'Pre-gain' control for Tonebender Mark 3?

[tracer03]

I had a request to build a Tonebender Mark 3 with a 'pre-gain' control (basically an input level control that would emulate changes to the guitar's volume knob, so he could 'set and forget') - I'm using a modified version of the Mark 3 layout with an onboard voltage inverter.

I modified the Park Fuzz Three-knob layout from here: Original Park-Fuzz-3-knobbie-and-2-knobbie

My plan was to route the guitar signal input to lug 2 of the pot, wire lug 1 to ground and lug 3 to the circuit input. Using a 500k Rev Log pot (to simulate the guitar's volume control - Strat).
Would there be any issues with doing this? Thanks in advance.

[fx-fidden]

I don't expect any issue adding a pre-gain control. You should try it and see how it feels.

Maybe I'd advice just another approach: guitar signal input to lug 3, lug 1 to the ground, lug 2 to the input circuit. And a 500k linear pot could be easy to set.

[tracer03]

fx-fidden wrote

I don't expect any issue adding a pre-gain control. You should try it and see how it feels.

Maybe I'd advice just another approach: guitar signal input to lug 3, lug 1 to the ground, lug 2 to the input circuit. And a 500k linear pot could be easy to set.

Great - thanks for the input! (and I'm sure you're correct on the lug wiring, I wasn't sure if it made sense to
reverse those or not).

[tracer03]

So, I tried adding the pregain pot, and it's...'okay'. It's not really smooth and the fuzz gets a bit flabby.

After some further research, I see that the Prescription Electronics also uses a 'gain' pot - but it runs the Gain pot between the Tone and Volume - so I'm not sure how I would add that. Below is the layout I'm using - I thought I could change the 68k resistor to 18K, and connect to a 50k 'Gain' pot (lugs 1&2), and connect lug 3 to Volume 3 - as is done in the Yardbox.

Any thoughts? Help?

Yardbox Layout