Slightly odd output stage configuration. Thoughts ?

[David Nebenzahl]

On 2/25/2011 11:29 PM Phil Allison spake thus:

"David Nebenzahl"

Phil Allison spake thus:

Also, the power output will of course drop in triode mode and
each EL84 will dissipate more heat under overdrive. Combined with
their use of a "concertina" phase splitter, I suspect that
overdrive clipping will not be symmetrical.

If you wouldn't mind indulging my relative ignorance for a minute,
that "concertina" stage business got my curiosity up. So I found
the two triode (12AX7) stages before the EL84s, and it looks to me
like the first stage (V3A) is a phase inverter,

** With an imagination like that - you should be writing fiction for a
living.

A " phase inverter" ( or phase splitter) has equal and opposite polarity
outputs.

OK, my bad: poor choice of terminology. What I meant to say is that both
stages are inverting stages, being common cathode. Correct? Since one
pair of EL84s seems to be driven from V3As plate and the other from V3Bs
plate, isn't this basically how this phase splitter works? One pair of
output tubes gets an inverted signal, the other pair gets an
inverted-inverted one.


--
The phrase "jump the shark" itself jumped the shark about a decade ago.

- Usenet

 

[Arfa Daily]

"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:8st8guFqjiU1@mid.individual.net...

"William Sommerwanker "

** ROTFLMAO !!
Wot a fucking moron the stupid pommy cunt is.
Only posts questions he already THINKS he knows the answers to.
Just so the pommy cunt can smugly contradict anyone who dares to reply.
Wot a fucking MORON !!!!!!!!!!!!


I guess you have never been unsure about something, and asked for
confirmation.

** That is NOT what the CUNT did !!

You illiterate, fuckwit bloody TROLL.

Oh boy. The Antipodean twat is off and running again ... What is it with
you Philip ? I know we all take the piss out of you about forgetting to take
your meds, but is that really the case ? Or do you smoke funny stuff that
addles your dumbarsed brain or something ? Or maybe you've got a drink habit
? Whatever it is pal, you seriously, and I mean SERIOUSLY need to address it
before you one day do something that you are really gonna regret when you
sober up / come down / remember to take your meds again. The really sad
thing is that when you are in control, you are actually lucid and make real
sense. I was actually treating you as an adult in this thread, and being ok
with you, but stupid me for being fooled by you again. How many times is it
that you've gone off on one to me now ? Five ? Six maybe, over the years ?
And still you haven't learnt, have you ? I simply don't fucking CARE, you
dopey twat. You can call me what you like, it will still be you that's the
stupid one on here, that everybody is laughing at. Read that carefully.
Laughing AT, not WITH.

Now be a good boy and do whatever you need to get your sensible head back
on. And if you can do that, and come back into the conversation making some
sense, then that's fine, and we'll all have a little chuckle, and put it
down to good ol' Philip, just having one of his little episodes. And if you
can't, then just turn off your computer, and crawl back into your darkened
room or back under your rock or wherever it is you sleep, and don't come
back out until you've learnt how to behave again. Capiche ?

Arfa

 

[Phil Allison]

"Charles the Puke "

Until P.A. develops a reasonable command of English

** Whaaattttt ??

My command of the English language is second to none

- you vile, autistic shithead.

 

[Phil Allison]

"Arfa Daily = 100% MORONIC TROLL "

Well, that one is a well known and documented mod for that amp, so I'm not
too concerned about doing it.

** ROTFLMAO !!

Wot a fucking pommy moron !!!

Only posts questions it already THINKS it knows the answers to - when it
has not got one clue.

Just so the pommy cunt can smugly contradict anyone who dares to reply.

Wot a fucking MORON !!!!!!!!!!!!

Kick the vile pommy ass totally off the NG.




...... Phil

 

[Phil Allison]

"David Nebenzahl"
Phil Allison spake thus:

If you wouldn't mind indulging my relative ignorance for a minute,
that "concertina" stage business got my curiosity up. So I found
the two triode (12AX7) stages before the EL84s, and it looks to me
like the first stage (V3A) is a phase inverter,

** With an imagination like that - you should be writing fiction for a
living.

A " phase inverter" ( or phase splitter) has equal and opposite polarity
outputs.

OK, my bad: poor choice of terminology. What I meant to say is that both
stages are inverting stages, being common cathode. Correct?

** I already explained the circuit - but you decide to snip the lot.

Here is the schem:

http://www.el34world.com/charts/Schematics/files/peavey/peavey_classic30.pdf

Here is the missing explanation:

" V3A is a voltage amplifier ( gain of about 50 before NFB) while V3B is
the
"concertina" phase inverter. Concertina circuits always have equal plate and
cathode resistors and in operation, the voltage between the plate and
cathode grows and falls with audio drive like a concertina being pumped in
and out.
The cathode of V3A acts as a negative ( opposite phase) input for feedback
from the output transformer secondary. "

Since one pair of EL84s seems to be driven from V3As plate

** You looking at the schem above or not ?

V3A drives V3B which delivers TWO anti-phase signals (one from the plate and
one from the cathode) so the push-pull output stage can work.

V3B has a gain of 2 as the output is across the plate and cathode.




..... Phil

 

[William Sommerwerck]

When you're "sober", you almost always give intelligent advice. You're like
Jekyll and Hyde -- cubed.

I hope all this is "deliberate", because you can change if you want to. And
when you do, you will wonder why you didn't do it earlier.

 

[Phil Allison]

"William Sommerwanker"


** Bill,

if you were merely a fuckwit

- you would not be even half so bad




...... Phil

 

[William Sommerwerck]

"William Sommerwanker"
** Bill,

if you were merely a fuckwit
- you would not be even half so bad

And your point is...?

 

[Phil Allison]

"William Sommerwanker"

** Bill,

if you were merely a fuckwit
- you would not be even half so bad

And your point is...?

** You could not have made for me it any better.....

ROTFL


..... Phil

 

[William Sommerwerck]

I fixed the Subject line and edited your comment
to reflect the truth. No need to thank me.

Thank you, anyway.

How many times do we have to tell you, Phil, that we are neither impressed
with nor frightened my your rude remarks?

Aren't you bothered that other people consider you psychotic? And to what
end?

 

[Meat Plow]

On Sun, 27 Feb 2011 09:02:59 +1100, Phil Allison wrote:

"Phil Allison is a Lying Retarded PIG "

I fixed the Subject line and edited your comment to reflect the truth.

No need to thank me.


--
Live Fast, Die Young and Leave a Pretty Corpse

 

[Jamie]

William Sommerwerck wrote:

I fixed the Subject line and edited your comment
to reflect the truth. No need to thank me.


Thank you, anyway.

How many times do we have to tell you, Phil, that we are neither impressed
with nor frightened my your rude remarks?

Aren't you bothered that other people consider you psychotic? And to what
end?


You haven't yet blocked him?

Jamie

 

[Mark Zacharias]

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
news:76jap.26428$To7.25344@newsfe12.ams2...

"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:8st8guFqjiU1@mid.individual.net...

"William Sommerwanker "

** ROTFLMAO !!
Wot a fucking moron the stupid pommy cunt is.
Only posts questions he already THINKS he knows the answers to.
Just so the pommy cunt can smugly contradict anyone who dares to reply.
Wot a fucking MORON !!!!!!!!!!!!


I guess you have never been unsure about something, and asked for
confirmation.

** That is NOT what the CUNT did !!

You illiterate, fuckwit bloody TROLL.




Oh boy. The Antipodean twat is off and running again ... What is it with
you Philip ? I know we all take the piss out of you about forgetting to
take your meds, but is that really the case ? Or do you smoke funny stuff
that addles your dumbarsed brain or something ? Or maybe you've got a
drink habit ? Whatever it is pal, you seriously, and I mean SERIOUSLY need
to address it before you one day do something that you are really gonna
regret when you sober up / come down / remember to take your meds again.
The really sad thing is that when you are in control, you are actually
lucid and make real sense. I was actually treating you as an adult in this
thread, and being ok with you, but stupid me for being fooled by you
again. How many times is it that you've gone off on one to me now ? Five ?
Six maybe, over the years ? And still you haven't learnt, have you ? I
simply don't fucking CARE, you dopey twat. You can call me what you like,
it will still be you that's the stupid one on here, that everybody is
laughing at. Read that carefully. Laughing AT, not WITH.

Now be a good boy and do whatever you need to get your sensible head back
on. And if you can do that, and come back into the conversation making
some sense, then that's fine, and we'll all have a little chuckle, and put
it down to good ol' Philip, just having one of his little episodes. And if
you can't, then just turn off your computer, and crawl back into your
darkened room or back under your rock or wherever it is you sleep, and
don't come back out until you've learnt how to behave again. Capiche ?

Arfa

I am proud to call Geoff Darby, (Arfa) a friend.

Mark Zacharias

 

[Wild_Bill]

I haven't any background experience to make suggestions, but this perplexing
circuit you're seeing sounds a like the schematic I looked at for the
*Peavey Mace A* series (6, 6L6GC output tubes).
That's sounds like how the schematic was drawn, although I haven't see the
actual circuit layout of that model.. separate resistors were used for each
tube of one pair.. then another pair was wired direct, while the third pair
had 2 more separate resistors shown between those pairs (appearing like the
2 resistors were wired in series between those 2 pairs).

There seem to be numerous similarities in many PV amp model schematics of
the power output sections, but then some specific oddities in a couple of
models' schematics that look out of place (to me, anyway).

One thing that I have discovered recently, is that there are a huge number
of PV amp users, and lots of forum discussions about many modifications
(some that have produced results, and some that don't) and also repairs.
You're probably already aware that many forum discussions wrt electronic
circuits can include unintentional errors and/or other misleading info (this
mod I came up with is the ultimate! for example), so that much of the forum
info needs to be pondered and then either accepted or rejected by one's
better judgement and/or experience.. and compared to the rule: if it werks,
don't fuck with it.

As I've only recently started dabbling in this area, I've noticed one thing
that's prevalent.. practially every component in/on guitars and amps have
been tampered with and replaced, and the majority of reports of the actors
claim that the acts produce amazing results.

--
Cheers,
WB
..............


"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
news:ZeR9p.55357$XM7.40303@newsfe18.ams2...

A muso customer has asked me to carry out some tonal mods to his Peavey
Classic 30. All pretty straightforward cap changes and so on. However, he
also asked me to look into fitting a pentode / triode switch whilst I was
at it. At first glance, this didn't look like a problem. The output stage
is a fairly classic AB class using 4 x EL84 tubes as two paralleled pairs.
Anodes of each pair commoned. Cathodes all commoned and decked. Grids of
each pair commoned via individual 47k stoppers. But then, things get a
little odd around the screen grids. One tube of each pair, has its screen
grid fed by a 100 ohm 5 watt resistor off the "screen" supply rail, whilst
the other of each pair, has its screen grid fed *direct* from the "screen"
supply rail.

I don't think I've seen this done before. I've seen one screen resistor
feeding both tubes of a pair, or one resistor per screen, but not just one
tube having a screen feed resistor. Apart from anything else, I wouldn't
normally have considered it very good design practice to have no current
limiting at all in place. Also, it will mean that the screen voltage will
be higher on one tube of the pair, than the other. I doubt that it would
have a significant effect on the operation of the stage, but just
interested as to whether anyone else has come across this configuration,
and knows the design reasoning behind it. Anyone got any opinions about
just strapping the screens to the anodes on each pair via a switch, to
implement a triode mode ?

Arfa

 

[Phil Allison]

"William Sommerwanker"


** Bill - you are just another boring usenet wanker, a TROLL and a complete
fuckwit.

D R O P DEAD

 

[Phil Allison]

"Mark Zacharias"

I am proud to call Geoff Darby, (Arfa) a friend.

** My god you must be a desperate poofter to lick the bullshitting fool's
arse in public like that.

Makes YOU into a moronic troll too.

Piss off.


..... Phil

 

[Arfa Daily]

"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:8t084vFsvuU1@mid.individual.net...

"Mark Zacharias"


I am proud to call Geoff Darby, (Arfa) a friend.

Why thank you. Mark ! And back atcha

** My god you must be a desperate poofter to lick the bullshitting fool's
arse in public like that.

Makes YOU into a moronic troll too.

Piss off.


.... Phil

Such a shame, Mark. Philip is obviously desperate to have someone offer the
same sentiment to him. Must be hard to have everyone thinking that you're a
twat ...

Arfa

 

[Phil Allison]

"Arfa Daily"


** Go DROP DEAD

- you ridiculous, fucking FAKE !!!

 

[Michael A. Terrell]

Arfa Daily wrote:

"Phil Allison" ?phil_a@tpg.com.au? wrote in message
news:8t084vFsvuU1@mid.individual.net...
?
? "Mark Zacharias"
?
?
?? I am proud to call Geoff Darby, (Arfa) a friend.

Why thank you. Mark ! And back atcha

?
?
? ** My god you must be a desperate poofter to lick the bullshitting fool's
? arse in public like that.
?
? Makes YOU into a moronic troll too.
?
? Piss off.
?
?
? .... Phil
?

Such a shame, Mark. Philip is obviously desperate to have someone offer the
same sentiment to him. Must be hard to have everyone thinking that you're a
twat ...

Even his blow up sheep are ignoring him.


--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

 

[Phil Allison]

"Wild_Bill"

One thing that I have discovered recently, is that there are a huge number
of PV amp users, and lots of forum discussions about many modifications
(some that have produced results, and some that don't) and also repairs.
You're probably already aware that many forum discussions wrt electronic
circuits can include unintentional errors and/or other misleading info
(this mod I came up with is the ultimate! for example), so that much of
the forum info needs to be pondered and then either accepted or rejected
by one's better judgement and/or experience.. and compared to the rule: if
it werks, don't fuck with it.

** That a good rule to live by....

As I've only recently started dabbling in this area, I've noticed one
thing that's prevalent.. practially every component in/on guitars and amps
have been tampered with and replaced, and the majority of reports of the
actors claim that the acts produce amazing results.

** But they *would* say that - wouldn't they ?



..... Phil