What do you think can be done with this distortion circuit?

[ic-racer]

I am going to be re-caping my beloved Fender Super Twin Reverb. I have had this amp for almost 30 years and would never get rid of it. It has the best bass response of any amp I have ever owned. However, true to ledgend, the 'Distortion' circuit does not produce sound that is appealing to the ears of vertabrates.

Every 10 years or so I get the idea that by just removing that diode or doing a simple mod this circuit can be made usable. Anyway, while I am in there for the cap change I thought I would explore posibilities.

Also, after spending so much time studying Dumble schematics to see patterns that make things sound good, I thought I might learn something by studying a circuit that sounds so bad.

In the circuit the 6C10 is like a 12ax7 with 3 triodes instead of 2.

In clean mode, the circuit still has to go through U2, so doing much with this tube can compromise the clean sounds (which are good).

My impression is that they (CBS etal) designed a very clever voltage dividing circuit that uses negative charge from the bias supply to turn the output of the distortion tube (U1 in the schematic) on and off with a siimple SPST switch to ground. Avoiding the use of a relay. After they fingured that out they slapped a diode in there and packaged it for sale. It probably didn't sound right to them so they slapped a choke in there too. And thus was created the worst sounding distortion of any tube amp ever made.

Any thoughts on the circuit? All the voltages and annotations came right from the Fender Schematic. I have not done any tests on the circuit yet.

[Andy Le Blanc]

the diode D1 next to R2 looks like it might be there to introduce asymetrical clipping.....if its a silicon look into replacing it with a germanium
or fiddle with D1 and R2 ... or replace with a diode and or LED network to change clipping levels witout messin with the rest of the circuit....