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[mhakman]

Hello Friends,

I wrote a scientific paper on differences in audio produced by electronic vacuum tubes and that of semiconductor devices. The article is freely available at Vacuum Tube Sound Revisited. Thanks.

[mschneid]

Nicely done.

You put current numbers to how much 2nd order distortion you have in tubes and its large dynamic range....  I did not see any measures on how quick each device is and that may be important in that higher order thing we call musicality.  (quick read of the paper)

Oh...I pine for the days when music was not compressed  to 6 db dynamic ranges during production.  You would highly value the "forgiveness" of your tube amplifiers .

The  ability to perceive the measured differences is of course a long standing debate. 

Double blind testing asks a specific question... Can you discern a difference between A and B.  In focused testing conditions, the answer is usually no!  Even controlling for listener fatigue and mental fatigue, age, golden ears etc and many other factors.     Of course, in testing a human... the biology of said human is always in a steady state and remarkably dynamic.  In general the studies come back... NOPE... can't distinguish A from B... For example,  MP3 compression at 320  passes these tests... However, the money question is... which do you prefer? Compressed or uncompressed and that can't be tested as easily.   The cues may be subtle and deep in the measurement noise.   The preference issue seems to emerge over time for people who care about such things.. To the degree that High Res audio pushes sampling to 196K that some people value.    It may have something to do with timing and the precision that biology encodes timing information to the brain and even those pyschoacoustiic measurements to test timing issues  fail to show a significant difference in choosing A from B. 

I usually take the point of view of a biologist on these matters..   Biology is inherently non linear. and encodes order of magnitude greater signals then the most sophisticated electronics.. The natural world is filled with harmonics and distortions... Hell,   the inner ear generates distortion  tones when it processes two tones as it is... And the levels vary with hormonal changes.  The nonlinearities in sound amplification  (mitigated by compression and gain creep) and sound reproduction  contribute to the sound we can generate in our room.   So, the only reason we listen intently is for our personal pleasure AND we always have the opera hall where NOTHING gets amplified!

So, quality engineering has an enormous role to play mitigating noise, jitter, distortion at all levels and this improves the experience.  But...  at the end of the day.... the live experience is the best.   Next best is some quality tube amplification in my reproduction chain.

YMMV.