Potentiometers: does such a thing exist??

[PonchoGreg]

Right, I'm a bit of a weirdo: I like linear pots for volume controls in my guitar. I know, right?

I'm therefore looking to replace the volume control in my strat to a linear pot, keeping the two tones audio.

Does CTS (or any other manufacturer for that matter, make a SHORT shaft 250k, linear pot (with the threaded shaft measuring around 6.3mm)? I know it's really easy to find regular CTS linear pots, but the threaded shaft on these seems to be closer to 9.5mm.

I know I could get those and fit two nuts to control the height (I've done it before) but it's not very tidy in an otherwise crowded control cavity.

So basically what I'm looking for is this, but with a linear taper:



Does such a thing exist? Any pointers would be mucho appreciated!

[Guitarmonkey]

Seems they do http://r.ebay.com/Pw0cVQ

Seller is away though and website appears compromised.

[PonchoGreg]

Nope, threaded shaft on these is 9.5mm... I should know, I've ordered one (from a different seller) recently.

Thanks for the help though!

[Guitarmonkey]

Sorry, listing title says short and I didn't read the description!

[ICBM]

You can cheat, if you have to - add a resistor between the top and middle terminals of the pot to modify the taper.

A Log pot has 1/10th of the full value at half rotation, and a Linear has half the value. So at half rotation, a 250K Log pot has 25K between the rotor and ground and 225K between the rotor and hot. To convert this to linear, you need to parallel the 225K with a value that gives 25K - ie 28K (27K is the nearest preferred value).

The problem with this is that then the load on the pot is only 50K, which will dull the tone - so you may have to compromise on 'linearity' a bit to avoid this. I would try something that gives about a 100K total load to start with - ie 75K in the upper section of the divider, which requires an extra resistor of 112K... 100K is close enough to try.

This won't give true linear operation, but probably close enough - certainly a lot better than Log, anyway. Resistors are pennies, so it wouldn't hurt to buy a few values in the 27K-120K range so you can change t if it doesn't give quite what you want first go.

[PonchoGreg]

Cheers ICBM, that's well interesting. i might give that a go.

[ICBM]

Forgot to add - if the tone dulling is a problem, you can also add a treble-pass cap to brighten it up again. Normally, people do this the other way round - treble-pass cap first to cure the usual treble loss, then they find the effect is too drastic and thins the tone out at low volume settings, so they add the resistor (usually a higher value) to alter the taper and bring the low-end back up a bit... but you can do it the other way for the opposite reason.

[Guitarmonkey]

Could you maybe cannibalise two pots by taking the log from a linear pot and dropping it in a short shaft pot? Or just swapping the top bit (the shaft) if easier?

[PonchoGreg]

Could you maybe cannibalise two pots by taking the log from a linear pot and dropping it in a short shaft pot? Or just swapping the top bit (the shaft) if easier?

I was actually thinking of doing just that... I have a few spare CTS short shafts (the Fender ones, audio taper though) laying around at home, I'll dismantle one for funsies.

[Guitarmonkey]

I meant of course the *track* from a linear pot. (must read before send!)