Guv' nor Tonestuck Equivalent Resistor

[antonis]

After a year of a modified Guv' nor design I decided to build the pedal (daughter's Cristmas present.. ) and realized that I'm unable to accurately calculate tonestuck's equivalent resistor...
(for tone bypassing without volume change..)

Propably I'll replace the the resistor with a trimm pot ( Rx in scematic ) so is there any suggestion for it's (rough) value..??

Or, even better, is ther any - non function/differential/derivative/integral - way for calculating the respecive resistance..??



P.S.
I know that Friday isn't the most convenient day for something like this but please show some mercy...

edit: SW2 fixed..

[PBE6]

Just ran a quick simulation on CircuitLab, and it looks like this tone stack loses about 13 dB when set flat, give or take. That's roughly a 4.5x drop in voltage. If you're running the pedal on full volume, the equivalent resistor should be about 4.5*100k - 100k = 350k to lose the same amount of volume, so a 500k trimpot would be a good choice.

[antonis]

Thnx a lot PBE6...!!!  :beer:  :beer:  :beer:

P.S.
13dB..  Hmmm.. So the original pedal's gain is about 35dB (if I calculate correctly the overall gain minus the tone loss..)

Maybe I'll add an output boost...

Or maybe I'll leave it in peace..

[PBE6]

I think a booster would be a good idea. Although there is a significant amount of gain upfront (33 dB in the first stage and 37 dB in the second), the voltage will be limited by the clipping diodes (about 0.7 V for single silicon diodes, about 1.8 V for LEDs). LEDs will be louder, but the tone stack will cut 1.8 V down to about 0.4 V. Any input signals larger than 0.4 V will actually be attenuated. Adding a final boost stage that has a gain of about 7x (17 dB) should give you a final voltage of about 2.8 V with the LEDs, which is plenty loud but will avoid clipping an opamp running on a 9V battery

[GibsonGM]

I think a booster would be a good idea. Although there is a significant amount of gain upfront (33 dB in the first stage and 37 dB in the second), the voltage will be limited by the clipping diodes (about 0.7 V for single silicon diodes, about 1.8 V for LEDs). LEDs will be louder, but the tone stack will cut 1.8 V down to about 0.4 V. Any input signals larger than 0.4 V will actually be attenuated. Adding a final boost stage that has a gain of about 7x (17 dB) should give you a final voltage of about 2.8 V with the LEDs, which is plenty loud but will avoid clipping an opamp running on a 9V battery

I often run a Guv'nor with an AMZ Mosfet boost after it...makes it 'come alive', IMHO.  Nice pedal as-is, but I feel that addition of a booster would totally improve what you're going to get out of it...