TRS jacks for adding expression options

[Hollytron]

Hi,

I would like to add an expression jack to a DOD fx 90 delay pedal to control the mix pot. I recently purchased some TRS jacks but they are not switched jacks and upon doing a bit more research it looks like switched jacks are usually called for in such an endeavor.

I do wonder if the regular jacks would still work but perhaps only if there is a trs plug in the jack.

Any illumination on this subject is greatly appreciated

 

[Robert]

You need a switched jack to make the pot in the pedal active when nothing is plugged into the TRS jack.

Depending on where it is in the circuit, you might (will most likely) need an insulated jack.


You need a switched TRS jack to make the pot in the pedal active again when nothing is plugged into the expression jack.

If you absolutely must use a regular non-switched TRS jack you have two options:

1) Disconnect the pot in the pedal entirely. It will no longer function at all and the pedal won't function properly without an expression pedal connected.

2) Connect the the jack in parallel with the existing pot. The knob on the pedal and the expression jack will simultaneously be active (and be highly interactive with each other), and the range of the expression control might be affected, but the pedal will still work as normal without an expression pedal.