setting up dual pot on shared gear, old thomas stereo fuzz wah vol retrofit

[joegagan]

these tricks would work well for anyone wanting to run two  pots at same time. in most cases preferable to dualgangs for good reasons:

1. pot availability. dual gangs are expensive and very limited.

2. you can mix and match any tapers and values, again very difficult or near impossible with odd values etc unless you order a bajillion pots.

3. you can rotate the pots to let each one run at its exact correct orientation. not  very possible with dualgangs.

4. the distant/ onesided stress of foot action on dualgangs is hard on them in my experience. this setup spreads the load in a more even way.


some notes:

the brass bushing was epoxied to the inside of the gear. one half of the gear was the stock D inside ( right side), the other is fully round to allow each pot to be set to optimum.

lot of fitting and careful drilling to fit the brass bushing into the gear. gluing was done on spare shaft in photo to assure concentric & square aligment. to keep epoxy from bonding the whole thing to the shaft, wrap the shaft with a thin ply of plumber's teflon tape.


brass bushing was sacrificed from a small dakaware knob.

[joegagan]

probably obvious - in the top photo, the top pair of pots is just set above the old stock setup to show how it will fit.

[Mark Hammer]

Frickin' brilliant! 

[tubegeek]

Great stuff.

The pots are spinning in reverse directions though, right? I guess that's not an issue with a pair of linear pots but for a pair of tapered pots doesn't that require you to match a rev log with a log if you want them to have the same taper?

[joegagan]

good point.
the way the hotpotz has the curve all condensed into 30 to 40 % of the rotation, there are big dead spots on both ends. the smaller hotpotz2 makes it easy retrofit, you can turn each pot 360% in its mount provided you have some flying leads to hook up.

the above picture might already be obsolete in my setup, since i realized that  all i needed to do was shorten the shafts and stick the gear in between the 2 pots, then they can be tightened in their saddles at the optimum setting for each.

[joegagan]

update- all the above horsesh*t was not needed. took the pics down.
simply cut the pot shafts shorter, install the standard d hole dunlop gear on the two pots as you bolt them in, calibrate ( take good notes before removing original pots),  wire up, re-assemble, adjust, rock out.

do the pot to pot calibration while the bracket is out of the pedal. the pots must be oriented properly to each other for the pedal to work and sound right.

UPDATE, i tried it through two amps, it sounds and works great, but i now want to make sure that using two condensed log pots instead of one regular, one reverse is not hurting the sound or feel. i did not spend enough time with it before taking the original pots out to make a good comparo. looking for a 2nd unit to do a side by side compare.

tubegeek, thanks for reminding me to take a look at the original pots. they WERE the classic thomas fast taper what i loosely call ' condensed log', but one is reverse, like you suspected. thomas did a really great job engineering these. i can help but think they lost their ass on all the tooling + R&D.

[tubegeek]

i can help but think they lost their ass on all the tooling + R&D.

Take care not to replicate THAT particular original feature!