In this third edition of our tech corner series, I’ll explain a simple and easy way to use a volume pedal as an expression pedal. This cool little trick was shared with us by our good friend Chad. This article will be the last on expression pedals specifically, although there are many other interesting diy projects we can do in the future with the EXP input on Strymon gear.
If you’ve got a volume pedal hanging around that doesn’t get much use or better yet one already on your board, you can use it as an expression pedal with one special cable. It’s called a TRS (tip/ring/sleeve) insert cable and the purpose of this cable is normally to break out a TRS insert jack (commonly found in mixers) to the separate send and return signals. Luckily we can take advantage of this wiring to convert our volume pedal into a standard 1/4″ TRS equipped expression pedal.
One example of this type of insert cable is the Hosa STP-201 seen below.
Once you have a TRS insert cable, simply plug the TRS plug into your exp input, the “ring” plug into the volume pedal input, and the “tip” plug into the volume pedal output. That’s all there is to it! Now you can use volume pedals like the popular Ernie Ball VP Jr or the new Dunlop DVP-1 as expression pedals for your Strymon gear and most other gear featuring expression pedal control. What is actually going on here is that we’re taking advantage of the design of a passive volume pedal and re-wiring it as an expression pedal with this cable. Note that your volume pedal needs to be passive, not active and the impedance (value of the resistance) in the volume pedal’s potentiometer isn’t critical. One thing that may be a little bit different about using the volume pedal as an expression is that if the volume pedal uses an audio taper potentiometer you won’t get a linear sweep of expression pedal values from toe to heel. In other words, much of the action will happen at one extreme of the pedal.
As you can see, the expression pedal schematic from Tech Corner #1
is functionally identical to using a volume pedal with a TRS insert cable.
Here is a video walk-through:
Hopefully this has been a useful trick to get you rocking that expression pedal.