Increasing the sweep of a wah pedal

[trjones1]

Has anyone ever tried increasing the sweep of a standard Crybaby wah pedal by shaving down the "heel" end of the rocker pedal, thereby allowing the front to lift higher?  Would this be a worthwhile mod if the wah pot is already sweeping from 0 to its highest resistance?  If you were going to try this how much extra sweep would you be after?  Would 1 mm be enough or would you want as much as possible?  I've been thinking about doing this, but don't know if it's worth chopping up a perfectly good pedal.

[NaBo]

I can answer one part of that fairly competently!

Would this be a worthwhile mod if the wah pot is already sweeping from 0 to its highest resistance?

In a word, NO!  And, assuming the resistance limits occurred at the MECHANICAL limits of the pot's rotation, shaving the pedal down will not only do absolutely nothing to the sweep range, it would also probably wear down your pot a lot faster... Cuz then the pressure at each end of the rocking motion would be shouldered by the pot itself and not the butt and tip of the pedal and the chassis.  Uh... it makes sense in my head anyway.

[Narcosynthesis]

i think you would gain a littel extra sweep, not sure how much though

as for the rotation of the pot and its limits, there is enough extra travel on the pot to move it round a couple of notches to tailor the sweep a bit more, so it would depend on how much more travel you would be getting

you can move the sweep by moving the pot round, so you could gain a little extra at the toe down position, but it would sacrifice a bit at the heel down position...

i would check exactly how much extra rotation the pot has and how much extra you will need by modifing the pedal, and also check if its useful sweep to you

David

[petemoore]

All the wahs I setup...
 had enough sweep to get bassy, then have rotation left, or get so trebley...
 I always used the existing pot taper, take the back off, toe rubber banded down, loosen the pinion set screw, and set the gears together, indexing 1 gear notch on the pinion each try, [towards 'more' toe down] 'till I'm sure it's barely too trebly, accounting of course guitar tone, volume and amp tones, then turn it back 1 notch.

[R.G.]

If you've read "The Technology of Wah Pedals" at GEO, you already know the answer. Since the inductor style wah depends on the forward gain of the first transistor to multiply the capacitance off the second transistor's emitter, and since the wah pot changes the gain from max to zero, the only really good way is to increase the max gain of the first stage.

Of course, you have to do this in a way that doesn't disturb the other good things of the wah. Worse, the frequency of the LC filter is f = sqrt(LC), then the range only extends by the square root of the amount you increase the gain, so you have to work hard to get a smallish return.

[Fret Wire]

Yes and no. The Vox 847 and the Crybaby use the same Hotpotz II. The Vox has a longer pedal throw than the Crybaby, yet the Vox doesn't reach the mechanical limits of the pot rotation (assuming proper rack/pinion adjustment). RG already answered what you'll get out of that.

[Gladmarr]

What about just changing the pot from a 100k (standard Crybaby) to a 50k.  I've actually done this with several Shin-Ei wahs that I have and I really liked the result.  It seems to give a longer range to the wah, but it seems counterintuitive.   It's worth a try....

[trjones1]

What I was really thinking about was changing the hotpotz 1 in my crybaby shell (the only parts left over from one of my first diy projects) to an Icar taper pot.  I've heard suggestions that the crybaby shell doesn't get the most out of this pot because it doesn't allow for travel throughout the full taper range.  The hot potz in there now reaches it's max resistance (125K ohms) before the end of the pedal travel, so it's not an issue at the moment, just wondering for future projects.  I hadn't really thought about the extra stress on the pot from increasing the angle that the saw tooth moves in.  That's enough to make me give up the idea right there.

[audioguy]

I shaved the rubber stopper on the heel of my Cry Baby. Mainly because I was using it as a tone filter and it was SO CLOSE to perfect all the way open, so I trimed off like a 1/4 inch from the rubber stopper and now I really love it at full open. Its not much od a difference, but I can hear it and thats whats important.