Foot-on-pedal / True Bypass Crybaby Wah Mod

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A guy with a passion for playing guitar, engineering and of course DIY... and beer too.

Intro: Foot-on-pedal / True Bypass Crybaby Wah Mod

UPDATE: The old wiring diagram contained errors (sorry, I wasn't too familiar with electronics and wiring diagrams, this was one of my first projects and my first instructable). There were also questions about the blue wires going to the wah pot, I drew the wah pot to make things clear.


This makes your Crybaby wah switch on when you put your foot on it, and turn off when you remove your foot!. It will also be equipped with true bypass. That means that the circuit is actually bypassed when the wah effect is off, instead of passing through its transistor bypass circuit (that ruins your sound, removes clarity, makes distortion sound like a bad fart, etc).

If you might want to control your wah the original way for some reason, then there's a miniswitch on the side that lets you choose between the two modes. When the wah is in foot-on-pedal mode, a green led lights up to indicate this. I also placed a red led that indicates that the wah is on AND in original mode. The thing I hated most about the standard crybaby is that you could not see whether it was on or not!

-- VIDEO --

Step 1: Buy Parts

You have to buy a few parts for this mod. I bought them all together for about 10-15 euro's:
- 3PDT stomp switch, to replace the stock one
- green 3mm LED
- red 3mm LED
- 350 ohm resistor*
- 390 ohm resistor*
- 3PDT miniswitch
- DPDT mini momentary switch, with button.
- thin electrical wire
- superglue or two led holders

Tools you (might) need
- plyers, for cutting the wires and tightening the nuts
- a wire stripper. You can use the plyers if you dont have one, but be careful not to cut the wire
- a drill and a set of drill bits
- soldering iron
- screwdriver

*If you can't find these specific resistor values, take the the nearest value you can find. A higher value is good, but don't get significantly lower because that will cause the LED to burn out. Also, if you think the LED's are too bright, try higher value resistors such as 1K or higher.

Step 2: Replacing the Original Switch

Put the wah on its back and grab a screwdriver. Unscrew the four screws holding the baseplate.

Now, cut the wires coming from the stomp switch. Cut them close to the lugs, we still need these wires! Now, remove the switch (use plyers to unscrew the nut).

Put in the new switch, and test it by kicking down the pedal. You should hear it click when you apply firm amount of pressure. Adjust the height with the nut and washers to get it working. You don't want to have to apply 10 tons of pressure on the wah to turn it on, but on the other hand, you don't want your wah to switch off when you just press the pedal down right? Fiddle around a bit and find out what works best for you.

Step 3: Drill Holes for New Components and Fitting the Leds

Now it's time to start drilling ! This is probably the hardest part. You have to drill through solid steel, and Its pretty hard steel too. I strongly recommend a drill press for this, since it is more stable and powerful.

Lets start with the biggest hole: the one for the momentary switch. It has to be drilled right through the top surface of the pedal. The best spot to drill is probably between the 'A' and the 'I' (there's AMPLIFIER on the left and INSTRUMENT on the right). Grab a drill bit (i think it was 5 or 6 mm, can't remember actually. Measure the switch shaft to find out) and drill right through it. Don't rush, just drill gently with a firm amount of pressure on the drill bit.
Now take a slightly bigger drill bit, and use it to chip away some extra rubber around the hole. Don't drill into the metal this time. Now you have space to put the nut for the momentary switch. Press it in there, if it doesn't work, chip away some more rubber.
We're not going to place the momentary switch yet. You won't be able to wire it anymore if you do.

Now the side of the pedal. We need 3 holes: 2 3mm holes for the leds, and a hole for the miniswitch. I drilled them next to the output and the DC in. Check out the picture below. Put the switch through the hole and screw on the nut.

Now, lets fit the leds. Grab one, and just force it into the hole. You can also use special led holders, these require slightly bigger holes. Then put a small drop of superglue on the led and wah casing (at the inside!). Wait 2 minutes and your done, these leds won't be going anywhere!

Step 4: Wiring the Thing

Ok, soldering time. Use my wiring diagram. It should be clear from that. Don't worry, you will not destroy your wah if you mix up wires.

IMPORTANT:
- Pay attention to the C NO NC symbols on the side of the momentary switch
- pull the wires for the momentary switch through the pot hole, and solder the switch outside the casing. This because you have to install the momentary switch with the wiring already attached to it, and it can't go through the pot hole (learned that the hard way)

This step will keep you busy for a while believe me ;)

Tip: use different colored wires. It makes debugging a LOT easier, since you can track where the wires are coming from.

After you've wired everything, install the momentary switch. Use both hands to screw in the momentary switch (you're turning the switch, not the nut. The nut is locked in place by the rubber). The switch wires now twist into a nice solid string. Be careful not to damage the wiring!

Step 5: TEST

Lets do the first test!
Plug a guitar cable into the instrument input, and hook up a 9V power supply (battery or adapter, doesnt matter). The pedal is now powered. If the green led is on, flick the miniswitch. If you see no green led light up at all, check your green led. Its probably wired in reverse, so swap the leads and try again. If your green led works, press the momentary switch. The green led should not go off, if it does, you probably made a serious wiring mistake. If everything works, flick the switch and test the other mode:

- NO LEDS ON - The pedal is probably in the original switching mode. Stomp the pedal down. The red led should light up. If it doesn't light up, its probably wired in reverse. Swap the leads and try again. Also, try to push the stompswitch down with your finger. The switch might not actually switch because it's not mounted properly. Try raising it if this works.
- RED LED ON - The pedal is in the original switching mode. Stomp the pedal down. The red led should go off. If is doesn't, you've made a wiring mistake. Maybe you bypassed the switch somehow. Recheck the wires with the diagram. Also, try to push the stompswitch down with your finger. The switch might not actually switch because it's not mounted properly. Try raising it if this works.

If this all works fine, there is a big chance that the actual wah will work as well. Plug in a guitar and turn on your amp. Don't crack it up yet, it might squeal or buzz. THIS WILL NOT KILL YOUR AMP OR GUITAR, don't worry. Try the wah in both foot-on-pedal and standard mode. Possible problems you can face:
- buzz, and no guitar sounds. Solution: a wire is not connected. If it doesn't work in both modes, with wah on and off, it is one of the main wires coming from the circuit board, going to the miniswitch. If it doesn't work in one of the two modes, check out that mode for loose wires. If it only works when the wah is off, or only when the wah is on, check the wires on that side of the switch.
- squeal. solution: you mixed up the two wires from the wah circuit to the miniswitch. Just swap them and it should work fine. Again, if it only works in one mode, just check the faulty mode and those particular wires.
- nothing. Just silence. This means there is a shortcircuit somewhere. Check if there is any bare wire that hits another wire or lead. Also, check for mixed up wires. Again, try to isolate the problem by testing all modes.

Don't give up. Testing is always the hardest (and most boring) part. But eventually you will get it working!

Step 6: Have Fun With It!

Congrats, you succesfully finished your wah mod! Have fun with it ;) !

here is my video
-- VIDEO --

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62 Discussions

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paul.oakley.92

3 years ago on Step 4

Don't know if you still check this (the last comment was 3 years ago!), but I'm slightly confused... Where the wires are connected to the components on the circuit board, do you remove that end of the component from the board (where you attach the flying lead), or is the wire a junction from the component?

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mnuru1

4 years ago

Great mod!I have a question tho, if I wanted to keep the buffered bypass but do everything else in the mod, what changes would I make to the current schematic. Thanks!

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lsalles

7 years ago on Step 4

In this diagram, can I withdraw the buffer components or this is not necessary and that will be true bypass even with the buffer there?
Thanks, bro!

1 reply
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KoenBlsalles

Reply 7 years ago on Step 4

I believe the buffer circuit is also bypassed, but i'm not a 100% sure. You can test it by plugging in the wah with out power and turning it on and off. If it really is true bypass, you'll still be able to hear sound coming out of the amp when the wah is turned off.

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Fopat

7 years ago on Introduction

Thanks for this mod! The momentary switch to enable the wah is a very good idea!
However, I think one step is missing to make the mod really true-bypass. From what I have read on the 2 websites below, to be true bypass, the circuit between the input jack and the buffer input needs to be cut:
http://www.geofex.com/Article_Folders/bypass/bypass.htm
http://www.stinkfoot.se/andreas/diy/mods/dunlop.htm
Else, the green cable soldered on the capacitor has no use. Or maybe I misunderstood something?

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rpdiggs

8 years ago on Step 1

I found this mini momentary DPDT switch for the US..  Certainly hard to find.  Haven't ordered it yet but think it's my best option.

http://shop.willyselectronics.com/browse.cfm/switches/snap-action/miniature/30-2750--mini-snap-action-pushbutton-momentary-dpdt-1a-125v-solder/4,4768.html

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barkley

8 years ago on Step 1

Where can I find a DPDT mini momentary switch?
Ive looked everywhere!
The site mentioned by somerockerguy doesnt have them and niether does that dutch one you mentioned!

2 replies
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KoenBbarkley

Reply 8 years ago on Step 1

My local electronics shop sells them, but i dont know where they get them from (an they probably wont tell me). I tried a bit of googling using the image search and found this after a while https://www.photonage.com.au/new-c-71_39.html?page=1008&sort=20a

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KoenBKoenB

Reply 8 years ago on Step 1

... i dont know if theyre shipping worldwide though..

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ludoheavy

8 years ago on Step 4

tank you for the new diagram!!

But i have the same question of Link0126, where goes the blue wire from the harness?

1 reply
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KoenBludoheavy

Reply 8 years ago on Introduction

I can image this being confusing. I'll update the schematic again to make it clear. It should be up in under an hour.

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KoenBstupidityisagift

Reply 9 years ago on Introduction

Not 100% sure but i think it will work. All the volume pedal mod does is removing one capacitor, no major circuit changes, so it will probably work.

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lainage

9 years ago on Introduction

Can you post a link to the mini-momentary switch supplier? I cannot find a mini one anywhere. Awesome mod by the way.

1 reply
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KoenBlainage

Reply 9 years ago on Introduction

I bought it at my local electronics shop here in town. I dont really know any online suppliers, maybe google can help you ;)

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go2ldook

9 years ago on Introduction

Your wiring schematic is wrong in terms of the momentary switch. Here is how it should go:
4 5 6 (looking at lugs with the common to left, normally closed to right.
1 2 3 and lugs numbered as shown)
C NO NC

1= Purple wire (Output to amp, to middle lug of middle row on 3pdt switch)
2= Blue wire (The effect loop return, goes to wah pot)
3= Green wire (Input from guitar, goes to the PCB harness)
4= Green wire (The effect loop input, goes to top right lug of the 3pdt switch)
5= Solder your jumper wire from 5 to 3)
6= No wire here
With this arrangement the switch (as long as it is the same type of momentary switch with the same C-NO-NC orientation as shown in the drawings in the instructable) should work as expected.

As drawn in the instructable the wiring diagram results in no signal with foot off (C-NC connected, which as drawn means the guitar input flows to the effect loop return). With the Foot On you get Clean (C-NO connected, the guitar input connects to the amp output). At least this is what I see...I had wired it as shown in the instructable, and posted stating that I had no signal foot off, and wah with foot on, but I may have been frustrated at the time and wrote the wrong thing...if you follow the signal paths, foot on should give you a clean signal as it is currently diagrammed.

Also, for other who know nothing about these switches, the lug are flat. To orient the 3PDT stomp switch and 3PDT mini toggle switch correctly for wiring as shown in the instructable, the lugs should look like this:
I I I ON _ _ _ ON
I I I for the stomp, but like this: _ _ _ for the mini switch.
I I I _ _ _

I think that is correct for all stomp switches. For the mini 3PDT toggle, you just need to make sure the "ON" throws are on the left and right as shown.

Sorry to be so verbose, but I am not an electronics hobbyist, so having this spelled out in the instructions would have saved me a lot of pain. No offense to the author...this is a cool project, and thanks for posting it!

1 reply
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go2ldookgo2ldook

Reply 9 years ago on Introduction

Sorry, my attempt at drawing a schematic for the 3PDT switches failed when it got reoriented at posting! Hopefully people get the idea.

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go2ldook

9 years ago on Introduction

Have wired this up and checked over it numerous times. My LED's light fine. With the momentary switch I get no bypassed signal, but when I depress it I get the wah. If I switch back to standard switching, I get the wah effect whether the switch is turned on or off. Can't figure this out. The two wires that go to the pot...do they go to the same lug on the pot that the blue wire to the PCB goes to? Any ideas what I have done wrong?

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link0126

9 years ago on Step 4

do the two blue wires coming from the wah pot indicate the one wire from the pot as well as the other one coming from the harness? does it matter which one goes on which switch? thanks