Expression pedal and Mod Duo X

Hello everybody.
I’m trying to use my expression pedal , a behringer fc 600, with my Mod Duo X but I can’t.
I have tried all cables, all polarity options and nothing happens.
I think there’s a bug because sometimes the CV/EXP input setting changes on its own.
Is there someone here that can use a expression pedal with a Mod Duo X and the latest firmware?

Hi @Julien,
The unit will switch back from EXP to CV mode when the EXP port is shorted as a security measure. On our to-do list there is still a task to give a clear popup when that happens, sorry for the confusion.

Are you using TRS cables to connect the expression pedal?
If so you should be able to assign the expression input when you press “Manage CV ports”. perhaps this wiki page helps!


I’m using a TRS cable. Positive is on the tip.
I’m able to choose Exp in the plugin.
But nothing happens

Hmm one more thing to try is to connect the MOD CV meter plugin to the exp input and see if the values relate to the position of your expression pedal.

If that does not work, please reach out to so this can get sorted.

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Hi Jan.
Thanks for your help.
I don’t know what happened, I just did like you say and plug the Cv meter on the exp input, Isaw that there is a signal from 0 to 10, and now it works.
I use the same cable, the same Exp setting (signal on ring), the same pedal board, the same expression pedal and it works!



i got a similar issue. i’m using behringer fc 600 with my Mod Duo X too.
but unable to make it work
i was reading about the resolutions but there’s no data displayed on my cv meter.
any idea how to make it work?

i mean there’s data… but min value, max value, and current value are all 0

Do you have it configured properly on the device settings?

Thanks. I got data now and it’s triggering.
The max value i got from fc600 is only 1 (i.e. 0 to 1) though instead of 10.
my other pedal is even worse (i.e. the other pedal has range of 0.2 to 0.6)
Is there a way to adjust this signal so one can properly trigger the full range on the wahwah effect plugin (e.g. Guitarix WahWah)?
Currently, it only moves from 0.00 to 0.21 if use Cv Exp Pedal.
it moves from 0.00 to 0.11 if i use the output from the CV meter.

How to make it move from 0.00 to 1.00 in the wah?

You can try to use either the Advanced setting while assigning (although this works to decrease the range) or perhaps you can try something using CV plugins. I’m not checking how to do it right now, but for sure with those, you will find a way.