Ian Iveson wrote:

"Patrick Turner" wrote

I would expect customers to be satisfied but not ecstatic. His
stuff
seems solidly built and reliable, but I see no evidence of
optimisation or inspiration. I do get a general impression of
fumbling.

Just as well I don't worry about what your impressions are
or what you cannot see.

I can see the fumbling.

Make a better line of gear to sell to to your
lucky customers do you?

I don't sell audio equipment. If I did I wouldn't be here. It would
no longer be a recreation and I would consider my presence dishonest
and grovelling.

You are a pathetic sort of bloke imho.

You would deny someone a fair go on the grounds of him being
commercially active.
Its as bad as being a hard assed racist.


If I were to buy a machine, not a thoroughbred or a work of art,
but
one which did the job in a workaday workhorse kind of way, I
wouldn't feel like shouting about it. After a hundred years I
might
comment on its longevity though.

But do music lovers choose amps just because they are heavy?

No, but they love the music they get from all that weight.

Prove it.

I don't have to, just for you.
It'd be a waste of time.


OTOH, there are not many commercial valve amps available that
don't
skimp on their OPTs. A discerning buyer may put Patrick Turner on
his shortlist, and be informed by such consideration, but is
likely
to buy elsewhere in the end. Lack of an attractive "unique
selling
point". No coherent message.

"Coherence" and "message" and "uniqueness" are all marketing
tools.

Well spotted, but they should be more than that, and genuinely are
in most cases. They have to be, because the world is not full of
fools, as you seem to believe.

I don't employ marketeers.

You don't employ winders, but you wind.

Its better I wind all my own trannies.
I know what sort of quality they will be.
I make the wages of a winder, rather than pay
a pile of $$$ for some ignorant goon to do what I want.



I make amps, and I prefer a minimum of BS used to
propel sales.

But you are nothing but BS.

Well why reply to any post of mine?

If you are not unique then you have
nothing to contribute to the market. If you have no message you have
nothing worth saying. However, since you lack coherence, nobody
cares.

People who have a deeper than stupid modern superficial set of values
recognise
my wares for what they are, no more, no less.
It turns out they think they are better than the rest.

That you say nobody cares is just sheer unadulterated pomme ****ing BS.



You snap at the heels of professionals out of pure bitterness.

You snap at the heels at anyone who is successful like me.
Jealous are you? Bitter that I make a lotta sense to many folks?
and that I can sustain a living by honest hard work in the audio
industry?

No need to answer, please feel free to STFU.


Tube amps have been around for about 80 years, and
there are a select group who believe they do well with music, and
these
folks
sometimes vote on the issue with their wallets.

I let the amps sell themselves after someone has a good listen.

No you don't, liar.

You won't ever win anything by picking a blue with me Ian.

I will make a monkey of you if I have to.




I raise my hat to all the other brands out there and wish my
competion
the very best of luck.

No you don't, liar. You slag them off at every opportunity.

I level justified crioticism at anyone who attracts it.
I am normally very polite about it.



Should anyone wish to invest 5 million dollars to produce
a batch of 100 amps and hawk them around the globe and get all the
right
reviews
in the right magazines, then they could do worse than contact me.

You mean better I assume. This time you are right.

Again you show you are cretinous moron, with not the slightest idea
what its like to run a business.



I am actually happy without the stresses of big business.

It's not stressful if you know what you are doing. Far less than
stressful than embittered and poor. Not as stressful as mining
though, or being a philosophy student, which **** ppl up no end.

OK, being a coal miner has its days.
But all the rest of what you say is total BS.

Being a philosphy student is stressful?
You gotta be out of your mind.
Maybe you have periods where you are insane, and need medication.




The "stress at the top" myth was exposed long ago. Mostly those
people enjoy their lives and have good pensions to look forward to.

To get to the "top"
takes ruthlessness and 80 hrs a week.
Its stressful, believe me.

But you probably bludge your way through life, and have never
had much responsibility, so WTF would you know about being at the top?



But I will continue to make a few fine sounding amps without such
commercial backing that many other makers have attracted, such as
Halcro, of Sth Aust, and probably CJ, ARC, and many other brands.

This must be just about the only place in the world you can find
people impressed by this silly Davy Crockett drivel. That's why
you're here I suppose. A mascot for the cranky die-hard hill-billy
wannabes.

Again you show your moronic personal style.

You never qualified at Personal Assessment at Cambridge or Oxford, now
did you.
The School of Life should fail you.

Wake up Ian and get a life, before we all start thinking you are a
complete dickhead.

Patrick Turner.



cheers, Ian

Patrick Turner wrote:

John Stewart wrote:

The core loss test results below were taken from a recent production
Hammond 125E Universal OPT. As usual, I powered the secondary (first
column) & measured the power loss. With an HP 334A & 10X attenuator I
adjusted the drive so that there are equal voltage increments at the
primary. The 10X attenuator is a must since even a one meg load at the
high impedance of the primary results in measurement errors. The last
column shows the equivalent parasitic resistor in parallel with the
primary. That is what is in parallel with your OPT & output tube.

V ma mw mva PF Primary Rpri
Volts

0.468 3.47 1.21 1.62 0.75 10 82.64K
0.942 6.28 4.94 5.91 0.83 20 80.97
1.425 8.87 11.07 12.65 0.88 30 81.3
1.899 11.28 19.29 21.40 0.90 40 82.94
2.353 13.48 29.03 31.73 0.91 50 86.12
2.826 15.72 41.13 44.43 0.93 60 87.53
3.33 17.97 55.7 58.9 0.93 70 87.97
3.81 20.08 71.7 76.5 0.94 80 89.26
4.26 22.03 88.4 93.8 0.94 90 91.63
4.76 24.19 109.1 115.1 0.95 100 91.66

5.64 27.83 149.7 156.9 0.95 120 96.19

6.47 31.7 197 205 0.96 140 99.49

7.40 35.4 252 262 0.96 160 101.59

8.32 38.9 314 324 0.97 180 103.18

9.26 42.4 382 393 0.97 200 104.71

11.10 48.9 531 542 0.98 240 108.47

I don't have any of the exotic OPT's such as Partridge or McIntosh
here to try but I think the results would probably follow a similar
pattern to what I see here today. For sure the losses would have to be
less since that is what one pays for. But the results would probably
be a surprise to many.

Cheers, John Stewart

I don't see the Frequency for the voltage applied for the above figures.

Those were all done at one KHZ & I should have posted that information. But
don't expect luxo performance from that transformer. The cost is very low
while the OPT does many things with it's many possible winding combinations.
Having said that, over many years I've used quite a few of the 125E & it's
predecessors, primarily the 125D with good results.

After reading many of the comments reference transformers I became
suspicious of my measurement setup, so yesterday refined it somewhat. I will
post more results later, possibly today. I have an alternative setup in mind
so as to cross check the new measurement data. Should be an interesting
exercise.

Cheers, John Stewart

John Stewart wrote:

Patrick Turner wrote:

John Stewart wrote:

The core loss test results below were taken from a recent production
Hammond 125E Universal OPT. As usual, I powered the secondary (first
column) & measured the power loss. With an HP 334A & 10X attenuator I
adjusted the drive so that there are equal voltage increments at the
primary. The 10X attenuator is a must since even a one meg load at the
high impedance of the primary results in measurement errors. The last
column shows the equivalent parasitic resistor in parallel with the
primary. That is what is in parallel with your OPT & output tube.

V ma mw mva PF Primary Rpri
Volts

0.468 3.47 1.21 1.62 0.75 10 82.64K
0.942 6.28 4.94 5.91 0.83 20 80.97
1.425 8.87 11.07 12.65 0.88 30 81.3
1.899 11.28 19.29 21.40 0.90 40 82.94
2.353 13.48 29.03 31.73 0.91 50 86.12
2.826 15.72 41.13 44.43 0.93 60 87.53
3.33 17.97 55.7 58.9 0.93 70 87.97
3.81 20.08 71.7 76.5 0.94 80 89.26
4.26 22.03 88.4 93.8 0.94 90 91.63
4.76 24.19 109.1 115.1 0.95 100 91.66

5.64 27.83 149.7 156.9 0.95 120 96.19

6.47 31.7 197 205 0.96 140 99.49

7.40 35.4 252 262 0.96 160 101.59

8.32 38.9 314 324 0.97 180 103.18

9.26 42.4 382 393 0.97 200 104.71

11.10 48.9 531 542 0.98 240 108.47

I don't have any of the exotic OPT's such as Partridge or McIntosh
here to try but I think the results would probably follow a similar
pattern to what I see here today. For sure the losses would have to be
less since that is what one pays for. But the results would probably
be a surprise to many.

Cheers, John Stewart

I don't see the Frequency for the voltage applied for the above figures.

Those were all done at one KHZ & I should have posted that information. But
don't expect luxo performance from that transformer. The cost is very low
while the OPT does many things with it's many possible winding combinations.
Having said that, over many years I've used quite a few of the 125E & it's
predecessors, primarily the 125D with good results.

After reading many of the comments reference transformers I became
suspicious of my measurement setup, so yesterday refined it somewhat. I will
post more results later, possibly today. I have an alternative setup in mind
so as to cross check the new measurement data. Should be an interesting
exercise.

Cheers, John Stewart

I think that any full measure of the core losses at any F in the audio band for
a decent OPT
should result in low core losses, and low enough to be neglected in the design
process.

However, in a Quad II tranny, at full output voltage the core loss at 40 Hz may
be considerable
since saturation is near.

But of course at normal listening levels the losses may be
lower, and will not affect the sound in any meaningful manner.

At a kHz, the core losses should be very low indeed.

Patrick Turner.

"Patrick Turner" wrote

The reactance of the inductance, ZLp, should be less than RL
at 20 Hz.

Do you mean Zp, rather than RL? It should be *much greater*, surely?
But it will depend on the voltage used when measuring. There will
always be a signal level below which ZLp dips below Zp.

So for an SE OPT, if RL is 5k, then at 20 Hz the Lp = 40 H.
If its 2k, then 16 H is ok.

Depending on the voltage used when measuring Lp

But many crap OPTs have Lp for an 8k tranny at 15H in a radio.
Saturation is awful at full power at maybe 80 Hz...

It could be misleading in the context of this thread to make a
direct link between Lp and saturation. They are crap because they
saturate, they have a low value of Lp, but they don't saturate only
because of the low Lp, but also because they are crap.

cheers, Ian

Ian Iveson wrote:

"Patrick Turner" wrote

The reactance of the inductance, ZLp, should be less than RL
at 20 Hz.

Do you mean Zp, rather than RL? It should be *much greater*, surely?

Getting *much greater* is impossible with SE unless the tranny is huge.
But sorry, i meant ^not^ less than Rl at 20 Hz.
No need for it to be much more.


But it will depend on the voltage used when measuring. There will
always be a signal level below which ZLp dips below Zp.

Not with a gapped core where the ZLp stays fairly constant
since inductance stays fairly constant.

The voltage would that at anywhere above low power.

Any reduction in primary inductance in most OPTs does not
result in an impossibly low impedance across the RL.




So for an SE OPT, if RL is 5k, then at 20 Hz the Lp = 40 H.
If its 2k, then 16 H is ok.

Depending on the voltage used when measuring Lp

But many crap OPTs have Lp for an 8k tranny at 15H in a radio.
Saturation is awful at full power at maybe 80 Hz...

It could be misleading in the context of this thread to make a
direct link between Lp and saturation. They are crap because they
saturate, they have a low value of Lp, but they don't saturate only
because of the low Lp, but also because they are crap.

I might need a trained linguist to work out what you meant.

With any gapped OPT core with a lot of DC flow in one direction only,
with no gap, there is early saturation and not much L.
Then as the gap is increased, the L rises and amount of voltage required
for saturation
also rises.
Then there is a point where the L stays about constant for an increasing
ability
to withstand saturation.
Then with further slight increase of the gap, the Lp starts to fall, but
the ability
to not saturate increases and so at this point, it is where we want
the RL to equal or be less than the reactive impedance of Lp.
This will allow the amp input to be held constant, and the
roll off of signal from initial full power voltage will not cause
saturation below 20 Hz.
Its easy to say we should have ZLp = RL at 10 Hz, or 5 Hz, but then
the OPT becomes way bigger than required.
Radio makers used to have ZLp = RL at a much higher F above 20 Hz.
There was no need because there was no aim for real hi-fi, and the
speakers used
has an Fs = say 100 Hz, and they couldn't handle any signal below about
80 Hz.

But for hi-fi we should aim for the real mc'coy.

In my most recent SE 35 watt amps the core is a 55 mm stack of 44 tongue
GOSS,
and with about 2,000 primary turns, and the design follows the above
criteria.
and since RL = 1,200 ohms, the Lp is about 15H at 20 Hz, and at about
1/2 power.
The u of the core material when fully interleaved would be 17,000,
but when gapped with 0.56 mm across the EIs the u drops
to a few hundred.
The magnetic length is effectively increased by the gap, and this
dominates
the equations for inductance.

I might add that SE cores have to be tested in the amp to get the
optimal
Lp for a given value of Ip DC.
never assume you got the gap right unless you made sure you got it right

by doing the tests and plotting the inductance for various gap sizes and
with
nearly full signal voltage applied.

So that rules out anyone being able to sell me a ready made SE tranny
with a fixed gap.
I have to know for myself it is right.

So I wind and test my own to make damn sure.

Patrick Turner.










cheers, Ian

"Patrick Turner" wrote

Just as well I don't worry about what your impressions are
or what you cannot see.

I can see the fumbling.

Make a better line of gear to sell to to your
lucky customers do you?

I don't sell audio equipment. If I did I wouldn't be here. It
would
no longer be a recreation and I would consider my presence
dishonest
and grovelling.

You are a pathetic sort of bloke imho.

Sticks and stones...

You would deny someone a fair go on the grounds of him being
commercially active.

Not in a position to deny you anything, and neither would I. If you
want to be dishonest and grovelling, it's up to you.

Its as bad as being a hard assed racist.

I don't think so.

If I were to buy a machine, not a thoroughbred or a work of
art,
but
one which did the job in a workaday workhorse kind of way, I
wouldn't feel like shouting about it. After a hundred years I
might
comment on its longevity though.

But do music lovers choose amps just because they are heavy?

No, but they love the music they get from all that weight.

Prove it.

I don't have to, just for you.
It'd be a waste of time.

Not just for me, for the world. Prove it.

I don't employ marketeers.

You don't employ winders, but you wind.

Its better I wind all my own trannies.
I know what sort of quality they will be.
I make the wages of a winder, rather than pay
a pile of $$$ for some ignorant goon to do what I want.

Point was that just because you don't employ "marketeers", doesn't
mean you don't do marketing, clot. It's just that you are not good
at it. That is in part because you think the world is full of
"ignorant goons", "bull****ters", "beancounters", "pathetic blokes",
and any other excuse you can think of for failing to sell your
products.


I make amps, and I prefer a minimum of BS used to
propel sales.

But you are nothing but BS.

Well why reply to any post of mine?

I didn't on this occasion. The thread is about how stupid you are.
On other occasions, I may point out your bull**** if we are involved
in the same thread, which is usually when you come in after me, coz
I generally try to avoid talking to you.

If you are not unique then you have
nothing to contribute to the market. If you have no message you
have
nothing worth saying. However, since you lack coherence, nobody
cares.

People who have a deeper than stupid modern superficial set of
values
recognise
my wares for what they are, no more, no less.
It turns out they think they are better than the rest.

So you say. If in reality they all think they are crap would you say
so? You are not in a position to be honest, and it is dishonest to
pretend you are.

You snap at the heels at anyone who is successful like me.

But you constantly whinge about how unsuccessful you are.

Jealous are you? Bitter that I make a lotta sense to many folks?
and that I can sustain a living by honest hard work in the audio
industry?

Er...no. I make sense to those I respect, and they make sense to me.
That is most people I know, and most people I meet.

No need to answer, please feel free to STFU.

Sorry, too late.

I let the amps sell themselves after someone has a good listen.

No you don't, liar.

You won't ever win anything by picking a blue with me Ian.


Sore spot, liar. Truth hurts, liar. You have said many times that
you don't sell from stock.

I will make a monkey of you if I have to.

Please. Quite fancy being a monkey for a while. Do you do eagles or
albatross?

I raise my hat to all the other brands out there and wish my
competion
the very best of luck.

No you don't, liar. You slag them off at every opportunity.

I level justified crioticism at anyone who attracts it.
I am normally very polite about it.

"ignorant goons", "bull****ters", "beancounters", "pathetic blokes".
Liar.

Again you show you are cretinous moron, with not the slightest
idea
what its like to run a business.

Wrong. What would you know?

I am actually happy without the stresses of big business.

It's not stressful if you know what you are doing. Far less than
stressful than embittered and poor. Not as stressful as mining
though, or being a philosophy student, which **** ppl up no end.

OK, being a coal miner has its days.
But all the rest of what you say is total BS.

No it isn't, and it's not opinion. Stress is rather vague in common
usage. Miners and philosophy students fair badly in studies relating
stress-induced medical conditions to occupation.

Being a philosphy student is stressful?
You gotta be out of your mind.

What would you know?

Maybe you have periods where you are insane, and need medication.

Is this the "making a monkey" part? Actually, I am unusual in that,
due to circumstances unrelated to medical condition, I have stacks
of documentary evidence that I am not insane, and do not need
medical attention.

The "stress at the top" myth was exposed long ago. Mostly those
people enjoy their lives and have good pensions to look forward
to.

To get to the "top"
takes ruthlessness and 80 hrs a week.

Another myth.

Its stressful, believe me.

Why, what would you know? The heart attacks are due to stuffing
themselves with fat and sugar and doing no physical work. Generally,
the more you feel on top and in control, the less stress you suffer.
Miners aren't on top, and phil students tend to lose their sense of
control...and vice versa.

But you probably bludge your way through life, and have never
had much responsibility, so WTF would you know about being at the
top?

What does bludge mean? Life is what we make it, and you know very
little about mine. You have failed what little few responsibilities
you had, from what you say, lots, day after day, week after week,
year after year.

This must be just about the only place in the world you can find
people impressed by this silly Davy Crockett drivel. That's why
you're here I suppose. A mascot for the cranky die-hard
hill-billy
wannabes.

Again you show your moronic personal style.

Thanks. No-one ever said I have style before. I feel a warm glow...

You never qualified at Personal Assessment at Cambridge or Oxford,
now
did you.

Eh?

The School of Life should fail you.

Oh, please...

Wake up Ian and get a life, before we all start thinking you are a
complete dickhead.

Aha, couldn't resist that "we" in the end. Nearly made it without
that nasty bullying streak showing. Your sadly misguided arselickers
are free to think I am a complete dickhead, and "ignorant goons",
"bull****ters", "beancounters", "pathetic blokes", and all the rest
of it. Don't care. Don't try to make money here. Just having fun.

cheers, Ian

"Jason R." wrote in message
u...
Just in case you people hadn't noticed, Google have a newer interface for
the groups thingie which isn't as nasty as the old one:
http://groups-beta.google.com/group/rec.audio.tubes
It's pretty up to date and is of course, free.

Jason

Hi Jason -
Yeah, I use it, and I don't mean to knock Google - it's my "homepage" - they
do the best they can, and the product's great - no better place to start
searching.
Carrying NG's on an HTTP server's just a bit difficult, kind'o like using
a chainsaw to make furniture - possible, but less than an ideal choice of
tools...
OTOH, it's a "bear ridin' a bicycle" - one's not impressed by how well the
bear does it, but by the bear's ability to do it at all. We're all so used
to the whistles & bells of our news readers, that having a less- than
perfect front end, or even having to learn a new one, seems like too much of
a bother... And NG's are more of a "luxury" thing - a bit like bored
housewives taking continental philosophy at a night school - their kids
ain't going to go hungry if they don't do it, Barton's Book of Familiar
Quotations (is that the name?) will give them more ammo than they need to
fake sophistication at cocktail parties, outrageous surplus of well -
written books where they can get the straight dope on the subject(s) they
(may) be interested in, etc., etc. And NG's surely aren't the essential
"milieu of great minds" like Prague, Vienna, Zurich, etc., etc. used to be
for scientists & artists of yesteryear, and what places like MIT & Cal Tech
became in recent times.
So we come here 'cos we've got some time, it's a convenient and pleasant
way to kill it while suckin' down the morning cup of coffee, a way to get
info without doing any work (boy, am I guilty!), a ready soapbox (ditto),
and it's so *convenient*. Once the convenience factor is lowered, NG's lose
their appeal. Might as well join a mailing list (I'm still gettin' the
Ampex Digest, and haven't read it in weeks...).

There are plenty of free school-supported free news servers (strangely
enough mainly dutch & german), and they don't carry any NG's they don't feel
like, with the (correct) assumption that 95% of .bin groups are warez &
porn. Bein' pretty much pro bono, they *do* listen when people request a
certain group to be carried, and, if enough people emailed them, they pick
up a group (it took just *one* email from me, and it was a real person on
the other end, the same one who wrote me that Bob E Bob didn't sound like a
real name - a name I use to fill out registration forms...)
/ramble

"BFoelsch" wrote in message
...

"Jon Yaeger" wrote in message
...
Doug,

Permit me to pose a distantly related question to the above thread:

For a very low wattage single ended application (read: headphone
amplifier)
what specific transformer attributes determine the -3db low point of
frequency response? I'm thinking in terms of a 250 mW max. output
(delivered to load)

Or put another way: can small ****ty transformers have wide bandwidths
at
low power, where saturation would not (ever) occur?

Thanks in advance,

jon

Maybe.

The only real mechanisms that affect LF are the Volt-Hertz capability of
the
core (saturation), and the primary circuit resistance. As long as the flux
is changing, voltage is induced in the secondary. Problem is, as the
frequency decreases the reactance of the primary decreases, but the
primary
circuit resistance remains constant. At some point the resistance equals
the
reactance, giving you a -3 dB point. Note, however, that the resistance of
the whole primary circuit contributes to the problem, not just the
resistance of the primary winding itself. Driving the primary from a
perfect
voltage source gives the ideal situation, but you are still limited by the
resistance of the primary winding itself.

Small transformers can indeed have good LF at low power; think about
microphone transformers.


I thought about using mic/line transformers as outputs for SE headphone
amps, using a current source (dummy toob) *slightly* less than the idle
current of the output tube to keep the core from saturating, but getting it
past the point of magnetosticktion (0 crossover point, which looks an awful
bunch like crossover distortion on stuff like tape heads, where the voltages
are *real* low). I bet it could be done, but cap- couplin' the transformer
to the output tube seems like a much more straightforward solution. What
seems even more practical is a doughnut (torroidal) core in a
cathode-follower OT stage - won't saturate (ceramic core), low, or even 1:1
windings ratio (wound bi-fillar (sp?) - great couplin', low C due to few
turns) - what would the disadvantage be? (haven't actually tried that...)
-dim

Ian Iveson wrote:

"Patrick Turner" wrote

You are a pathetic sort of bloke imho.

Sticks and stones...

You would deny someone a fair go on the grounds of him being
commercially active.

Not in a position to deny you anything, and neither would I. If you
want to be dishonest and grovelling, it's up to you.

Its as bad as being a hard assed racist.

I don't think so.

But from what you say you are a bowl of contradictions, adding up to
nothing.

Go to a surgeon Ian, and ask him for a sex change operation
to convert you from a bitch to a man.

The rest of you last reply only deserves deleting.

Patrick Turner.

shiva wrote:

"Jason R." wrote in message
u...
Just in case you people hadn't noticed, Google have a newer interface for
the groups thingie which isn't as nasty as the old one:
http://groups-beta.google.com/group/rec.audio.tubes
It's pretty up to date and is of course, free.

Jason

Hi Jason -
Yeah, I use it, and I don't mean to knock Google - it's my "homepage" - they
do the best they can, and the product's great - no better place to start
searching.
Carrying NG's on an HTTP server's just a bit difficult, kind'o like using
a chainsaw to make furniture - possible, but less than an ideal choice of
tools...
OTOH, it's a "bear ridin' a bicycle" - one's not impressed by how well the
bear does it, but by the bear's ability to do it at all. We're all so used
to the whistles & bells of our news readers, that having a less- than
perfect front end, or even having to learn a new one, seems like too much of
a bother... And NG's are more of a "luxury" thing - a bit like bored
housewives taking continental philosophy at a night school - their kids
ain't going to go hungry if they don't do it, Barton's Book of Familiar
Quotations (is that the name?) will give them more ammo than they need to
fake sophistication at cocktail parties, outrageous surplus of well -
written books where they can get the straight dope on the subject(s) they
(may) be interested in, etc., etc. And NG's surely aren't the essential
"milieu of great minds" like Prague, Vienna, Zurich, etc., etc. used to be
for scientists & artists of yesteryear, and what places like MIT & Cal Tech
became in recent times.
So we come here 'cos we've got some time, it's a convenient and pleasant
way to kill it while suckin' down the morning cup of coffee, a way to get
info without doing any work (boy, am I guilty!), a ready soapbox (ditto),
and it's so *convenient*. Once the convenience factor is lowered, NG's lose
their appeal. Might as well join a mailing list (I'm still gettin' the
Ampex Digest, and haven't read it in weeks...).

There are plenty of free school-supported free news servers (strangely
enough mainly dutch & german), and they don't carry any NG's they don't feel
like, with the (correct) assumption that 95% of .bin groups are warez &
porn. Bein' pretty much pro bono, they *do* listen when people request a
certain group to be carried, and, if enough people emailed them, they pick
up a group (it took just *one* email from me, and it was a real person on
the other end, the same one who wrote me that Bob E Bob didn't sound like a
real name - a name I use to fill out registration forms...)
/ramble

I don't know too many dutch or german free news service providers.
The one I do know and currently use is News.individual.net based at Berlin Uni
and it
is about to start charging fees.

But you are right about the exclusion of some news groups, ie,
exclusion of ALL the binaries groups, because its 95% girly pics for
sex starved men.
The data traffic based on sex is ginormous compared to a bit of text.

But News.individual won't carry alt.binaries.pictures.radio,
or alt.binaries.schematics.electronic,
and these groups are never girly.

I just emailed my ISP to see if they can locate a better news service that is
more up to the minute with posts from around the globe.
I am not holding my breath waiting for them to succeed.

Patrick Turner.

shiva wrote:

"BFoelsch" wrote in message
...

"Jon Yaeger" wrote in message
...
Doug,

Permit me to pose a distantly related question to the above thread:

For a very low wattage single ended application (read: headphone
amplifier)
what specific transformer attributes determine the -3db low point of
frequency response? I'm thinking in terms of a 250 mW max. output
(delivered to load)

Or put another way: can small ****ty transformers have wide bandwidths
at
low power, where saturation would not (ever) occur?

Thanks in advance,

jon

Maybe.

The only real mechanisms that affect LF are the Volt-Hertz capability of
the
core (saturation), and the primary circuit resistance. As long as the flux
is changing, voltage is induced in the secondary. Problem is, as the
frequency decreases the reactance of the primary decreases, but the
primary
circuit resistance remains constant. At some point the resistance equals
the
reactance, giving you a -3 dB point. Note, however, that the resistance of
the whole primary circuit contributes to the problem, not just the
resistance of the primary winding itself. Driving the primary from a
perfect
voltage source gives the ideal situation, but you are still limited by the
resistance of the primary winding itself.

Small transformers can indeed have good LF at low power; think about
microphone transformers.


I thought about using mic/line transformers as outputs for SE headphone
amps, using a current source (dummy toob) *slightly* less than the idle
current of the output tube to keep the core from saturating, but getting it
past the point of magnetosticktion (0 crossover point, which looks an awful
bunch like crossover distortion on stuff like tape heads, where the voltages
are *real* low). I bet it could be done, but cap- couplin' the transformer
to the output tube seems like a much more straightforward solution. What
seems even more practical is a doughnut (torroidal) core in a
cathode-follower OT stage - won't saturate (ceramic core), low, or even 1:1
windings ratio (wound bi-fillar (sp?) - great couplin', low C due to few
turns) - what would the disadvantage be? (haven't actually tried that...)
-dim

Using pentode plate circuits to drive transformers in IST and small signal apps
is a no-no.
And you are right that the distortion at low levels looks like
crossover distortion; 3H levels can be quite high.
So always try to use the lowest plate resistance possible with the best
core material for the job.
CF tranny drivers are good, but also consider gapping an AC tranny, because that
reduces
the change in impedance during each cycle that appears to cause the distortion.
You need to use more turns to give the wanted inductance though.

There is an art to making low distortion signal trannies....

Patrick Turner.

"Patrick Turner" wrote in message
...


shiva wrote:

"BFoelsch" wrote in message
...

"Jon Yaeger" wrote in message
...
Doug,

Permit me to pose a distantly related question to the above thread:

For a very low wattage single ended application (read: headphone
amplifier)
what specific transformer attributes determine the -3db low point of
frequency response? I'm thinking in terms of a 250 mW max. output
(delivered to load)

Or put another way: can small ****ty transformers have wide
bandwidths
at
low power, where saturation would not (ever) occur?

Thanks in advance,

jon

Maybe.

The only real mechanisms that affect LF are the Volt-Hertz capability
of
the
core (saturation), and the primary circuit resistance. As long as the
flux
is changing, voltage is induced in the secondary. Problem is, as the
frequency decreases the reactance of the primary decreases, but the
primary
circuit resistance remains constant. At some point the resistance
equals
the
reactance, giving you a -3 dB point. Note, however, that the
resistance of
the whole primary circuit contributes to the problem, not just the
resistance of the primary winding itself. Driving the primary from a
perfect
voltage source gives the ideal situation, but you are still limited by
the
resistance of the primary winding itself.

Small transformers can indeed have good LF at low power; think about
microphone transformers.


I thought about using mic/line transformers as outputs for SE headphone
amps, using a current source (dummy toob) *slightly* less than the idle
current of the output tube to keep the core from saturating, but getting
it
past the point of magnetosticktion (0 crossover point, which looks an
awful
bunch like crossover distortion on stuff like tape heads, where the
voltages
are *real* low). I bet it could be done, but cap- couplin' the
transformer
to the output tube seems like a much more straightforward solution.
What
seems even more practical is a doughnut (torroidal) core in a
cathode-follower OT stage - won't saturate (ceramic core), low, or even
1:1
windings ratio (wound bi-fillar (sp?) - great couplin', low C due to few
turns) - what would the disadvantage be? (haven't actually tried
that...)
-dim

Using pentode plate circuits to drive transformers in IST and small signal
apps
is a no-no.
And you are right that the distortion at low levels looks like
crossover distortion; 3H levels can be quite high.
So always try to use the lowest plate resistance possible with the best
core material for the job.
CF tranny drivers are good, but also consider gapping an AC tranny,
because that
reduces
the change in impedance during each cycle that appears to cause the
distortion.
You need to use more turns to give the wanted inductance though.

There is an art to making low distortion signal trannies....

Patrick Turner.



Hi Patrick -
I got to run out now, but, if you remember the post where I asked you to
talk me through the RIAA stage of a QUAD 22 preamp I'm re-doing (can't find
the original right now)?
You've mentioned that a part of the RIAA is accomplished through feedback
from the plate of ef86 to G1? You told me to re-draw the circuit (and you
asked why I thought the switches were sh8t - one of the reasons is the
convoluted & needlessly long path a low level signal takes through a whole
gang of them - i had to trace the diagram with a pen... and I still could
be missing something, 'cos I don't *see* the feedback loop - what I'm seeing
is a purely passive *part* of a network, with (what I assume to be inside)
the "PU Adaptors", which are supposed to plug into the (no longer existent)
sockets. I'm looking at a diagram I got from Ned's site, so if you could
point out how the plate gets to see G1 (did you mean the screen?), i'd
appreciate it. Didn't have much time to play with this, but did see
different "PU Adaptors" for sale on the 'net - do they complete the RIAA?
Everything past the ef86's is clear, but the switch bank diagram is drawn by
a sadist... The way I have it set up is with 2 rotary switches, one being
a phono on/off, and the other selecting line-level inputs. There's also a
ganged pot which, basically, changes the values of R21 & R22 simultaneously,
allowing for less gain /more feedback (interacts with the bal. pot.) Sheesh,
I'm late already...
-dim

shiva wrote:

"Patrick Turner" wrote in message
...


shiva wrote:

"BFoelsch" wrote in message
...

"Jon Yaeger" wrote in message
...
Doug,

Permit me to pose a distantly related question to the above thread:

For a very low wattage single ended application (read: headphone
amplifier)
what specific transformer attributes determine the -3db low point of
frequency response? I'm thinking in terms of a 250 mW max. output
(delivered to load)

Or put another way: can small ****ty transformers have wide
bandwidths
at
low power, where saturation would not (ever) occur?

Thanks in advance,

jon

Maybe.

The only real mechanisms that affect LF are the Volt-Hertz capability
of
the
core (saturation), and the primary circuit resistance. As long as the
flux
is changing, voltage is induced in the secondary. Problem is, as the
frequency decreases the reactance of the primary decreases, but the
primary
circuit resistance remains constant. At some point the resistance
equals
the
reactance, giving you a -3 dB point. Note, however, that the
resistance of
the whole primary circuit contributes to the problem, not just the
resistance of the primary winding itself. Driving the primary from a
perfect
voltage source gives the ideal situation, but you are still limited by
the
resistance of the primary winding itself.

Small transformers can indeed have good LF at low power; think about
microphone transformers.


I thought about using mic/line transformers as outputs for SE headphone
amps, using a current source (dummy toob) *slightly* less than the idle
current of the output tube to keep the core from saturating, but getting
it
past the point of magnetosticktion (0 crossover point, which looks an
awful
bunch like crossover distortion on stuff like tape heads, where the
voltages
are *real* low). I bet it could be done, but cap- couplin' the
transformer
to the output tube seems like a much more straightforward solution.
What
seems even more practical is a doughnut (torroidal) core in a
cathode-follower OT stage - won't saturate (ceramic core), low, or even
1:1
windings ratio (wound bi-fillar (sp?) - great couplin', low C due to few
turns) - what would the disadvantage be? (haven't actually tried
that...)
-dim

Using pentode plate circuits to drive transformers in IST and small signal
apps
is a no-no.
And you are right that the distortion at low levels looks like
crossover distortion; 3H levels can be quite high.
So always try to use the lowest plate resistance possible with the best
core material for the job.
CF tranny drivers are good, but also consider gapping an AC tranny,
because that
reduces
the change in impedance during each cycle that appears to cause the
distortion.
You need to use more turns to give the wanted inductance though.

There is an art to making low distortion signal trannies....

Patrick Turner.



Hi Patrick -
I got to run out now, but, if you remember the post where I asked you to
talk me through the RIAA stage of a QUAD 22 preamp I'm re-doing (can't find
the original right now)?
You've mentioned that a part of the RIAA is accomplished through feedback
from the plate of ef86 to G1?

yes.

You told me to re-draw the circuit

The Quad 22 control unit circuit is quite difficult to follow.
There is a lot going on.
Lots of switches, and don't forget the darn plug modules at the rear for eq.
So to understand, i think one should draw the basic circuit neatly on a large
sheet of paper,
and as it is connected when the switches are set in a given position.
That makes it easier to understand.
Quad service ppl got good at serviceing because they did it all the time, but
when one doesn't,
you have to get re-aquainted.......



(and you
asked why I thought the switches were sh8t - one of the reasons is the
convoluted & needlessly long path a low level signal takes through a whole
gang of them - i had to trace the diagram with a pen... and I still could
be missing something, 'cos I don't *see* the feedback loop - what I'm seeing
is a purely passive *part* of a network, with (what I assume to be inside)
the "PU Adaptors", which are supposed to plug into the (no longer existent)
sockets.

What happened? someone remove the PU module sockets?

I'm looking at a diagram I got from Ned's site, so if you could
point out how the plate gets to see G1 (did you mean the screen?), i'd
appreciate it.

Have you got the Quad 22 schematic?

I didn't mean for you to trace the circuit, although sometimes we have to do
that to service something.
You re-draw from the schematic. This is illuminating.

Didn't have much time to play with this, but did see
different "PU Adaptors" for sale on the 'net - do they complete the RIAA?

Yes, they are a vital part of the record playback eq.


Everything past the ef86's is clear, but the switch bank diagram is drawn by
a sadist... The way I have it set up is with 2 rotary switches, one being
a phono on/off, and the other selecting line-level inputs. There's also a
ganged pot which, basically, changes the values of R21 & R22 simultaneously,
allowing for less gain /more feedback (interacts with the bal. pot.) Sheesh,
I'm late already...
-dim

Quad 22 service is for ppl with lots of time to understand; it was built to
deliberately
upset impatient folks, and folks who like simplicity.
The carbon composition resistors and Hunt's caps give an amusing twist to the
outcomes from inadequate servicing.
At least Quad put in plenty of stuff that you have to later take out, but then
this is the case with all electronics before plastic film C and metal film R,
ie, before about 1960.
There is plenty to justify the price you gotta charge for a fix.
Pots can go noisy after all those years as well.....


But Quad switches are fairly reliable I have found, believe me.

I use about 1/3 of the number quad use in a typical strip out and total
re-design
and rebuild.

I have the schematic here someplace for what I have done with these critters.

I keep saying I'll never revise another Quad 22, but they keep turning up on the
bench for a fix.
The phono section loses HF and LF if never serviced. Just the MF is left.
Even the hunts caps drift to a higher value.....

Patrick Turner.

"Patrick Turner" wrote

Do you mean Zp, rather than RL? It should be *much greater*,
surely?

Getting *much greater* is impossible with SE unless the tranny is
huge.
But sorry, i meant ^not^ less than Rl at 20 Hz.
No need for it to be much more.

You are quite right about SE. For all OPTs, if Zp is not *much*
greater than ZLp then µr is significant in the transfer function.
With PP, µr is non-linear so distortion will result if it is
significant. "Much greater" seems to mean an order of magnitude
greater at least, maybe 20 or 30 times, but test data isn't
generally easy to find.

This book needs a glossary.

With SE, you rely on µr being linear, because of the gap and the
bias, and so you can get away with Zp = ZLp, more or less.

Obviously you know all this already. Just dropped in to correct your
slip.

I might add that SE cores have to be tested in the amp to get the
optimal
Lp for a given value of Ip DC.
never assume you got the gap right unless you made sure you got it
right

by doing the tests and plotting the inductance for various gap
sizes and
with
nearly full signal voltage applied.

Of course, although I guess with enough maths it could be closely
predicted. Easier to just get on with it in practice though.

So that rules out anyone being able to sell me a ready made SE
tranny
with a fixed gap.
I have to know for myself it is right.

So I wind and test my own to make damn sure.

Of course. That's because you don't repeat. Repetition is necessary
for industrial production.

OTOH, repetition obviously takes place in the market as a whole. You
tend to use valves that are available from current production, and
your output stages are generally straightforward, so several
standard OPTs will be available from quality suppliers such as
Sowter, Plitron, Lundahl, etc. They will have got the gaps right by
now.

Unless you feel the need to fine tune them for the customer's
particular system.

Your position in the market is not a necessity, but something you
have chosen. It is your marketing strategy.

cheers, Ian

Ian Iveson wrote:

"Patrick Turner" wrote

Do you mean Zp, rather than RL? It should be *much greater*,
surely?

Getting *much greater* is impossible with SE unless the tranny is
huge.
But sorry, i meant ^not^ less than Rl at 20 Hz.
No need for it to be much more.

You are quite right about SE. For all OPTs, if Zp is not *much*
greater than ZLp then µr is significant in the transfer function.
With PP, µr is non-linear so distortion will result if it is
significant. "Much greater" seems to mean an order of magnitude
greater at least, maybe 20 or 30 times, but test data isn't
generally easy to find.

PP amps using latter day GOSS cores have much less distortion
than old day 1955 iron, and the ZLp to RL ratio
is much more favourable than the case for SE amps, where
the DC necessitates gapping, and then you have to still have just enough
inductance.

The original Williamson design had about 100H at low levels ( worst case
)
so at 20 Hz, Zlp = 12.56 kohms, and this in parallel with 10k RL
was not going to reduce the response much at 20 Hz with triodes
with Ra-a = 3.2k.
But at higher levels, LP peaks at 600H, and
the Zlp becomes negligible even at 20 Hz.

The SE amp on the other hand has ZLp about = RL at 20 Hz
at *all* levels of operation because the gapping makes the
core have a much more constant inductance value.

the modern steels I use now would gibe the original Williamson design
a low level Lp = 340H, and maximum Lp = 2,040H,
rather a lot, so the original
Williamson core size and primary turns could be reduced at least
70% if we were to allow Fsat to be 14 Hz instead of 10 Hz as it is with
the original design.
Modern GOSS still saturates like the older steels.

Better still is to increase the core size to reduce the P turns,
and the whole design profits with lower winding losses, far lower
leakage,
more capacity for overload or higher power, etc.


This book needs a glossary.

With SE, you rely on µr being linear, because of the gap and the
bias, and so you can get away with Zp = ZLp, more or less.

Obviously you know all this already. Just dropped in to correct your
slip.

I might add that SE cores have to be tested in the amp to get the
optimal
Lp for a given value of Ip DC.
never assume you got the gap right unless you made sure you got it
right

by doing the tests and plotting the inductance for various gap
sizes and
with
nearly full signal voltage applied.

Of course, although I guess with enough maths it could be closely
predicted. Easier to just get on with it in practice though.

If I had to build a thousand amps, one still needs to calculate a bit,
then get a prototype working flawlessly, and then copy it 1,000 times.

After the first 20 attempts at OPTs, one sort of looks at a spec, and
immediately
the brain presents a start point for an OPT.
Theen its a case of checking the guess, and optimizing it.

I am currently working on a program to allow folks to wade through
about 45 steps to arrive at truly very good designs.





So that rules out anyone being able to sell me a ready made SE
tranny
with a fixed gap.
I have to know for myself it is right.

So I wind and test my own to make damn sure.

Of course. That's because you don't repeat. Repetition is necessary
for industrial production.

OTOH, repetition obviously takes place in the market as a whole. You
tend to use valves that are available from current production, and
your output stages are generally straightforward, so several
standard OPTs will be available from quality suppliers such as
Sowter, Plitron, Lundahl, etc. They will have got the gaps right by
now.

Perhaps.

There is the school of though that says,
"let us buy a big muther of an OPT, and examine what its good for,
and then let us arrange the tubes to suit the tranny."

Its a perfectly valid design option for those who can't design an OPT
let alone make one themselves.

But they do have to have a flexible mind and not have too many limiting
preset ideas about what is a good sounding tube or not.
The 13E1 is a ratbag tube if ever there was one when its used as an SE
beam tetrode
output tube.
Its never going to be the darling of the hi-fi hi-end cognescenti or the
hi-fi press,
and the transfer curve is as straight as a dog's hind leg.
But so darn what?

But with 66% UL, or triode, wow, you really have something.
The tube is totally transformed to something very good, both in terms of
measure and sonics.
I still have to try the tube with CFB, and I expect more power, less
thd,
good spectra, low Ra', and even better music.


Unless you feel the need to fine tune them for the customer's
particular system.

Sometimes I do. The SE35 I made last year were tailored
to suit one guy's idea. They worked well when he bought them
for use as mid-treble amps in a bi-amped system with an 8585 for the
bass,
complete with inbuilt bass filters to allow the benefits of bi-amping.

I thought the whole idea was extravagant, but I am mainly here to do or
die,
and not always to reason why.....


Your position in the market is not a necessity, but something you
have chosen. It is your marketing strategy.

In another thread you were slightly less polite.

But you are right, I am not needed, I could be parcelled out with the
rubbish
and and almost nobody would care.

He, he, I don't care about who might throw me out.
Enough people buy my production to keep me
off the streets and outa jail, and well employed.

Patrick Turner.






cheers, Ian

"Patrick Turner" wrote

The 13E1 is a ratbag tube if ever there was one when its used as
an SE
beam tetrode
output tube.
Its never going to be the darling of the hi-fi hi-end cognescenti
or the
hi-fi press,
and the transfer curve is as straight as a dog's hind leg.
But so darn what?


13E1 has been in and out of fashion amongst some cognoscenti. Prices
still seem high. Is triode similar to 6550? What did Denis advocate
for CFB pentode, EL360? Basically, you need stacks of *perveance*.

I have some 3D21 pulse valves that I could only find pulse data for
until now. I got them because they were cheap and look mean and have
the nice ST logo on the glass. The anode is flat like a big triode.
I tried mapping them on my valve tester but they kept turning blue
and running off the scale.

Now I have found some curves. Tetrode is a dogs dinner, but triode
could be nice...data is sparse for sensible currents though. They
will tolerate half a watt of grid current too.

http://www.mif.pg.gda.pl/homepages/f...7/3/3D21WB.pdf

I haven't got a simulation model for a really kinky pentode. I am
wondering whether CFB pentode mode will still be quite wiggly at the
low voltage / high current end of its working range. CFB triode
would be good if there is enough gain.

cheers, Ian

Ian Iveson wrote:

"Patrick Turner" wrote

The 13E1 is a ratbag tube if ever there was one when its used as
an SE
beam tetrode
output tube.
Its never going to be the darling of the hi-fi hi-end cognescenti
or the
hi-fi press,
and the transfer curve is as straight as a dog's hind leg.
But so darn what?

13E1 has been in and out of fashion amongst some cognoscenti. Prices
still seem high. Is triode similar to 6550?

13E1 is about equal to 2 x 6550 strapped together, or 3 x EL34.

What did Denis advocate
for CFB pentode, EL360? Basically, you need stacks of *perveance*.

I have some 3D21 pulse valves that I could only find pulse data for
until now. I got them because they were cheap and look mean and have
the nice ST logo on the glass. The anode is flat like a big triode.
I tried mapping them on my valve tester but they kept turning blue
and running off the scale.

Now I have found some curves. Tetrode is a dogs dinner, but triode
could be nice...data is sparse for sensible currents though. They
will tolerate half a watt of grid current too.

http://www.mif.pg.gda.pl/homepages/f...7/3/3D21WB.pdf

Pretty awful as a tetrode, but triode is fine.

UL would be OK.





I haven't got a simulation model for a really kinky pentode. I am
wondering whether CFB pentode mode will still be quite wiggly at the
low voltage / high current end of its working range. CFB triode
would be good if there is enough gain.

CFB works like UL in that where Eg2 is fixed at the optimum value,
usually
lower than Ea, the CFB is applied not only around the grid circuit but
also to the screen circuit.
The more CFB you have, the more the tube relative conditions approach
UL.

The main purpose of the UL connection in SE amps is to reduce odd order
Dn and render the
spectra to equal triodes, or mainly even order.
SEUL Dn isn't much less than tetrode Dn as a %, but the spectra is more
benign than tetrode.

To force a tetrode to have triode like spectra with CFB, a lot of CFB
has to be applied.
Then the fb also applied around the g1 circuit reduces this benign thd
down further.

Using a similar amount of global FB around a gain tube and tetrode fails
to
improve the spectral ****tiness of the tetrode; the % thd is merely
reduced.

Its for these reasons I like CFB, or even UL

QE08 is also another brute of a ratbag tetrode which is even better than
13E1 in that in works
well with just 500v, and in UL, etc, and it had graphite slabs for the
anode, and 3
cathodes, not just two like 13E1 has....

Bloody ripper tube alright.
They are used in transmitters, but are probably not being made anymore.
It has a top cap too.
It makes an 807 look like a toy.


Patrick Turner.








cheers, Ian