Fender sweet spot trick. Hbamp Fender RI mod.

[stretch2011]

I know this is dead simple, but for clarification a schematic should be drawn up.

[dinkotom]

Yes, please

[hbamp]

Sweet Switch Schematic!!!! You are right Sluckey I Changed the schematic. So this should be just about the same. Can't load the RI PDF file in Visio. So look at the RI schematic for the other little differences in the RI LFO circuit.

[sluckey]

Sweet Switch Schematic!!!!

That's not right. Gotta look at the reissue schematic. Reverb switch is in a different location. Also, notice the use of SPDT switches in the RI footswitch.

[martin manning]

In the '65 Twin Reverb the ring terminal of the footswitch connects downstream of the reverb recover stage (unlike the AB763 shown above, where it connects to the reverb recover stage grid).

In the '65 Twin, the effect of shorting the ring to the tip will be a DC bias shift at the reverb wet/dry mixer stage, V4b. According to the schematic the no-load voltage at the ring is -8.5V. Connecting that to the tip terminal will shift the bias of V4b negative by a few volts. It's that change in the operating point that is producing the effect you are hearing.

[hbamp]

Here it is Sluckey.Found a converter for PDF to JPG. Here the RI schematic with Sweet SWitch MOD. I did it the simple way and put the mini switch in the vib rev footswitch.

[dinkotom]

Thanks!

[hbamp]

Oh yeah, Always change the driver tube to a nice NOS 12AU7.

[rooster]

Well, you're connecting the reverb signal to the open Tremolo switch connection. Which is weird because that connection has some negative voltage on it. Hm..

So the typical load resistor for the reverb return is a 220K resistor, and your switch is changing this load. Weird.

Tell me, does the tremolo and verb work with this switch engaged?