Wah gurus...Dallas Arbiter Wah Face with a stock pot measuring 436K?

[Nocaster Cat]

I'm replacing what I believe to be the stock pot on an Aribiter Wah Face (solder joints looked untouched). I was measuring it for an accurate replacement and it measured out at 436K which I thought was not only odd but high for a wah. I double checked and also tested my multimeter for accuracy with some metal film reisitors, so I know nothing is wrong with it. Has anyone else seen a wah with a pot value this high? Thanks.

[reverberation66]

I'm pretty sure the schematic on this calls for a 100K wah pot, that's quite a discrepancy, I've never looked at one of these in the flesh before so can only speculate.  Maybe pot isn't original after all, maybe a larger value could give a broader sweep range if the set-up only allows for a limited pot rotation.  does the pot that's in it work at all?

[mth5044]

Did you you measure the resistance separate from the circuit? Might that have had an effect on your readings?

[Thomeeque]

I'm replacing what I believe to be the stock pot on an Aribiter Wah Face (solder joints looked untouched)

Which joints? On the pot?

[R.G.]

See "The Technology of Wah Pedals" at geofex.com for how that works.

The wah pot in an inductor style wah is used in a purely voltage divider mode, so that as long as the thing that loads the wiper doesn't load it too much, and the thing that drives the wah pot can drive it easily enough, the actual value doesn't matter much. There are always second- and third-order side effects, but to a first approximation the exact value is not critical.

Pots often have a 20% tolerance on end-to-end resistance, so this is likely a 500K pot that happens to be on the really low side.

All that being said, all of the wah face schemos I've seen say it's 100K nominal. Perhaps the solder joints are merely old, not original, or perhaps they had problems getting 100K that week when it was made.

[Nocaster Cat]

An update...

The pot casing is stamped 100K but it for sure measures out at 436K. Maybe a 5 o'clock Friday pot? 

[Electron Tornado]

See "The Technology of Wah Pedals" at geofex.com for how that works.

The wah pot in an inductor style wah is used in a purely voltage divider mode, so that as long as the thing that loads the wiper doesn't load it too much, and the thing that drives the wah pot can drive it easily enough, the actual value doesn't matter much. There are always second- and third-order side effects, but to a first approximation the exact value is not critical.

I don't have my reference material on wahs handy, but I recall a discussion on one of these forums regarding a couple of different pot values that had been used in wahs. Along with 100k, I think the other values were 250k and 500k? Even if the actual pot value doesn't make much difference, will it have any effect (no pun intended) on the sound or the feel of the wah?

Man, i hate trying to type on an iPad.

[R.G.]

The pot casing is stamped 100K but it for sure measures out at 436K. Maybe a 5 o'clock Friday pot? 

Could be. I would check the resistance from end to wiper for both ends, turning the pot and watching for dead spots and high resistance at the "zero resistance" end. It could be a wiper going bad and having a few 100K of series resistance in the contact slider (see "The Secret Life of Pots", geofex.com) or a place in the resistive track that's worn thin and almost not making.

Or it could be a 5pm Friday pot. I laugh sometimes when I hear people dumping on Chinese or other non-USA manufacturing as substandard because I remember the days when anyplace OUTSIDE the USA was thought to be superior just because of the sloppy practices of USA manufacturing. The same bosses that made USA manufacturing get a reputation for being sloppy then dumped USA factories as too expensive and went offshore, demanding the cheapest junk they could get from *those* factories.

Have I ever mentioned "MBA Disease"?   

[zombiwoof]

One version of the Dunlop-made Jimi Hendrix Crybaby used a 470k ohm HotPotz (HotPotzIII I think), that was the version of the wah that was slightly tweaked to give a lowered frequency sweep.  So, it is not unknown for a wah pot to measure that high.  The original 470k HotPotz had the silver metal case like the 100k HotPotzI, later versions changed to the black plastic case, sealed-type pot like the later100k HotPotzII.  Since yours measures 436k, it makes me wonder if it might be a 470k HotPotz replacement, as a 436k reading would be within the tolerance for that pot.  What does the pot say on it, such as manufacturer and codes?.  Does it look like the military-style pots in the older CryBaby's, or is it the black plastic case sealed type?.

Al

[Nocaster Cat]

I'll look later on but it's not stamped Hot Potz.