Expression Pedals

If I wan to get a cheap expression foot pedal for the DuoX what short shoul I look for? I’m out of date and while I know of CV I think there where problems with the CV inputs anyway?

Thought I’d have a go at this


Hi @Steve_Lee

The CV circuitry is currently not yet active in the DuoX. This same circuitry is used for the expression pedal input.

So for now, standard expression pedals can only work through a converter box (either EXP to MIDI or EXP to Control Chain). We have a blogpost from quite a while ago about building your own EXP to Control Chain converter using the MOD Arduino Shield. You can find it here:

With that said, once the CV inputs get enabled, any kind of standard expression pedal should work. Regardless of whether the signal is wired to the tip or to the ring of the TRS connector on the expression pedal.

Hope that clarifies it!


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The Melo Audio expression pedal seems to work pretty well FWIW. Cheap too (but fairly sturdy).

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Yes, indeed . I thought It was the CV inputs yo uwere havingproblems before when deciding whether to ship or not :slight_smile:

Do you have a rough ETA? It’s years since my last hobby electronnics project and while that Sheild would be a lot of fun I can wait for the CV inputs if soon-ish.



what’s the status of expression pedals via control voltage?

As current firmware is v1.9.0 and it’s not release candidate status anymore this should be working, right?

I’ll try out using Morley M2 Voltage Control / Expression Pedal (M2VC) [1], but I’m new to handling CV. Is there anything I need to consider? Has anybody run into issues or want to share some experiences? At first I want to control a gain plugin or a Wah effect and maybe explore Wammy later.



That is correct, if you have 1.9 installed it should just work.

Important to do before plugging in:

  1. press+hold endless knob 1 to open the menu
  2. scroll down to system on the left screen
  3. enter the inputs menu
  4. set CV/EXP INPUT to EXP
  5. set EXP MODE to the appropriate mode for your expression pedal.

On the Morley FAQ ( I found that they use the “signal-on-tip” wiring, so that would be the EXP MODE to select from your device menu to get it working.

You can do one of two things now:

  1. Map to any parameter (multiple params possible): simply start mapping your parameter, select “CV” and then select “CV Exp Pedal” from the dropdown.
  2. Use the bottom CV input in the web interface and patch the cable to any plugin that has a CV input.

Happy exploring!



Thank you very much for your extensive hints on CV and the Morley pedal. I’d like to recommend this pedal and suggest a wiki site for supported expression pedals similar to the MIDI controller page.

Personaly this device is too chunky and heavy (1.5 kg) for me, but it was fun playing with it and learning about more features of my MDX.

So I’m looking for another pedal solution. Are there affordable recommendations? I’m not familiar with expression pedals and it’s relation to CV. Can I use a plain expression pedal or does it need to be CV?

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i think any variable resistor type pedal works.
i use my Ernie Ball volume pedal with the DuoX CV ports.

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Ok, I see. So what about Electro Harmonix Single Expression Pedal [1].

I’m trying to find a reasonable MIDI foot controller at the same time and just saw that you contributed to the list of tested devices.

While writing this I realize that buying an expression pedal for about € 50 and a MIDI foot controller like the Source Audio Soleman [2] for € 270 to € 300 is the same as going for the Keith McMillen SoftStep 2 [3] refering to the price.

So would you recommend it? What are possibilities and which limitations have you encountered so far?


So I got a cheap-o pedel and using the “CV Meter” plugin I get a range range 1.6 to 5. is that good?

I set the input to EXP frm the default CV but not sure what the difference is

So this is a nektar NX-P universal expression pedal which cost 20GBP from amazon. Works fine. Pretty good construction quality for the price. Certainly good for studio, not sure about gigging.

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