems
to last. No argument from me.

OTOH, I have heard others besides Rich say that
in amps that work them hard, modern 6550s don't
last anywhere nearly as long as the GE6550As.
This doesn't surprise me (see my 6L6/6L6GC bit.)
They get weak quickly, losing power, the sound
turning to mush. Just like any tube that has
been pushed too hard, too long. The questions
are, what is too hard, and what is too long?

Just curious, what is your experience in this
case? Is it with tubes run really hard under
adverse conditions (SVT or PS400 on stage), or
more lightly under tube-friendly conditions
(low power per tube, air conditioned living
room)? Not flaming, just trying to see what
life on your planet (Mostly Hi Fi?) is like
compared to mine (mostly Guitar Amp).

-Miles

[1] Not looking to start political discussion, I
am just being precise. The USSR was no more
communist than I am a hedgehog. Neither is
China.


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  #103   Report Post  
kyser
 
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"Miles O'Neal" wrote in message
news
By all accounts, Mr. Fender didn't originally plan for distorted sounds.

But they took off, and he grudgingly accepted that.

AFAIK, Leo Fender was a country music aficianado, and despised rock 'n
roll/"distorted" music in any form. While some earlier Fender amps
can/could be overdriven to a degree by "hot" pickups, I doubt it was ever a
specific design intention.

(Many of his engineers did not, and after Leo left the company, they

drastically cleaned up the sound, annoying many, many customers).

If you mean the post-1965 CBS "Silverface" amps, I think the intention of
going ultralinear on the Twin Reverb etc was more a horsepower race (a
claimed 135 watts and, AFAIK nothing like it, from a quad of 6L6s) to
compete with the new loud/clean MusicMan amps for which Leo Fender was a
consultant (having signed an exclusion contract with CBS on leaving FMI).
There were some other circuit changes, but they can be converted back to
"Blackface" specs readily enough.

Jim Marshall, OTOH, wanted to duplicate the Bassman sound, then listened to

the musicians, some of whom wanted distortion and some of whom didn't. So
he was intentionally including some.

It's worth remembering that many of the mid-60s British Beat/R&B groups were
running their VOX AC30s pretty hard and wanted more power ....

But some of the sound *did* come from the parts available in the price

range. Design meets luck, and a star is born.

True, eg a Les Paul, and a JTM45 with KT66s and 2x12" Celestions .... 8^)


  #104   Report Post  
Rich Koerner
 
Posts: n/a
Default



"James Angelo Ruggieri, P.E." wrote:

So you are telling me that you have no basis to conclude these other

tubes
are so bad.


Did I say that? Please read on...


Yes you did by deferring to experts - implying that you did not know. On the
other hand - you could have cited accepted industry documents, references,
or publications --but you did not. Had you offered some reasonable
scientific basis for your opinions - then it was possible you could have
swayed me.

This thread was posted to alt.guitar.amps. Are you also a musician? How

many
different tubes have YOU experimented with in a Marshall 2204? What style

of
guitar do you play? How many different guitar amps do you own? What are

your
tube choices and why?


But it manifested in alt.rec.audio.tubes. Yes, I am a musician, I play the
guitar - however, not as much as I used to. I also don't own as many guitar
amps as I used to, and I'm not familiar with the Marshall 2204 - however, I
suspect it to be similar to the characteristic Marshall line of tube amps
that prevailed in the sixties - a rot gut simple and cheap push pull audio
amplifier with intentionally substantive distortion characteristics when
subject to overdrive.
When selecting tubes for these inherently imprecise devices, I use the
following criteria:

Does the tube fit into its octal socket
Will the tube perform without denigration within the given design parameters
of the amplifier
Are the tube elements loose such as to short out when the amp is subject to
expected shock and vibration



ONLY *FEAR* OF THE *POLISHED TURD*, would bring such a thought to the front of the mind.


I don't care what the data sheets say, I don't care what the curves look

like.
I sometimes can't keep the grid and screen straight in my mind. What I

care
about what they SOUND like in my gear, and how long they will perform.


I also don't care too much what the data sheets say owing to the fact that
the QC and reproducibility of manufacturer among the subject tubes to be
more consistent than the application of being used in inherently and
intentionally imprecise instruments.


And such, breeds such.

It was the existence of the precise vacuum tube devices that brought us to this point in
technology.

The road was paved in vacuum tubes.

Yet this way of thinking in the past, would would make you wonder, if this thinking was in
place in the past, would way be here at the same place in technology.

I think not.





Don't assume that I'm some yahoo just because you don't know me or because

you
have a different perspective on tubes.


I don't know where you got this from - I simply asked you for the basis of
your opinions. But you admit that your basis to be subjective --which is OK

So you are telling me that distortion is desirable and important to

you -
well - isn't distortion (a non-linear characteristic) a feature normally
inherent with poor tubes or poor circuits?


I thought you knew Marshalls, Sun, Fender, Ampeg...


But I do - as explained above. I also know that their desirable qualities
are owed in large measure to their imprecise performance.


They can by no more precise than the individual and the polished turd makes them.

Yet, with the right mind and vacuum tube, precision with repeatability will be found.



I can tell you that it produces a better sounding
midrange distortion in my Marshall and most of my other equipment. I've

tried
many, I've had others swap tubes so I judge them blind. I prefer Mullards

with
a slight preference for the long plates.


Then - you will admit that perhaps your Mullard with the long plate may not
sound so good in another Marshall amp.


Does kind a make you wonder about something, don't it.

Like, why is there not a graph included in the tubes family of curves, that represents the
tubes sonic characteristics.

Hmmmmmmmmmmmmmmmmm...................!!!!!!!!!!!!! !!!!!!!

Kind a makes ya wonder. Don't it!!!!!!!!!

Hmmmmmmmmmmmmm....................!!!!!!!!!!!!!!!! !!!

Can the sonic *window* of an audio vacuum tube be defined!!!!!!!!!!!!!!!!


Is that why NOS GE's cost so much? NOS Tung Sols? Telefunken? Mullard?

Bugle
Boy? Or do you believe that it is just non "experts" that don't know any
better, and we'd all be better off with Sovteks or Chinese?


I guess the answer here is the use of the NOS - indicating scarcity. As you
know the audiophile and music business is the playing ground for some of the
most intense marketing hype and appeal to subjectivity.


Which prevails in BOTH camps of the audio fields!!!!!!!!!!!!!!

And both fall victim to their own Voodoo!!!!!!!!!!!!!!!!!!!




From Monster Cable
to all sorts of nonsense. Of course, antiques typically commands high prices
because they are scarce. The scarcity, together with the subjective hype
will result in increased prices. But, and I'm sure you will agree, that to
say that my grandmother's old Singer sewing machine will perform better than
a newer machine is a bit off - no matter how many self-made tekkies weigh in
on the matter.


My father worked for Singer all his life, and was instrumental for the precision and
quality that is found in that sewing machine.

If as much was mindful thought was put into the making of today's polished turds, there
would be none.

Today, it's those in the peanut gallery, who've become the polished turd huggers who
re-write the past, for their agenda.

It's no different than the global warming debates of the two camps!!!!!



I'd just like to see some scientific data to support the opinions.


Why bother!!!!!!!!!!

With the concepts and attitudes present, having such would be a waste on the garden
slug!!!!!!!!!!

He wouldn't have a clue what to do with them, if he had them.

Besides, it wouldn't change the dialog here in the least, when even the existence of
factual data is already dismissed as meaningless to the issues at hand.

Oh, almost forgot.

The curves are elsewhere in the thread.



Regards,

Rich Koerner,
Time Electronics.
http://www.timeelect.com

Specialists in Live Sound FOH Engineering,
Music & Studio Production,
Vintage Instruments, and Tube Amplifiers
  #105   Report Post  
James Angelo Ruggieri, P.E.
 
Posts: n/a
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Just curious, what is your experience in this
case? Is it with tubes run really hard under
adverse conditions (SVT or PS400 on stage), or
more lightly under tube-friendly conditions
(low power per tube, air conditioned living
room)? Not flaming, just trying to see what
life on your planet (Mostly Hi Fi?) is like
compared to mine (mostly Guitar Amp).

For many years and many years past - I worked at what used to be Guitar Lab
on 48th Street in NYC - and came onboard right after DeMarzio left. I fixed,
modified, and designed/built many tube cadence amps - and also did the same
with many SS amps. The simple tools and techniques I used then, are the same
tools and techniques I use now, although now it is a hobby. We did work for
Manny's, Sam Ashe, We Buy, etc and just about everyone on the block, as well
as most, if not all of the recording studios in the area. Although it has
been many years since, and now I do work on ship electric propulsion and
power distribution systems, I am glad to see that tube technology has not
evolved since those days where I cut my youthful teeth

Not looking to start political discussion, I
am just being precise. The USSR was no more
communist than I am a hedgehog. Neither is
China.

Certainly not anymore



--
JAMES RUGGIERI
"Miles O'Neal" wrote in message
news
On Tue, 24 Feb 2004 12:09:05 -0500, James Angelo Ruggieri, P.E. wrote:

Did you even read what Rich said
earlier? The GE6550A was engineered
to be much more robust than the 6550
(note lack of "A" suffix). Just as
the 6L6GC is much more robust than a
6L6, 6L6G, or 6L6GB


Yeah - I read what everybody had to say. What does "more robust" mean

and
how was this determined. Also, how does this assertion map to the

Russian
tubes? Everyone I speak to, and personal experience shows the Russian
tubes to be as good if not better than the GE's. Now if you have
something specific in mind, then identify what the shortcomings are in
these "foreign" tubes.


Rich has detailed it. If not in this discussion,
then before. He also published the GE6550A
specs, for comparison with the old 6550 specs.
I have no experience with either, perosnally.
Nor do I have a problem, per se, with "foreign"
tubes, as you call them. I mostly deal with
smaller amps, and while I love the good NOS
tubes, on a daily basis, I work with JJs,
Sovteks, EH, and a variety of other, modern
tubes - which are all so far from either current
or former so-called "Communist" countries. [1]
I really like some of them. I have amps in
which mothing can touch a Raytheon 6BQ5 of all
things, and another in which I have yet to
find anything that sounds as good as a pair
of EH EL84s. No idea if the EH will hold up
like the Raytheons (they run hard for years and
years), but they're certainly easier to find,
and they sound better in that amp. I have
another SE amp I thought the Raytheon would be
the ticket for, but the JJ rules. And seems
to last. No argument from me.

OTOH, I have heard others besides Rich say that
in amps that work them hard, modern 6550s don't
last anywhere nearly as long as the GE6550As.
This doesn't surprise me (see my 6L6/6L6GC bit.)
They get weak quickly, losing power, the sound
turning to mush. Just like any tube that has
been pushed too hard, too long. The questions
are, what is too hard, and what is too long?

Just curious, what is your experience in this
case? Is it with tubes run really hard under
adverse conditions (SVT or PS400 on stage), or
more lightly under tube-friendly conditions
(low power per tube, air conditioned living
room)? Not flaming, just trying to see what
life on your planet (Mostly Hi Fi?) is like
compared to mine (mostly Guitar Amp).

-Miles

[1] Not looking to start political discussion, I
am just being precise. The USSR was no more
communist than I am a hedgehog. Neither is
China.


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  #106   Report Post  
dw
 
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Miles O'Neal wrote:

I'll have to reply to Rich and Patrick
here, since the original posts haven't
showed up...

JAMES RUGGIERI
"Patrick Turner" wrote in message ...

Rich Koerner wrote:

Miles O'Neal wrote:
Can we even *get* a set of curves???????????


Coming up!!!!!

http://timeelect.com/images/6550ap1.gif

No, Rich. I meant for the EH and other
current production tubes!




Here's some for the JJ KT88/6550 -

http://www.jj-electronic.sk/tube_kt88.htm

dw

  #107   Report Post  
Jim Anable
 
Posts: n/a
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I simply believe that the prevailing notions being conveyed in this forum to
dismiss Chinese and Soviet Tubes as "junk" or "polished turds" to be
unfounded nonsense - perhaps rooted in either racist or protectionists bias.


You're simply wrong. It's not racist or protectionist bias, it's preference
based on experience. We have ears. We can hear what they sound like. I, for
one, have a tube tester. Why is it that many current tubes come new with low
transconductance? I have OLD tubes that are stronger than the some new Sovtek's
that I have purchased. Do you agree that there is more variation in current
tubes than back in the 50's and 60's?

In either case, an element of ignorance seems to be present.


Most of us don't give a red rat's rump about the technical aspects. We want a
tube that sounds good in our gear and that has a decent life span. If you
cannot understand that, you need to just accept it and move on.

If someone is
going to call something junk - I'd like to know why - and so far, no one has
offered anything scientifically reproducible.


Well, as far as the "scientific" aspect of my personal taste, I have conducted
bliind "taste tests" of preamp tubes (I don't have enough power tubes to make
this test worthwhile, and the bias time would kind of ruin the fun). Somebody
else did the swapping, I did the playing. I consistently picked Mullard tubes
in my Marshall. I don't know of a "scientific" machine that I can plug a tube
in and have it read out whether or not I like it. Nor do I need one. I know
what I like, and that's all that matters. I also know that current production
tubes cannot hold a candle to quality U.S., British and German tubes of the 50's
and 60's when it comes to longevity.

  #108   Report Post  
Fred Gilham
 
Posts: n/a
Default


Peter Völpel writes:

Patrick Turner schrieb:

I have described what I know to be class A.
Its when each tube in a PP circuit has less than 5% thd in its signal *current*.

Once 5% is exceeded, usually its then running class AB.


An amplifier is class A when it is biased for class A
and always conducts therefore 360 degrees.
There is no level where it transits to class AB.
An amplifier biased for AB is still no class A, even the
tubes conduct 360 degrees up to a certain level.


According to the RCA Receiving Tube Manual, the class of an amplifier
is dependent both on the bias *and* the input grid voltage.

"A class A amplifier is an amplifier in which the grid bias and
alternating grid voltages are such that plate current in a specific
tube flows at all times."

So I think Patrick's point is valid. To make an amplifier "pure class
A" you'd have to limit the input voltage so it never drove the tube(s)
into cutoff. On the other hand, a given push-pull amplifier that, for
a given input and bias, has both tubes conducting all the time, is
running in class A mode.

The point is that most class AB amps spend a lot of the time with both
sides of the push-pull circuit conducting on both halves of the audio
waveform. This is "class A" power because it doesn't have the
distorting effects of driving tubes into cutoff. It's the distorting
effects that are of concern because they affect the sound.

--
Fred Gilham
It is also well to note that there are probably not ten hand-grenades
in the entire philosophical community. -- John Lange
  #109   Report Post  
Peter Völpel
 
Posts: n/a
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Fred Gilham wrote:

An amplifier is class A when it is biased for class A
and always conducts therefore 360 degrees.
There is no level where it transits to class AB.
An amplifier biased for AB is still no class A, even the
tubes conduct 360 degrees up to a certain level.


According to the RCA Receiving Tube Manual, the class of an amplifier
is dependent both on the bias *and* the input grid voltage.


right, that what I wrote above, 360 degrees conduction angle=class A


"A class A amplifier is an amplifier in which the grid bias and
alternating grid voltages are such that plate current in a specific
tube flows at all times."


right


So I think Patrick's point is valid. To make an amplifier "pure class
A" you'd have to limit the input voltage so it never drove the tube(s)
into cutoff.


when it is driven into cutoff, there is no 360° conduction angle

a class A amplifier is class A, there is nothing like
"pure class A"

that is what my Telefunken tube manuals explain to me ;-)


On the other hand, a given push-pull amplifier that, for
a given input and bias, has both tubes conducting all the time, is
running in class A mode.


of course it behaves like class A, but could be biased for AB
which then is a class AB amplifier

a class AB amplifier behaves like class A conduction wise on low drive
and like class B on high drive, that is where its name came from...


The point is that most class AB amps spend a lot of the time with both
sides of the push-pull circuit conducting on both halves of the audio
waveform. This is "class A" power because it doesn't have the
distorting effects of driving tubes into cutoff. It's the distorting
effects that are of concern because they affect the sound.


true, any amplifier driven into cutoff or clipping has distortion
effects

Peter
  #110   Report Post  
scottp
 
Posts: n/a
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I agree its what ever works for you.
I like the sound of the GE6550As in
some gear, svetlana 6550B in other
gear. I think the russian tubes are good
and last a long time if ran at there spec.
They don't have the plate dissapation
of the GE6550A or the KT90. But in
the right application the russian stuff
works great.

I think some of the chineese tubes
are good too, like the 6l6gc. The chineese
KT88 has a bad reputation, but I've ran them
with a plate voltage of 450V and 40ma
bias and they seem to run OK there.
They sound really good too to me.

I would certainly not try to run them
in a SVT. I think the KT90 would run
fine in the SVT though. I wonder if
anyone has tried that?

Scott

Miles O'Neal wrote:

On Tue, 24 Feb 2004 12:09:05 -0500, James Angelo Ruggieri, P.E. wrote:



Did you even read what Rich said
earlier? The GE6550A was engineered
to be much more robust than the 6550
(note lack of "A" suffix). Just as
the 6L6GC is much more robust than a
6L6, 6L6G, or 6L6GB


Yeah - I read what everybody had to say. What does "more robust" mean and
how was this determined. Also, how does this assertion map to the Russian
tubes? Everyone I speak to, and personal experience shows the Russian
tubes to be as good if not better than the GE's. Now if you have
something specific in mind, then identify what the shortcomings are in
these "foreign" tubes.



Rich has detailed it. If not in this discussion,
then before. He also published the GE6550A
specs, for comparison with the old 6550 specs.
I have no experience with either, perosnally.
Nor do I have a problem, per se, with "foreign"
tubes, as you call them. I mostly deal with
smaller amps, and while I love the good NOS
tubes, on a daily basis, I work with JJs,
Sovteks, EH, and a variety of other, modern
tubes - which are all so far from either current
or former so-called "Communist" countries. [1]
I really like some of them. I have amps in
which mothing can touch a Raytheon 6BQ5 of all
things, and another in which I have yet to
find anything that sounds as good as a pair
of EH EL84s. No idea if the EH will hold up
like the Raytheons (they run hard for years and
years), but they're certainly easier to find,
and they sound better in that amp. I have
another SE amp I thought the Raytheon would be
the ticket for, but the JJ rules. And seems
to last. No argument from me.

OTOH, I have heard others besides Rich say that
in amps that work them hard, modern 6550s don't
last anywhere nearly as long as the GE6550As.
This doesn't surprise me (see my 6L6/6L6GC bit.)
They get weak quickly, losing power, the sound
turning to mush. Just like any tube that has
been pushed too hard, too long. The questions
are, what is too hard, and what is too long?

Just curious, what is your experience in this
case? Is it with tubes run really hard under
adverse conditions (SVT or PS400 on stage), or
more lightly under tube-friendly conditions
(low power per tube, air conditioned living
room)? Not flaming, just trying to see what
life on your planet (Mostly Hi Fi?) is like
compared to mine (mostly Guitar Amp).

-Miles

[1] Not looking to start political discussion, I
am just being precise. The USSR was no more
communist than I am a hedgehog. Neither is
China.


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  #111   Report Post  
Rich Koerner
 
Posts: n/a
Default



RonSonic wrote:

On Tue, 24 Feb 2004 03:30:29 -0500, Rich Koerner wrote:

Thank You Miles!!!!!!!!!!!!!!!!!!!!!!!!!!!




Miles O'Neal wrote:

snip to get to the important stuff


NO. BY DEFINITION (yes, I am shouting
in hopes it will get your attention)



Yeah, You have to do that sometimes.

Then there is the 50 gallon drum I keep in the back yard with a 2x4 soaking in it 24/7.

That's there so when I have to smack someone's head, to get their brain cells jump
started, I don't break the 2x4.


Ahh, the Patented Koerner Klue-Stick (tm).

Ron



SWEET!!!!!!!!!!!!!!!!!!!!!!!!!!!


Regards,

Rich Koerner,
Time Electronics.
http://www.timeelect.com

Specialists in Live Sound FOH Engineering,
Music & Studio Production,
Vintage Instruments, and Tube Amplifiers
  #112   Report Post  
Steve Eaton
 
Posts: n/a
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"James Angelo Ruggieri, P.E." wrote in message
news:mLH_b.1328$Ri6.387@lakeread04...
Although I have designed and built both HiFi and Cadence devices, I cut

my
teeth on Cadence devices, and I can appreciate and discern the performance
requirements for both. I'm uncertain if the Marshall designer(s) intended
the distortion characteristics inherent in their amps - or if it was an
unintended consequence, and the design was driven by economics. I suspect
the latter - given the period of time the general design was developed.


Well, regarding Marshall amps. I believe that the first ones were
pretty much knock offs of Leo Fenders. (which of couse was likely
a take off on an old Westinhouse circuit or it's like). And the distorted
sound of those old Fenders was well known, so I'd say that it was done on
purpose.
Now I've heard that old Leo never really did understand why people
used his amps past distortion generating levels. So I'd say that for
him it was just a happy little accident. But by the time Jim Marshall
got into the game distortion was already considered a disirable elemnt for
many
players. I figure he probably chose the fender Bassman to base his amp
on because of it's pleasant distortion.



I
love the sound of a Marshall for a guitar - and much prefer that "sound"
than say piping my guitar through a Crown DC 300, for instance. However,

I
would also not pipe my CD player through a Marshall, unless I wanted to
annoy my neighbors.


Good sound (no pun intended) policy in both cases I'd say.




I simply believe that the prevailing notions being conveyed in this forum

to
dismiss Chinese and Soviet Tubes as "junk" or "polished turds" to be
unfounded nonsense -


I pretty much agree although I can tell the difference in sound between
the way different tubes react in my amps, and in most cases, I have to say I
prefer the NOS stuff, whether they be English, American,European or
Japanese. But there are some Chinese tubes that I like very much as well.
Also a few Russian tubes. Even so they usually seem to fall just short of my
old favorite tubes, when I A/B them for preference.

But I wouldn't call the new import stuff junk (maybe the new amps, but I
digress).





perhaps rooted in either racist or protectionists bias.


No, I don't think there is anything more sinister to it than a bit
of nostalgia coupled with the fact that most of us do hear a bit of
difference.

In Rich's case I think he is just parochial when it comes to his Fender
PS400
bass amp and the GE6550, but then his name is on the engineering and that
amp was the testbed for developing the GE6550, so it's understandable.
BTW Rich also puts his deeds where his words are. Last I heard
he and his partners have prototyped what he says is a brand new type
of vacuum tube, hopefully to be marketed.




In either case, an element of ignorance seems to be present. If someone

is
going to call something junk - I'd like to know why - and so far, no one

has
offered anything scientifically reproducible.

Regards
JAMES RUGGIERI


Maybe someone will take you up on that and post the math. As for me,
while I prefer NOS tubes overall, I use a fair number of new imports as
well, and am pretty happy with some of them also.

But someone with more expertise than I have will have to show the
info. I love tube amps, but I am not an amp tech per se, I just bias them
and play them.






--


"Steve Eaton" wrote in message
...

"James Angelo Ruggieri, P.E." wrote in message
news:TBy_b.1221$Ri6.2@lakeread04...
I'll leave the specifics to the "experts."

I have an ear. I can hear the difference in how different tubes

distort.
Distortion characteristics are important to guitar players. Hi-fi

uses
just
want clean, and they don't make the same sorts of demands on the

tubes.

So you are telling me that distortion is desirable and important to

you -

Tell me that you are joking ?


well - isn't distortion (a non-linear characteristic) a feature

normally
inherent with poor tubes or poor circuits?


Wouldn't you characterize, lets say, a Marshall amp an example
of poor circuits? By audio REPRODUCTION enthusiast standards,
I would say so. But the audiophile standards have little currency
as regards the needs and desires of musicians using the distortion to
PRODUCE
music. A different endeavor entirely from listening to music.

No, I wouldn't say that distortion is only to be found using poor tubes.
Any tube will distort if you desire it to. I would call a tube poor if

the
characteristic sound of the distortion it produces is not musical to my
ears.
And I CAN hear both objective and subjective differences of the

distortion
components of different tube types and brands. Some I like better than
others.

Most of my guitar amps use 6L6 type power tubes so I am most familiar
with those. In this case, just for example, every set of Sylvania's that

I
have had sound similar to each other and different from let's say

Sovteks.
And in every case they sound better. But that is not to say that all the
current tubes
are junk. I think that the cheap Shuguang 6L6 sounds very close to
those old Sylvanias

If you are a HiFi enthusiast, I suspect that to you, the idea that the
massive distortion
of relatively unstable circuits running tubes above their design limits,
is a desirable effect may seem odd. But millions of music fans would
disagree
as the distorted guitar amp has been one of the more widely recognized
sounds
used in music for the last 60 years.

I can understand why an audiophile might not like that sound, but I

don't
understand
how an audiophile, who would certainly hear the subtle differences in

the
sounds of tube types and brands when the tube is running clean, could

doubt
that there are even more exagerateded differences that can be heard when

a
tube
is clipping.





What kind off distortion do you
speak of?


Harmonic distortion for the most part I would suspect.




.






  #113   Report Post  
Rich Koerner
 
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Default



Patrick Turner wrote:

WakyAmps wrote:

Patrick Turner wrote in
:



Miles O'Neal wrote:

Patrick Turner responded to WakyAmps, who said:


Actually, it was Miles who said... but I've a few questions of
my own.

[humongous snip]

Not sure we're all speaking the same language here ('least I'm
sure as hell not...)

In my dictionary[1], a push-pull amp biased class B has one
output tube in cutoff when the other is conducting. Class A has
both tubes conducting for the entire waveform. Class AB1 has
each tube conducting for somewhat more than half of each cycle,
though the outputs still alternate between cutoff[2].

I think we'll all agree that an AC-30 runs the bejeezus out of
its outputs. However, please explain to me, for a P-P AB1
biased amp, the difference between the "Class A watts" and the
"Class B watts". I don't think I've ever seen those terms used
in that context before.


Most guitar amps are class AB1 amps.
This means that for say the first 5 watts, both output tubes
operate with low distortion content in their currents,
and are like two single ended tubes but working together to change the
opt primary
voltage in a balanced manner.
Beyond the 5 watt power level, one of the tubes recieves a large enough
negative going grid voltage to cut the current flow right off.
The other tube grid is getting a positive going voltage to turn on the
tube
current much more, and so power is produced by one tube only
during the crests and troughs of the sine wave. Only the zero crossing
part of the sine wave power cycle is where both tubes mutually
contribute power.

So over 5 watts in the above typical amp, the power can be said to be
classB.
But viewed as a whole, during a maximum level sine wave,
the operation is class AB.
AB1 indicates tubes are not driven to draw grid current, AB2 means
the amp is driven hard to make the grids draw grid current.

Once upon a time, nearly all makers used a much lower screen voltage
than today, where the trend is to have both anode and screen supplies
quite high, say both at 450v.
Originally, 6550 and 6L6 and 807 were configured with screens
set at 300v max, and then anode voltages could be much higher.
Even 807 were run with 600v at the anode, and 300v for screens,
and 80 watts class AB2 were available.

The lower the screen voltage, the lower the grid1 bias voltage,
and the lower the AB1 power output ability into a low value RL.
So to get more anode swing, the grid1 is damn well forced to swing
more, and above 0V ie, positively, when it conducts current,
so a cathode follower drive stage is required.

The result is that the screen currents overall tend to stay low, and the
screen dissipation
tends to stay well within the operational ratings, and the tube lives to
a ripe old age,
and it don't die screaming.


Are you saying that an AB1 amp where the outputs conduct for,
say, 80% of the signal has more "class A watts" than an amp
where the outputs conduct for 70% of the signal? The latter, of
course, having more "class B watts"?


Indeed.

Most guitar amps have maybe 5 watts of what is class A power,
and the remaining 55 watts are class B.
That's a total of 60 watts of class AB.


Oops, oops,.... stop right there.

You have forgotten to mention the Fluff Factor, as it relates to all this, amplifier to
amplifier.

You see many do not know, or if they know, believe in the existence of the Fluff Factor.


Or, many times, is not even noticed, like the slight of hand of the magician.


Yeah, each amplifier is actually pull a slight of had act one most experts, and they are
not even aware of it at all.

THAT, is because they are SO caught up in the moment of analysis, speculation, and
theory,... that they totally miss the Fluff Factor.

So what you are going to ask is, what is Fluff, and the Fluff Factor...

OK, coming up.


In the above explanation, on assumes a stable voltage to be in place on two elements of
the tube.

Of which, it is not, and varies amplifier to amplifier.

Thus creating that ever popular problem of, the numbers don't line up exactly right.
Like, for some reason there is the appearance, there are a few missing and unaccounted
free electrons who got lost somewhere.

Where did they go!!!!!!

Well, it have been found that Fluff Factor is directly proportional to the number of
missing free electrons.

Hey, what the hell is a few missing electrons anyway.

But, when the number of missing *In Action* free electrons starts to grow in number, and
no longer can go un-noticed, the Fluff Factor goes through the roof!!!!!!!!!!!!

For Example, take the amplifier supposed for the case in point. Which was used in the
explanation above.

We all sat here nodding our heads in front of the monitors. Right!!!!!

You were so focused on the hands of the magician and things looked like,... Hey, we're in
the REAL world, and everything is cool.

But, if you re-wind the tape, and replay it through another amplifier, you are going to
get a DIFFERENCE.

So, in order to establish this existence of Fluff, and the Fluff Factor, we have to set
some rules, or if you will, a standard for both cases.

The original explanation, and the one to come. Thus, producing the presence of Fluff, and
the resultant, Fluff Factor.

First, the input to output CHARACTERISTICS of the amplifier, which is the basis of the
original explanation, for the support of this explanation of classes of operation of an
output stage, MUST be documented precisely, in EVERY way possible.

Remember, everything about this amplifier is assumed to be IDEAL!!!!!!!!!

But, it isn't.

It isn't IDEAL!!!!!!

So, for the moment, let's make some changes to that original amplifier, so there will NOT
be any assumptions about anything.

The First Thing, we are going to do, is make this the ideal amplifier, by disconnecting
ALL the internal voltage sources. A complete, power supply, disconnect, with all its
branches.

Then, in the place of these disconnects, is attached laboratory grade power supplies,
throughout the amplifier.

One for just the filaments of those output tubes.

One for the bias supply to the control grids of those output tubes.

One for the screen grids of those output tubes.

One for the the anodes of those output tubes.

One for each stage in front of the output stage.

Each is a regulated variable voltage source, with unlimited current availability.

In short, ZERO sag EVERYWHERE.

NOW, let's match the exact voltages found in the original amplifier, and repeat this
again, and compare the differences.

Well, doesn't this change things a bit!!!!!!!!!!!!

I guess you can now SEE a piece of the Fluff now.

You you are SURE as Hell, going to be USING IT, as soon as you take a breath to comment on
this so far.

But there is more yet, to be seen, than the obvious with respect to the anodes of the
output tubes now.

And that, is the the simultaneous impact, that the CHANGE, from sagging power supply has
on both the AC and DC characteristics, changing AC to DC ratio of the output stage,...
Plus, the change of input drive to the output stage from such.

Now, think of ALL those external power supplies, now supplying unlimited energy to the
amplifier system.

Now, compare those input data sheets of both examples, and tell me now, how those amps
line up again.

Did those 6550's meet max specs.

For that matter, how do those output tubes match the curves for the GE-6550A now.

Hey, those curves are from a naked tube with lab supplies on them.

Zero variables present.

Which is not the case with all the case points offered in support of polished turds.

The friend to a Polished Turd is, a sagging power supply!!!!!!!!!!!!!!


What, what did you say!!!!!!!!!!!!!!!!

Oh,... that.

Sorry,.....

Fluff, is the of verbal tap dancing used by the experts to glorify the Polished Turd from
a technical point of view!!!!!!!!!!!!!!!


Huh, what,.... Oh!, the Fluff Factor!!!!!!!

THAT, is the *amount* of *fancy foot* work required to explain those NEW FOUND, missing
Free Electrons, from before, that now appear to now be flowing through those output tubes,
giving higher gain and signal yield then previously.

Oh, what was that question again.

What, What,......??????

Speak up, it's hard to hear ya with everyone else talking at the same time.

Oh, got ya.....

They are called a Fluffer Nutter!!!!!!

Hey guys, simmer down a bit,......

What's a Fluffer Nutter,... is that what ya asked!!!!!!!!!!!!!!!!!!!

OK,.....

Well simply,.......

A Fluffer Nutter, is a nicer term for a former Expert, turned Turd Hugger!!!!!!!



Regards,

Rich Koerner,
Time Electronics.
http://www.timeelect.com

Specialists in Live Sound FOH Engineering,
Music & Studio Production,
Vintage Instruments, and Tube Amplifiers
  #114   Report Post  
Rich Koerner
 
Posts: n/a
Default



Rich Koerner wrote:

Patrick Turner wrote:

WakyAmps wrote:

Patrick Turner wrote in
:



Miles O'Neal wrote:

Patrick Turner responded to WakyAmps, who said:

Actually, it was Miles who said... but I've a few questions of
my own.

[humongous snip]

Not sure we're all speaking the same language here ('least I'm
sure as hell not...)

In my dictionary[1], a push-pull amp biased class B has one
output tube in cutoff when the other is conducting. Class A has
both tubes conducting for the entire waveform. Class AB1 has
each tube conducting for somewhat more than half of each cycle,
though the outputs still alternate between cutoff[2].

I think we'll all agree that an AC-30 runs the bejeezus out of
its outputs. However, please explain to me, for a P-P AB1
biased amp, the difference between the "Class A watts" and the
"Class B watts". I don't think I've ever seen those terms used
in that context before.


Most guitar amps are class AB1 amps.
This means that for say the first 5 watts, both output tubes
operate with low distortion content in their currents,
and are like two single ended tubes but working together to change the
opt primary
voltage in a balanced manner.
Beyond the 5 watt power level, one of the tubes recieves a large enough
negative going grid voltage to cut the current flow right off.
The other tube grid is getting a positive going voltage to turn on the
tube
current much more, and so power is produced by one tube only
during the crests and troughs of the sine wave. Only the zero crossing
part of the sine wave power cycle is where both tubes mutually
contribute power.

So over 5 watts in the above typical amp, the power can be said to be
classB.
But viewed as a whole, during a maximum level sine wave,
the operation is class AB.
AB1 indicates tubes are not driven to draw grid current, AB2 means
the amp is driven hard to make the grids draw grid current.

Once upon a time, nearly all makers used a much lower screen voltage
than today, where the trend is to have both anode and screen supplies
quite high, say both at 450v.
Originally, 6550 and 6L6 and 807 were configured with screens
set at 300v max, and then anode voltages could be much higher.
Even 807 were run with 600v at the anode, and 300v for screens,
and 80 watts class AB2 were available.

The lower the screen voltage, the lower the grid1 bias voltage,
and the lower the AB1 power output ability into a low value RL.
So to get more anode swing, the grid1 is damn well forced to swing
more, and above 0V ie, positively, when it conducts current,
so a cathode follower drive stage is required.

The result is that the screen currents overall tend to stay low, and the
screen dissipation
tends to stay well within the operational ratings, and the tube lives to
a ripe old age,
and it don't die screaming.


Are you saying that an AB1 amp where the outputs conduct for,
say, 80% of the signal has more "class A watts" than an amp
where the outputs conduct for 70% of the signal? The latter, of
course, having more "class B watts"?


Indeed.

Most guitar amps have maybe 5 watts of what is class A power,
and the remaining 55 watts are class B.
That's a total of 60 watts of class AB.


Oops, oops,.... stop right there.

You have forgotten to mention the Fluff Factor, as it relates to all this, amplifier to
amplifier.

You see many do not know, or if they know, believe in the existence of the Fluff Factor.

Or, many times, is not even noticed, like the slight of hand of the magician.

Yeah, each amplifier is actually pull a slight of had act one most experts, and they are
not even aware of it at all.

THAT, is because they are SO caught up in the moment of analysis, speculation, and
theory,... that they totally miss the Fluff Factor.

So what you are going to ask is, what is Fluff, and the Fluff Factor...

OK, coming up.

In the above explanation, on assumes a stable voltage to be in place on two elements of
the tube.

Of which, it is not, and varies amplifier to amplifier.

Thus creating that ever popular problem of, the numbers don't line up exactly right.
Like, for some reason there is the appearance, there are a few missing and unaccounted
free electrons who got lost somewhere.

Where did they go!!!!!!

Well, it have been found that Fluff Factor is directly proportional to the number of
missing free electrons.

Hey, what the hell is a few missing electrons anyway.

But, when the number of missing *In Action* free electrons starts to grow in number, and
no longer can go un-noticed, the Fluff Factor goes through the roof!!!!!!!!!!!!

For Example, take the amplifier supposed for the case in point. Which was used in the
explanation above.

We all sat here nodding our heads in front of the monitors. Right!!!!!

You were so focused on the hands of the magician and things looked like,... Hey, we're in
the REAL world, and everything is cool.

But, if you re-wind the tape, and replay it through another amplifier, you are going to
get a DIFFERENCE.

So, in order to establish this existence of Fluff, and the Fluff Factor, we have to set
some rules, or if you will, a standard for both cases.

The original explanation, and the one to come. Thus, producing the presence of Fluff, and
the resultant, Fluff Factor.

First, the input to output CHARACTERISTICS of the amplifier, which is the basis of the
original explanation, for the support of this explanation of classes of operation of an
output stage, MUST be documented precisely, in EVERY way possible.

Remember, everything about this amplifier is assumed to be IDEAL!!!!!!!!!

But, it isn't.

It isn't IDEAL!!!!!!

So, for the moment, let's make some changes to that original amplifier, so there will NOT
be any assumptions about anything.

The First Thing, we are going to do, is make this the ideal amplifier, by disconnecting
ALL the internal voltage sources. A complete, power supply, disconnect, with all its
branches.

Then, in the place of these disconnects, is attached laboratory grade power supplies,
throughout the amplifier.

One for just the filaments of those output tubes.

One for the bias supply to the control grids of those output tubes.

One for the screen grids of those output tubes.

One for the the anodes of those output tubes.

One for each stage in front of the output stage.

Each is a regulated variable voltage source, with unlimited current availability.

In short, ZERO sag EVERYWHERE.

NOW, let's match the exact voltages found in the original amplifier, and repeat this
again, and compare the differences.

Well, doesn't this change things a bit!!!!!!!!!!!!

I guess you can now SEE a piece of the Fluff now.

You you are SURE as Hell, going to be USING IT, as soon as you take a breath to comment on
this so far.

But there is more yet, to be seen, than the obvious with respect to the anodes of the
output tubes now.

And that, is the the simultaneous impact, that the CHANGE, from sagging power supply has
on both the AC and DC characteristics, changing AC to DC ratio of the output stage,...
Plus, the change of input drive to the output stage from such.

Now, think of ALL those external power supplies, now supplying unlimited energy to the
amplifier system.

Now, compare those input data sheets of both examples, and tell me now, how those amps
line up again.

Did those 6550's meet max specs.

For that matter, how do those output tubes match the curves for the GE-6550A now.

Hey, those curves are from a naked tube with lab supplies on them.

Zero variables present.

Which is not the case with all the case points offered in support of polished turds.

The friend to a Polished Turd is, a sagging power supply!!!!!!!!!!!!!!

What, what did you say!!!!!!!!!!!!!!!!

Oh,... that.

Sorry,.....

Fluff, is the of verbal tap dancing used by the experts to glorify the Polished Turd from
a technical point of view!!!!!!!!!!!!!!!

Huh, what,.... Oh!, the Fluff Factor!!!!!!!

THAT, is the *amount* of *fancy foot* work required to explain those NEW FOUND, missing
Free Electrons, from before, that now appear to now be flowing through those output tubes,
giving higher gain and signal yield then previously.

Oh, what was that question again.

What, What,......??????

Speak up, it's hard to hear ya with everyone else talking at the same time.

Oh, got ya.....

They are called a Fluffer Nutter!!!!!!

Hey guys, simmer down a bit,......

What's a Fluffer Nutter,... is that what ya asked!!!!!!!!!!!!!!!!!!!

OK,.....

Well simply,.......

A Fluffer Nutter, is a nicer term for a former Expert, turned Turd Hugger!!!!!!!

Regards,

Rich Koerner,
Time Electronics.
http://www.timeelect.com

Specialists in Live Sound FOH Engineering,
Music & Studio Production,
Vintage Instruments, and Tube Amplifiers


--


Regards,

Rich Koerner,
Time Electronics.
http://www.timeelect.com

Specialists in Live Sound FOH Engineering,
Music & Studio Production,
Vintage Instruments, and Tube Amplifiers
  #115   Report Post  
Rich Koerner
 
Posts: n/a
Default



Premature send button hit!!!!



Sorry.


Patrick Turner wrote:

WakyAmps wrote:

Patrick Turner wrote in
:



Miles O'Neal wrote:

Patrick Turner responded to WakyAmps, who said:


Actually, it was Miles who said... but I've a few questions of
my own.

[humongous snip]

Not sure we're all speaking the same language here ('least I'm
sure as hell not...)

In my dictionary[1], a push-pull amp biased class B has one
output tube in cutoff when the other is conducting. Class A has
both tubes conducting for the entire waveform. Class AB1 has
each tube conducting for somewhat more than half of each cycle,
though the outputs still alternate between cutoff[2].

I think we'll all agree that an AC-30 runs the bejeezus out of
its outputs. However, please explain to me, for a P-P AB1
biased amp, the difference between the "Class A watts" and the
"Class B watts". I don't think I've ever seen those terms used
in that context before.


Most guitar amps are class AB1 amps.
This means that for say the first 5 watts, both output tubes
operate with low distortion content in their currents,
and are like two single ended tubes but working together to change the
opt primary
voltage in a balanced manner.
Beyond the 5 watt power level, one of the tubes recieves a large enough
negative going grid voltage to cut the current flow right off.
The other tube grid is getting a positive going voltage to turn on the
tube
current much more, and so power is produced by one tube only
during the crests and troughs of the sine wave. Only the zero crossing
part of the sine wave power cycle is where both tubes mutually
contribute power.

So over 5 watts in the above typical amp, the power can be said to be
classB.
But viewed as a whole, during a maximum level sine wave,
the operation is class AB.
AB1 indicates tubes are not driven to draw grid current, AB2 means
the amp is driven hard to make the grids draw grid current.

Once upon a time, nearly all makers used a much lower screen voltage
than today, where the trend is to have both anode and screen supplies
quite high, say both at 450v.
Originally, 6550 and 6L6 and 807 were configured with screens
set at 300v max, and then anode voltages could be much higher.
Even 807 were run with 600v at the anode, and 300v for screens,
and 80 watts class AB2 were available.

The lower the screen voltage, the lower the grid1 bias voltage,
and the lower the AB1 power output ability into a low value RL.
So to get more anode swing, the grid1 is damn well forced to swing
more, and above 0V ie, positively, when it conducts current,
so a cathode follower drive stage is required.

The result is that the screen currents overall tend to stay low, and the
screen dissipation
tends to stay well within the operational ratings, and the tube lives to
a ripe old age,
and it don't die screaming.


Are you saying that an AB1 amp where the outputs conduct for,
say, 80% of the signal has more "class A watts" than an amp
where the outputs conduct for 70% of the signal? The latter, of
course, having more "class B watts"?


Indeed.

Most guitar amps have maybe 5 watts of what is class A power,
and the remaining 55 watts are class B.
That's a total of 60 watts of class AB.


Oops, oops,.... stop right there.

You have forgotten to mention the Fluff Factor, as it relates to all this, amplifier to
amplifier.

You see many do not know, or if they know, believe in the existence of the Fluff Factor.


Or, many times, is not even noticed, like the slight of hand of the magician.


Yeah, each amplifier is actually pulling a slight of hand act on most experts, and they
are
not even aware of it at all.

THAT, is because they are SO caught up in the moment of analysis, speculation, and
theory,... that they totally miss the Fluff Factor.

So what you are going to ask is, what is Fluff, and the Fluff Factor...

OK, coming up.


In the above explanation, one assumes a stable voltage to be in place throughout the
example.

Of which, it is not, and varies amplifier to amplifier.

Thus creating that ever popular problem of, the numbers don't line up exactly right.

Like, for some reason there is the appearance, there are a few missing and unaccounted
free electrons who got lost somewhere.

Where did they go!!!!!!

Well, it have been found that Fluff Factor is directly proportional to the number of
missing free electrons.

Hey, what the hell is a few missing electrons anyway.

But, when the number of missing *In Action* free electrons starts to grow in number, and
no longer can go un-noticed, the Fluff Factor goes through the roof!!!!!!!!!!!!

For Example, take the amplifier supposed for the case in point. Which was used in the
explanation above.

We all sat here nodding our heads in front of the monitors. Right!!!!!

You were so focused on the hands of the magician and things looked like,... Hey, we're in
the REAL world, and everything is cool.

But, if you re-wind the tape, and replay it through another amplifier, you are going to
get a DIFFERENCE.

So, in order to establish this existence of Fluff, and the Fluff Factor, we have to set
some rules, or if you will, a standard for both cases.

The original explanation, and the one to come. Thus, producing the presence of Fluff, and
the resultant, Fluff Factor.

First, the input to output CHARACTERISTICS of the amplifier, which is the basis of the
original explanation, for the support of this explanation of classes of operation of an
output stage, MUST be documented precisely, in EVERY way possible.

Remember, everything about this amplifier is assumed to be IDEAL!!!!!!!!!

But, it isn't.

It isn't IDEAL!!!!!!

So, for the moment, let's make some changes to that original amplifier, so there will NOT
be any assumptions about anything.

The First Thing, we are going to do, is make this the ideal amplifier, by disconnecting
ALL the internal voltage sources. A complete, power supply disconnect, of all its
branches.

Then, in the place of these disconnects, is attached laboratory grade power supplies,
throughout the amplifier.

One for just the filaments of those output tubes.

One for the filament of the rest of the amplifier.

One for the bias supply to the control grids of those output tubes.

One for the screen grids of those output tubes.

One for the the anodes of those output tubes.

One for each stage in front of the output stage.

Each is a regulated variable voltage source, with unlimited current availability.

In short, ZERO sag EVERYWHERE.

NOW, let's match the exact voltages found in the original amplifier, and repeat this
again, and compare the differences.

Well, doesn't this change things a bit!!!!!!!!!!!!

I guess you can now SEE a piece of the Fluff now.

You are SURE as Hell, going to be USING IT, as soon as you take a breath to comment on
this so far.

But there is more yet, to be seen, than the obvious, with respect to the anodes of the
output tubes now.

And that, is the the simultaneous impact, that the CHANGE, from sagging power supply has
on both the AC and DC output tube characteristics, changing AC to DC ratio of the output
stage,...
Plus, the change of input drive to the output stage from such.

Now, think of ALL those external power supplies, now supplying unlimited energy to the
amplifier system.

Now, compare those input data sheets of both examples, and tell me now, how those amps
line up again.

Did those 6550's meet max specs.

For that matter, how do those output tubes match the curves for the GE-6550A now.

Hey, those curves are from a naked tube with lab supplies on them.

Zero variables present.

Which is not the case with all the case points offered in AGA in support of polished
turds.
Though, the example includes class of operation points for consideration, and comparisons.


Note - The friend to a Polished Turd is, a sagging power supply!!!!!!!!!!!!!!


What, what did you say!!!!!!!!!!!!!!!!

Oh,... that.

Sorry,.....

Fluff, is the of verbal tap dancing used by the experts to glorify the Polished Turd from
a technical point of view!!!!!!!!!!!!!!!


Huh, what,.... Oh!, the Fluff Factor!!!!!!!

THAT, is the *amount* of *fancy foot* work required to explain those NEW FOUND, missing
Free Electrons, from before, that now appear to now be flowing through those output tubes,
giving higher gain and signal yield then previously on the load.

Oh, what was that question again.

What, What,......??????

Speak up, it's hard to hear ya with everyone else yelling at the same time.

Oh, got ya.....

They are called, a Fluffer Nutter!!!!!!

Hey guys, simmer down a bit,......

What's a Fluffer Nutter,... is that what ya asked!!!!!!!!!!!!!!!!!!!

OK,.....

Well simply,.......

A Fluffer Nutter, is a nicer term for a former Expert, turned Turd Hugger!!!!!!!



Regards,

Rich Koerner,
Time Electronics.
http://www.timeelect.com

Specialists in Live Sound FOH Engineering,
Music & Studio Production,
Vintage Instruments, and Tube Amplifiers


  #116   Report Post  
Miles O'Neal
 
Posts: n/a
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On Mon, 23 Feb 2004 12:57:53 +1100, Patrick Turner wrote:

In the land of hi-fi amps, class A means that the power input increases
not more than 10% when clipping is reached into the rated class A load.
each of the tubes conducts for 360 degrees of a cycle, but distortion
*currents* do not have more than about 5% 2H in each tube.


That may be an accepted, practical definition,
but it's purely one of convenience. Again, if
you want to use your own patois, fine, but using
it outside your own hood is asking for trouble.

Most pentode/tetrode guitar amps are mostly class B amps


You've said this several times now. Is
this a typo? Did you mean to type "Class AB",
or did you mean this?


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  #117   Report Post  
Miles O'Neal
 
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On Mon, 23 Feb 2004 05:34:34 +0000, Fred Nachbaur wrote:

The reason I used this example is that I built such a thing not long ago,
and when documenting it on my website had to find a way of giving an idea
at what power levels the two significant non-linearities entered (the
first being cutoff, the second being grid conduction). I opted for an
approach much like what Patrick uses in explaining this. Below a certain
power level, this Class AB2 amplifier actually *behaves* like a Class A
amp. Above that, but below grid conduction, it *behaves* like a Class AB1
amp. Beyond that, to the hard-clipping point, it actually behaves like
what it is - a Class AB2 amplifier.


Thank you! This is exactly what I have been trying to say.


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  #118   Report Post  
Miles O'Neal
 
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On Tue, 24 Feb 2004 14:31:12 -0500, James Angelo Ruggieri, P.E. wrote:

For many years and many years past - I worked at what used to be Guitar
Lab on 48th Street in NYC - and came onboard right after DeMarzio left. I
fixed, modified, and designed/built many tube cadence amps


So what is this "cadence" amplifier you keep
refering to?

Not looking to start political discussion, I
am just being precise. The USSR was no more communist than I am a
hedgehog. Neither is China.

Certainly not anymore


Never were. Just more fascists
in disguise. Unless communism
includes the concept of "equality
for all, but some are more equal
than others" as did the slavery
era of teh Old South in USA history.
8^/



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  #119   Report Post  
Miles O'Neal
 
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On Wed, 25 Feb 2004 04:09:54 +1000, kyser wrote:


"Miles O'Neal" wrote in message
news
By all accounts, Mr. Fender didn't originally plan for distorted sounds.

But they took off, and he grudgingly accepted that.

AFAIK, Leo Fender was a country music aficianado, and despised rock 'n
roll/"distorted" music in any form. While some earlier Fender amps
can/could be overdriven to a degree by "hot" pickups, I doubt it was ever
a specific design intention.


That's the long version; we have the
same view here.

(Many of his engineers did not, and after Leo left the company, they

drastically cleaned up the sound, annoying many, many customers).

If you mean the post-1965 CBS "Silverface" amps, I think the intention of
going ultralinear on the Twin Reverb etc was more a horsepower race (a
claimed 135 watts and, AFAIK nothing like it, from a quad of 6L6s) to
compete with the new loud/clean MusicMan amps for which Leo Fender was a
consultant (having signed an exclusion contract with CBS on leaving FMI).
There were some other circuit changes, but they can be converted back to
"Blackface" specs readily enough.


That's part of it, but by all accounts,
a lot of the engineers chafed under Leo's
refusal to let them produce more *clean*
headroom. They wanted more power, Scotty,
but they also wanted it clean. "Green"
music power. 8^)

....
But some of the sound *did* come from the parts available in the price

range. Design meets luck, and a star is born.

True, eg a Les Paul, and a JTM45 with KT66s and 2x12" Celestions ....
8^)


I was referring to trannies and such, but yeah!



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WakyAmps
 
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"Miles O'Neal" wrote in
news
Patrick,

There's an excellent example of running an amp
into an open load in a thread that just started
in alt.guitar.amps today. In a nutshell, the
player fired up his old Marshall stack with a
bunch of pedals hooked up. He didn't realize
he'd tripped over the speaker cable and it had come
loose. He assumed the lack of sound was because
of a problem with the effects pedal setup. He
has probably arced 1 or more sockets and fried
at least one tube.

You can see details via http://groups.google.com/
with newsgroup of "alt.guitar.amps" and a subject
of "Amp advice sought and cautionary tale (long)".

I'd guess this happens a few times a day all across
the USA, nevermind elsewhere.

-Miles


'cept in Australia they burn up the other way around.
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