• Silverface tweed channel conversion

On the larger blackface and silverface Fender amps, there are two channels. The Normal channel is a pretty straight-forward preamp, and lacks the tremolo and reverb found on the Vibrato channel. It was originally intended for another guitarist, but usually doesn't get much use.

To add a little flexibility to the amp, it can be voiced differently. This mod changes it to a Fender Tweed style preamp, which uses a single tone control to roll off treble. The insertion loss is less than the treble-middle-bass tone arrangement, so the preamp is hotter than the BF preamp and distorts more easily. The Normal channel has 3 controls, but only two are needed by the tweed circuit, so a master volume can be added for more control over the amount of distortion.

The right side of this diagram shows the schematic of a BF or SF preamp, and the left side is my sketch of the layout. Not everything is shown on the layout diagram, only the parts of interest.