Iain M Churches wrote:
"Nick Gorham" wrote in message
...

Iain M Churches wrote:



That seems to be exactly the conditions under which it is used. No-one
seems to play Jethro Tull on a 300B:-)


Takes all sorts, Tull works fine for me with a 211.

Then again, I am no a great fan of 300b's at the best of times.

--
Nick


So you are a member of what Stewart calls the "audio lunatic fringe" ? :-)
Having had the opportunity to listen to an SET amp, I must say I was
more than impressed.


Yes, I am one of those nutters :-). I must say though I agree with Stew
in part of what he says, There are a lot of crap commercial SET's out
there, that seem to sell to people who do want a effects box, and that
nice lush 300b sound, I prefer the sound of the transmitting triodes
myself. Though I also like 2a3's, The second triode in the 6em7 is not
unlike a 2a3, and I may just use a DHT for the first stage, just for the
fun of it.

45's and PX4, PX25's are nice, though hard to get hold of NOS.

I have head a PX4 SET driving a set of ELS63's and ok it was not loud,
but sounded rather nice, I suspect you would like the effect.

No I am not going to clame they don't add something to the sound, they
do, just something that I prefer, and think allows the music to be
communicated to my dull mind in a way that I find more pleasant than
when produced by SS amps.

Its certainly true that on the whole you either "get" SET's or don't. If
you do, then everything else seems lacking, and I guess the same is true
the other way :-). They also do provoke a certain "evangelical" response
from their owners :-)

Its because of this amp, that I sone have that strong a feeling about
cap sound ATM, the final cap will be replaced with a interstage
somewhere along the line, and all the bipass caps are black gates. I
will be eventually be using polyprop and paper in oil in the power supply.

If nothing else, the BG's are worth it IMHO for the much longer working
life. Pity they are stopping making them :-(

I would be interested to know a little more about your amplifier
and speaker combination. I am thinking to build/beg/steal/borrow
an SET amp for further listening in the future.

Well, this is what it was some time ago,

http://www.lurcher.org:8080/nick/audio/set/gm70ckt.gif

The GM70 is now a 211, (I will go back to GM70 for the next one :-)),
and the first stage is not the small 6em7 triode but a 6sn7.

Waiting on new transformers (The are being wound this afternoon I have
heard today), so that will let me up the B+ to 1200 and see what it can do.

Speakers are ProAc Studio 125's, 98db/w rated, but in a small room, so
almost load enough for me for most things, increasing the B+ and maybe a
bit of A2 should make it more than loud enough.

I like it anyway :-)

--
Nick

"Nick Gorham" wrote in message
...
Iain M Churches wrote:

So you are a member of what Stewart calls the "audio lunatic fringe" ?
:-)
Having had the opportunity to listen to an SET amp, I must say I was
more than impressed.


Yes, I am one of those nutters :-). I must say though I agree with Stew in
part of what he says, There are a lot of crap commercial SET's out there,
that seem to sell to people who do want a effects box, and that nice lush
300b sound, I prefer the sound of the transmitting triodes myself. Though
I also like 2a3's, The second triode in the 6em7 is not unlike a 2a3, and
I may just use a DHT for the first stage, just for the fun of it.

This is a domain in which I have little experience, but I must say first
impressions were most favourable. I can however, see that SET is
severely limited in its use, and for someone like me, who listens to
a huge range of music, it is probably not suitable. Still, I would not
knock it, just for the sake of doing so:-)

I have head a PX4 SET driving a set of ELS63's and ok it was not loud, but
sounded rather nice, I suspect you would like the effect.

I notice you call it an "effect", which supports what Don said:-)

No I am not going to clame they don't add something to the sound, they do,
just something that I prefer, and think allows the music to be
communicated to my dull mind in a way that I find more pleasant than when
produced by SS amps.

I don't think anyone would make such a claim for SET. From my own brief
experience at low levels I was fascinated that such a simple amp could
produce such beautiful music.

Its certainly true that on the whole you either "get" SET's or don't. If
you do, then everything else seems lacking, and I guess the same is true
the other way :-).

I have noticed:-)

Its because of this amp, that I sone have that strong a feeling about cap
sound ATM, the final cap will be replaced with a interstage somewhere
along the line, and all the bipass caps are black gates. I will be
eventually be using polyprop and paper in oil in the power supply.

Someone else, in the cap testing thread, pointed out thatone might be more
likely to detect a difference between caps in an amp with a low parts count.
That's why the µ-follower stage seemed such a good idea.

The GM70 is now a 211, (I will go back to GM70 for the next one :-)), and
the first stage is not the small 6em7 triode but a 6sn7.

I think the Reznekov amp was 211. Jim asked me about the power level.
I could only say "low" What can a 211 deliver, and and what kind of THD
levels?

Waiting on new transformers (The are being wound this afternoon I have
heard today), so that will let me up the B+ to 1200 and see what it can
do.

Hmm! Keep the kids and the cat away from that one:-)

Speakers are ProAc Studio 125's, 98db/w rated, but in a small room, so
almost load enough for me for most things, increasing the B+ and maybe a
bit of A2 should make it more than loud enough.

I will be interested to try the Reznekov in my own room, if I can ever
persuade
its owner to lend it to me.

I like it anyway :-)


That's what matters:-))

Iain

Iain M Churches wrote:



I think the Reznekov amp was 211. Jim asked me about the power level.
I could only say "low" What can a 211 deliver, and and what kind of THD
levels?


Depends, but I would expect something like 15-20W from a 211, depends on
the B+, to get the most from them (unlike a 845) they need driving A2,
which adds it own problems. I would think 1-2% at 15W would be the sort
of output you would expect, almost entirly 2nd harmonic. But with much
lower distortion at lower output. Depends on the design as always. Maybe
its a Ongaku type circuit.

211's are very dependednt on transformer quality, the high Ra, means
that you can have HF problems if its not a well made (expensive)
transformer.

You can get 40W ish out of a GM70 SET though, so its not all small stuff.

I have a fellow "nutter" getting 75W out of a 212 SET at the moment...

You can increase power output by paralleling the valves, but IMHO that
produces problems with the resultant sound.

--
Nick

"Nick Gorham" wrote in message
...
Iain M Churches wrote:



I think the Reznekov amp was 211. Jim asked me about the power level.
I could only say "low" What can a 211 deliver, and and what kind of THD
levels?


Depends, but I would expect something like 15-20W from a 211, depends on
the B+, to get the most from them (unlike a 845) they need driving A2,
which adds it own problems. I would think 1-2% at 15W would be the sort of
output you would expect, almost entirly 2nd harmonic. But with much lower
distortion at lower output. Depends on the design as always. Maybe its a
Ongaku type circuit.


Hmm. That's interesting. I think that the front end is two
halves of a 6SN7. It is difficult to say, but I think we were
listening at perhaps only 3-5W.
There was no audibler distortion (or at least none that
I could detect:-) at this level.

211's are very dependednt on transformer quality, the high Ra, means that
you can have HF problems if its not a well made (expensive) transformer.

I listened carefully to the 1st violin. It was perfectly clean. The
limited lower range of the cello did not give me a chance to
evaluate the LF performace of the amplifier. The transformer was,
I assume, Russian made.

Thanks for the info.

Iain

In article , Iain M Churches
wrote:

"Nick Gorham" wrote in message
...
Iain M Churches wrote:
[snip]

This is a domain in which I have little experience, but I must say first
impressions were most favourable. I can however, see that SET is
severely limited in its use, and for someone like me, who listens to a
huge range of music, it is probably not suitable. Still, I would not
knock it, just for the sake of doing so:-)

Well, one of the aims of the kind of points I make (e.g. about o/p
impedance) is to see if it may be possible to establish that the 'cause' of
the preference might be due to an identifiable factor which could then be
replicated - if people so choose - with amp designs that do not share the
power limitations or practical difficulties of a SET.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

In article , Iain M Churches
wrote:

"Jim Lesurf" wrote in message
...
[snip]

] From: Iain M Churches Subject: DBT a flawed
] method for evaluating Hi-Fi ? Date: Tue, 11 Jan 2005 14:25
] Newsgroups: uk.rec.audio
]
] I don't know what motivates people who listen to Stravinsky to buy
] SET amps. But the fact is that they do, as a matter of choice.

The second first sentence refers to "people" who fit the conditions
you specify. The second makes a statement as a "fact" about their
choice. Tje wording seems to me to indicate that you wish the
statements to be taken as a general indication which is reliable for
all those "people" referred to in your first sentence.

I simply make an observation, and wonder why it may be so.

That is OK given that we have clarified that your observation is based only
on a small grouping of individuals. This means it is a curious observation,
but we can't really draw any conclusions from it in isolation. The problem
is that the number of people involved is small, and may be subject to a
'selection' effect or sheer chance. Thus the 'reason' may simply be a mix
of 'chance' and some factor linked with happening to know someone like
yourself.


To be able to make such a statement, you would need to have reason to
show it was reliable for such a group. Yet your reply only refers to
your own "music circle" and "three" people.

Three from fifteen, makes 20%, a much greater percentage than I would
have expected. Three others have PP valve amps, so that makes 40% who
use something other than SS. I wonder why there should be such a high
percentage in a classical music group?

Given the small sample, and the possible selection factors, it is not
obvious that the reasons are more than 'chance' and a bias due to a
selection effect. I don't know figures, but I suspect that only a tiny
fraction of those who enjoy listening to music on domestic audio systems
use valve amps. In itself, all this would tell us is that most people are
quite happy listening without using such an amp.



On that basis your statement seems to simply say, "I know some people
who prefer SET amplifiers and who also listen to Stravinsky". That may
be so, but does it tell us anything applicable beyond that specific
set of a few individuals?

Your interpretation of what I say is correct. I still wonder why these
people choose SET. Any ideas?

WRT Stravinsky as a parameter, no. :-)

Otherwise, I have some "ideas" if you mean hypotheses that might be
relevant, yes. However I have no real reason to be convinced said
hypotheses *are* explanations, either entirely, or as factors. Too many
variables, too little in the way of reliable evidence. :-)



I'm not clear why the group you pick out should be of particular
significance. But since you make a statement about them, I'd be
interested to know the answer to my question.

I use the music group as an example, because they are people I know,
with audio systems with which I am acquainted. It may be that others in
this NG have no one in their immediate circle with an SET amp. This
gives 0% - also a figure that I accept. If this was so in my own case,
I could have written "I wonder why none of those who listen to
Stravinsky use SET"

Well, I listen to Stravinsky, but do not use SET. Never occured to me that
there might be any relationship at all TBH.

I am not really concerned with how many people listen to SET. But I *am*
interested to know why. Maybe an SS dominated group is not the right
place to ask the question:-))

My first concern would be to establish some evidence of statistical
significance before I looked for "reasons" for what might be chance or
selection. Otheriwise it may be a waste of mental effort to try and form a
more specific hypothesis.


It seems that SET performs especially well with small classical
ensembles.

I appreciate that this may be your opinion, and that of the specific
few people you know and were referring to. The problem is that your
wording seemed to be implying that this was something established as
being 'valid' on a more general basis. However the wording you now use
is quite "weak" in that it includes "It seems" instead of "fact". And
"especially well" is a value judgement/opinion of relative merit,
which might mean "does not sound as awful as SET used for some other
things" just as easily as it might mean "better than anything else".
:-)´

What is uyour personal opinion? Do you disagree that SET performs
especially well with small ensembles?

Can't really comment on the basis of personal experience as the only SET I
have used in 'living memory' was the transistor design I had a student
make.

However I can speculate (a la the "ideas") mentioned earlier.

May be that at low powers the limited available power becomes irrelevant,
so does not impede use.

May be that with small ensembles what low-order nonlinearity there is
produces low-order intermod and harmonics that colour the results in a way
that suits the nonlinear processes of human hearing

May be that the o/p high impedance interacts with many speakers to alter
the tonal balance and offset reponse factors elsewhere in the chain and
give a more pleasing result.

However the above are really 'plausible speculations' rather than firm
theories that could be well supported.



In this context, it seems odd that those producing the recordings do
not do so using, say, SET amps, *if* they feel this would give
'better' results.

I think, Jim, the explanation is simple. SET cannot produce the power
required for a large monitoring set up.

That is not, I think, a completely satisfying reason. I assume the aim in
the recording process is to get 'good' results. I would therefore suspect
that if those recording, etc, the music felt that SET sounded better they
would adopt a suitable SET based system - even if it meant a lower
monitoring level and/or high efficiency speakers. In effect, the question
would become "why monitor/balance using a high level when a lower level may
give 'better' results?" Particularly when most people at home may well be
listening at lower levels.

Above said, it strengthens my curiousity about what makes some people
prefer SET. If the factors could be identified and made sense, then it
seems reasonable to suspect that they could be applied using other types of
amp that can supply higher powers...

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

In article , Iain M Churches
wrote:

"Jim Lesurf" wrote in message
...


The obvious point here is that most of the SET amps I have seen
reviewed in consumer mags have - where a value is given - o/p
impedance of around 1 Ohm even midband at low power.

I seem to recall than Andre told me they sometimes have a DF of 1.

If you mean DF=1 into 8 Ohms, that is a remarkably low (poor) value! With a
Quad ESL57 I'd expect it to produce changes in the frequency response of
over 10 dB if using the 8 Ohm o/p taps. Having such a poor o/p - LS ratio
might well also affect the distortion and peak power levels quite markedly.

Thus using such an amp rather than one with a low o/p impedance might
well change the frequency response by the order of 3dB. Hardly
surprising if this has an audible effect. Then a matter of
circumstances if this is preferred, I guess...

Yes indeed. I am still intrigued to know how an amplifier with such a
poor test bench specification can sound so good. I have no axe to grind
here. I do not own an SET amp.

From what you say, maybe you preferred the resulting frequency response
which would have been *very* different than when used with an amp with a
nominally flat response and a low o/p impedance.

A complication is that the 57 can provoke oscillations in amps that are not
unconditionally stable. The low and reactive speaker impedance can also
aggravate 'd.c. ducking' effects that can generate off LF effects as well
with musical dynamics. No idea if these have any relevance in this case,
though.

The difficulty of estimating amp-speaker interactions is that -
particularly with low-feedback and single rail designs like SET - a lot of
data would be needed to determine what *might* be happening. Alas, your
report, as many magazine ones, does not give the relevant information, so
we can't do more than speculate.

The CD player was a Studer A730.

OK. I don't regard that as likely to be particularly significant in
this context.

I mentioned it because I was sure you would ask if I did not:-))

Fair enough. ;-


Another interesting point here is that ESLs tend to provide lower
distortion than cone-and-box speakers. Yet SETs tend to provide higher
distortion than common SS amps.

At lowish listening levels, the SET distortion was not even faintly
audible. I daresay that at higher levels it might have been so. I was
not invited to touch the level controls, and did not do so.

OK. At low powers I would expect the distortions to fall and hence what you
say seems entirely plausible to me.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

Iain M Churches wrote:

The whole object of the excercise was for you to build an SS equivalent
of Andre's SET amp, so that we lesser mortals could build both and compare
like with like. If your amplifier does not meet the criteria, then you
cannot be credited with even getting to the starting gate.

What are the criteria?
It would be amusing to design and build a minimalist amp.
Do Darlingtons count as two transistors?

--
Eiron.

Iain M Churches wrote:


Hmm. That's interesting. I think that the front end is two
halves of a 6SN7. It is difficult to say, but I think we were
listening at perhaps only 3-5W.
There was no audibler distortion (or at least none that
I could detect:-) at this level.

No I wouldn't expect you would hear any distortion from a 211 at those
sorts of levels.

211's are quite easy to drive in A1, as they have quite a high mu. But
if you look at their curves they are meant to be used in A2, so are
often driven by a cathode follower.

My plan involves using a 2a3 to drive the 211 via a 1:1 interstage, so I
should be able to have some a2 operation if I need. The 2a3 (current
plan) will be using a 6sn7 in a direct reactance drive sort of
arrangement, or maybe normal DC coupling, depends on how the DRD works
out. Seems fine in Spice, but the reality may be different...



211's are very dependednt on transformer quality, the high Ra, means that
you can have HF problems if its not a well made (expensive) transformer.


I listened carefully to the 1st violin. It was perfectly clean. The
limited lower range of the cello did not give me a chance to
evaluate the LF performace of the amplifier. The transformer was,
I assume, Russian made.

Well, LF, tends to be ok, as to handle to 1200v at 70ma that a 211 would
normally be working at, you tend to have a lot of iron to avoid
satuartion. Its the HF thats the challange for the winder, the 10K or
higher primary load that a 211 needs means you need good design to avoid
lots of parisitic capacitance, and combined with the high impedance that
will limit your HF response.

--
Nick

On Thu, 6 Jan 2005 17:36:14 -0000, "Richard Wall"
wrote:
What has however shocked me recently is
mains cables which I have always felt should make no difference at all. I
now however have a load of Kimber cables !!!

Oh, dear - 'nuff said...................

NURSE!!
--

Stewart Pinkerton | Music is Art - Audio is Engineering