Gentlemen,

is the phase splitter circuit shown at the following
link known under a particular name?

http://www.tubes.mynetcologne.de/roe...c/splitter.jpg

Tnx2u,

Tom

--
The first rule of magick is simple: Don't waste your time
waving your hands and hoping, when a rock or club will do.

"Tom Schlangen" a écrit dans le message de news:
...
Gentlemen,

is the phase splitter circuit shown at the following
link known under a particular name?

http://www.tubes.mynetcologne.de/roe...c/splitter.jpg

Tnx2u,

Tom

Hi,

If R5 and R7 (with the pot.) was tied on the other side of the respective
links caps,
it would be named "paraphase" here in froggy land.
More than ever, R5 and R7 are the grid leak of the next stage with R6 more
or less equal to R5.
But, as is, V1b is probably fully saturated ;)

Yves.

Tom Schlangen said:

Gentlemen,

is the phase splitter circuit shown at the following
link known under a particular name?

http://www.tubes.mynetcologne.de/roe...c/splitter.jpg


I think it is known as the DPS: the Dreadful Phase Splitter ;-)

--
Sander de Waal
" SOA of a KT88? Sufficient. "

"Tom Schlangen" wrote in message
...
is the phase splitter circuit shown at the following
link known under a particular name?

http://www.tubes.mynetcologne.de/roe...c/splitter.jpg

Looks like a paraphase, with the gain of the second tube reduced by local
shunt NFB instead of a voltage divider or balancing feedback to the first
tube.

Tim

--
"I've got more trophies than Wayne Gretsky and the Pope combined!"
- Homer Simpson
Website @ http://webpages.charter.net/dawill/tmoranwms

On Sat, 05 Feb 2005 14:46:49 +0100, Tom Schlangen wrote:

Gentlemen,

is the phase splitter circuit shown at the following link known under a
particular name?

http://www.tubes.mynetcologne.de/roe...c/splitter.jpg


Looks like some kind of direct-coupled paraphase to me. Does this version
actually work?

--
Mick
(no M$ software on here... :-) )
Web: http://www.nascom.info
Web: http://projectedsound.tk

Hi Mick,

Does this version actually work?

Yes, it does :-)

Tom

--
Do not meddle in the affairs of wizards,
for you are crunchy and good with ketchup.

Hi Tim,

Looks like a paraphase, with the gain of the
second tube reduced by local shunt NFB instead
of a voltage divider or balancing feedback to
the first tube.

Yes, obviously that's how it works.

Tom

--
Knowledge is power - knowledge shared is power lost.
-- A. Crowley

Hi Yves,

But, as is, V1b is probably fully saturated ;)

Did you actually try it? Obviously not ;-)

Tom

--
To err is human - to purr feline.
- R. Byrne

Tom Schlangen said:

Hi Tim,

Looks like a paraphase, with the gain of the
second tube reduced by local shunt NFB instead
of a voltage divider or balancing feedback to
the first tube.

Yes, obviously that's how it works.

But will it still work when the tube's parameters alter because of
age?

--
Sander de Waal
" SOA of a KT88? Sufficient. "

Tom Schlangen wrote:

Gentlemen,

is the phase splitter circuit shown at the following
link known under a particular name?

http://www.tubes.mynetcologne.de/roe...c/splitter.jpg

Tnx2u,

Tom

--
The first rule of magick is simple: Don't waste your time
waving your hands and hoping, when a rock or club will do.

V1b appears to be running with a +ve grid. A quick calc yeilds 100
volts on the grid if we take the parallel combo of POT 1 & R7 to be
100K. That with the other 100K of R5 puts a 50K resistance in
serires with a 105 volt source. Shove all that into the 1M of R6 &
if unloaded you get 100 volts. Looks to me you are missing a
coupling cap between R6 & the resistors above it.

Since V1b otherwise is an anode follower it's internal impedance is
much lower than the V1a side. That sometimes is a cause of unbalance
when driving the output stage but in this case there is an
adjustment pot to fix that.

Cheers, John Stewart

On Sat, 05 Feb 2005 16:15:25 +0100, Tom Schlangen wrote:


Does this version actually work?

Yes, it does :-)


Hmmmm.... I'm going to add that to my list of things to try then... :-)

--
Mick
(no M$ software on here... :-) )
Web: http://www.nascom.info
Web: http://projectedsound.tk

"Tom Schlangen" a écrit dans le message de news:
...
Hi Yves,

But, as is, V1b is probably fully saturated ;)

Did you actually try it? Obviously not ;-)

Tom

This bother me, indeed.
At least a link cap looks necessary between the R5 / R7 junction and the V1b
grid .
What do I miss ?

Yves.

"John Stewart" a écrit dans le message de news:
...
Tom Schlangen wrote:

Gentlemen,

is the phase splitter circuit shown at the following
link known under a particular name?

http://www.tubes.mynetcologne.de/roe...c/splitter.jpg

Tnx2u,

Tom

--
The first rule of magick is simple: Don't waste your time
waving your hands and hoping, when a rock or club will do.

V1b appears to be running with a +ve grid. A quick calc yeilds 100
volts on the grid if we take the parallel combo of POT 1 & R7 to be
100K. That with the other 100K of R5 puts a 50K resistance in
serires with a 105 volt source. Shove all that into the 1M of R6 &
if unloaded you get 100 volts. Looks to me you are missing a
coupling cap between R6 & the resistors above it.

Since V1b otherwise is an anode follower it's internal impedance is
much lower than the V1a side. That sometimes is a cause of unbalance
when driving the output stage but in this case there is an
adjustment pot to fix that.

Cheers, John Stewart

That is my opinion too !
I've seen somewhere a resistor added in serie with the "plate follower"
output.
The paraphase was implemented with a 6DJ8 SRPP in each branch to drive a
6AS7 PP with local (plate to grid) feedback.
Perhaps a Plitron design ? Can't remember !

Yves.

"Yves" said:

I've seen somewhere a resistor added in serie with the "plate follower"
output.
The paraphase was implemented with a 6DJ8 SRPP in each branch to drive a
6AS7 PP with local (plate to grid) feedback.
Perhaps a Plitron design ? Can't remember !


Menno van der Veen, the "6AS7 Maurits" to be exact.
There's no feedback present other than the ordinary loop from output
to input cathode.

--
Sander de Waal
" SOA of a KT88? Sufficient. "

is the phase splitter circuit shown at the following
link known under a particular name?


I don't particularity like circuits that require a
trimpot. Something that has to be tweaked in
production and later on in its life. I prefer
circuits that will perform despite component drift.

But will it still work when the tube's parameters alter because of
age?


That must be what the trimpot is for. But I don't
like circuits that you have to tweak to make it
work again. PITA, also is a pain for manufacturing
companies for warranty issues.

Yves wrote:

"John Stewart" a =E9crit dans le message de n=
ews:
...
Tom Schlangen wrote:

Gentlemen,

is the phase splitter circuit shown at the following
link known under a particular name?

http://www.tubes.mynetcologne.de/roe...c/splitter.jpg

Tnx2u,

Tom

--
The first rule of magick is simple: Don't waste your time
waving your hands and hoping, when a rock or club will do.

V1b appears to be running with a +ve grid. A quick calc yeilds 100
volts on the grid if we take the parallel combo of POT 1 & R7 to be
100K. That with the other 100K of R5 puts a 50K resistance in
serires with a 105 volt source. Shove all that into the 1M of R6 &
if unloaded you get 100 volts. Looks to me you are missing a
coupling cap between R6 & the resistors above it.

Since V1b otherwise is an anode follower it's internal impedance is
much lower than the V1a side. That sometimes is a cause of unbalance
when driving the output stage but in this case there is an
adjustment pot to fix that.

Cheers, John Stewart

That is my opinion too !
I've seen somewhere a resistor added in serie with the "plate follower"=

output.
The paraphase was implemented with a 6DJ8 SRPP in each branch to drive =
a
6AS7 PP with local (plate to grid) feedback.
Perhaps a Plitron design ? Can't remember !

Yves.

You may have seen the circuit in 'Valve Amplifiers' by Morgan Jones where=
he
calls it a 'floating paraphase', again using a 6DJ8. Then he redraws it s=
o
you can see the anode follower hidden inside. He also recommends the R in=

series with the output from V1b to equalize the source resistances as see=
n by
the following stage.

BTW, without that coupling cap, that circuit will not work. I think that =
is
simply an omission by whoever drew the circuit & easily fixed.

I haven't seen the version driving the 6AS7. But I've got my own version =
for
driving low mu triodes which I like much better.

Cheers, John Stewart

"robert casey"


But will it still work when the tube's parameters alter because of
age?


That must be what the trimpot is for.


** Nope - it is to match the antiphase output levels after manufacture.

( It could also be used to trim out gain imbalance in the output tubes.)


But I don't
like circuits that you have to tweak to make it
work again.


** V1B operates as a *unity gain* inverter - fixed resistor and trim pot
values set the gain to exactly unity while any drift in tube gain only has a
very minor effect as a result of all the NFB.

Any drift in gain from V1A is simply matched by V1B and the outputs stay in
balance.


PITA, also is a pain for manufacturing
companies for warranty issues.


** Shame you cannot read a simple tube circuit and see how it works.


BTW

There is that missing grid coupling cap in the drawing.





................ Phil

Here's the link to the complete amp schematic:

http://www.jogis-roehrenbude.de/Roeh...503/EL503a.jpg

Tom

--
When in doubt, use brute force.
- Ken Thompson

"Tom Schlangen"
Here's the link to the complete amp schematic:

http://www.jogis-roehrenbude.de/Roeh...503/EL503a.jpg




** Err - that same grid coupling cap is still missing.





............. Phil

"Yves" wrote

That is my opinion too !
I've seen somewhere a resistor added in serie with the "plate
follower"
output.
The paraphase was implemented with a 6DJ8 SRPP in each branch to
drive a
6AS7 PP with local (plate to grid) feedback.
Perhaps a Plitron design ? Can't remember !

It's ok as long as the input Rs of the following stage are high.

Not quite Menno's design...not my version anyway that uses just one
pair 6DJ8.

Menno uses nfb from anode to grid of input valve/inverter to reduce
its output impedance. Otherwise he suggests using a CF as a buffer
on its high impedance output if necessary.

He uses series rather than shunt adjustment for the AC balance.
Parallel seems better to me coz less current through the pot.

Morgan compensates with resistor in series with low impedance output
of cathodyne, but with this form of paraphase splitter the resistor
would be in the loop.

Menno is not keen on diff. pairs. Morgan loves them.

Morgan has a new book out BTW

cheers, Ian

"Phil Allison" wrote

** Err - that same grid coupling cap is still missing.

Could be misdrawn. Divider for driving that grid should be *after*
coupling caps to next stage.

Ian

"Ian Iveson"
"Phil Allison"

** Err - that same grid coupling cap is still missing.

Could be misdrawn. Divider for driving that grid should be *after*
coupling caps to next stage.



** Very doubtful - the 1 Mohm becomes superfluous if that were the case.

Plus that shifts the LF pole an octave higher.

Occam's razor says there is a 0.1 uF missing cap.




............. Phil

"Phil Allison" wrote

** Very doubtful - the 1 Mohm becomes superfluous if that were
the case.

Plus that shifts the LF pole an octave higher.

Occam's razor says there is a 0.1 uF missing cap.

OK. Either way is common. If the feedback is taken after the
coupling caps, then it responds to difference in frequency response
of the two outputs.

Where does your octave come from? Doubled an effective resistance or
halved an effective capacitance...can't quite see where though.

cheers, Ian

"Ian Iveson" = ****ing CONTEXT snipper - Grrrrrrrrrrrrr
"Phil Allison"


** Putting it BACK where it belongs !!!!


** Err - that same grid coupling cap is still missing.

Could be misdrawn. Divider for driving that grid should be *after*
coupling caps to next stage.

** Very doubtful - the 1 Mohm becomes superfluous if that were the
case.

Plus that shifts the LF pole an octave higher.

Occam's razor says there is a 0.1 uF missing cap.



OK. Either way is common.


** What a complete non sequitur !!!

You cannot ignore the 1 Mohm resistor issue or you lose.



If the feedback is taken after the coupling caps, then it responds to
difference in frequency response of the two outputs.


** No hint of relevance in sight ????

Is explaining your tedious pointoids to arduous - Mr Iveson ?



Where does your octave come from?


** The extra 100kohms load on each coupling cap - silly.

Now go read up on Occam's razor - and be careful not to cut yourself in
the process.




............. Phil

"Phil Allison" wrote

"Ian Iveson" = ****ing CONTEXT snipper - Grrrrrrrrrrrrr

Deliberately, so you wouldn't make the mistake of thinking I was
addressing that particular context. Then I figured you might not
make the further mistake of thinking I was suggesting what the
designer had missed out of the diagram.

** Putting it BACK where it belongs !!!!

No, no it DOESN'T, I took it out !!!!!.....!

Try looking "could" up in a dictionary.

Childish literalism may lead to another fit of petulance...

** What a complete non sequitur !!!

....Oops, too late...

** The extra 100kohms load on each coupling cap - silly.

Right. Mistook your remark for an interesting thought. No indication
of the intended frequency response though, so not evidence either
way.

Arguing about what an unknown designer missed out of the circuit
*is* silly. Discussing ways of making it work is more constructive.

If the feedback is taken after the coupling caps, then it
responds to difference in frequency response of the two outputs.


** No hint of relevance in sight ????

Can't you see it ????? ?

cheers, Ian

Phil Allison wrote:

"Ian Iveson" = ****ing CONTEXT snipper - Grrrrrrrrrrrrr
"Phil Allison"

** Putting it BACK where it belongs !!!!

** Err - that same grid coupling cap is still missing.

Could be misdrawn. Divider for driving that grid should be *after*
coupling caps to next stage.

** Very doubtful - the 1 Mohm becomes superfluous if that were the
case.

Plus that shifts the LF pole an octave higher.

Occam's razor says there is a 0.1 uF missing cap.



OK. Either way is common.

** What a complete non sequitur !!!

You cannot ignore the 1 Mohm resistor issue or you lose.

If the feedback is taken after the coupling caps, then it responds to
difference in frequency response of the two outputs.

** No hint of relevance in sight ????

Is explaining your tedious pointoids to arduous - Mr Iveson ?

Where does your octave come from?

** The extra 100kohms load on each coupling cap - silly.

Now go read up on Occam's razor - and be careful not to cut yourself in
the process.

............. Phil

I have not read all the posts on the subject due to work today.

But yes, Phil is dead right about a missing 0.1 uF cap.

I think it should be between the junction of 1M and 180R at V1B grid
and the junction of the "plate to plate" resistor network between the two
triodes.
V1B acts as an anode follower to reverse the phase of V1A, and the 1M pot
is there to adjust the amplitude of the two phases to equality, or however
anyone likes it to be within the ranges of imbalances.
Once set, and if the pot lasts ok, the circuit will stay set for years because
slight gain changes
in V1B are reduced due to the NFB applied, which reduces the gain from about
10 to
unity.

I recall seeing similar versions with cathodes tied together, and then the
distortion
is lower, and in fact the commoned cathodes can be taken to a -ve voltage
and the thing becomes a differential pair, LTP, but with balanced "paraphase"
drive.

The circuit as shown will produce 2H in V1A, and it is also inverted by V1B
and 2H is applied
to the output tubes in differential mode, so the PP amp that this circuit
drives will have considerable 2H
in its output along with the 3H normally found in all PP amps.

I always prefer to use an LTP, which will have far less 2H, slightly
better bandwidth and is simpler.
It can always be direct coupled to an input tube anode.

The Conrad Johnson 140 and Luxman amps came in for service this week
have the LTP with direct coupling to an input triode, like the old Mullard
circuit.


Patrick Turner.

Tom Schlangen wrote:

Gentlemen,

is the phase splitter circuit shown at the following
link known under a particular name?

http://www.tubes.mynetcologne.de/roe...c/splitter.jpg

Tnx2u,

Tom

--
The first rule of magick is simple: Don't waste your time
waving your hands and hoping, when a rock or club will do.

See http://www.bonavolta.ch/hobby/en/audio/split.htm
for a good listing of phase splitters. A few pages in you will find
the Paraphase hooked up so that it's anode follower portion is
driven by the following stage DC conditions.

Take a look over at ABSE where I have posted a circuit that showed
up here on the NG a few months ago. Altho it is using one of the
triodes as a CF the other is still an inverting anode follower in
order to make the PP output stage happy.

Cheers, John Stewart

"Patrick Turner" wrote

I recall seeing similar versions with cathodes tied together, and
then the
distortion is lower...

Voltage feedback around just the first valve is arguably a better
solution. That decreases output impedance from that valve, and
reduces distortion at source. The second valve contributes no gain
so doesn't want feedback at its cathode.

But all sorts of variations have been used. If you want to minimise
low odd order harmonics, a paraphase is one possibility.

I always prefer to use an LTP, which will have far less 2H,
slightly
better bandwidth and is simpler.

Depends on which LTP, and which paraphase, and on the context. Some
argue that cutting 2H at the expense of adding 3 and 5H is not
worthwhile.

Saying one splitter is better than another appears futile
considering how many times they have all been used successfully.

cheers, Ian

"Phil Allison" wrote

Now go read up on Occam's razor - and be careful not to cut
yourself in the process.

Missed this bit. Occam is kind of OK in this context (Kinda cute
actually, I thought.), which is why I originally accepted you were
right.

But where Occam is used in less trivial manner, you should be wary.
Simplest is merely to fit in best. Revolutions happen; fitting in is
not and never has been sufficient in the end, and is stupefyingly
boring anyway.

You appear to have the mental ability to kick free. Give it a try
sometime.

Asleep just now, I guess.

cheers, Ian

Yves wrote:

"Tom Schlangen" a écrit dans le message de news:
...
Hi Yves,

But, as is, V1b is probably fully saturated ;)

Did you actually try it? Obviously not ;-)

Tom

This bother me, indeed.
At least a link cap looks necessary between the R5 / R7 junction and the V1b
grid .
What do I miss ?

Yves.



It seems to me that this circuit is a practical joke of the Philips
application laboratories. The circuit has been uncritically copied
into a booklet by Fritz Kühne published by Franzis. It has also been
published in FUNKSCHAU AFAIK. There is another mistake in the circuit.
The screen voltage is 275V and the Plate voltage is 265V. I guess
the sound of this amplifier, provided one adds the missing cap
to make it work at all, will be "pretty" harsh and distorted.
If you look into the circuits used by GELOSO, HOHNER, KLEMT etall
published on the same website of Jogi, you will see that nobody
ever thought of building an EL503 amp according to the Philips app-
note. Philips did never do this fine tube justice. So it died in
childhood or better to say: It was killed by the beancounters.

Kind regards, Eike
--
Lions go to absurd lengths to retain the posession of their skins.
- Stewart Edward White 1913

"Ian Iveson"
"Phil Allison"

"Ian Iveson" = ****ing CONTEXT snipper - Grrrrrrrrrrrrr

Deliberately, so you wouldn't make the mistake of thinking I was
addressing that particular context.


** Sorree - that is a debating CRIME.

You cannot arbitrarily and secretly change the context and STILL pretend
you are replying to another's words.

Unless you WANT people to think you are an intellectually dishonest
dead****.



Then I figured you might not make the further mistake of thinking I was
suggesting what the designer had missed out of the diagram.


** Quote from Ian Iveson "Could be misdrawn."

So a possible drawing error is the subject.



** Putting it BACK where it belongs !!!!

No, no it DOESN'T, I took it out !!!!!.....!


** You cannot do that.


Try looking "could" up in a dictionary.


** Try looking up " vile pommy prick " in the dictionary.


** What a complete non sequitur !!!

You cannot ignore the 1 Mohm resistor issue or you lose.


...Oops, too late...


** What - did you **** in your pants Ian ??

Nappy change time ?


Where does your octave come from?

** The extra 100kohms load on each coupling cap - silly.

Right. Mistook your remark for an interesting thought.


** Simply a fact that cannot be ignored - even by a pommy ****head.

Like that ugly 1 Mohm resistor.



No indication of the intended frequency response though,
so not evidence either way.


** You forgot about Occam - so are allowing many unjustified
complications in your hypothesis.

Ergo - you have a fool's case.

Same as always for you.



Arguing about what an unknown designer missed out of the circuit *is*
silly.


** Glad to see you now agree what a stupid prick you are.


Discussing ways of making it work is more constructive.


** Been done long ago.

Where were you ?



If the feedback is taken after the coupling caps, then it responds to
difference in frequency response of the two outputs.


** No hint of relevance in sight ????

Can't you see it ????? ?


** Is explaining your tedious pointoids to arduous - Mr Iveson ?

Now go change that nappy you just shat in.



.............. Phil

"Eike Lantzsch, ZP6CGE" wrote:

Yves wrote:

"Tom Schlangen" a =E9crit dans le message=
de news:
...
Hi Yves,

But, as is, V1b is probably fully saturated ;)

Did you actually try it? Obviously not ;-)

Tom

This bother me, indeed.
At least a link cap looks necessary between the R5 / R7 junction and=
the V1b
grid .
What do I miss ?

Yves.



It seems to me that this circuit is a practical joke of the Philips
application laboratories. The circuit has been uncritically copied
into a booklet by Fritz K=FChne published by Franzis. It has also been
published in FUNKSCHAU AFAIK. There is another mistake in the circuit.
The screen voltage is 275V and the Plate voltage is 265V.

Not a mistake. Simply the voltage drop thru the output transformer primar=
y winding
resistance caused by the EL503 plate current. That happens in any power a=
mp. But
the missing cap in the phase splitter is a serious problem.

Cheers, John Stewart

I guess
the sound of this amplifier, provided one adds the missing cap
to make it work at all, will be "pretty" harsh and distorted.
If you look into the circuits used by GELOSO, HOHNER, KLEMT etall
published on the same website of Jogi, you will see that nobody
ever thought of building an EL503 amp according to the Philips app-
note. Philips did never do this fine tube justice. So it died in
childhood or better to say: It was killed by the beancounters.

Kind regards, Eike
--
Lions go to absurd lengths to retain the posession of their skins.
- Stewart Edward White 1913

"Ian Iveson" = what a wacko !!


"Phil Allison"
Now go read up on Occam's razor - and be careful not to cut
yourself in the process.

Missed this bit.


** When did you ever "catch" anything ????


Occam is kind of OK in this context (Kinda cute
actually, I thought.), which is why I originally accepted you were
right.


** But thoughtfully hid that to confound the debate ??


But where Occam is used in less trivial manner, you should be wary.


** Clearly you have not studied the correct use of Occam's razor.


Simplest is merely to fit in best.


** QED.


Revolutions happen; fitting in is
not and never has been sufficient in the end, and is stupefyingly
boring anyway.


** Since your premise is wrong so are subsequent conclusions.




................. Phil

Ian Iveson wrote:

"Patrick Turner" wrote

I recall seeing similar versions with cathodes tied together, and
then the
distortion is lower...

Voltage feedback around just the first valve is arguably a better
solution. That decreases output impedance from that valve, and
reduces distortion at source. The second valve contributes no gain
so doesn't want feedback at its cathode.

But all sorts of variations have been used. If you want to minimise
low odd order harmonics, a paraphase is one possibility.

I always prefer to use an LTP, which will have far less 2H,
slightly
better bandwidth and is simpler.

Depends on which LTP, and which paraphase, and on the context. Some
argue that cutting 2H at the expense of adding 3 and 5H is not
worthwhile.

The well set up LTP has no more 3H than a well set up SET on its own.
No more 3H is added just because we have chosen an LTP.
But the 2H from both halves of the LTP is virtually eliminated,
and that is always an ideal outcome, and one not as a result of applied
NFB
in the normal sense, unless you see the cathode load of the first 1/2 of
an LPT
as the cathode resistor of the second 1/2, and so forth.

The vast majority of distortions occur in the output tubes.
So what the driver tubes contribute is usually 20 dB lower, so
it isn't a big issue



Saying one splitter is better than another appears futile
considering how many times they have all been used successfully.

True, but I am surely allowed to have my preferences, now ain't I?

I have reasons for those preferences. I believe they add up
with all the other factors when wanting good sound from tubes.

The best sounding guitar amp I ever heard had a pair of 6V6 in the
output in
with 66% UL taps, and had another 6V6 and transformer PI .
I don't know if the idea is prteferable for a hi-fi amp.
But making an IST act blamelessly with enough bandwidth and still allow
some
NFB is a big ask, so I prefer the CT choke fed LTP, etc, as you all know
about.

Allen Wright says if you have a typical class A PP output stage
and have a CCS tail to the commoned cathodes of the output tubes, you
can
have a normal PI of any sort, or ground one output grid, and
just power the other grid with say 50 vrms instead of the usual 25 vrms.

He says perfect current cancelling occurs because
of the CCS, rather than the common Rk like in the original Williamson,
or where you have separate Rk and bypass caps.

If an SET is used to power such a class A output stage, then you get
only the 2H of the driver stage, which is easy to minimize well below
what you'd
get with an SET output stage. Any other way of phase inversion in the
output stage
always has the distortion of one tube fed into the other, like the
paraphase system which
I don't like for this reason.

Of course such an output stage cannot move into class AB if the load
value is reduced from
what permits class A. But its no worse a situation that where you have
an SE tube,
whether it be a triode or tetrode/pentode, or UL etc.

Allen challenged me to try setting up an output stage like this.
I haven't time right now, so I'll challenge you guys to try
it and get back tot he group.

Never ever think you have tried everything.

Some might say that an output stage CCS for 150 mA is a bit hard to do,
but a couple of bjts do nicely.
Also a choke in series with a resistor can also work ok,
just as long as the common cathode current sink has a high impedance at
signal F.



Patrick Turner.





cheers, Ian

Ian Iveson wrote:

"Phil Allison" wrote

Now go read up on Occam's razor - and be careful not to cut
yourself in the process.

Missed this bit. Occam is kind of OK in this context (Kinda cute
actually, I thought.), which is why I originally accepted you were
right.

But where Occam is used in less trivial manner, you should be wary.
Simplest is merely to fit in best. Revolutions happen; fitting in is
not and never has been sufficient in the end, and is stupefyingly
boring anyway.

You appear to have the mental ability to kick free. Give it a try
sometime.

Asleep just now, I guess.

Are ye talkin about Liam O'Ccam?

I knew him weel, he took a razor to all the village people,
because they disagreed with his politics....

Patrick Turner.



cheers, Ian

Revolutions happen; fitting in is
not and never has been sufficient in the end, and is stupefyingly
boring anyway.

** Since your premise is wrong so are subsequent conclusions.

................ Phil

One ought to read the history of the Prague Jazz Club in the 1980s,
and the exception that the regime took to the club and its
attitude/involvement with Frank Zappa.
Nah, the club members wouldna fit in. Bloody rebels, actually.
But they wanted democracy.

Please do not try to fit in.

Whenever a fresh regime takes power, always join the resistance,
lest democracy be crushed from your spirit.
With luck those who rule over us won't trample to heavily
when reminded of their duties of care, and how easily
they could lose their rights to power.

When somebody parleys about transistors, raise a tube
in defiance.

Patrick Turner.

John Stewart wrote:
"Eike Lantzsch, ZP6CGE" wrote:

[snip]
published in FUNKSCHAU AFAIK. There is another mistake in the circuit.
The screen voltage is 275V and the Plate voltage is 265V.

Not a mistake. Simply the voltage drop thru the output transformer
primary winding resistance caused by the EL503 plate current.
That happens in any power amp.

Yes it does, but that does not mean that it is good. We had the
discussion about screen voltages some days ago on this newsgroup.
It would be interesting to try that tube with different screen
voltages. A screen resistor and a cap should do the trick.
An indicator for problems with higher screen voltage than plate
voltage on this tube is the use of chokes on the screen leads
to avoid RF-oscillation.
But I think that any argument about the EL503 is moot because
this tube is so scarce that the remaining stock shall only be used
to restore vintage equipment. There is no replacement for EL503 that
I know of, with the low plate voltage and low Ra of this jewell.

Kind regards, Eike
--
Lions go to absurd lengths to retain the posession of their skins.
- Stewart Edward White 1913

"Phil Allison" wrote

"Ian Iveson" = what a wacko !!

This is a bit feable. You should have waited 'til after breakfast.

Now go read up on Occam's razor - and be careful not to cut
yourself in the process.

Missed this bit.


** When did you ever "catch" anything ????

Here, where you first mentioned it:

Occam's razor says there is a 0.1 uF missing cap.


OK...

See how I clearly accepted your point and agreed with you? That's
why I wrote:

Occam is kind of OK in this context (Kinda cute
actually, I thought.), which is why I originally accepted you
were
right.


** But thoughtfully hid that to confound the debate ??

Not hid. In front of your nose.


But where Occam is used in less trivial manner, you should be
wary.


** Clearly you have not studied the correct use of Occam's razor.

Studied? Correct? You disappoint me. Like I said, I thought you
might have the wit to break free.

Simplest is merely to fit in best.


** QED.

You are two premises short of a legitimate argument. An example of
extreme misapplication of the razor perhaps. There again, for the
totally clueless, the simplest and safest argument is no argument at
all. I suppose you must believe in god.

Talking of which, monastic scholars had a much simpler model of the
world than modern science. The bible is much shorter than the
collected works of science. The idea that the earth was not the
centre of the world appeared to them a ludicrous complication.

Science redefined simplicity. It *became* more simple to see the sun
at the centre of the solar system. It became more simple because it
added least complexity to the *new* model, at the expense of adding
complexity to the old one. New data necessitated a paradigm shift.

I believe Occam was aware of this, as you seem not to be. His razor
works within, but not between, alternative views of the world. He
did not argue that the least complex of equally valid theories is
most likely to be true; only that it provides the best workable
assumption for practical purposes.

That's why I said:

Revolutions happen; fitting in is
not and never has been sufficient in the end, and is stupefyingly
boring anyway.

Now that is *my* point, never attributed to Occam. I assumed,
wrongly as it is turning out, that you know something about his
principle.

** Since your premise is wrong so are subsequent conclusions.

Not a premise, but a conclusion of my own. You would need a very
substantial argument to shift me from it. Twaddle won't do at all.

Incidentally, in an effort to clamber back on topic, the view that
linearity is the sole criterion of domestic audio equipment quality
is an excellent application of Occam's razor. To state that
linearity is best, or even necessary, for high fidelity strays into
metaphysics, which is just where no-one should take him. His
principle is not about truth, but about best assumption in the
absence of complete data.

So the best assumption is that your cap is missing from the diagram.
That has no bearing on the truth, which we will probably never
discover.

But ask the question "How can this circuit be fixed?", and there are
several simple answers. The method I suggested saves a cap and one
or two resistors compared to yours, although it assumes that the
output stage is cathode biased.

In passing, are you sure your octave is correct, given that the caps
are in a closed loop in my scheme? True for one side but not the
other perhaps. Of course I would resize as necessary, since I am not
applying the razor.

Occam can presumably be applied in reverse. Because my method is
simpler, and because designers choose otherwise, there must be
something wrong with mine. But what?

cheers, Ian

On Mon, 07 Feb 2005 14:40:24 GMT, "Ian Iveson"
wrote:
Talking of which, monastic scholars had a much simpler model of the
world than modern science. The bible is much shorter than the
collected works of science. The idea that the earth was not the
centre of the world appeared to them a ludicrous complication.

Says it all, really.................. :-)

Science redefined simplicity. It *became* more simple to see the sun
at the centre of the solar system. It became more simple because it
added least complexity to the *new* model, at the expense of adding
complexity to the old one. New data necessitated a paradigm shift.

I believe Occam was aware of this, as you seem not to be. His razor
works within, but not between, alternative views of the world. He
did not argue that the least complex of equally valid theories is
most likely to be true; only that it provides the best workable
assumption for practical purposes.

Nope - read it again:

"Pluralitas non est ponenda sine neccesitate" or "plurality should not
be posited without necessity."

This is pretty universally interpreted as meaning that, when presented
with both complex and simple answers to a problem, the simple answer
is likely to be correct. Not *guaranteed*, of course, but likely.


Occam can presumably be applied in reverse. Because my method is
simpler, and because designers choose otherwise, there must be
something wrong with mine. But what?

For this we require Albert Einstein:

"Everything should be made as simple as possible, but not simpler."

--

Stewart Pinkerton | Music is Art - Audio is Engineering