[patrick-turner]

On Tuesday, 6 November 2012 11:31:56 UTC+11, Phil Allison wrote:
"John L Stewart" Phil has shown us that the harmonic content of the amp he has for repair varies quite a bit as the power level is changed. ** Duh !! The percentage goes up with output level. You cannot stop paraphrasing a false characterising - can you ? I would not depend on curvature correction as a cure for amp distortion. ** Pompous bull**** and a classic " straw man " fallacy. The THD may go down but what about the higher order harmonics & IM? ** Converting a lot of 2H into a small amount of 3H can only be good. It has been shown by many tests that these are the objectionable components in the reproduced sound. ** Blah, blah, blah.... Another ****wit "straw man" fallacy. 10% 2H distortion ( as seen with many SET amps) represents a HUGE amount of IM with a complex wave - maybe as much as 50%. Reduces music to purest mud. .... Phil

The very worst designs of SE amps generate 10% 2H at 1dB below clipping.
The best SET amps maybe make 4% at -1dB. This is without GNFB. Using adequate GNFB of say 12dB and using average PO limited to 1/10 of the clipping PO means N&D are usually tolerable at least, and below limits of audible perception by most ppl. But when used with horn loaded speakers the SET performs with typical PO averaging 1/100 of clipping PO, ie, say 0.2Watts out of a possible 20W. Since Dn reduces with Vo, it sounds OK.

In many past long tortuous arguments here and especially at aus.hi-fi there were those who could never grant any SET amp hi-fi status, and they labelled SET amps as illitimate, ie, ******* audio products. The loudest and most stubborn accusers of SET amps tended to have incomes derived from selling solid state gear, and they were never ever to agree the purchase of an SET amp was sensible in any way - bad for business. But despite the flames the SET amp buyers have kept on buying SE amps. They refused to accept they ever needed more than a few watts of triode power.

I have heard fabulous music from SET amps when used wisely and sensibly. But There is no point comparing one lone 300B making 8 piddly watts to say a 100W SS amp when both are tried at very loud levels with speakers rated for 88dB/W/M. Horses for courses.
Patrick Turner.