You mean the circuits inside the amp or the button you push?
Some amps have gain stages, others (like vintage Marshalls) you just drive them by cranking up the volume. Actually, driving the amp is a really cool method to get a Brown Sound distortion (aka overdrive). Peavey's 5150 is really good at that, hence why it is a Van Halen Sig amp. But they also have gain stages to produce some massive distortion.
Not sure if this answers your question, if not, sorry about the ramble :winkx:
well the thing is i have a broken amp the speakers still good and it had the overdrive butten on it i was wondering if anyone could give me an idea of where its at so i cant take it out and wire it to my new ampand yes the circuts is what i meant
First off is it a tube amp or solid state amp if it a tube amp it is done with the staging of the tubes and the voltage applied to them and that voltage can kill you real easy but if it is solid state it is done with ic's either way you would be better off buying a good pedal cause the solid state one uses lots of the circuits on the pc board to do this but you could take out the ic's that you need and make your own pc board but 9 out of 10 times if you don't know what you are really doing you will mess up the ic's on removal and the ic's are cheap like $4 if you want to build one get a DIY kit comes with everything you need.