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previous: John Greene We want bo... -- 4/3/1998 1:03 PM

Re: Let's do something fun

4/6/1998 5:42 AM
MHelin	Re: Let's do something fun There are only two preamp stages before the phase-splitter. The input tube, which can't be overdriven... .. and it may be that if there's odd number of overdriven stages the preamp creates more even order harmonics. When you look into Jack's diode clipping FFTs at DMZ (http://members.aol.com/jorman3/fft.html) for one diode, it doesn't seem to generate dominant second-order distortion, 3rd and 5th harmonics are well above 2nd. The 2nd harmonic is in fact a sound an octave above fundamental tone. The 3rd is nicely produced with two clipping diodes. In tube amps the 2nd and 3rd are dominant, there are less higher order harmonics. So what I mean with this is that asymmetric clipping does not in fact produce enough 2nd order harmonics, and there are too much higher order harmonics which should be avoided. In fact the same FFT's show that back-to-back LED's produce more 2nd harmonics than single clipping diode. If just there were a way to cut out the 5th and above harmonics... Anyway, it would be wise to try (and build) different pre-amp and power-amp emulators, separately of each other. Maybe we should try the power amp first. I vote for for a push-pull power amp emulator... -Mikko

4/6/1998 5:42 AM

MHelin

Re: Let's do something fun

There are only two preamp stages before the phase-splitter. The input tube, which can't be overdriven...

.. and it may be that if there's odd number of overdriven stages the preamp creates more even order harmonics. When you look into Jack's diode clipping FFTs at DMZ
(http://members.aol.com/jorman3/fft.html)
for one diode, it doesn't seem to generate dominant second-order distortion, 3rd and 5th harmonics are well above 2nd. The 2nd harmonic is in fact a sound an octave above fundamental tone. The 3rd is nicely produced with two clipping diodes. In tube amps the 2nd and 3rd are dominant, there are less higher order harmonics. So what I mean with this is that asymmetric clipping does not in fact produce enough 2nd order harmonics, and there are too much higher order harmonics which should be avoided. In fact the same FFT's show that back-to-back LED's produce more 2nd harmonics than single clipping diode. If just there were a way to cut out the 5th and above harmonics... Anyway, it would be wise to try (and build) different pre-amp and power-amp emulators, separately of each other. Maybe we should try the power amp first. I vote for for a push-pull power amp emulator...

-Mikko