How to mod a Crybaby Wah pedal

I went to see Steve Vai the other day. As well as feeling like I knew nothing about the guitar, I also felt like I needed to use some of the techniques and gear he uses. I can live without a whammy bar to be honest, but his use of a wah pedal in so many different ways reminded me that I had one at home, and I needed to use it.

There's only one problem, it's a Jim Dunlop Crybaby wah, and while I can get some half decent sounds out of it at home, it gets lost in a live situation, and the sweet spot of the wah is in such a small part of the pedal sweep it's just not usable. So how do people get such good sounds out of it? Does it prefer humbuckers and high gain? Should I just buy a Vox?

I've modded the pedal already in the past but not to the point where I was 100% happy, so I'm going to go all out and do almost all the mods to see if I can improve on it. The only two I won't do is to replace the pot and the inductor. In my opinion if you have to go that far you might as well buy a different wah because they're the most expensive parts, after the shell.

The essential resource for these mods is wah-wah.co.uk. I also like the instructions for the Build Your Own Clone wah pedal as that has all the mods built in, so it's easy to get an idea for component values and how to mod. So here are the mods:

Adjust the pot/pinion

The simplest mod. I tried this a few times, never really got the sweet spot I was looking for. But definitely worth remembering when adjusting the other mods. 

True bypass / add LED

The existing footswitches in these wah's don't take the circuit completely out of the signal path, instead they use a buffer to bring back some of the high end when in 'bypass' mode. I found this mod does clean up the pedal when bypassed and in a chain of other pedals. The LED isn't entirely necessary but it's good to know for sure when the effect is on/off. I had to file the bezel down for the LED so it wouldn't physically interfere with the pedal. Some people like to put the LED in the side of the pedal but that seems silly to me.

Remove the input buffer

With the pedal true bypassed you don't really need this buffer any more, although it won't do any harm to leave it in. I read something about it interfering with fuzz pedals because of the impedance, so I decided to take it out to be sure. Besides I like taking away as much as possible from a circuit without compromising the sound. 

Trimpot mods

I already tried the 'Q' mod with a pot, very usable, gives the wah a lot more of a quack. But now I'm going to bring all the mods onto a bit of veroboard and have it all inside the pedal. It's easy enough to open up, and having knobs outside the wah shell just takes up even more pedalboard real estate. The other mods are 'volume', 'bass', and 'mids'. I tried a fixed resistor for one of these already, I think it made the sound worse so I look forward to being able to dial it out again. All I'm looking for is a consistent sweep without the bass-treble jump. 

Capacitor mod

This will adjust the frequency range the wah effects, which will give you the difference between a regular wah and a bass wah etc. I plan on having two socketed areas on the board for two capacitors in parallel so I can either just use the one, or use two, which will be the sum of the capacitance for extra choice. I fixed a rotary switch to the side of the wah once but never got round to hooking anything up. Again I'd prefer to just set and forget inside the pedal now. 

The daughterboard

The plan is to sit this beneath the battery compartment, so it's a tight fit. Also I need to leave room to put the standoffs through it. The trimpots are pretty big considering, 5x3 rows on the vero. The wipers are jumpered to the right hand lugs in case any of them fail (extremely unlikely). This means you may get a crazy wah sound all of a sudden, but it won't cut out completely. The caps can sit in the 3 rows that the trimpots don't use, which saves some space.  I'll put some sockets in so I can change them at will.

Verdict

• True bypass/buffer/LED mods help to clean up the signal when not in use and lets you know when the pedal is on
• I ended up moving the pinion so the pot made it to full sweep in the toe position
• The volume mod gave quite a boost but also meant the lower end sweep sounded distorted, so I left it at a moderate level
• The Q mod is essential for a quackier sound, I just left it maxed out
• The bass mod was interesting, it also affects the gain and resonance a bit, but the best feature is you can tune what note the wah resonates at in the heel position. I tune it to F Sharp because you can really get that Bulls on Parade sound. Too much bass caused a lot of honkiness when sweeping the pedal, even on high notes
• The mids mod interacts with the bass a lot. I thought I wanted to smooth the bass/treble transition but it turned out is sounds better doing the opposite
• The caps mod: This nailed the sound I wanted. Rather than the stock 10n, or 0.01uF, I put in two 4n7's which gives 9.4n. Very slight difference you might say, but this just tipped the wah into the frequency I'd been looking for. I had to lower the Q value because it sounded a bit synthy and extreme. I tried the bass wah mod for a laugh, it knocked the other mods out of place so I gues having a rotary switch for different values wouldn't get you far because I had to adjust bass and Q a fair bit each time I changed caps. 
• p.s. the caps made the daughterboard too high for the enclosure, so I had to put the standoffs in the other side and clip them a bit. 

Summary

No wonder so many of these end up for sale. The slightest change in values give you all sorts of different sounds, more bad than good. I doubt two wahs sound the same what with component tolerances etc. I'm not done tuning this thing, but for now I'm very happy, and I definitely recommend at least swapping the cap and adjusting the pot if you're unhappy with your wah.