Modifing a taper of the pot

[JebemMajke]

I would like to modify a taper of the pot, so that it works like those wah pots. Because it's a bit too expensive.

I've found a couple of old EKO, Itallian made, vol pedals and I've converted them into wah's. Now one is finished, and other's paint is drying at the moment. What i wanted is to make one ibanez WH10 clone and other ether Electro Harmonix Queen Wah, or Colorsound fuzz wah. Basically, a Inductor based wah.

Now the parts, Fasel inductor and hot potz II, together cost around 40 euros. That's too much. Also I've paid 10 euros for a shell ...

I would like to modify a regular linear or log pot to work like wah pots.

Is that doable?

[armdnrdy]

That would be a no.

The wah guru, Joe Gagan would be able to tell you the exact specifics of the taper for each year and model for just about every wah ever made....but I can just tell you that they are custom taper pots.

[JebemMajke]

Ok, is it possible to make a custom taper pot?

[armdnrdy]

Not like a wah taper. It's a very specialized taper.

http://www.geofex.com/article_folders/wahpedl/wahped.htm

http://www.diystompboxes.com/smfforum/index.php?topic=102233.0

[JebemMajke]

How about this way?

Using just a lin 100k pot. I am aware that it won't simulate wah taper, but it would be interesting to try.

[armdnrdy]

Give it a go and report back what it sounds like.

The thing that gives a wah pot the unique sound is that there is an abrupt step in the taper. You can't get that from a vactrol or LED/LDR combo.

But...try it out to see if this will work for you.

[tommycataus]

I have to tell you that I tried this. I ordered a Halo inductor and got an ICAR taper 100K pot whilst I was at it. The inductor was great but the pot got crackly very quickly. Very audible on clean settings.

I tried messing around with linear and log 100K pots, and I went for the LDR option too. It works, but the 'quack' in the wah is non-existent. What I mean is, that clicking sound at the start of Hendrix's Voodoo Chile (slight return) or Greg Howe's Howe 'Bout It is something you can never achieve with this.

I highly recommend getting a proper pot that is of high quality. I hate to say it, wah circuits being fairly basic in the grand scheme of things, but if you want a really awesome sounding wah there are three things that you just cannot cut corners with:
1 the enclosure
2 the inductor
3 the pot

[JebemMajke]

Well you can go without an inductor ( ibanez WH10 ) but now I see that it's a no fly zone without a very expensive hot potz II ... 25 @#$%ing euros ... Damn.

Thanx guys.

[tommycataus]

I'm sure I read somewhere, maybe even Geofex, that people have successfully modified the taper of a pot. I wouldn't know how successful it was, but it may be possible to bodge if you have a few spare 100K pots lying around that you don't mind messing with then that may be a cheaper way. It has crossed my mind before, but I wasn't game and there is little info out there.

Like you say, you can make wahs without inductors, just for me personally nothing beats the classic sound and the ones I've heard without don't quite do it for me. It's a personal taste thing so I guess it's each to their own. I hope you manage to find a cheaper solution that makes you happy though buddy!

[joegagan]

if you have a good quality pot, you can alter the taper. you are removing carbon, so you must start with a pot of lower value. start  with 5 pots of the lower value, you might wreck 4 to get it right.

slowly remove carbon, you will see the overall value rise. experiment to see how removing more carbon in certain areas affects taper.

keep in mind that you are also shortening the life of the pot since you are removing the material.

i've successfully done it. i will modify a nice rv4 pot for anyone ( within certain R parameters) for $100 per pot. plus shipping.

[Blitz Krieg]

The taper only changes the "feel", right?  All the "sounds" are theoretically still available, it seems.

[joegagan]

The taper only changes the "feel", right?  All the "sounds" are theoretically still available, it seems.

well, not sure. i have a theory, that when it comes to wah, the taper actually DOES affect the sound. it has to do with the time element - the charge/ discharge of the  4.7 u to ground off inductor.  if a wah taper passes through R range too quickly, the cap possibly fails to charge completely. thinner tone?

[PRR]

With a panel-knob pot, taper fixes the problem of all the action being crammed into a small part of the rotation. So you could say it is just "feel".

With a pedal-activated pot you are very limited in pot rotation. You usually get much less than 270 degrees rotation. So a special taper is almost essential.

And NOT readily gotten by loading.

[commathe]

The taper only changes the "feel", right?  All the "sounds" are theoretically still available, it seems.

well, not sure. i have a theory, that when it comes to wah, the taper actually DOES affect the sound. it has to do with the time element - the charge/ discharge of the  4.7 u to ground off inductor.  if a wah taper passes through R range too quickly, the cap possibly fails to charge completely. thinner tone?

I think this would only be possible if your foot moved faster than the speed of sound.

[joegagan]

^^ not so sure. with a regular wah pot - the resistances go by very fast.