overview picture of the Therevox Expression Pedal
curled cable with connectors detail showing bottom side profile of pedal overview picture of the Thereox Expression pedal

Expression Pedal

We originally designed the ET-4 to be used with an expression pedal. On the ET-4.1 and ET-4.2 an expression pedal allows you to control the timbre of the instrument by changing the filter cutoff frequency. With the ET-4.3, you can use two separate expression pedals at the same time to control a combination of different sonic qualities.

Inside our expression pedal is a sealed conductive plastic potentiometer manufactured by Dunlop that is rated for 1,000,000 cycles - this is the smoothest and most reliable potentiometer we could find anywhere. The enclosure is made of cast aluminum and powder coated to match the ET-4 series instruments. The nameplate on this pedal is made of the same Black Walnut we use on the ET-4 and finished by hand with the same process. The included 3-conductor cord is designed to perfectly mate with the ET-4 and is made using cotton overbraid wire with a right-angle Amphenol connector for the instrument and a straight connector for the pedal.

Details and Specifications

  • Cast aluminum enclosure with durable powder coat finish
  • Dunlop "HotPotz II" 100K sealed conductive plastic potentiometer
  • Reliable rack and pinion gear mechanism
  • Switchcraft jack
  • Cotton overbraid 5' cord with Amphenol connectors
  • Point-to-point hand wired
  • Solid Black Walnut name plate hand-rubbed with an oil finish
  • Outside dimensions: 9.5 x 4 x 3"
  • Made in Canada


For more videos, see the ET-4 Series playlist on our YouTube channel.

Our EXP-1 expression pedal was produced in 6 runs between 2013 and 2018. We are now in the progress of designing an updated version of this product, if you are interested drop us a line.