Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Early 90's stereo chorus which needed U8 replaced to get the chorus working again. Now I find that I only get chorus effect at one output amp - I believe it is a "stereo" effect   ???

I get the correct outputs at the preamp 1/2 (dry/mix). Where or how is the stereo chorus generated or routed?

BTW - why do people dis these amps? I have nothing but praise for Peavey designs and support.

Well as far as I understand one speaker will put out a chorus effect while the other speaker is the dry signal. Some amps will have the chorus effect through both speakers or just one speaker on a single combo. IMHO and many other's the chorus sounds deeper and stronger with one speaker effected, while the other one remains dry.

Agree, the chorus effect only comes out the one speaker.

In many "chorusing" amps, there is a chorus effect blended into the dry effect.  Chorus is a swirling change in phase relation between the dry signal and the effect signal.  In this amp, and most Peavey chorusing amps, in chorus mode, one speaker continues to produce only the dry signal. The other channel produces the chorused effect ONLY, no dry blended in.  So your two speakers will pass in and out of phase, creating the chorus sound.

So it truly IS a stereo effect - you have two completely different signals coming out of the two speakers.

If you untangle the signal path around the "Pre Out 1/Dry" and "Pre Out 2/Mix" (middle of your posted circuit, ref: C5) you will see that the chorus is only applied to one output channel.  The internal chorus return is at C66 (ref: B4) and is switched via FET Q15.

I just had a look at the Roland Jazz Chorus circuit and they do the same thing, chorus to one output only.