This is a great dissertation on how to modify and change guitar amp preamp circuits to your liking. I don't remember where I found this on the internet; I've had it for several years. If you know who wrote it let me know and I'll give credit where credit is due. – Attila

Given the renewed interest in tube amplifiers, it's likely we're going to start seeing more books and kits expressly designed for experimentation. Kevin O'Connor, author of "The Ultimate Tone", is coming out with a book of such projects in the very near future. The audio world is way ahead of us guitarists, as they already have a great many kits for both valve preamps and entire amps.

While we're focusing on distortion producing circuitry, nearly all of the general principles apply to lower gain amps, like Fender Twins, and the clean channels of modern guitar amps. A Mesa-Boogie is really just a Fender amp with a couple of extra gain stages.

I'm gonna deal primarily with increasing gain, though reading this, you'll get some knowledge of altering tonal response through capacitor changes. .......... for more info download your copy from : http://ratcliffe.co.za/sundry/Modify_Preamp_Circuitry.pdf


Ps thanks goes to Alan for hosting the download

Peace .... Attila