Julf wrote: > So how do you measure what a SET does well? I was wondering if someone would ask that!
The part that seems to make the difference is a monotonically decreasing harmonic structure. The third harmonic is a little less than the second, the forth is a little less than the third etc, all the way down to the noise floor. Today this is a very easy measurement, a good sound card and FFT software on a computer can do it. But up until 20 years or so ago it took an expensive spectrum analyzer to resolve the harmonics all the way down. This is VERY different than the "typical" solid state amp. With these the 2nd harmonic will be very low or almost non-existant, then the third will be much higher, then the forth very low, then the fifth a little less than the third. In this sequence the even harmonics are very low or almost absent and the odd harmonics are much greater. And somewhere around the 7th or 9th harmonic the odd ones start getting higher. This is a very different looking harmonic structure. You can't just stop at the 3rd or 4th harmonic, you have to go up to the 13th or 15th to really see what is happening. That means don't just look at 1KHz signals, look at some lower frequency ones as well. For some reason the human perceptual system likes the monotonically decreasing harmonic structure better, even though the total amount of distortion is greater. As I mentioned it IS possible to make both tube and solid state amps that have this harmonic structure and significantly lower overall distortion, but they have not "taken over the market", probably because most of these designs are very inefficient. For example my big tube amp gives 25W per channel, but takes 350 W. It wouldn't exactly pass modern efficiency standards! John S. ------------------------------------------------------------------------ JohnSwenson's Profile: http://forums.slimdevices.com/member.php?userid=5974 View this thread: http://forums.slimdevices.com/showthread.php?t=99360 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
