Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

Jim Lesurf wrote:

In article , Patrick Turner
wrote:

Harmonics in music are its very essence, so a fraction of a percent more
or less harmonics if they are 2h, 3h, 4h or 5h or 6h makes little
difference. At a concert, each person at a different seat in the
audience gets a different balance of harmonics. But the music is spoiled
if the imd mounts up as a result of excessive thd, because the imd
products are not harmonius with the musically related tones.

I am inclined to agree.

At least someone does.
Tones produced by wayward electronics are not musical.
tones produced by musical instruments are musical.
But some folks loathe saxophones and Tom Waits.



I would also point out that some/many(?) of the
waveforms produced by musical instruments are asymmetric and have a high
peak/rms crest factor even with sustained waveforms (see one of my websites
for examples). This means that how the nonlinearity varies with signal
level may be quite important, and a single sinewave THD value does not
indicate this.

Its IMD that you speak of.

Old radios have a real "valve sound", and often not a happy one,
if the output tube is a pentode, so its current drive, and often not a stitch
of NFB, and so its 4% thd evem listening to the cricket.

The HF reception of AM is so bad, those sets need every bit of thd they can
muster to replace the
real HF content of the programme, hence those radios swindled your ears from
what you should be hearing.




I must say I have not witnessed much 7h in anything I have tested,
unless the level was taken to the brink of clipping, when by that time
the the mix of harmonics has mushroomed, as opposed to am amp working at
1/10 of its maximum power, where the mix of harmonic products is less
complex, and also the imd mix is less complex.

My experience (mostly with SS amps) is similar. Indeed, my experience even
20+ years ago was that this was often less of a problem than many people
assumed.

Perhaps the dynamic IMD action going on in what are essentially class B amps
is the main reason for concern with SS.

The crossover distortion is one thing, it may not be serious, and the IMD
another.

But Bryston manage to do OK; they use both pnp and npn each side of the rail,
so the turn on turn off transfer curve is identical, so their design inherently
addresses
the wide current gain differences between p amd n devices.
Most amps have p and n devices in the output stage, and the differences
are equivalent to using a 6L6 and an EL34 in the same PP tube amp circuit.

A tubed class B amp wouldn't sound too good
unless it has over 40 db of total NFB.
EAR 509, McIntosh are samples.
The EAR still sounds worse than a class A amp above 3 watts.
The same glassware used in class A for 1/2 the watts and with 1/2 the NFB,
or ten times less at 20 dB, will sound better.

Patrick Turner.


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

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

On Thu, 18 Nov 2004 09:04:38 +0000 (GMT), Jim Lesurf
wrote:

In article , Don Pearce
wrote:
On Wed, 17 Nov 2004 19:39:16 +0000, Kurt Hamster wrote:


As I said, you can waffle as much as you like. Transistor technology is
57 years old, any new advances are still based on old technology.

To use your analogy then doesn't that preclude, $DEITY forbid, someone
using valves on a state of the art computer motherboard?


So your position is that transistors now are the same as transistors 57
years ago - there is no current state of the art. You are entirely
clueless.

Valves, on the other hand, are exactly like they were 57 years ago -
there have been no advances and the state of their art is far from
current.

I am not quite sure how:

A) multiple field emitters, polotrons, and various other vacuum-state
devices.

B) high mobility / ballistic or quantum well/dot or multiple barried SS
devices.

fit into the above picture. My understanding is that they have been
developed during the last couple of decades, and in some cases required new
understanding of the relevant physics and/or novel fabrication methods.

Don't know if any of them have been used in audio, though. :-)

I think that last sentence sums up the position of valves in the
mainstream. And are your B) devices products of valve research or
solid state research?

d
Pearce Consulting
http://www.pearce.uk.com

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

On Thu, 18 Nov 2004 15:24:36 +0000, Kurt Hamster
wrote:

On Thu, 18 Nov 2004 01:17:33 +0000 (GMT), Dave Plowman (News) used
to say...

In article ,
Trevor Wilson wrote:
Reformed alcoholic, but still addicted to nicotine? Seriously deranged
and dangerous!!

**Ah, so Keith WAS a drinker. That explains a great deal. The damage has
already been done.

And by his outburst about being teetotal, without qualification, hopefully
not in denial.

So you maintain that an alcholic can't become teatotal then?

Basically, he *has* to, doesn't he?
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

In article , mick
wrote:
On Wed, 17 Nov 2004 23:35:44 +0000, Ian Molton wrote:

snip

mick - if you wish to continue discussing this Im happy to respond to
you.

Cheers, Ian.

This is all just playing with ideas. I don't profess to be an expert on
hearing, recording or amplification or anything remotely connected with
them! Somebody, somewhere *must* have written books on this stuff, but I
probably wouldn't understand them... grin

I can see where you are coming from: "If listening to a live
performance, for the sake of argument, from a point source instrument,
our 'inherent distortion' is the only thing impacting on the signal."

I am not sure what the "point source" aspect has with to do with
nonlinearities.

But our ears don't perceive an instrument as a point source. We hear
positional information - possibly phase and/or frequency shift sensing -
which must include reflected sound and, possibly, THD inherrent in any
frequency shift detection. There are no point source sounds that we can
detect in isolation - except maybe in an anechoical chamber!

A change in frequency response is not the same thing as distortion. They
are different in kind.

Nonlinear distortion can/will create frequencies that were not in the
orginal signal, and which may not be at simple integer harmonics of the
frequencies that were present. Consider intermodulation distortion as a
simple example of this process. In such cases nonlinearity produces effects
that you won't get as a result of room acoustics or the departures from
flat response of something like an amp or speaker.


Even stereo point sources with perfect reproduction *may* be
insufficient to reproduce all the necessary information as much of it
must be at very low level (where it could be detectable with logarithmic
hearing but not with linear amplification - the source information would
be lost at the microphone).

Not clear what the comment about "detectable with logarithmic hearing
but not with linear amplification" means. Nor about the "source
information".


In real life we would be producing a point-source representation of the
original, with all the location information stripped from it. It would
measure perfectly, but information would be missing. It would be
analagous to a painting, which is a 2D represdentation of a 3D space.

Real sound sources are not normally "point sources". Easy enough to
establish this by measuring the sound radiated from something like cello as
a function of direction and distance.


I just have a hunch that the THD produced by a valve amp is doing more
than just giving a "warm" and "easy" feeling to the sound. I am
wondering if it is fooling the ear/brain combination in some way.

That might be so. But the above comments do not all relate to what you say
here.


I don't know. Someone must have done, or be doing, research on this.

It would be nice to think so, but I've not yet found any that seems
reliable to me. Interested to hear references to some...

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

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

On Fri, 19 Nov 2004 02:31:25 +1100, Patrick Turner
wrote:

Mike Gilmour wrote:

The problem is that chinese amps might look nice, even sound nice,
but the detailed examination of the circuit and output transformer quality
often leaves a lot to be desired.

They seem to be improving slowly.

Get over there, you'd make a shed load of cash designing machines to make
wide band width OPT for future audiophile amplifiers

The designs for these have been common knowledge for 60 years at least,
and all the info on how is spelled out in RDH4.
But the chinese like to make copies, and they overlook the inner details,
and some of the product is like a Rolex watch made in HK.

Likely better than a Swiss-made one...... (not a Rolex fan - like SET
valve amps, all marketing and no substance)

Mechanised winders for transformers have been around for years,
and the asians don't need lessons or lectures from me.

The Zero was no match for a Huricane or Spitfire eh.

Not designed to be, as it was a carrier-borne fighter/bomber, and
usually regarded as the finest such aircraft of the '40s. It was
certainly a match for the ocean-going Spit, the Seafire.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

On Thu, 18 Nov 2004 15:15:55 +0000, Kurt Hamster
wrote:

On Wed, 17 Nov 2004 23:56:43 +0000 (UTC), Stewart Pinkerton used
to say...

On Wed, 17 Nov 2004 19:31:09 +0000, Kurt Hamster
wrote:

On Wed, 17 Nov 2004 19:24:50 GMT, Don Pearce used
to say...

On Wed, 17 Nov 2004 19:20:41 +0000, Kurt Hamster
wrote:

On Wed, 17 Nov 2004 18:31:09 GMT, Don Pearce used
to say...

On Wed, 17 Nov 2004 17:59:33 +0000, Kurt Hamster
wrote:

I don't think anyone will argue that valves are old technology, but does
that as such have any bearing on anything ?

Are you suggesting that new is always better ?

Transistors aren't exactly state of the art either are they?

Er.... yes - they are actually. Unless you know of something more
advanced.


Ah so you agree that old technology (57 years old) CAN be state of the
art then?

Oh I do like it when pedants pounce on what they think is a mistake :)


Listen carefully. Transistors are state of the art because they are
where all the research is happening - they are moving forwards with
new and better geometries, and advances in integration.

Valves stopped evolving many years ago, and represent an obsolete art
with no current "state".

OK?

Nope, you can waffle as much as you like the transistor was invented in
1947. The transistor itself hasn't evolved much since then.

Ignorant ****.

Would you class yourself as an ignorant **** because you didn't know how
to canulate, or intubate, or defibrillate or perform cardio-version, or
use InDesign, Quark, Photoshop?

I haven't heard of InDesign, so point taken.

Educated ****.

The 'transistor', in the sense of the solid-state
amplification device, has improved *massively* since then. OTOH,
valvies are still scrabbling after enormously expensive NOS Western
Electric 300Bs made before WWII started..............

When did I say it hadn't improved? I said it was old technology.

No, it's not. Modern solid-state devices are not made of the same
materials as those of 1947, nor are they made in the same way, nor do
many of them operate on the same principle.

Most
technology BASED on transistors is still evolving e.g. microchips,
surface mount technology etc, but even then most of that evolution is
based on how many can fit in a finite space and how to get them to work
without setting themselves alight.

Hardly any of that technology is bipolar, hence it's not at all
related to Schockley's devices.

The principle of the transistor has not involved, it doesn't matter how
its physical form takes it's still 57 year old technology.

Totally untrue. MOSFETs for instance, work on a completely different
principle from those first transistors, as do junction FETs and tunnel
diodes, while modern devices use silicon, gallium arsenide and other
materials not dreamed of in such an application in 1947. Compare and
contrast with valvies, who seem to think that the best valves were
designed *and made* in the '30s.

If I was 57 I
wouldn't consider myself to be young, would you?

Yes, I would - only got about 50 days to go............ :-)

Your ignorance of engineering evolution is noted. Funny how that all
changes when valvies whine that VAIC et al are designing new versions
of the 300B..................

1) I'm not a "valvie"

If it walks like a duck and quacks like a duck..............

2) I'm not an engineer

Ain't that the truth! Doesn't seem to stop you sticking your oar into
technical discussions though................

3) A transistor still does what it did 57 years ago does it not?

Not if it's a FET, as are more than 99% of all modern active devices.
As it happens, the output stage of audio power amps is one of the very
few places where you're still in with a good chance of finding a
bipolar transistor.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

In article ,
Stewart Pinkerton wrote:
So you maintain that an alcholic can't become teatotal then?

Basically, he *has* to, doesn't he?

No. An alcoholic can carry on drinking. Until he dies. As he will.

What's not possible is for an alcoholic to go back to moderate 'social'
drinking. It's stop or nothing.

--
*Black holes are where God divided by zero *

Dave Plowman London SW
To e-mail, change noise into sound.

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

In article , Patrick Turner
wrote:

The thd is less than 0.1% at up to 10 watts into any load between 4
and 12 ohms, which means that at 1 watt its down around 0.03%, even
though it is an SE amp.

That is quite good in itself. Does it maintain that into reactive
loads, or in 'intermod' situation where both LF and HF are present?

Its no worse than any other amplifier which is class A, and which
measures with such low thd.

Afraid that doesn't really tell me much. Do you include something like a
'Krell' design in your "any other amp which is class A", or are you
limiting what you are comparing? e.g. I assume you are limiting your
comparison in some (unstated) manner as I'd expect any amp with an output
transformer to have some effects imposed by that, and which are transformer
dependent.


I'd also be interested to know the (complex) o/p impedance as a
function of frequency and perhaps power level....

Ro = 0.5 ohms at 1 kHz, with about 7 uH inductance in series. The
leakage inductance in a tube amp is similar to the LR zobel network
fitted to the output of an SS amp to stop the transistors ****ting
themselves with a capacitive load.

Slight typo, there, I think. :-)

What about as you go down to 20Hz?

FWIW I tend to regard the RC shunt as 'Zobel', and any series parallel pair
of LR as being something else. In the power amps I've done the inductor
would be shunted with a resistor as well.

But with the tube amp the leakage L is included in the FB loop, wheras
the L on the SS amp isn't, and many SS amps give a worse peaked response
into capacitive loads.

Afraid I don't have the statistics to know what your 'many' might mean
here. Can't say I am concerned much if a passive LC resonance occurs at HF
well above 20kHz and them amp is unconditionally stable.

(Interesting, though, to note over the years how many magazine reviews
confuse passive resonances like this with stability.)


But an SS amp needs to have 10 times lower thd at the same levels of
the tube amp, say 0.003% because they mainly operate in the middle
of the switching region of the output transistors, and although the
thd is low,

I note the "mainly" in your statement. :-)

Well, they do.

All that does is repeat your initial claim, but without giving any
actual supporting evidence.

Can you give me some references that establish this on a statistical
basis for a representative sample of commercial designs? I'd also be
interested to see your definitions for some of the terms you use like
"middle of the switching region". Also for why it has to be "10 times" as
opposed to some other value, etc....

Many transitor amps have declining thd with output voltage, and its
difficult to see any thd in the signal at 3vo of output.

I recently built a tranny amp with ten MJL21193/94 devices per channel,
and after some effort, I got thd down to 0.01% at 157 watts, mainly 3H,
and then at 10 watts it was 0.004%, and little more than the thd in my
test signal, and it fell towards zero as po was reduced.

You don't specifiy the load or the frequency.

But the thd was modulated by the rail swings from the mains jitter,

"Mains jitter"? Do you mean ripple?

so the thd level changed dynamically.. Under normal conditions, class B
amps have somewhat large swings on their supply rails and these modulate
all other frequencies. Unless one regulates the rails or uses 100,000 uF
caps, the thd is far worse than what one measures with a sine wave.

Partly, I'd agree. That was why I tended to design amps with care w.r.t.
being good at rejecting powerline fluctuations. (Must admit to also being a
fan of big caps... :-) ) Also why I used to test for the kinds of non-sine
and asymmetric waveforms implied in what you say. That said, I didn't make
any Class B designs, just AB ones.

Class A tube amps have the advanatage ofr common mode rejection in the
CT OPT output stage. SE class A tube designs have a continuous drain of
power, and in any case huge supply caps are used, say 1,000 uF.

All class B amps which include nearly all SS amps used today

My understanding is that most are AB, not B. Hence I would not agree
with the statement you make above.

really need all the NFB they can muster because of the nature of their
intermodulation production.

I'd guess that Class B would be difficult. However this is why I've avoided
it, and assume that other have as well.

Usually, because SS amps measure 10 times less thd than a tube amp, they
often cannot be distinguished from a decent tube amp which measures well
enough. But I think the dynamic distortion mechanism within SS class B
amps is 10 times

Well, in measurement terms, the valve power amps I've seen in magazines
sometimes seem to give THDs somewhat more than x10 the values for the SS
designs. However I have no statistics for this. Can't say that it bothers
me much once the nonlinearity is reasonably low. (And, of course, avoiding
Class B.)

worse than the mainly class A tube amp, so the ten times greater NFB
amount leaves the two genres somewhat similar sounding to many people.
But not to all ppl, and some hear a lot more though a decent tube amp,
and it ain't got much to do with measurements if the buyers of SET 300B
amps are witnessed.

Regulated rails are one solution for class B amps.

Again, I can't actually recall designing or using a Class B amp. I've
used/built A and AB, but not B. That said, I'm not clear why Class B
amps should require regulated rails specifically.

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

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

"Kurt Hamster" wrote in message

On Thu, 18 Nov 2004 17:07:57 +0000 (UTC), Stewart Pinkerton used
to say...

On Thu, 18 Nov 2004 15:15:55 +0000, Kurt Hamster
wrote:

3) A transistor still does what it did 57 years ago does it not?

Only in the same sense that an automobile does what it did 100 years ago.

For one thing, the transistor that was invented 57 years ago was a point
contact germanium device. Modern devices are generally not made of
germanium, and are generally not point contact devices.

How different is a modern transistor from the transistor made 57 years ago?
Well, if the modern transistor was a tube, it wouldn't have a vacuum (i.e.,
not the same conductive element as the early model) and it wouldn't have
anything like the same physical structure. Unlike transistors, tubes never
got to be thousands of times smaller over their development life. Note that
a present-day 12AX7 isn't that much smaller than an early tube. Unlike
transistors, tubes never got that much more energy-efficient than the first
ones, either. Furthermore few if any of the transistors that were used 30
years ago are available for the purpose of constructing new equipment. In
contrast, tubies are still lusting over and building new equipment with
tube types like the 211 which dates back about 70 years, the 813 which dates
back about 60 years, and the 12AX7, which dates back about 50 years.

Not if it's a FET, as are more than 99% of all modern active devices.
As it happens, the output stage of audio power amps is one of the
very few places where you're still in with a good chance of finding a
bipolar transistor.

If it's a FET then it's not a "transistor" is it, why else would it
have a different name?

Kurt shows his ignorance of the well-known meaning of FET, particularly the
*T* part. It seems like being a tubie is partially dependent on gross
ignorance.

Valve amp (preferably DIY) to drive apair of Wharfedale Diamond II's
 

"Stewart Pinkerton" wrote in message
...
On Fri, 19 Nov 2004 02:31:25 +1100, Patrick Turner
wrote: ...Clippidy do da.....

Mike Gilmour wrote:
Likely better than a Swiss-made one...... (not a Rolex fan - like SET
valve amps, all marketing and no substance)

I'm surprised and interested by your remark remark that Rolex watches are
effectively a substandard product? On what do you base this opinion on?


Stewart Pinkerton | Music is Art - Audio is Engineering