[Ian Bell[_2_]]

Phil Allison wrote:
"Ian Bell"
I am not sure that choice is actually involved. The source material is
inevitably coloured. If it is an old recording it was recorded using tubes
or old transistor and transformer technology all of which adds its own
colour. If it is a modern recording it is certain to have been 'processed'
digitally which also adds its own particular colour.

Having a totally transparent replay chain therefore has little effect.


** So Ian simply does not believe in " hi-fi " - the basic idea of which
is that the equipment should not degrade or otherwise alter the audio
signals presented to it.

No, I don't believe it is often achieved in a normal domestic situation.
When I was at Neve in 70s I had the opportunity to visit many studios
and hear first hand the original recordings on professional speakers in
properly treated rooms. The sound quality is stunning. My own hi-fi was
so poor by comparison it put me off playing music at home for many years.


Maybe when he goes to visit an art gallery or watch movie, he wears his
favourite rose tinted glasses ??


So you think the lighting in art galleries is exactly as the artist
intended - you fool. You think the quality of a picture several hundred
years old is as good as when it was first painted - you fool.

I don't very often go to the movies - the sound quality is so poor.

Perhaps he has a whole bunch of different coloured tints and perspective
altering lenses too.

Wot a ******.



Cheers

Ian

...... Phil

[fryzz]

On Dec 3, 5:16 pm, cipher wrote:
fryzz wrote :



On Dec 3, 3:56 pm, cipher wrote:
ok..

my mastersound amp..

love the sound of it. got it for a great price.

BUT... every month or two, a channel would go out. id look inside and
one of the resistor legs would be desoldered or one of the resitors
would be completely desoldered and rattling around in the case. one
time, the resistors were completely heat destroyed, totally crumbling
heaps of powder. this happens about once a month. i love the amp, but
damn. who can make this thing work for me?

at a loss here.

http://s99.photobucket.com/albums/l292/thebullards/?
action=view&current=dueventischematic.jpg

http://www.yousendit.com/download/TT...YStTSURIRGc9PQ

Do you have a schematic, a multimeter, and some technician skills? Is
it always the same resistor? Do the output tubes ever run too hot,
with the plates are glowing cherry red?

The first thing to look at is what the output tubes' idle current is.
You can measure the resistance of the plate windings on the output
transformers, and with the amp on and the inputs shorted, measure the
voltage between plate and V+. Then use that, with the resistance, and
Ohm's law, to calculate the plate current. Multiply that current by
the plate voltage to get the plate dissipation. You can look up the
tube characteristics, and then determine if they are being run within
ratings. If that all looks good, maybe the resistors used by the
manufacturer are under rated.

You can also use the drop across the cathode resistor (assuming it's
cathode biased), remembering that this value will also include the
screen current.

I have that crude schematic. I do have a nice multimeter, yes. The tubes do
actually run hot, yes with them glowing like close encounters or
something......that has happened several times.

I cant see why the ones used by the manufacturers woould be underrated??
they are a company of pretty good reputation, but..I am not a tech guy.

www.mastersoundsas.it

Oh, the chances are that they chose the right ratings for the parts
and the fact that they are burning up means something else is amiss.
There is often an electrolytic bypass capacitor connected across the
cathode resistor. If this resistor is electrically leaky, then it
will have the effect of lowering the effective resistance of the
cathode resistor, causing the output tubes to be under-biased, which
would in turn cause the output tubes to draw excess current. It is
not at all unusual for a capacitor to become intermittent.

I can only speculate without knowing more specifics. If you want to
send me a copy of your schematic and if you can mark on it which parts
are frying, I will tell you what I can.

Unless you're keen on learning how to do this work yourself, you might
be better off taking it to a qualified technician.

[Phil Allison]

"Ian Bell the ****wit "
Phil Allison wrote:
"Ian Bell"

I am not sure that choice is actually involved. The source material is
inevitably coloured. If it is an old recording it was recorded using
tubes or old transistor and transformer technology all of which adds its
own colour. If it is a modern recording it is certain to have been
'processed' digitally which also adds its own particular colour.

Having a totally transparent replay chain therefore has little effect.


** So Ian simply does not believe in " hi-fi " - the basic idea of
which is that the equipment should not degrade or otherwise alter the
audio signals presented to it.

No, I don't believe it is often achieved ......


** Not relevant to the point - ****WIT !!


Maybe when he goes to visit an art gallery or watch movie, he wears his
favourite rose tinted glasses ??


So you think the lighting in art galleries...


** Not relevant to the point - ****WIT !!


I don't very often go to the movies ..


** Not relevant to the point - ****WIT !!

Wot a ****ing useless ******.



...... Phil

[Phil Allison]

"flipper"
Arny Krueger

Sonically transparent tubed amps can and have been built and sold.
However,
they tend to be far larger, heavier, more wasteful of natural resources,
less reliable, more expensive to mainatin, and far, far more expensive
than
a SS amp that sounds the same.

That is a matter of opinion and it should be obvious, by now, that not
everyone agrees.


** Massive logical fallacy.

Facts are not determined by taking a popular vote.

IOW, the half baked opinions of the ill informed masses have no bearing on
matters of fact.


If transparent tube amps were the kinds of amps that tube hobbiest were
building, then so be it, it is their time and money. However, SE and
anti-inverse-feedback have become stylish. Still no problem, as it is
still
the tubies time and money. But then they get all weird and tell the rest
of
the world that this is the holy grail and the only way to obtain good
sound.
Foul!


The only 'foul' I see are SS (appropriate coincidence) fascists


** Yawnnnnnn.....

More half baked opinion presented in lieu of any kind of case.

The pre-historic reptile brain is still alive an well inside any " tube head
".



....... Phil

[cipher]

"Phil Allison" wrote in
:


"cipher"

r68.. the problem children


** Jeez - it took a while to squeeze THAT simple fact out of you.

What a ****head you are.

The " problem children " are not the resistors but the EL34s, you
colossal JERK.

Get some good new ones (Russian not Chinese) and set the bias to 5
volts on each 68 ohm cathode resistor.



..... Phil





you know what (and my apologies to Mr. Wieck and Mr. Flipper), **** you.

I mentioned before that I am not a goddamned technician, and depend on the
graces of POLITE GENTLEMEN like Mr. Wieck for what ****ing advice I can get
from this mother****ing cynic circle jerk dick wagging site.

and as I said before, you ****ing dick..

were you missing the point where I said that the resistor legs seemed to
have been desoldered somehow, after replacing them at least 3 times?(the
resistors, guh yup!!!)

Ive gone through 5 sets of mother****ing tubes. 3 sets of mother****ing
resistors and about 10 bottles of xanax with this mother****er and
goddamnit I come here to ask for advice nicely giving my proper sirs and
thanks yous and providing what information I had BECAUSE GUESS WHAT????
PROVIDE INFORMATION HELPS WHO??? Well goddamn!!! ME!!! replace resistors
multiple times, replace tubes multiple times, and just meebbee it sounds
like its neither one of those ****ing causes.

my holding back on information was because guess what!!! YEP AGAIN!! THATS
ALL THE INFORMATION I HAD!! IT is not part of some black op ts-3a
classified s2 mission to keep some ****ing information from you or anybody
else.

I spent a good bit of my goddamned life in the us army infantry, 3 years in
iraq and i know how to render courtesy when it is called for, but hell ,
man, or sir , or maam or it or whatever the ****... I can be a
confrontational asshole too, but id rather not, so either be nice or shut
the **** up already!


if it is such a pain to help out, do me a favor and keep your chest puffing
depakote mainlining sociopath kneejerk bull**** out of my ****ing AO!


Mr. Wieck, and Mr. Flipper, and whoever is interested in helping...I thank
you for your help, I am requesting a "real" schematic.

[cipher]

flipper wrote in
:

On Thu, 04 Dec 2008 12:09:27 -0600, cipher wrote:

flipper wrote in
m:

On Wed, 03 Dec 2008 14:56:46 -0600, cipher
wrote:

ok..

my mastersound amp..

love the sound of it. got it for a great price.

BUT... every month or two, a channel would go out. id look inside
and
one of the resistor legs would be desoldered or one of the resitors
would be completely desoldered and rattling around in the case. one
time, the resistors were completely heat destroyed, totally
crumbling
heaps of powder. this happens about once a month. i love the amp,
but
damn. who can make this thing work for me?

at a loss here.

http://s99.photobucket.com/albums/l292/thebullards/?
action=view&current=dueventischematic.jpg

http://www.yousendit.com/download/TT...YStTSURIRGc9PQ

Which 'resistors'?

If I were to guess I'd imagine it's the EL34 cathode resistors but
you
really need to be more detailed.

Just looking at the schematic the first thing that pops out is
whether
it's biased properly. I.E. Those two pots down on the 20V winding.

The second thing is those adjustment pots are not reliable, as
designed. The wiper is all 'alone', meaning if it breaks contact,
which can happen, bias goes bonkers. And that would be consistent
with
seeming to work fine for a while and then, all of a sudden, run
away.

Out of curiosity, why didn't you just post the schematic pic itself
instead of a 'screen shot'?


I posted what I had, bud.

All I did was ask, 'bud', because it's hard to read.

I sure as hell wouldnt hold anything back...

Maybe not intentionally but it has the appearance. When you say "a
channel," is it always the same channel or either or random?

When was the 'first time' and who repaired it? What was diagnosed and
what was replaced, and with what? And who repaired it the subsequent
times? How diagnosed and replaced with what?

Is it always the same channel *and* the same tube? Have you tested the
tubes? Have they ever been replaced or moved to different sockets?
When was the last time bias was checked?

Are you able to read component values? If so, then trace it out and
put some values on that schematic.

And some meter readings would be nice. Are all the cathodes at 6V like
the schematic says they should? But don't try if you're not skilled
with high voltage circuits.

r68.. the problem children

I cant tell, for sure, from the picture which one is 'r68'. The
sharpened 'blur' looks like it might be the cathode resistor under the
left EL34.

Just one? Because your description said "resistors:" plural.

for the life of me, I cannot figure out why one seeking help would hold
back information?? I called you bud as a friendly term.. apparently
slurring each other is more appropo..

as for the technical stuff...working on it.

[Arny Krueger]

"Ian Bell" wrote in message


So why have a completely transparent amp when the
speakers and room are so relatively poor.

The reality of the situation is that a good listener can in some real world
situations hear a +/- 0.5 dB difference in amp response, in a room/speaker
situation where overall response is +/- 5 dB. However, you can't hear a +/-
0.1 dB difference in the amp, no matter how good the room+speakers are.

Similarly, in some real-world situations nonlinear distortion that creates
0.1 % THD in the 15-20 KHz range can be heard, even though the
room+speakers have equal or greater distortion.

To obtain high fidelity you need to address all aspects of the system
not just the amp.

Agreed, but that doesn't mean that you intentionally make the strongest link
into the weakest link.

[Phil Allison]

"cipher"

** Christ alive, we have ourselves a red hot **** HEAD folks !!!


r68.. the problem children


** Jeez - it took a while to squeeze THAT simple fact out of you.

What a ****head you are.

The " problem children " are not the resistors but the EL34s, you
colossal JERK.

Get some good new ones (Russian not Chinese) and set the bias to 5
volts on each 68 ohm cathode resistor.


you know what (and my apologies to Mr. Wieck and Mr. Flipper), **** you.


** You are so * totally ****ed * already that insult has no value.


I mentioned before that I am not a goddamned technician,


** But what you ARE is a 100% GODDAMED ****WIT !!!!!


were you missing the point where I said that the resistor legs seemed to
have been desoldered somehow, after replacing them at least 3 times?


** Hey, you ****ing ASSHOLE !!

You never posted WHICH ONES THEY WERE !!!!!!!!!


Ive gone through 5 sets of mother****ing tubes.


** You never posted that info before - either.

Now how about you post what brand EL34s they were and where you got them ?

YOU COLOSSAL ****ING MORON !!!!!



3 sets of mother****ing
resistors and about 10 bottles of xanax with this mother****er and
goddamnit I come here to ask for advice nicely giving my proper sirs and
thanks yous and providing what information I had BECAUSE GUESS WHAT????
PROVIDE INFORMATION HELPS WHO??? Well goddamn!!! ME!!! replace resistors
multiple times, replace tubes multiple times, and just meebbee it sounds
like its neither one of those ****ing causes.


** Wot a complete lunatic !!!!!

Too far gone for any shrink or medication to help.



my holding back on information was because guess what!!! YEP AGAIN!! THATS
ALL THE INFORMATION I HAD!! IT is not part of some black op ts-3a
classified s2 mission to keep some ****ing information from you or anybody
else.


** Wot a complete lunatic !!!!!

Too far gone for any shrink or medication to help.



I spent a good bit of my goddamned life in the us army infantry, 3 years
in
iraq and i know how to render courtesy when it is called for, but hell ,
man, or sir , or maam or it or whatever the ****... I can be a
confrontational asshole too, but id rather not, so either be nice or shut
the **** up already!


** Wot a complete lunatic !!!!!

Too far gone for any shrink or medication to help.

Bet he was discharged for gross metal instability.



Mr. Wieck, and Mr. Flipper, and whoever is interested in helping...I thank
you for your help, I am requesting a "real" schematic.


** There is a chance the demented cretin will electrocute himself.

We can only hope.



..... Phil

[Phil Allison]

"flipper the ****head "


** Massive logical fallacy.

Nice try, but no.


Facts are not determined by taking a popular vote.

You are correct. 'facts' aren't. Unfortunately for your argument we're
talking 'opinion'.


** You have ZERO comprehension of the topic.

So **** the HELL OFF

- you PATHETIC, hee hawing ASS !!!




... Phil

[cipher]

"Phil Allison" wrote in
:


"cipher"

** Christ alive, we have ourselves a red hot **** HEAD folks !!!


r68.. the problem children


** Jeez - it took a while to squeeze THAT simple fact out of you.

What a ****head you are.

The " problem children " are not the resistors but the EL34s, you
colossal JERK.

Get some good new ones (Russian not Chinese) and set the bias to 5
volts on each 68 ohm cathode resistor.


you know what (and my apologies to Mr. Wieck and Mr. Flipper), ****
you.


** You are so * totally ****ed * already that insult has no value.


I mentioned before that I am not a goddamned technician,


** But what you ARE is a 100% GODDAMED ****WIT !!!!!


were you missing the point where I said that the resistor legs seemed
to have been desoldered somehow, after replacing them at least 3
times?


** Hey, you ****ing ASSHOLE !!

You never posted WHICH ONES THEY WERE !!!!!!!!!


Ive gone through 5 sets of mother****ing tubes.


** You never posted that info before - either.

Now how about you post what brand EL34s they were and where you got
them ?

YOU COLOSSAL ****ING MORON !!!!!



3 sets of mother****ing
resistors and about 10 bottles of xanax with this mother****er and
goddamnit I come here to ask for advice nicely giving my proper sirs
and thanks yous and providing what information I had BECAUSE GUESS
WHAT???? PROVIDE INFORMATION HELPS WHO??? Well goddamn!!! ME!!!
replace resistors multiple times, replace tubes multiple times, and
just meebbee it sounds like its neither one of those ****ing causes.


** Wot a complete lunatic !!!!!

Too far gone for any shrink or medication to help.



my holding back on information was because guess what!!! YEP AGAIN!!
THATS ALL THE INFORMATION I HAD!! IT is not part of some black op
ts-3a classified s2 mission to keep some ****ing information from you
or anybody else.


** Wot a complete lunatic !!!!!

Too far gone for any shrink or medication to help.



I spent a good bit of my goddamned life in the us army infantry, 3
years in
iraq and i know how to render courtesy when it is called for, but
hell , man, or sir , or maam or it or whatever the ****... I can be a
confrontational asshole too, but id rather not, so either be nice or
shut the **** up already!


** Wot a complete lunatic !!!!!

Too far gone for any shrink or medication to help.

Bet he was discharged for gross metal instability.



Mr. Wieck, and Mr. Flipper, and whoever is interested in helping...I
thank you for your help, I am requesting a "real" schematic.


** There is a chance the demented cretin will electrocute himself.

We can only hope.



.... Phil




\

nah, I am fine really. I was just engaging in your native tounge.

As for the tube types?? came from the dealer with EH tubes which I dont
like at all for various reasons, biggest being they have a bad
reputation. I called the dealer infuriated and asked for replacements
(thinking it was just bad tubes) so he sent me JJs. Those worked fine
for a while, until one day while doing a freq sweep cd I heard a pop and
a dead channel...opened it up(the amp) saw a blown fuse and a resistor
out of place, so I took it to my neighbor(who restores antique radios on
the side) to see if he could put it back together. He soldererd the
resistor back and it worked for a couple months..then one day...pop,
channel goes out again...so I take it to another guy who takes it apart
in front of me and discovers that the resistors had turned to dust,
basically...he said from heat, but I dunno....anyway, he orders new ones
of the same type and value from mouser and solders it.....I assumed I
hadf the problem licked so I ordered some sed winged c el34 from
thetubedepot.com

was in bliss for a couple months then pop channel goes out(last week)...

so the manufacturer has agreed to ship it over to italy for extensive
repairs....but putting the resistors , soldering them back fixes it for
a while., then they become desoldered....

[Peter Wieck]

On Dec 5, 9:15*pm, cipher wrote:

so the manufacturer has agreed to ship it over to italy for extensive
repairs....but putting the resistors , soldering them back fixes it for
a while., then they become desoldered.


8 gets you 20 you don't get the same amp back.

Perhaps the same sheet-metal, but I suspect it will be otherwise
gutted almost entirely.

And as for shipping it back to Italy - that is mind-boggling. Their
local reps must be entirely clueless and/or know that something is
radically wrong or both and don't quite want to admit it.

Peter Wieck
Melrose Park, PA

[Ian Bell[_2_]]

Phil Allison wrote:
"Ian Bell"

So why have a completely transparent amp when the speakers and room are so
relatively poor.


** Very accurate, low distortion speakers are readily available - but not
necessarily cheap.


Indeed, and there's the rub for most people.

Treating a listening room so it does very little harm to the sound

MORON. The whole point is that an untreated roo does a lot of harm to
the room.

is a
quite straightforward exercise and can be done fairly cheaply.


You clearly have little knowledge of practical acoustics. It is
certainly not straightforward and is definitely not cheap.

Transparent amplifiers are virtually a dime a dozen - choosing to NOT use
one is kinda insane.


Indeed, but that is not the point. Choosing a transparent amp in an
already seriously flawed system is pointless.


Except, of course, if you simply do not believe in "hi-if" at all


Believe? Is this a matter of faith now!!!!


Cheers

Ian
- like this demented clown.



..... Phil

[mick]

On Fri, 05 Dec 2008 22:43:23 -0600, flipper wrote:

snip (about time someone did!)

OK. As you probably saw in my other posts, first time around I missed
the PDF but have it now.

Have you asked Mastersound, themselves, why the amp does this? And
what's their explanation for it?


It looks as if the "68" is the value, not the resistor number, doesn't
it? I was confused too... (I frequently am nowadays... :-( )

cipher: I hope we are talking about the same amp here. Is your amp the
big black one in the pics? If so, I assume that you have rectifier tubes
(GZ34 or something?) instead of the bridge recs shown in the pdf? If so,
we can't read too much into the B+ voltage as we don't know what your
mains transformer is really like.

Personally, I'm not happy about trusting the production schematic (pdf)
for a demo amp. Too many things may have changed.

If that pdf is right then the 2 output cathode resistors should probably
be about 2W rating for comfort. Any idea what's fitted, cipher? The
standing dissipation is just over 0.5W (if you use the recommended 6v
across the resistors) so I wouldn't like to risk 1W types if the chassis
is at all cramped.

Phil's suggestion of reducing the voltage to 5v looks good if you want a
longer tube (and resistor!) life. Everything will run a bit cooler. You
could comfortably fit 1W resistors in this case.

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
Filtering everything posted from googlegroups to kill spam.

[Ian Bell[_2_]]

Phil Allison wrote:
"flipper the ****head "

** Massive logical fallacy.
Nice try, but no.

Facts are not determined by taking a popular vote.
You are correct. 'facts' aren't. Unfortunately for your argument we're
talking 'opinion'.


** You have ZERO comprehension of the topic.

So **** the HELL OFF

- you PATHETIC, hee hawing ASS !!!


You can always tell when Phil is losing an argument! LOL

Cheers

IAn

[Ian Bell[_2_]]

Arny Krueger wrote:
"Ian Bell" wrote in message


So why have a completely transparent amp when the
speakers and room are so relatively poor.

The reality of the situation is that a good listener can in some real world
situations hear a +/- 0.5 dB difference in amp response, in a room/speaker
situation where overall response is +/- 5 dB. However, you can't hear a +/-
0.1 dB difference in the amp, no matter how good the room+speakers are.

Similarly, in some real-world situations nonlinear distortion that creates
0.1 % THD in the 15-20 KHz range can be heard, even though the
room+speakers have equal or greater distortion.


Is this simply your opinion or can you cite research that demonstrates
these?

|Cheers

Ian

To obtain high fidelity you need to address all aspects of the system
not just the amp.

Agreed, but that doesn't mean that you intentionally make the strongest link
into the weakest link.


Indeed, but that was not the point I was making originally. And I am so
tired of reiterating it I am not going to bother doing so again.

Cheers

Ian

[Arny Krueger]

"Ian Bell" wrote in message

Phil Allison wrote:
"Ian Bell"

So why have a completely transparent amp when the
speakers and room are so relatively poor.

** Very accurate, low distortion speakers are readily
available - but not necessarily cheap.

The prices are coming down, and they are not prohibitive.

Indeed, and there's the rub for most people.

Treating a listening room so it does very little harm to
the sound

MORON. The whole point is that an untreated room does a
lot of harm to the room.


So resolved, if you have rotten speakers and a very poor, untreated room,
then tubed audio is for you!

[Arny Krueger]

"Ian Bell" wrote in message

Arny Krueger wrote:
"Ian Bell" wrote in message


So why have a completely transparent amp when the
speakers and room are so relatively poor.

The reality of the situation is that a good listener can
in some real world situations hear a +/- 0.5 dB
difference in amp response, in a room/speaker situation
where overall response is +/- 5 dB. However, you can't
hear a +/- 0.1 dB difference in the amp, no matter how good the
room+speakers are. Similarly, in some real-world situations nonlinear
distortion that creates 0.1 % THD in the 15-20 KHz range can be heard,
even
though the room+speakers have equal or greater
distortion.

Is this simply your opinion or can you cite research that
demonstrates these?

I could, but you seem to be so biased that you wouldn't be able to
comprehend it. You might also have to pay some money to buy copies of the
papers.

[Phil Allison]

"Ian Bell is Full of **** "

** Very accurate, low distortion speakers are readily available - but not
necessarily cheap.


Indeed, and there's the rub for most people.


** ********.


Treating a listening room so it does very little harm to the sound
is a quite straightforward exercise and can be done fairly cheaply.


You clearly have little knowledge of practical acoustics.


** Yawnnnnnnnnnnnnnn.

No facts, no logic = no case to answer.


Transparent amplifiers are virtually a dime a dozen - choosing to NOT
use one is kinda insane.


Indeed, but that is not the point.


** Yes it is - you boring as bat ****, autistic PITA ****head.


Except, of course, if you simply do not believe in "hi-if" at all


Believe?


** Yep.

The basic concept of " hi-fi " is an inherently desirable goal.

Non believers merely need to say so.

Like non believers in democracy, science, fairness or the search for truth.

Then we know exactly WHO to totally ****ing ignore.


So go drop dead -

you asinine, psychotic pommy ****.




...... Phil

[Ian Bell[_2_]]

Arny Krueger wrote:
"Ian Bell" wrote in message

Arny Krueger wrote:
"Ian Bell" wrote in message


So why have a completely transparent amp when the
speakers and room are so relatively poor.
The reality of the situation is that a good listener can
in some real world situations hear a +/- 0.5 dB
difference in amp response, in a room/speaker situation
where overall response is +/- 5 dB. However, you can't
hear a +/- 0.1 dB difference in the amp, no matter how good the
room+speakers are. Similarly, in some real-world situations nonlinear
distortion that creates 0.1 % THD in the 15-20 KHz range can be heard,
even
though the room+speakers have equal or greater
distortion.

Is this simply your opinion or can you cite research that
demonstrates these?

I could, but you seem to be so biased that you wouldn't be able to
comprehend it. You might also have to pay some money to buy copies of the
papers.




LOL. So name the articles then and let me decide whether or not to pay
for them..

Cheers

Ian

[Ian Bell[_2_]]

Arny Krueger wrote:
"Ian Bell" wrote in message

Phil Allison wrote:
"Ian Bell"

So why have a completely transparent amp when the
speakers and room are so relatively poor.

** Very accurate, low distortion speakers are readily
available - but not necessarily cheap.

The prices are coming down, and they are not prohibitive.

Indeed, and there's the rub for most people.

Treating a listening room so it does very little harm to
the sound
MORON. The whole point is that an untreated room does a
lot of harm to the room.


So resolved, if you have rotten speakers and a very poor, untreated room,
then tubed audio is for you!



No, all I said was a transparent amp in an already seriously flawed
system is pointless.

Cheers

Ian

[fryzz]

On Dec 3, 3:56 pm, cipher wrote:
ok..

my mastersound amp..

love the sound of it. got it for a great price.

BUT... every month or two, a channel would go out. id look inside and one
of the resistor legs would be desoldered or one of the resitors would be
completely desoldered and rattling around in the case. one time, the
resistors were completely heat destroyed, totally crumbling heaps of
powder. this happens about once a month. i love the amp, but damn. who can
make this thing work for me?

at a loss here.

http://s99.photobucket.com/albums/l292/thebullards/?
action=view&current=dueventischematic.jpg

http://www.yousendit.com/download/TT...YStTSURIRGc9PQ

I just spotted your schematic, duh.

Sorry if this is redundant, I just didn't feel like wading through all
the vituperative infantile bull**** that collects around here in order
to be sure I wasn't repeating what someone else may have already said.

I'm guessing you have an intermittent bias problem. Your amp has a
separate bias supply, so the 68 ohm resistors are mostly just a
convenient way of adjusting the idle current. If those bypass
capacitors on the 68 ohm jobs are leaky, it would actually have the
effect of increasing the negative voltage on the grid, which reduces
the idle current, so that's not why the tubes would draw too much
current.

The first thing I would look at is the bias potentiometers, pots do
tend to be trouble prone due to the moving parts. You could try
cleaning them with something like Caig Deoxit. You might also try
feeling those two filter caps in the bias supply after the amp has
been on for a while. They'll pick up some heat just from being in a
tubeamp, but if one is warmer than the other it's a sign that cap is
leaking. Another thing you might try is touching up all of the solder
joints in the bias supply. You might also just leave your multimeter
hooked up, to see if the output of the bias supply is dropping when
the amp gets that "close encounters" look. When you measure the
output of the bias supply, it should be stable and noise free.

Hope this helps

[Ian Bell[_2_]]

Phil Allison wrote:
"Ian Bell is Full of **** "

** Very accurate, low distortion speakers are readily available - but not
necessarily cheap.

Indeed, and there's the rub for most people.


** ********.


You want to rub your ******** that's fine with me.


Cheers

Ian

[Arny Krueger]

"Ian Bell" wrote in message

Arny Krueger wrote:
"Ian Bell" wrote in message

Phil Allison wrote:
"Ian Bell"

So why have a completely transparent amp when the
speakers and room are so relatively poor.

** Very accurate, low distortion speakers are readily
available - but not necessarily cheap.

The prices are coming down, and they are not
prohibitive.
Indeed, and there's the rub for most people.

Treating a listening room so it does very little harm
to the sound
MORON. The whole point is that an untreated room does a
lot of harm to the room.


So resolved, if you have rotten speakers and a very
poor, untreated room, then tubed audio is for you!

No, all I said was a transparent amp in an already
seriously flawed system is pointless.

Right, but since when is our pursuit of the audio hobby about intentionally
using a seriously flawed system?

[mick]

On Sat, 06 Dec 2008 06:33:27 -0600, flipper wrote:

snip

Those pics are of a different amp.


I was wondering. If you reckon on two of the GT bottles being individual
rectifiers for each channel then it could possibly be a dual mono amp on
a single chassis. Mind you, that doesn't explain the, possibly EZ81-type
thingy and there is one too many small B9A bottle. That may just be
enough changes between a prototype and a production version though. It
*could* have a valve rectifier for bias and an extra amplification stage.

Come on, cipher, let us into the secret! ;-)

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
Filtering everything posted from googlegroups to kill spam.

[cipher]

mick wrote in news:Mds_k.3938$fw1.2824
@newsfe25.ams2:

On Fri, 05 Dec 2008 22:43:23 -0600, flipper wrote:

snip (about time someone did!)

OK. As you probably saw in my other posts, first time around I missed
the PDF but have it now.

Have you asked Mastersound, themselves, why the amp does this? And
what's their explanation for it?


It looks as if the "68" is the value, not the resistor number, doesn't
it? I was confused too... (I frequently am nowadays... :-( )

cipher: I hope we are talking about the same amp here. Is your amp the
big black one in the pics? If so, I assume that you have rectifier tubes
(GZ34 or something?) instead of the bridge recs shown in the pdf? If so,
we can't read too much into the B+ voltage as we don't know what your
mains transformer is really like.

Personally, I'm not happy about trusting the production schematic (pdf)
for a demo amp. Too many things may have changed.

If that pdf is right then the 2 output cathode resistors should probably
be about 2W rating for comfort. Any idea what's fitted, cipher? The
standing dissipation is just over 0.5W (if you use the recommended 6v
across the resistors) so I wouldn't like to risk 1W types if the chassis
is at all cramped.

Phil's suggestion of reducing the voltage to 5v looks good if you want a
longer tube (and resistor!) life. Everything will run a bit cooler. You
could comfortably fit 1W resistors in this case.


Hey Sir,

it appears as though the pictures from that PDF are from the newer Due
Venti(my amp model) with Auto-Bias. Mine does not have auto bias. I just
figured out that the models with the green led are the newer ones, and mine
(red LED) are older.

[cipher]

mick wrote in news:Mds_k.3938$fw1.2824
@newsfe25.ams2:

On Fri, 05 Dec 2008 22:43:23 -0600, flipper wrote:

snip (about time someone did!)

OK. As you probably saw in my other posts, first time around I missed
the PDF but have it now.

Have you asked Mastersound, themselves, why the amp does this? And
what's their explanation for it?


It looks as if the "68" is the value, not the resistor number, doesn't
it? I was confused too... (I frequently am nowadays... :-( )

cipher: I hope we are talking about the same amp here. Is your amp the
big black one in the pics? If so, I assume that you have rectifier tubes
(GZ34 or something?) instead of the bridge recs shown in the pdf? If so,
we can't read too much into the B+ voltage as we don't know what your
mains transformer is really like.

Personally, I'm not happy about trusting the production schematic (pdf)
for a demo amp. Too many things may have changed.

If that pdf is right then the 2 output cathode resistors should probably
be about 2W rating for comfort. Any idea what's fitted, cipher? The
standing dissipation is just over 0.5W (if you use the recommended 6v
across the resistors) so I wouldn't like to risk 1W types if the chassis
is at all cramped.

Phil's suggestion of reducing the voltage to 5v looks good if you want a
longer tube (and resistor!) life. Everything will run a bit cooler. You
could comfortably fit 1W resistors in this case.


Hey Sir,

my amp has 4 EL 34 components for the power amp section and 2 x ecc 82. the
preamp tubes have never given me a problem, but the power amp section
(specifically, the EL-34 in the back right slot (if looking at it from the
front) always flare up....... it happens like this..

the tube grows bright red, the channel goes out completely.. I open it up
and find desoldered resistors(or in one instance, "rotted" ones)



what could be causing this much heat to desolder the connection??? the
solder joints are nice, doesnt look shoddy or anything.. i am just going to
open it up and take a picture.

[cipher]

mick wrote in news:LCx_k.17960$uy1.13602
@newsfe23.ams2:

On Sat, 06 Dec 2008 06:33:27 -0600, flipper wrote:

snip

Those pics are of a different amp.


I was wondering. If you reckon on two of the GT bottles being individual
rectifiers for each channel then it could possibly be a dual mono amp on
a single chassis. Mind you, that doesn't explain the, possibly EZ81-type
thingy and there is one too many small B9A bottle. That may just be
enough changes between a prototype and a production version though. It
*could* have a valve rectifier for bias and an extra amplification stage.

Come on, cipher, let us into the secret! ;-)


http://www.mastersoundsas.it/NEW%20S...20Due%20Venti%
20manuale%20ingleseA.pdf

yes, this PDF is not of my amp..mine is an older model without autobias.

[cipher]

mick wrote in news:LCx_k.17960$uy1.13602
@newsfe23.ams2:

On Sat, 06 Dec 2008 06:33:27 -0600, flipper wrote:

snip

Those pics are of a different amp.


I was wondering. If you reckon on two of the GT bottles being individual
rectifiers for each channel then it could possibly be a dual mono amp on
a single chassis. Mind you, that doesn't explain the, possibly EZ81-type
thingy and there is one too many small B9A bottle. That may just be
enough changes between a prototype and a production version though. It
*could* have a valve rectifier for bias and an extra amplification stage.

Come on, cipher, let us into the secret! ;-)


nd Sir, I wish I knew what the secret was. it has been very frustrating ,
this whole thing..

what was once excstasy , hearing the sound of that amp, has been replaced
by anger and bitterness at dealing with the mechanical/electrical issues.

aint no free lunch i guess.

http://s99.photobucket.com/albums/l292/thebullards/?
action=view&current=dueventischematic.jpg that one is mine.

[Ian Bell[_2_]]

Arny Krueger wrote:
"Ian Bell" wrote in message

Arny Krueger wrote:
"Ian Bell" wrote in message

Phil Allison wrote:
"Ian Bell"

So why have a completely transparent amp when the
speakers and room are so relatively poor.
** Very accurate, low distortion speakers are readily
available - but not necessarily cheap.
The prices are coming down, and they are not
prohibitive.
Indeed, and there's the rub for most people.
Treating a listening room so it does very little harm
to the sound
MORON. The whole point is that an untreated room does a
lot of harm to the room.

So resolved, if you have rotten speakers and a very
poor, untreated room, then tubed audio is for you!

No, all I said was a transparent amp in an already
seriously flawed system is pointless.

Right, but since when is our pursuit of the audio hobby about intentionally
using a seriously flawed system?



Who said intentionally? The average hi-fi person does not have a clue
about acoustics.

Cheers

Ian

[mick]

On Sat, 06 Dec 2008 18:33:22 +0000, Ian Bell wrote:

snip
Who said intentionally? The average hi-fi person does not have a clue
about acoustics.


....and often doesn't care! The idea is to listen to the music. It must be
awfully difficult for audio "professionals" to realise that this is the
ultimate objective for your average couch potato with any *affordable*
music reproduction gear. ;-)

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
Filtering everything posted from googlegroups to kill spam.

[mick]

On Sat, 06 Dec 2008 11:51:26 -0600, cipher wrote:

snip

my amp has 4 EL 34 components for the power amp section and 2 x ecc 82.
the preamp tubes have never given me a problem, but the power amp
section (specifically, the EL-34 in the back right slot (if looking at
it from the front) always flare up....... it happens like this..

the tube grows bright red, the channel goes out completely.. I open it
up and find desoldered resistors(or in one instance, "rotted" ones)



what could be causing this much heat to desolder the connection??? the
solder joints are nice, doesnt look shoddy or anything.. i am just going
to open it up and take a picture.


Is it *always* the same socket position that fails?

Please do take more pics! Are the problem resistors the 4 rectangular
ones each side of the 4 electrolytics at the rear of the pcb? If so, they
should be mounted well clear of the board, preferably by putting a kink
or loop in their leads. That way less heat is conducted back to the
connection. Keep them at least 10mm away for comfort...

The heat comes from the current that you are asking the resistor to pass.
More current = higher temperature. There can be several reasons for this
overheating to happen, e.g. the (fixed) bias may be out or there could be
another reason such as one or more leaky coupling capacitors - or just a
duff bottle if it's always the same one.

Would you be comfortable working on it "live"? You really need to know
the voltages at each output valve cathode (i.e. across the 68R
resistors). If this is more than +6v (to ground/chassis) on any of them
then you have started to find the problem!

Your description of the tube flaring up bright red then the resistor (or
connection) failing makes me think that your bias controls may well be
the problem. The circuit really needs to be changed, so that an open-
circuit control won't cause this (the present arrangement is not good at
all). It would be a case of adding a couple more resistors then setting
up the bias again. Could you handle that, given a circuit diagram to work
from?

Incidentally, it's a good job that the cathode resistors do fail if there
*is* a bias problem - they are protecting your tubes and output
transformers!

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
Filtering everything posted from googlegroups to kill spam.

[Peter Wieck]

On Dec 6, 12:47*pm, cipher wrote:
mick wrote in news:Mds_k.3938$fw1.2824
@newsfe25.ams2:





On Fri, 05 Dec 2008 22:43:23 -0600, flipper wrote:

snip *(about time someone did!)

OK. As you probably saw in my other posts, first time around I missed
the PDF but have it now.

Have you asked Mastersound, themselves, why the amp does this? And
what's their explanation for it?

It looks as if the "68" is the value, not the resistor number, doesn't
it? I was confused too... *(I frequently am nowadays... :-( *)

cipher: I hope we are talking about the same amp here. Is your amp the
big black one in the pics? If so, I assume that you have rectifier tubes
(GZ34 or something?) instead of the bridge recs shown in the pdf? If so,
we can't read too much into the B+ voltage as we don't know what your
mains transformer is really like.

Personally, I'm not happy about trusting the production schematic (pdf)
for a demo amp. Too many things may have changed.

If that pdf is right then the 2 output cathode resistors should probably
be about 2W rating for comfort. Any idea what's fitted, cipher? The
standing dissipation is just over 0.5W (if you use the recommended 6v
across the resistors) so I wouldn't like to risk 1W types if the chassis
is at all cramped.

Phil's suggestion of reducing the voltage to 5v looks good if you want a
longer tube (and resistor!) life. Everything will run a bit cooler. You
could comfortably fit 1W resistors in this case.

Hey Sir,

it appears as though the pictures from that PDF are from the newer Due
Venti(my amp model) with Auto-Bias. Mine does not have auto bias. I just
figured out that the models with the green led are the newer ones, and mine
(red LED) are older.- Hide quoted text -

- Show quoted text -

It would be no real trick to rebuild what you have to the "new"
configuration. Betcha that is what will happen when it gets back to
Italy.

The question is how much you are willing to take on to do this, or how
much you must farm out. If you farm it out - have the amp sent to
Italy as long as you are not paying the freight. Let them figure it
out and let them do it.

Peter Wieck
Melrose Park, PA

[cipher]

mick wrote in
:

On Sat, 06 Dec 2008 11:51:26 -0600, cipher wrote:

snip

my amp has 4 EL 34 components for the power amp section and 2 x ecc
82. the preamp tubes have never given me a problem, but the power amp
section (specifically, the EL-34 in the back right slot (if looking
at it from the front) always flare up....... it happens like this..

the tube grows bright red, the channel goes out completely.. I open
it up and find desoldered resistors(or in one instance, "rotted"
ones)



what could be causing this much heat to desolder the connection???
the solder joints are nice, doesnt look shoddy or anything.. i am
just going to open it up and take a picture.


Is it *always* the same socket position that fails?

Please do take more pics! Are the problem resistors the 4 rectangular
ones each side of the 4 electrolytics at the rear of the pcb? If so,
they should be mounted well clear of the board, preferably by putting
a kink or loop in their leads. That way less heat is conducted back to
the connection. Keep them at least 10mm away for comfort...

The heat comes from the current that you are asking the resistor to
pass. More current = higher temperature. There can be several reasons
for this overheating to happen, e.g. the (fixed) bias may be out or
there could be another reason such as one or more leaky coupling
capacitors - or just a duff bottle if it's always the same one.

Would you be comfortable working on it "live"? You really need to know
the voltages at each output valve cathode (i.e. across the 68R
resistors). If this is more than +6v (to ground/chassis) on any of
them then you have started to find the problem!

Your description of the tube flaring up bright red then the resistor
(or connection) failing makes me think that your bias controls may
well be the problem. The circuit really needs to be changed, so that
an open- circuit control won't cause this (the present arrangement is
not good at all). It would be a case of adding a couple more resistors
then setting up the bias again. Could you handle that, given a circuit
diagram to work from?

Incidentally, it's a good job that the cathode resistors do fail if
there *is* a bias problem - they are protecting your tubes and output
transformers!


Sir, I will take good detailed pictures and post them up.

who around these parts would be able to work on my amp?

im sure most of you could, but who would??

I suck at soldering, so id rather send it so someone that wont look like a
monkey ****ing a football.

[mick]

On Sat, 06 Dec 2008 15:18:51 -0600, cipher wrote:

snip
Sir, I will take good detailed pictures and post them up.

who around these parts would be able to work on my amp?


Around Mordor? Saruman Electronics, I suppose... Give him a *Ring*!

im sure most of you could, but who would??


Difficult to guess when no-one knows where you are, isn't it?


I suck at soldering, so id rather send it so someone that wont look like
a monkey ****ing a football.

Have you got, perhaps, a local guitar amp repair place or, maybe, a radio
amateur or someone like that who might do it?

There's a valid email address on my web site (Feedback and Links page) if
you want to take this off-group.

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
Filtering everything posted from googlegroups to kill spam.

[cipher]

mick wrote in
:

On Sat, 06 Dec 2008 15:18:51 -0600, cipher wrote:

snip
Sir, I will take good detailed pictures and post them up.

who around these parts would be able to work on my amp?


Around Mordor? Saruman Electronics, I suppose... Give him a *Ring*!

im sure most of you could, but who would??


Difficult to guess when no-one knows where you are, isn't it?


I suck at soldering, so id rather send it so someone that wont look
like a monkey ****ing a football.

Have you got, perhaps, a local guitar amp repair place or, maybe, a
radio amateur or someone like that who might do it?

There's a valid email address on my web site (Feedback and Links page)
if you want to take this off-group.


sent you an email Sir.

the guy that builds my mic amps is a Mick, too... Mick Hinton (dav
electronics in Twickenham)

[Ian Bell[_2_]]

mick wrote:
On Sat, 06 Dec 2008 18:33:22 +0000, Ian Bell wrote:

snip
Who said intentionally? The average hi-fi person does not have a clue
about acoustics.


...and often doesn't care! The idea is to listen to the music. It must be
awfully difficult for audio "professionals" to realise that this is the
ultimate objective for your average couch potato with any *affordable*
music reproduction gear. ;-)


I fully agree, as I was trying to point out to Phil when he suggested I
might wear rose tinted specs. at an art gallery. Beauty is in the eye or
ear of the beholder. That makes it even more pointless to have a
transparent amp.

Cheers

Ian

[Peter Wieck]

On Dec 6, 4:35*pm, mick wrote:
On Sat, 06 Dec 2008 15:18:51 -0600, cipher wrote:

snip

Sir, I will take good detailed pictures and post them up.

who around these parts would be able to work on my amp?

Around Mordor? Saruman Electronics, I suppose... Give him a *Ring*!

im sure most of you could, but who would??

Difficult to guess when no-one knows where you are, isn't it?

I suck at soldering, so id rather send it so someone that wont look like
a monkey ****ing a football.

Have you got, perhaps, a local guitar amp repair place or, maybe, a radio
amateur or someone like that who might do it?

There's a valid email address on my web site (Feedback and Links page) if
you want to take this off-group.

--
Mick * * * * * * * * * * *(Working in a M$-free zone!)
Web:http://www.nascom.info
Filtering everything posted from googlegroups to kill spam. * *

He is in Florida - and he would have to ship the amp anyway. So, as
far as practicalities are concerned, the Continental US is all the
same to him.

I would be glad to do it, if he didn't mind waiting 30 - 90 days, as
that is about how long it takes me to get to any fresh project these
days.

Peter Wieck
Melrose Park, PA

[bigwig]

On 6 Dec, 23:24, Peter Wieck wrote:
On Dec 6, 4:35*pm, mick wrote:





On Sat, 06 Dec 2008 15:18:51 -0600, cipher wrote:

snip

Sir, I will take good detailed pictures and post them up.

who around these parts would be able to work on my amp?

Around Mordor? Saruman Electronics, I suppose... Give him a *Ring*!

im sure most of you could, but who would??

Difficult to guess when no-one knows where you are, isn't it?

I suck at soldering, so id rather send it so someone that wont look like
a monkey ****ing a football.

Have you got, perhaps, a local guitar amp repair place or, maybe, a radio
amateur or someone like that who might do it?

There's a valid email address on my web site (Feedback and Links page) if
you want to take this off-group.

--
Mick * * * * * * * * * * *(Working in a M$-free zone!)
Web:http://www.nascom.info
Filtering everything posted from googlegroups to kill spam. * *

He is in Florida - and he would have to ship the amp anyway. So, as
far as practicalities are concerned, the Continental US is all the
same to him.

I would be glad to do it, if he didn't mind waiting 30 - 90 days, as
that is about how long it takes me to get to any fresh project these
days.

Peter Wieck
Melrose Park, PA- Hide quoted text -

- Show quoted text -

Cipher,
If you mean Twickenham UK. Then try John at http://www.chambonino.com/
He is the guy.
Your amp really does look rough. What is the switch on the back panel
in the middle of the warning label?. The fault is clearly a bias
problem but looking at the state of the thing it has more wrong than
that, its a mess. Dont be disheartened by this the transformers and
all major components should be fine. You could just go mad and strip
it right down. You then have no option but to learn. A great way to
get into valve gear!. This is what I would do.
Matt.

[bigwig]

On 7 Dec, 01:31, flipper wrote:
On Sat, 06 Dec 2008 11:59:49 -0600, cipher wrote:
mick wrote in news:LCx_k.17960$uy1.13602
:

On Sat, 06 Dec 2008 06:33:27 -0600, flipper wrote:

snip

Those pics are of a different amp.

I was wondering. If you reckon on two of the GT bottles being individual
rectifiers for each channel then it could possibly be a dual mono amp on
a single chassis. Mind you, that doesn't explain the, possibly EZ81-type
thingy and there is one too many small B9A bottle. That may just be
enough changes between a prototype and a production version though. It
*could* have a valve rectifier for bias and an extra amplification stage.

Come on, cipher, let us into the secret! *;-)

nd Sir, I wish I knew what the secret was. it has been very frustrating ,
this whole thing..

He's asking if those amp pics *in your album are of the Mastersound.



what was once excstasy , hearing the sound of that amp, has been replaced
by anger and bitterness at dealing with the mechanical/electrical issues..

aint no free lunch i guess.

http://s99.photobucket.com/albums/l292/thebullards/?
action=view&current=dueventischematic.jpg *that one is mine.- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

Eactly Flipper,
Its a bad bias design and just asking for a problem. My Tek scope
went absolutely haywire because of a failed wiper. It took me 6 weeks
to find it. I re-capped the power supply, totally modified the
feedback in one stage of the supply. I thought I had cured it but I
was only treating the symptoms. To my absolute delight and
embarresment it was a very high quality Bournes pot. Sorry about the
spelling.
Any way can you stick up a link to your site I had to rebuild my
laptop and lost all the good ****.
Matt.

[Paul G.]

On Sat, 6 Dec 2008 05:18:46 -0800 (PST), fryzz
wrote:

.....snip!.....
I'm guessing you have an intermittent bias problem. Your amp has a
separate bias supply, so the 68 ohm resistors are mostly just a
convenient way of adjusting the idle current. If those bypass
capacitors on the 68 ohm jobs are leaky, it would actually have the
effect of increasing the negative voltage on the grid, which reduces
the idle current, so that's not why the tubes would draw too much
current.

The first thing I would look at is the bias potentiometers, pots do
tend to be trouble prone due to the moving parts. You could try
cleaning them with something like Caig Deoxit. You might also try
feeling those two filter caps in the bias supply after the amp has
been on for a while. They'll pick up some heat just from being in a
tubeamp, but if one is warmer than the other it's a sign that cap is
leaking. Another thing you might try is touching up all of the solder
joints in the bias supply. You might also just leave your multimeter
hooked up, to see if the output of the bias supply is dropping when
the amp gets that "close encounters" look. When you measure the
output of the bias supply, it should be stable and noise free.

The fact that just ONE tube goes red, and not the pair, suggests
that the bias supply & adjustment is not a problem, since both tubes
on each channel run off the same connection. If it is just the one
tube that goes, and it's always the same socket (even if you switch
tubes around), then I'd zero in on the socket, or the traces on the
circuit board. That will require very careful inspection, resoldering,
or possibly checking the springiness of the socket contacts. Since the
socket gets alternately hot and cold with the accompanying
expansion/contraction, it is very common for the socket contacts to
break away from the circuit board. This is one of those applications
where point-to-point wiring can be more reliable than circuit boards.
I worked at RCA when they made tube sets..... there was no end of
troubles with printed circuits and tube sockets that were soldered
into them. I would also solder over the solder traces in case there
was a crack in the board. That might not be practical, since most
mfr.'s put stuff over the traces so when the boards are soldered, it
won't adhere and waste solder.
Very carefully inspect all the connections and traces between grid
(pin 5) of the EL34's and the bias control. Make sure nothing is
loose.
If the caps in parallel with the 68 ohms were to get real leaky and
short, the tube might get red, but the resistors would not cook (the
caps would shunt all the current). My guess is your problem is in the
grid circuit of the tube that cooks.
If the 0.68 uF caps were to fail and break down, you would see
symptoms similiar to what you're experiencing. Also if "R1K" and
"R220K" in the grid circuits were to open up, you would get similiar
behaviour. That's not very common for resistors, unless they have been
mechanically abused. "Opening up" by a poor solder connection, thermal
expansion, or bad trace would do the same (and more common).
I also assume that this unit unit used common solder with tin/lead,
and not the lead free (ROHS) kind. The lead free solder is not as
reliable (critical equipment can duck out of the lead-free
requirements!). How old is this unit? Did the manuals make any remark
about being lead-free?
A possible problem (but not likely, since the mfr. should have run
into this) is that the system could be oscillating at some very high
frequency. There are already grid stoppers, I'd be paranoid and put
stoppers (100 ohms) in the screen circuit. If it did oscillate,
probably both tubes would run red, and from your symptoms, that hasn't
ocurred.
I don't think you need this, but I would solder a resistor (100K)
from the wiper of the bias pot to the (-) end where the cap is. If the
wiper failed to make contact (as they do when dirty), you will still
maintain a bias that won't destroy anything.

Once you got mad in a previous post, and put down all the symptoms,
it became a lot easier to troubleshoot. Just to make sure, is it just
ONE tube that goes at a time? Does the same resistor cook each time?
If so, it's probably a circuit issue. If the problem moves around, it
MIGHT be a tube problem.
Usually when I have a customer bringing in a naughty piece of
equipment, it takes a few minutes of careful questioning to pin down
the problem. Just a list of symptoms from the customer aren't
enough..... I usually run them through what is for me a
"troubleshooting tree". Knowing the history of the unit, what it does
when naughty, what it does when you wack it (that's inevitable) helps
enormously. The fact that it misbehaves intermittently makes it very
difficult to service, and even more dependent on knowing the unit.
Chances are, that on a bench, this thing could run properly for years!

-Paul G.