Why An Expression Pedal? - That Guitar Lover

Why might you want to have an expression pedal, and what is an expression pedal in the first place?

What It Is

Expression pedals are tools that use circuitry mounted in a foot treadle to act as a remote controller for a function in another device, typically an effects pedal or digital modeller but sometimes even an amplifier. The pedal provides a variability capability different from an on/off style footswitch as we are accustomed to and often get as part of a package with an amplifier.

Expression pedals get connected to the device that is being controlled through a variety of means and this can make the purchase a bit confusing. Is the connection a simple TS connection, or does it require a TRS cable? Does the device have some particular specifications that define the build of the expression pedal? These are all questions to be answered, and sometimes this minor complication means that the musician avoids a tool that could be hugely advantageous.

Why Have One

Convenience is a big reason, especially if you are playing live or recording live. The simplest kind of expression pedal is the volume pedal. It takes the signal from your instrument output and passes it through a simple potentiometer that allows you to control the level sent down the chain. The most common use is to silence the instrument between songs but the really practical use is to vary the volume down the chain to allow for swells and dips. A volume pedal is a very inexpensive route to getting the sound of bowed strings from a guitar. It takes a bit of practice but becomes really valuable in short order. Volume pedals are typically simple devices using standard TS cables.

The next type of expression pedal is one that is built to control an effect parameter. Let’s suppose that you regularly use a rotary effect, or a phase shifter or a flanger, or a chorus. Modulation devices change their sound dramatically when you make adjustments to the knobs on the effect. You may be in a situation where bending down to tweak the knobs while you are playing is inconvenient, or where the location is so dark that you cannot see well. If your effect accepts an expression pedal, the device will already be preset to have the expression pedal control one of the effect parameters. Note that the knob on the device will not move as you move the treadle. The use of the expression pedal in this application allows you to modify the sound of the effect in real time while you are playing. At first if you have not used one, you may see little value, but when you try one with your effects, you are likely to have the experience where the pedal makes a value difference to you in your performance. And when you are just noodling, they can be a great source of experimentation.

Some delay units will take an expression pedal to control a parameter. While most delays today have a tap tempo function to set the delay time, some will allow an expression pedal to control the delay. Or perhaps the number of repeats, or the feedback settings. Your individual pedal will tell you what if anything an expression pedal can control, but some players like the expression pedal as a simple way to drive the delay into self-oscillation and then back it off when desired.

If you are using digital controllers such as a Kemper or Quad Cortex, they provide expression pedal connections that are routable and programmable to facilitate control of settings in a particular configuration. For example, I have two Mission Engineering expression pedals built for the Kemper attached to my Kemper Stage. Depending on the configuration, in one scenario, one pedal might be acting as a volume pedal and the second controlling tremolo rate. A change to a different configuration will make pedal one control the number of delay repeats and pedal two control the chorus depth. While the connection is via standard TRS cables, these units are so powerful that a specific expression pedal is best.

How Do I Choose?