General Asylum

Posted by tomservo (M) on July 03, 2011 at 13:54:54

In Reply to: RE: "And I knew that I was listening to several percent harmonic distortion." posted by Tre' on July 03, 2011 at 13:33:10

"It's not the THD that matters but the amount of upper ordered distortions."

VERY few people realize this, bravo.

The reason is "masking" the louder lower component can obscure the higher / upper component. The higher the order the component is, the less it is masked relative to the fundamental or lower component. With music, the broad band content "hides" distortion much more than a single tone too.

When applied to RF where all out of band content was "BAD", THD made perfect sense, when applied to similar amplifiers topologies, it made some sense but when applied to totally different amplifiers topologies (like SS vs tubes) it became close to irrelevant except as a marketing tool.
FWIW, at least some time back, a single triode stage of a 6SN7 had a lower spectral content per gain than any other approach.
Best,
Tom Danley
Danley Sound Labs