Strymon Tech Corner #2 – Build your own expression pedal

Recently, I ended up with a broken crybaby wah. I was already lucky enough to own a 70’s thomas organ crybaby which I love, so sacrificing this second newer crybaby for a project seemed like a fun idea. Since the crybaby chassis is extremely rugged and I like the action of the pedal, I set out to turn it into an expression pedal for my El Capistan. This article assumes that you have experience soldering and using basic tools like wire strippers, etc. Of course, always observe proper safety precautions and wear safety goggles while working on any type of electronics.

crybaby wah sitting on green felt
Here’s my wah on the workbench.
crybaby wah pedal with back cover removed
First, opening up this box couldn’t be easier. Just remove the 4 thumb screws from the back plate and remove the plate.
crybaby wah pedal with electronics removed
Then, unscrew the two jack nuts from the input and output jacks and also remove the single screw holding the PCB (printed circuit board) to the chassis. Unplug the cable connector, remove the PCB and set aside.
crybaby potentiometer and switch with wires desoldered
Connect your treadle pot to a standard 1/4″ TRS (tip/ring/sleeve) jack according to the schematic in tech corner #1. Desolder all wires from the pot and switch and set aside.
crybaby wah pedal with original electronics removed and re-wired as an expression pedal
The “sleeve” of the jack is ground, so first connect that to the pin of the post closest to the footswitch. Then, connect a 1k resistor to the wiper (center pin) of the pot. Connect the resistor to the “tip” of the jack. Lastly, connect the pin of the pot closest to the jack to the “ring.” You’ve got an expression pedal!

Watch the youtube video for a walkthrough of the build process and an El Capistan demonstration with our completed diy project:

Happy shredding,

*All product names used in this article are trademarks of their respective owners, which are in no way associated or affiliated with Strymon or Damage Control, LLC.

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81 Responses

  1. I own an el Capistan and LOVE it. I saw your “How to make an expression pedal out of a broken wah” and I was wondering if you’ve ever tried converting an old Sewing machine pedal into an expression pedal? I have very limited space on my board, and the sewing machine pedals are so much smaller than Wah enclosures. I have yet to find any schematics on how to go about converting a sewing machine pedal. Any ideas? Is it really just installing a 1/4 jack and changing out a pot for a 10k pot or so? Any help would be great. I love the El Cap and really want to be able to put an expression pedal on the board, I just don’t have room.
    Thanks so much guys… and I hope you can help.
    I look forward to hearing back from you.

  2. Great tutorial! On tech corner 1 you mention that the EV5 among others has a second pot on it to allow you to fine tune the range of sweep of the main pot. Could you show us know how to do add one of these extra pots to the above example?
    Any pointers would be much appreciated!

  3. Thanks, Terry! Very inspiring. I have an El Capistan and had briefly used an Ernie Ball Jr. Volume Pedal as an Exp. pedal. The 250k pot made it almost unusable, so a quick trip to “The Shack” today yielded a 10k pot, a stereo jack and a 1k resistor.

    It only took about 2 hours to modify the EB and have it up and running with the El Cap… amazing fun!

    The pot mount on the EB was the trickiest part, since the threaded shaft on the 10k pot was too short to allow the nut to lock it in; I ended up counter-boring the alum block a little to accommodate it, drilled a hole for the TRS jack on the front left, and voila… a solid aluminum expression pedal providing tons of versatility for the delay. I prefer it controlling the Mix function, but who knows what tomorrow shall bring. Fun stuff!

    I really love the El Cap… even moreso, now.


  4. Hi Everyone, thanks for all of the comments! This is really great.

    @Paul, It’s really just about getting the potentiometer to turn when you move your foot. The electrical setup is simple, but getting the pot to turn mechanically might be tricky.

    @Jeremy, this second minimum value pot would be set up as a series variable resistor in the connection to ground (the shield of the jack).

    @Derek, Nice work!

    Happy Shredding,

  5. I have a broken line 6 ex-1 and I want to replace the 20k pot with the 100k pot from the crybaby and put it back in the wah incosure. Will this work?

    1. That will work just fine if you follow the wiring instructions above. If the 20k isn’t damaged that will work fine as well, no need to steal the pot from the crybaby.

  6. One question: I would like to use the on/off switch under the pedal to also control some effect (on/off), using the second (now empty) opening of the original wah.
    Could you give me some info on how to do this?

    I would like to use this modded pedal along with my MFC101 Pedal board (for the Axe-FX Ultra), which has some decent wahs on board, so I could mimic the switching behaviour of a Wah-pedal when stomping on it.


    1. Hi Reinhard,

      It’s possible most likely, however I am not familiar with the MFC101 midi controller so I can’t give more specifics. The basic idea would be to wire the two switch poles from the unused wah switch to the second 1/4″ jack.


  7. Hi Terry!

    Thank you for your response!
    One question remains …. what is the 1K resistor for, that you mention in your video?


  8. Hi!!
    I was able to modify my old EX1..I put a pair of TRX female Jaks, a 50 k volumen pot and I leave the original 20 k pot…and it works fine controlling my Brigadier and El Capistan..both at the same time, no bugs,,works fine ..I hope there will be no future electric damage for my devices.


  9. Hi Terry!

    First i’m gonna say, you guys make some amazing pedals – i’m so excited about the sounds i get from my bluesky.

    I was wondering where I should if I want to buy the components to build an expression pedal. I don’t think my local guitar store have these components. Do you have any recommendations?

  10. Hello Terry!

    I want to made a expression pedal for my line 6 m5…
    what i need? a mono or stereo jack? i read that the pot is 10K. and the 1k resistance?


    1. Line6 does their expression pedals differently than pretty much everyone else. You use a mono cable and a 10k pot to vary the resistance from tip to sleeve.

  11. so for the line6 style would you use the same trs input jack but use a mono cable? and the crybabies pot would have to be changed to the 10k pot or would the original pot work?? Thanks allot!! I have 2 extra crybabies and would rather not by the plastic one that said company makes…

  12. I am building an expression pedal for my boss bass synth. I am using an old volume pedal but he value is to high I believe (250k audio). I used a stereo jack and wired it according to you schematic and used a stereo cable to connect. Nothing. I then used a mono cable and actually got an effect but not like it should. I guess my question is what value and type of pot would be best and should I use a tsr cable or standard mono?

    1. Hi Robbie, you would have to know what type of expression pedal input the bass synth is expecting. I’d consult the BOSS manual and see if it recommends a standard expression pedal with a TRS cable.

  13. Terry, I have modified a Cry Baby Wah to an Expresion pedal per your instructions, and of course it works! However, the sweep on the pedal is extremely short, making it unusable in practical terms – it goes from min to max with a very slight touch to the pedal. Is there a way to change the sweep so it is longer using resistors, or do I simply need to replace the original 100K pot with a 10K pot? ALSO, If I replace the pot should it be a linear taper pot and is 10k the right value?

  14. Hi, nice blog and site! I have a question about the resistor. What kind of effect is it on the 1K? Is it important to choose the right one?

  15. Thanks terry. I might as well buy some 1k resistors while I’m at it. Are the carbon film? And what wattage? Thanks for your help. This is gonna be fun.

      1. @gavin keogh – Sorry, but I’m not very clear on your question about another very old post here. Can you please provide full details on what you are trying to achieve? An email to us ([email protected]) would work best for this.

  16. So if I wanted to do this for to control my Line 6 DL4 what would be different from what you laid out above?


  17. I just took my crybaby, opened the back, and moved the pin connector over two places to the left (which bypasses the battery and who knows what else). After that, it actually works as an expression pedal. However, the pot makes it so that there is barely any sweep to it. However, this can be a pretty cool effect in itself with certain midi parameters so it is a free and totally reversible mod. Just thought I’d share.

  18. Hi,

    I have a Line6 M13 and an under utilized Vox Wah. I’m wondering if these 2 combinations would work? MonoStereo?

    Please advise.

    Thanks m/

  19. I am trying to build the expression pedal from an old CB 535Q and I was only able to get a 3 conductor 1/4″ stereo phone jack. Will this work?

  20. This is great! However, I’d really like to install another jack to control another pedal simultaneously. Is this possible?

    1. If both pedals are Strymon pedals it should work. With other brands, all bets are off because the control voltage specification could be different.
      A caveat to this is that you’ll likely create a ground loop and possible noise between the pedals by ganging them together.

  21. Can anyone walk me through how to do this with a crybaby 535 and a stereo guitar jack?
    The pot on mine looks different so I’m not sure where the wires go.
    Please email me at [email protected] if you can help. Thanks

  22. Wooow… speechless i was going to buy a line (cheap) 6 expression pedal for my m9 but now i think i´m going to just undust my old cry baby..3 questions though…1. do i need a new pot or the one in the cry baby will do the thick? 2. the resistance is necessary for this EP1-L6 clone and 3 . the jack on the cry baby is a regular, mono (TS) guitar cable…can i use that?? thanks terry your are indeed the man!! by the way i reckon They are wired Tip and Sleeve.

    1. Hi Gerard, the Line6 ep-1 is a non-standart expression pedal design. I believe it uses a 10k but I am not certain about that. I know that is does use a standard TS cable (not TRS) and simply varies the resistance of the pot between the tip and sleeve.

  23. Thanks for the great article! I have an EV-5 around that needs the potentiometer replaced. Do you have any idea what the specs for that pot is? The pot that shipped in mine is made by Alpha and is stamped with “8h3” (the 2nd pot that adjusts the range is stamped with “8h4”) but I haven’t managed to find any specs just yet.

    Are there any minimum / maximum specs that I should keep in mind or is a pot a pot and they simply vary by size? I believe the pots in the EV-5 or other wahs are described as rotory potentiometers. Is any difference between the form factor of such pots or are they all the same?

    Any suggestions for manufacturers of pots that are better quality than others?

    Thanks in advance for you help!

  24. I’m looking to convert an Ernie Ball volume pedal to be an EV-5 equivalent, so I ordered the EV-5 pot as a spare from Roland UK (current part number is 01678156). The pot has no obvious manufacturer mark and is labelled “10kΩB”. I’ve measured the resistance from “off”/-150° to “full on”/+150° in 10° increments; the pot reads <1Ω from -150° to -40° and 8.82kΩ from 60° to 150°, and from -30° to 50° the values are 1.01k, 2.11k, 3.07k, 3.98k, 4.97k, 5.95k, 6.84k, 7.90k, and 8.75k. So there you go – highly non-standard, flat at the sides and linear in the middle.

  25. Hi Terry,

    What about the same except using two pedals simultaneously (same brand) in order to use the expression feature for both. A la Pigtronix Dual Expression Pedal
    We could reuse both jacks and the switch on the pedal.
    What is your point? Could you show us hte way to achieve this?
    Thanks in advance!

  26. Hi! i have just done it, and have tried it with a digitech rp50 for the whammy effects. but instead of having the signal all dry at heel position and all wet at toe position, its only full wet in the middle and stays all dry in both heel and toe position. im using a stereo cable. what can i have done wrong?


    -btw, i’ve used a stereo jack like this one:
    does it matter?

    1. Did you ever get this working? I did read that this is a TS (Tip/Sleeve…eg. mono guitar cord not stereo, device): You might need to experiment with tying the wiper hi and llo, and use a standard mono patch cable… Lemme know how it goes, and what pot value that you used?

  27. Can’t wait to to convert my Boss FV-60 to a double CV pedal. One question- how do I know which pin on the pot is ground, just in case they aren’t labeled? I have a little knowledge of electronics and schematics. Once I know that I can do the rest.

  28. @Ron, if you watch the video, at the 3 minute mark, terry wires up the ground connection. On the pot, it’s the pin all the way to the left.

  29. I would like to convert my soon to be faulty crybaby into an expression pedal for my line 6 M13. I know they use a mono jack instead of TRS jack. Can this be done in a similar way to your tutorial above but wire the jack socket differently to suit the M13. Thanks.

  30. There’s one thing i’m not understanding – did you use the original 100k pot in the video? Where would you get a 10k pot that would work in the crybaby, with the treads?

  31. Hello. I`ve made everything according to the instruction but got no effect with strymon timeline. I believe that the problem is in the pot. The value of it A100K (audio). Do i need to switch to 10kB or 100kB or even something else in order to make it work with timeline?

  32. @Vasya, a 100k pot should work just fine. You could try switching it out to be something like 25k to see if that makes a difference. Also, make sure you are using a TRS cable to connect the expression pedal to the TimeLine with and make sure the Global menu for the Expression Pedal input on TimeLine is set to PEDAL and not TAP.

  33. Hi! I’m trying to mod my wah pedal into an expression pedal and it isn’t working; the pot works fine and my el cap works with other expression pedals fine; the only difference I had to work around was that my crybaby had a Hot Potz II instead of the Hot Potz I that the crybaby in your video had, but it wasn’t hard to find out which terminal was which. But when I plug my el cap into the expression pedal, it always reverts to the completely open position, no matter how I engage the wah pedal. The jack, resistor and pot all seem to be working perfectly fine; is there anything else that might not be working here?

  34. Hey, Terry. I hope you don’t hate me for asking… but will this work alright with my Timefactor?

    (I’m sorry.)


    1. This project pedal is designed to work with any pedal requiring a TRS expression pedal. The Timefactor web page states that the Expression input is a Mono input, which would not work, so you may want to check with Eventide to be sure.

  35. Great mod! After watching the video I went straight out and picked up an old Broken Crybaby and did the mod, however it works backwards with my Timeline, ie: heel=toe and vise versa. I swapped the tip and ring wires around but it’s still doing the same. My way pot looks a little different, lugs are on the back. Any advise? What have I done wrong?

  36. Hi there,

    Trank you for this awesome idea.
    I’d Love to do this to my crybaby but my Pot Looks a Little different.
    The three legs are not on top but on the back of the pot.
    One leg ist labeled SL (which I believe would be sleeve)
    One is labeled cw (clockwise?)
    And the last one ccw (counterclockwise?)
    Which terminal will I have to solder to which leg on the jack?

    Thank you for your great work!!!!

  37. For the guys who try and do this with a newer wah with the “hot-pot” style potentiometer, you have to wire it like this.

    the pot hac 3 lugs named cw, sl and ccw written on the side of the pot

    Ring=CCW, with resistor

    This is at least what seems to be working with my Ground control pro, heel=000 toe=127

  38. I just attempted this mod, my crybaby has a 100k pot different than yours, with ‘lug’ style terminals, maybe an “audio” pot and not a true linear pot. I’m not sure of the difference but it’s very narrow in the middle, and doesn’t seem to do much at the top or bottom of the rotation. Picking up linear 10k’s hoping to get good results

    1. @Scott – If possible, I would recommend picking up a linear 100k pot or higher to use with our pedals.

  39. Hi, I built this pedal a few years back out of an old Ernie Ball VPJR I had. Thanks for the details. Its been great. I’m wondering if theres a way to reverse the pedal so the toe/heel action is reversed. I think you do this with a polarity switch, but I can’t find any DIY instructions anywhere.

    1. @Kris – To reverse the polarity, you just flip the wires on the outer 2 contacts on the expression pedal potentiometer and leave the center for the wiper wire as is.

  40. Hi,

    Thanks for Tech Corner 2: Building an Expression Pedal.

    I have two precise locations of the expression pedal I would like to use, but none of the points in between them. So instead of an expression pedal, I want to make a simple switch between “off” and “some value”.

    Can I measure the resistance of the pot (of a separate, existing expression pedal) when it is at the “some value” that I want, then wire a resistor equal to that resistance to a switch? Would “off” just be the other pole of that switch, unconnected to anything?



    1. @Steve – Yes, if you use a SPDT switch, you can wire a resistor to one of the contacts to the desired resistance to toggle between that values and no resistance when ‘off.’

  41. I would like to perform this transformation of my broken Crybaby, but I have 2 questions-
    1. Where can i find a 3 pin Jack? I am searching the web and nothing is coming up…
    2. Will the existing pot in the crybaby work? i have read stuff about resistance, sweep, etc…

    thank you, great video.

    1. @Joey – These steps work for wah pedals that have a single potentiometer to solder to a TRS jack. It should work fine as long as the pot has 3 contacts to solder to the TRS jack.

  42. Thanks for this! I repurposed an old Cry Baby that was going unused to serve as an Expression Pedal for my Nord Stage 3.

    Worked with no problems – thanks again for the tip!

  43. Hey i am using an expression pedal i made according to this post and the information here is great! However i am trying to use it to control the distortion pot on a ds1. I am ising an a100k wah pot that i got at small bear the economy one. I figured that the sweep would be closer to a regular a100k than a hotpotz 1 or an ICAR one. The expression pedal works but only goes thru maybe 25% of the pot on the ds1. I need to mention that i changed the distortion pot on my ds1 to an a100k as from the b100k i dont have a b100k wah pot. The sweep on the ds1s distortion pot will almost make the signal clean at 0 and super distorted at 100. The wah pots sweep barely changes the distortion level at all. I ha e tried a b200k wah pot and that made it a little better but definately not the desired amount. I dont need the sweep to go from clean to distortion, i just need it to make enough a difference that u can tell theres a change. Any thoughts or things i could try?

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