Overdrive Channel Mod

Amplifiers contain voltages high enough to Kill you even after the amp has been powered Off !!! If you don't have enough electronic experience to identify and discharge the Filter Capacitors which contain these Deadly voltages, take your amp to a Qualified tech. If you don't know a qualified tech in your area, post a request in the alt.guitar.amps newsgroup, the folks there will be happy to help you.

The Mod:

This mod addresses Fender amps such as the Silverface Bassman, which don't have a Midrange control. This mod has three options, one which adds a midrange control, one that tailors the existing midrange to your liking, and the last makes one of the two channels permanently overdriven.

1. First Option: From the bass control to ground you'll find a 6.8k resistor. Disconnect this resistor and insert a 25k pot. This effectively gives you an adjustable midrange control.


2. Second Option: Install the 25k pot as above, adjust it to where you like the amp's tone, measure the resistance, and then remove the pot & install a resistor of that value. This permanently customizes the midrange to your personal tastes.


3. Last Option: Just remove the 6.8k reistor altogether. This will leave one channel with the stock bassman sound. And the second channel will be permanently overdriven.

If you decide to add a pot, don't drill any holes in your chassis! You can mount the pot in a variety of ways that don't permanently damage your amp. This would include fabricating a little mounting bracket that would screw into the inside of the cabinet. Or even by using a push pull pot configuration. Any mod that can't be reversed or removed without leaving permanent damage to the amp is a bad idea.