Univibe pedal pot

[StratLou]

Hi Guys,

   First time posting here (not sure if I'm posting this in the correct forum either) and hoping someone could help with some info. Recently purchased a 69/70 original Univibe and wasn't sure if the dual gang pot in the speed pedal was originally an audio/log, linear or reverse audiolog taper. Could anyone help with this and if anyone could let me know where I would find one of these, I would be most appreciative. Thanks very much and look forward to hearing from someone.

       Lou

[R.G.]

I haven't seen a real 'vibe pedal in a few years now, but as I remember, it was a log taper dual.

I think that the setup was such that the mechanical rotation caused by the pedal caused it to act like a reverse log.

You can tell easily enough - toe down is smallest resistance.

[StratLou]

The dual pot that is in my pedal, at half rotation, reads approx. 75kohms for one and 82kohms for the other. Would that make this a log pot or a reverse log pot? Thanks.

[R.G.]

Reads that much from wiper to which end - CW or CCW?

[StratLou]

Starting at lug 1 (the CCW lug) reading 0 ohms then turning the shaft in the CW direction to the halfway point to read 75k ohms and 82k ohms for the two pots respectively, and completing the CW rotation of the shaft to lug 3 to approx 97k ohms. I have a friend who's pedal measures 0 ohms in the CCW position to 7k ohms halfway to 95K ohms fully CW. His also reads "100k M" while mine reads "C 100k" if the letter codes mean anything. Thanks again.

[R.G.]

Yours is one of those rare things - a real reverse log taper pot.

[StratLou]

I guess the next question is what difference is there between using a reverse log vs. log style pot in the original Univibe? My reverse log pots seem to be wired a bit different than my friend's log pots as well. Don't know how an original actually sounds. Totally confused.

[R.G.]

The issue is purely the apparent "linearity" of pot rotation versus speed change.

When you have the correct taper and direction of rotation, the change in speed per degree of pot rotation appears to be linear: equal speed change per degree moved. When you have the incorrect taper, the speed change is all bunched up at one end or the other of the pot rotation.

[StratLou]

In your opinion, then, would it be the log taper that would yield that result in "linearity" or one of the other two tapers. Thanks again.

[The Tone God]

I believe Digikey now carries dual 100K reverse log taper pots.

Andrew