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arsclist Re: Tubes will not die



More from this list. I'll send back any responses on this list to the
>Htech list, unless you specify otherwise.

Frank

---------- Forwarded message ----------
Date: Wed, 13 Nov 2002 18:46:08 +0100 (CET)
From: Eugen Leitl <eugen@xxxxxxxxx>
Reply-To: transhumantech@xxxxxxxxxxxxxxx
To: transhumantech@xxxxxxxxxxxxxxx
Subject: [>Htech] Re: Tubes will not die (fwd)

---------- Forwarded message ----------
Date: 13 Nov 2002 10:05:36 -0800
From: James Rogers <jamesr@xxxxxxxx>
To: fork@xxxxxxxx
Subject: Re: Tubes will not die

On Tue, 2002-11-12 at 19:57, Jon O. wrote:
> 
> Readers: Please do not believe this about tubes, as I use them extensively
> in my stereo and will NEVER go back to solid state. The tubes provide a
> presence, sound stage and transparency which is far beyond the ability
> of the highest end SS gear. 


As a case in point:  Go to any high-end manufacturer that makes both
tube and semiconductor preamp models.  Look at the noise, total harmonic
distortion, dynamic range, and other specs relevant to audio fidelity. 
You will find that solid state amp designs basically kick the crap out
of tube amp designs, usually by orders of magnitude.

I suppose you can back up your assertion with scientific and engineering
data?  I actually have good tube gear and a suitable environment for
testing it, I just don't ascribe magical powers to it.  There is a
measurable lack of fidelity in tube gear that is far more expensive than
most of the solid state gear I compare it to.  Tubes sound different,
but they sure as hell aren't clean or transparent.  When people call a
tube system "clean" or "transparent", it is usually in comparison to
other tube systems.

I'm not saying that tubes cannot be clean and transparent enough for all
practical purposes (though that usually costs good money), I'm just
saying that making such a claim in any kind of absolute sense compared
to non-tube gear is a load of crap.  And this fact is trivially
measurable, so there is no excuse for it.


> I have done
> in home tests with the same gear all the way around and a small switch.
> Over and over the rebuilt 40$ amps *blow* away SS gear costing $2-5K
> to both myself and "blind" listening tests conducted on fellow music
> lovers, music teachers and friends.


Perhaps what attracts you to the sound of tube amps is the LACK of
fidelity?  Tubes often can sound different from solid state circuits,
but that difference isn't higher fidelity.  Lack of fidelity IS the
reason some people like the sound of analog circuitry e.g. in
synthesizers.

When overdriven or run hot, tubes do sound better than solid state amps,
but there is no reason to actually do this to solid state amps.

[...odd story about the greeks elided...]
 
> Think about this. CDs are data which recreates sound. During this recreation
> the sound information is red in "steps" instead of "vibrations" like you would
> on a record. This introduces a harshness which is often found on CDs. Compare
> a CD to a record of the same music, mastering, etc. on a reference system
> and you will see the distinction. 


There are no steps in the output of a CD.  That "stepping" is
information ADDED to the analog signal when it is encoded as PCM. 
Naturally, this added information is removed when the PCM is decoded
back into analog.  This is a very common misunderstanding.  All the
frequencies ("vibrations") in the original signal are found in the
playback signal, at least below the Nyquist limit (about 22kHz for a
CD).

Harshness is an artifact of bad PCM encoding/decoding of audio, usually
due to a sample clock jitter during encoding or incomplete decoding. 
Good converters are silky smooth and liquid, and these days, dirt
cheap.  Studio grade converters are almost perfectly neutral and
extremely transparent.  Converter flaws are additive, so it used to be a
rule of thumb to minimize the number of conversions in the signal chain
a number of years back.  These days the rule of thumb is mostly ignored
as the converters are effectively invisible, even after many
conversions.  Ironically, about the time converters became extremely
transparent was about the time that everything started to be routed
digitally, so it doesn't really matter for practical purposes anyway.

 
> This is also not true. Tubes "clip" when overdriven which creates a
> dirty sound, yes but in your home system you never want to drive the
> amp this hard as damage to the speaker can also occurr. Guitar amps
> are frequently the device used to "overdrive" the sound, but never
> ever consumer gear. 


Tubes do more of a "soft-clipping" whereas solid state stuff really does
tend to clip hard, hence why tubes sound better when you get "overs". 
Except as an intentionally added effect, there should never be clipping
in your gain stages if you know what you are doing.

 
> This again is not my experience and really the opposite of what I know
> to be true. I like clean, clear and pure reproduction of the sound 
> on the disk. Tubes again get this every time.


Your experience runs entirely against mine, and I have owned fairly nice
recording studios and am modestly competent at the whole audio
engineering thing.  I've owned all manner of audio gear, including tube
gear.  I've never known any audio engineer that chose to use tubes for
"clean, clear, and pure reproduction"; it was always to get "warmth" and
a little color (or occasionally a lot of color).  Any time you add a
tube to a good 24-bit audio system, you can hear the noise floor jump
dramatically which eats headroom.  Mind you, the noise doesn't really
bother me that much because I use other analog systems that generate
plenty of noise (more actually) on their own, but I don't pretend that
tubes are clean or pure.

Again, there isn't anything wrong with tubes, but they don't add
fidelity or clarity in any meaningful sense.

 
Cheers,

-James Rogers
 jamesr@xxxxxxxx



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