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previous: Ever Since this is a DIY forum, I have a... -- 4/2/1998 12:19 PM

Re: Let's do something fun

4/3/1998 3:26 AM
MHelin	Re: Let's do something fun So, step one would be what kind of distortion do we want? I'll start with two possibilities: preamp distortion or power amp distortion. preamp distortion will be primarily asymetrical while power amp distortion will be more symmetrical type clipping. We want both. Preamp distortion of tube amp is not primary asymmetrical. Each stage clips asymmetrically and inverts the phase, so the signal is symmetrically clipped in whole. I think Jack Orman's FET-Muff with diodes is a good tube preamp emulator. There should be some level control between the stages, and the tone control between the stages as well. Power amp clips symmetrically, but it should also emulate power supply sag. This can be done with JFETS whose supply voltages are are lower than that od the previous stage's, controlled by trim pots, sag created by caps. There should also be the EQ, which emulates output transformer by limiting the bandwidth when signal level is high. -Mikko

4/3/1998 3:26 AM

MHelin

Re: Let's do something fun

So, step one would be what kind of distortion do we want? I'll start with two possibilities: preamp distortion or power amp distortion. preamp distortion will be primarily asymetrical while power amp distortion will be more symmetrical type clipping.

We want both. Preamp distortion of tube amp is not primary asymmetrical. Each stage clips asymmetrically and inverts the phase, so the signal is symmetrically clipped in whole. I think Jack Orman's FET-Muff with diodes is a good tube preamp emulator. There should be some level control between the stages, and the tone control between the stages as well.

Power amp clips symmetrically, but it should also emulate power supply sag. This can be done with JFETS whose supply voltages are are lower than that od the previous stage's, controlled by trim pots, sag created by caps.

There should also be the EQ, which emulates output transformer by limiting the bandwidth when signal level is high.

-Mikko

Replies:

Mark Buckingham >There should also be the EQ, which... -- 4/3/1998 9:20 AM
John Greene We want bo... -- 4/3/1998 1:03 PM