On 22 Apr 2005 13:19:25 -0700, "
wrote:
Stewart, one often overlooked item is that transistors are by their
nature non-linear, so surrounding them with oggles of negative
feedback, is responsible for their low THD scores on a meter. But maybe
doesn't really reduce their inherent distortion - those distortions of
a non-harmonic nature... time related distortions and other types.
If you don't know, please don't make up non-existent 'distortions' to
justify your preference. There's no magic or arcane science lurking
behind the curtain here, it's a simple black box job. Take a device
with an input and an output, and you can easily characterise *all* the
distortions without having to know anything about what's in the box,
be it transistors, tubes or electric fairies.
So who is really so sure that tube amps are inherently more distorted ?
Depends on the amps in question, but 99% of the time it's true.
Of course, those few tube amps which lack an output transformer, do
seem to be more transistor like sounding in some ways, but are too few
and far in between to make up another category.
OTOH, they are also very bad at driving low speaker loads, which is
not at all 'transistor-like'.
Perhaps we need to have output transformered transistor amps for making
a rightious comparison ?
I believe McIntosh made quite a few of those, if you really must
destroy the linearity of a transistor amp by including an inherently
non-linear device like an output tranny.
Interesting that among vintage amps, those
amps known for unusually good sound often had an "interstage"
transformer, both expensive tube ones like the $100K. lunatic fringe
stuff and the transistor ones (like the old gold faced AR Integrated
Amp) which probably sounded better than its ancient 2N3054 Drivers and
2N3055 output transistors would otherwise have allowed, simply because
it had a huge interstage tranny in there.
That was only there because you couldn't get decent complementary
pairs in the early days. As soon as good complementary pairs arrived,
interstage trannies disappeared. We call it 'progress'.
So really maybe my speaker also has some of that euphoric even
harmonics stuff too, but really I don't rely on a meter to tell me what
sounds more like music and what sounds like SH^T.
Neither do I, I rely on level-matched blind listening tests.
I've done the tube
amp / transistor amp comparison here and had others doing the
listening. They all think bottles and silicon sound different, and in
general, the non-linearities of the transistor stuff is quite audibly
apparent.
Utter bull**** - good modern SS amps have no audible distortion
whatever. Bottles certainly can sound different, but they are *adding*
artifacts to the signal. It's well-known that these artifacts are
typically euphonic, so it's common enough to find a *preference* for
that rose-tinted sound - but it ain't hi-fi!
Also, similar transistor amps sound different too - worse as
the level of complexity goes up. Adding a single differential input
stage might make the THD meter go down to .005% from .05% for a
single-ended input stage, but the amp with the differential input
stage, being several transistors more complicated, sounds decidedly
WORSE on real world speakers.
Again, utter bull****, as I'll be happy to demonstrate in a *blind*
test.
Truth be told, all amps are "audibly distorting" just maybe in ways
your ear knows, but which would elude a THD Meter,
No, they aren't. This is easily proven by bypass testing, where you
can compare the output of an amp directly with its source signal.
that is why there
are half a dozen types of distortion, not "just" THD.
Certainly there are - and they're all easily measurable.
Stewart, why is it that the tube amp sounds more like "music" ?
I already explained that - they don't, it's just that they often *add*
euphonic artifacts.
Could
it be that the artifacts of the transistor amp are the result of the
feedback, which are subtractive to the music ?
There are *no* audible artifacts in any decent SS amp. Stop making
things up to suit *your* prejuduces.
If the nonlinearities
are in fact removing some harmonics that SHOULD be in there, the
resulting transistor amp sounds thin, unlike real music ?
That's just outrageously stupid.
So maybe tube amps DON'T produce Euphoric or Euphonic Effects,
Yes, they do.
transistor amps just LOSE the existing harmonics that should be in
there, and that shows up as low THD results, but the ear knows which
sounds like music.
Utter rubbish, a typical tubie fairy tale for which you can present
*zero* evidence. With *any* good amp, what goes in, comes out. Nothing
mysteriously 'lost' in the process. Works just as well for the few
really good tube amps such as the C-J Premier Eight and ARC VT 150, as
it does for the huge raft of competent SS amps.
As you'd expect, these excellent tube amps sound just like a good SS
amp in a level-matched blind test, where of course you *have* to trust
your ears as you don't *know* what's playing.
So who is to say which amp is more distorted, a THD Meter, or your ears
Stewart ???
My ears, which can tell the difference between any good amp (tube or
SS) and a *bad* amp, which is typified by the SET.
--
Stewart Pinkerton | Music is Art - Audio is Engineering
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