Wah Potentiometers

[tehfunk]

I know I already have a thread about wah modding, but this is not on the same topic, don't worry. I plan on building a WH10, and yes, I like John Frusciante, but I find its synth-like sound just psychedelic putting aside the fact that he used it. Anyway, a couple of general questions:

Do wah pots have to be special of special quality? For instance, heavy duty, to withstand the constant rocking?

What is the typical length for a wah pot? I wasn't sure because it has to be able to fit the pinion gear, and what about diameter of the shaft?

The WH10 requires a 50k linear pot:

Without considering resistance, I can't seem to find a simply linear wah pot, as in non icar or any other unique taper. (Note: this search disregards normal potentiometers because I am unsure whether some would work or not... so if my first question about quality is a no, then I guess all I have to look for is a linear 50k with a long shaft)

And, if anyone knows where to find a linear 50k wah pot, or linear wah pot of any resistance just leave a link.

Which brings me to my last question. If I cannot find a 50k lin that works then does the resistor on legs 1 and 3 achieve the same resistance characteristics just a smaller total resistance.

Thanks!

[tcobretti]

Yes, you just need a long shaft 50k linear pot.  I am pretty much positive that you cannot buy a 50k linear 'wah' pot.

You can get these pots for cheap at places like Mouser or Futurlec.

Yes, you can lower the value of a pot by putting a resistor across the outer legs.

[tehfunk]

Thank you, that makes it a lot easier. So, what about dimensions? Any preferred brands for durability?

You can get these pots for cheap at places like Mouser or Futurlec.

Futurlec offers long shaft pots? Where?

[MarcoMike]

the only problem is that you will end up wit a non-linear pot that way....

cool to see another Frusciante supporter!!

[lucaneo]

I have an ibanex wh-10, the stereo pot version, It's 500+50 k. I know where buy this pot, but is the "reissue version "  and the reissue pot is different, the wah sound with less basses.

By the way there is the black version of the wh-10 with a mono pot.  Are u building the dual pot version  or the single?

[tehfunk]

the only problem is that you will end up wit a non-linear pot that way....

cool to see another Frusciante supporter!!

What way? Do you mean by attaching a resistor to lugs 1 and 3, it will make it non-linear?

I have an ibanex wh-10, the stereo pot version, It's 500+50 k. I know where buy this pot, but is the "reissue version "  and the reissue pot is different, the wah sound with less basses.

By the way there is the black version of the wh-10 with a mono pot.  Are u building the dual pot version  or the single?

Cool! I am building the single pot version. Where can you buy the 500+50k

[tehfunk]

After looking at my potentiometer in my Vox wah i noticed just now  that it has to be a d-shaft potentiometer to accommodate the pinion gear. I also tried to do a rough measurement of the length of the pinion gear, and basically the length of the d shaped cut in the shaft and noticed that it is somewhere around half an inch. So, after searching through the stuff on mouser I could not come up with a single 50k linear d-shaft potentiometer that was up to size.   

[tehfunk]

I thought of something... what about sanding down the pinion gear to fit the smaller potentiometer?

[jakenold]

I use the Bourn's 91-series potentiometers.



They are REALLY good, lasts long and comes in a lot of different values. Just attatch a pinion-gear, add some grease and you're ready to go.

Jake

[tehfunk]

how do you attach the pinion gear don't they require d-shafts? What pinion gear are you using, and I'm assuming that your pot isn't mounted on the pcb, how are you soldering the wires on? But yeah, if there are pinion gears that go on the round ones then that would solve my problem... thanks!

[jakenold]

You can file them down, it's pretty easy. I've made a small PCB that mounts on top of the pot, with an IC buffer at the end - instead of running long wires back and forth to the main board.

Get them are your favorite supplier.

Jake

[tehfunk]

Thanks. I'll try them out, do you suppose I could just wrap the wires around the leads and then solder them together? What do you use em for?

Where do you buy yours?

[ayayay!]

More details jakenhold!  Any pics?  Where do you get the pinion? 

[aron]

Maybe you can do what Paul did and use a standard wah pot with parallel resistance?

[MarcoMike]

I ment than if you run a resistor in parallel of a pot (from lug 1 to 3) the final taper would be different, not linear anymore if it was lin.

take the curve res vs turn: it's something like this /   now take it as your reference: if it is like this now: | then it will turn like this (
start and end point are the same, but the resistance vs turn will be kind of anti-logaritmic, always higher tha if it was linear

I hope it makes sense to you... try with exel...

[tehfunk]

Yeah I get what you're saying with the change in the taper that you were referring to; that's exactly what I had in mind. Yeah, jakenold can you post some pictures of your work on the potentiometer to get it to work with the pinion gear. By the way ayayayay I am assuming he just gets the basic wah pinion gear, the dunlop one, you can get it at smallbear and  other diy effects suppliers.
-I am still curious as to where you get your 91 series potentiometers jakenold, mouser has a confusing supply of them, and am not quite sure which exact model of the 91 series would work best.

My largest worry with most of these potentiometers is the length, it seems that all the ones that are already d-shaft dont have long enough areas to hold the entire pinion gear. And shaving down of the shafts I think I would do, but yeah, shaft length overall seems to be a problem.

If anyone else has some suggestions of linear tapered potentiometers that would work well for a wah assembly. Thanks!

[MarcoMike]

mh, I ment excel, anyway....

the lack of linearity is not a real problem in my opinion, you are the one controlling the treadle, aren't you? and a 100kpot+100kres will result in a minor deviation from linearity...
also the "file the shaft" sounds good, and it's cheaper for sure! this would be my first choice.  if the shaft is too short to hold the whole gear, you might use some strong glue to stick them together..

[zombiwoof]

I'd say don't get hung up on the linear pot thing, the original "Icar" taper is supposed to be a "S" taper, whatever that is, it's probably part linear and part audio.  If you find that the taper is too abrubt or too smooth, you can modify it with tapering resistors, there's info on that in the FAQ here.

Al

[tehfunk]

if you've ever heard a wh10, i think part of what makes it special is that linear taper. it has a very interesting sound, it's hard to explain, but it's kind of like the entire freq range is one big mushy sweet spot. So, I am not exactly willing to compromise what I think may be one of the essential constituents in its unique sound.

What do you think would be the best way to file down the potentiometer to take the gear? A metal file? Sandpaper?

[tehfunk]

I was searching around, and I found another question.

Are cermet tapered pots okay to use. What are the advantages or disadvantages and is it better or worse than carbon comp?