Recommend me a good wah circuit, please

[MohiZ]

I just recently procured a real crappy wah with the intention of converting it into a super wah/volume/expression monster. I took the circuit board out and was left with the wah mechanism and the jacks. The wah pot is 100k dual-ganged, there's a DPDT switch and I was going to add an extra pot (for maybe adjusting the input buffer volume) and a toggle switch (though I don't know what to toggle with it yet  ). I want to use an inductor in it, and put the dual-ganged pot in good use in the wah circuit. And I want the pedal to function as a volume pedal and an expression pedal as well. So here's what I though so far for the signal path:

Either
Input jack -> Input buffer -> switch pos. 1 -> wah circuit (controlled by the rocker) -> output jack
or
Input jack -> Input buffer -> switch pos. 2 -> volume control (controlled by the rocker) -> output jack

And this is what I thought for the expression "mode":
The pedal is used as a variable resistor. Only one cord is connected to the output jack, and in switch pos. 2 the volume control (controlled by the rocker) varies the resistance between output jack tip and sleeve.

These are my questions:
1. Can you recommend me a good sounding wah circuit, preferably one that puts the dual-ganged pot to use. I've read the technology of wah pedals from GEOfex, which has an interesting op-amp wah circuit, but I haven't seen any other wah circuits around that use op-amps.
2. How do expression pedals usually work? I figured variable resistance?
3. What type of input buffer should I use? Op-amp or jfet? I figured it would be good to have a mild boost.
4. I'm not afraid to do a little modding

Thanks!

[Exactopposite]

I think you would be better served figuring out how to do these things individually first before trying to do it all in one pedal. That way you can tweak each of them to you liking before combining things. also, there is no way for anyone here to tell what wah you will like. Just tweaking a wah alone can be quite an endeavor if you are searching for a particular sound. I've spent a lot of time working on wahs, but I've never attempted anything that calls for a dual gang pot. If you are building a true bypass pedal, I'm not sure that there is anything to be gained from an input buffer on a wah . An output buffer can be very handy if you are planning on using a wah in front of a fuzz though.

[MohiZ]

Ok, thanks, I'll think about an output buffer then. I have a breadboard so it's pretty easy to play around with the different designs. I'm going to start by building the wah first. What I meant was that I haven't really found too many wah schematics online and no op-amp designs at all. Are wah circuits a more scarce resource than distortion circuits, for instance? I don't expect you to be able to tell me what sounds "the best" for me, but recommend something. I'm sure there are those wahs that are just bad no matter how you look at 'em, and I'd like to avoid them.

[Exactopposite]

i haven't tried any opamp wah's personally. the vast majority of the wahs our there are based on the old vox circuit. You have some things like the maestro boomerang, or the inductorless colorsound wahs that are a totally different beast but they are definitely in the minority. that's why you don't find very many different wah schematics. Personally I use  a vox based wah that is tuned to my liking. There is a boatload of info out there for your vox type wahs. If you are definitely going to build an opamp based wah there will be less info for you to rely on to aid you in your build. It'll take more digging to find the info that is out there about this sort of things simply because there is less of it. I always figured that if they really sounded great more people would be building them. I personally have never (to my knowledge) heard an opamp based wah though.

[Paul Marossy]

I say build a Maestro Boomerang or a ParaPedal, which would allow you to potentially use the dual ganged pot that you have.

[MohiZ]

Thanks, the ParaPedal looks promising, I'll probably have to tweak it to make it work with a 100k pot instead of a 10k pot, but I'm confident I can do it. I'm also going to try the Boomerang and other Vox based wahs.

[Hanglow]

was it one of those generic plastic wah/volume pedals, by Bespeco/Proel /nevada ?

I stuck a parapedal in mine with resistors across the lugs to get the right value and it worked fine. If it is one of them, then the wah is based on the colorsound inductorless wah and sounds great when you put the right value components into it, otherwise it sounds really weak

[MohiZ]

It was a Bespeco  Sounded really crude, but I bought it used just so I could use the enclosure. Too bad it's plastic, have you had any hum issues with yours? It has a pretty thick metal plate at the bottom and I laminated the inside with tin foil, so we'll see...

[aziltz]

with a dual gang wah pot i think you can make an Ibanez WH10... but i'm not familiar with the schematic.

[Hanglow]

It was a Bespeco  Sounded really crude, but I bought it used just so I could use the enclosure. Too bad it's plastic, have you had any hum issues with yours? It has a pretty thick metal plate at the bottom and I laminated the inside with tin foil, so we'll see...

there is a thread/schem on the "other" forum about this pedal. If you change a couple of caps and resistors you end up with the colorsound inductorless or indeed the same wah circuit that is in the Zvex series of wahs.  It is worth looking into I would say, I really like the sound of it

As for the parapedal, I didn't bother shielding anything and it is pretty quiet. I did one mod for a Q pot and used the smallest layout on geofex for the wah, although I did it on perfboard and it fitted in, just.

[MohiZ]

Ok good to know. I'm now in the process of experimenting with a basic Vox-style wah circuit, and I'm really likin' its sound even though it doesn't use a dual ganged pot. Maybe I'll even build two wahs to do some A/B!

[Mark Hammer]

if you have a dual-ganged 100k pot that seems to move smoothly in response to treadle movement, then I wholeheartedly endorse the Super Tone Control from the Craig Anderton EPFM book.  It is a state-variable filter, similar to what is found in the Mu-tron III and Q-Tron, such that it can provide highpass, lowpass, and bandpass function.  I made myself one once and it was terrific, some really interesting sounds, as well as the conventional ones.  Only downside is that it runs off a dual-battery supply, although you should be able to use charge pump chip like a 7660 to provide +/-9v from a battery or 9v adaptor.

[MohiZ]

Thanks Mark, I'll check it out!

if you have a dual-ganged 100k pot that seems to move smoothly in response to treadle movement, then I wholeheartedly endorse the Super Tone Control from the Craig Anderton EPFM book.

In regards to this, it seems like the pot value doesn't change until the treadle is about 2/5 of the way to the toe position. Is this normal? The mechanism turns the pot, but the pot value remains fixed until it is turned a certain amount. After that the pot operates smoothly and fine. It's not like the treadle movement is too small as of now, but it's kind of useless to have those extra centimeters in the heel position if they don't do jack. Should I just insert a wrench between the heel part of the pedal and the body? 

[Mark Hammer]

There is usually a few extra "teeth" of leftover rotation on most wah pots.  That is, the pot could be rotated a little more in each direction.  So, it is possible to move the rack and pinion system over one tooth in this direction or that.  Just be sure that you never push the pot all the way to either extreme, because it could break the pot.

[jrod]

What about the Freeper Wah? Does anyone have that circuit diagram? I heard some clips and it sounded really neat and different.

jrod

[Paul Marossy]

What about the Freeper Wah? Does anyone have that circuit diagram? I heard some clips and it sounded really neat and different.

jrod

Yeah, the Freeper wah is a cool one. I was going to build it once, but never did follow thru on it.

If anyone wants the schematic & PCB layout, PM me.