Wah as a Filter

[Joe Hart]

I want to use my wah pedal as a midrange filter. My idea is to get rid of the bassy (heel down) tones and the trebly (toe down) tones and just have the entire pedal sweep in the "mid"/"wah" portion of the tone. I hope this makes sense. Anyway, I figure that I could run a resistor across the pot to knock the entire pot's value to, say, 50K, then tack a 25K resistor on each end, so I still have the 100K in total (tweaking the values for the exact sweep I want). But maybe there's a better way to do this with a couple cap/resistor changes? I like doing the Michael Schenker wah thing, but it's kind of a pain to focus on moving the pedal tiny, tiny amounts to get a certain sound. Any thoughts?
-Joe Hart

[jasperoosthoek]

That sounds like a very good solution to your problem. You could also replace the 25k resistors by 100k log pots connected as variable resistors/rheostats. Then you can use it as a broadness pot. It won't keep the total resistance the same but at least you have some control.

[Joe Hart]

Well, yes, the values I gave were just for illustrative purposes. I was thinking of trimpots for all three so I could really dial in exactly what I wanted. But is there a way to do it any easier? Not that three trimpots are difficult, but it may mess with the taper too much? Actually, is there a way TO change the taper? To smooth out the "kink" in the middle? Now that I think about it, the little kink in the middle of the sweep IS the problem (it's too abrupt to really dial in differing mid tones). Is there a way to smooth that out without replacing the pot (I don't know if I can get a, say, 50K linear taper pot for a wah)? Thanks.
-Joe Hart

[starekase502]

have you checked out the jerry cantrell wah it has a 5k pot atached to the treble end of the main pot to dial out some of the highs.(i think i read that on this forum even)  you coul probaly wire one up on both sides of the sweep and dial them both in the the spot you want. maybe even use larger than 5k and use trimmers so you dont have 2 pots on the outside you will hardly ever use.

[Joe Hart]

Does the Cantrell wah just have the extra pot tacked onto the "treble" end of the wah pot? So, essentially, the "pot" part of the circuit is 105K rather than 100K? I know that the difference between 100K and 105K isn't that big a deal, but is it that simple without needing to "recalibrate" everything else? And is there a good way to smooth out the transition between highs and low on a wah? I mean, really smooth it out -- like a linear transition. Any thoughts? Thanks.
-Joe Hart

[Derringer]

maybe play with the "vocal" and "midrange" resistors
http://stinkfoot.se/archives/549

[jasperoosthoek]

That 5% wouldn't matter at all. I think most pots have 5% tolerance anyway. The wah circuit will not perform differently for pots from 50k to 200k. Maybe very subtle differences. Too small values will have an effect sooner, don't use 10k. I read some players even prefer a 200k pot that can be bought from small bear.

[Derringer]

the easiest way to tame the treble (toe down) is to rotate the pinion gear a notch or two (whatever the total pot travel allows) down and then re-secure the rack gear.

this won't really affect how the transition sounds though ... just where it occurs on the travel of the the rocker


you could always just go all out and build a systech harmonic energizer
http://www.youtube.com/watch?v=HlJ9-LCDjrs

madbean has a layout

[Johan]

some chinese made wha's use a pot with a too big gear. it reduces the sweep considerable...perhaps track one of those down. I believe the crome Carvin wha is one of those..I posted about this about two years ago..or was it three..hmm....
J

EDIT: found it.. http://www.diystompboxes.com/smfforum/index.php?topic=71497.msg576844#msg576844

[PW]

Just joined the forum to bring this document to your attention...

http://www.elby-designs.com/documents/tailoringpotentionometers.pdf

Not sure if it will help. It describes a way of changing the taper of pots by adding parallel resistance between one end and the wiper.

I know that most log taper pots have a kink in their characteristics, not sure if that's what you are referring to, but a smoother log characteristic is possible using the techniques described.

[Joe Hart]

Just joined the forum to bring this document to your attention...

http://www.elby-designs.com/documents/tailoringpotentionometers.pdf

Not sure if it will help. It describes a way of changing the taper of pots by adding parallel resistance between one end and the wiper.

I know that most log taper pots have a kink in their characteristics, not sure if that's what you are referring to, but a smoother log characteristic is possible using the techniques described.

VERY INTERESTING! Thank you! I've read (and reread over and over) "The Secret Life of Pots," but this link gives actual hard numbers and great visuals. I'll have to reread this and see if I can wrap my head around how to "straighten" out the stock wah pot (first I need to research what the pot taper is!). Thank you so much!!
-Joe Hart

[zombiwoof]

Maybe I'm misunderstanding your intent, but if you want to get the Schenker "fixed wah" type sound, why use a big bulky wah pedal?.  If you're going to find one setting and leave it, why not build one of those little boxes that do the same thing, with a pot/knob on it to set it?.  I know Dunlop made such a thing, and a couple of other companies.  It would take up much less space on your board, and accomplish the same thing.  Of course, if you want to make quick foot-adjustments, a wah would be good, but if you're going to set it and leave it, the small box might be better.

This the (now discontinued) Dunlop box I was talking about, in case I wasn't clear about it:

http://www.theguitarfiles.com/product_id-360.html

Al

[Joe Hart]

I'm not looking for a "fixed wah" so much as a "slightly moveable wah"! I like to hang on the wah to color my tone pushing it slightly forward and slightly back to accent certain things, but it's too easy to move it too far. I'll play with some of the recommendations this weekend and see what I can come up with. Ideally, I can get something where the entire pedal's travel is withing the range that I want, so it's all usable (to me, at least). Thanks.
-Joe Hart

[ChanchoPancho]

Hey, just joining the post... I hope I can bring it back to life..

I'm looking for the same thing as you, Joe, I modded my wah following recomendations made in this forum and in the web and dont like it very much.
The major problem is the abrupt change between the bass and treble setting. The other thing is that Q is too narrow. This last one is easy to correct, but
the other one needs more thinking. Looking for other people experience I got here so i ask you, after a cople of years:
Have you found an easier solution than 2 pots/trimmers?

regards,
FB