The Electro-Harmonix Single Expression Pedal is an analog, single-output expression pedal designed to control virtually any device with an expression input. It came out in 2017 and, unlike most pedals on a board, it needs no power at all: it connects to the device it controls with a single 1/4-inch TRS cable and draws nothing from your supply1.
Controls and setup
The pedal keeps things simple: one knob and two buttons, all aimed at making it work with as much gear as possible1.
| Control | What it does |
|---|---|
| Range knob | Adjusts the minimum setting of the expression pedal1 |
| REV button | Reverses the sweep direction of the expression pedal1 |
| TRS +/- button | Reverses the polarity of the TRS jack for expanded compatibility with other devices1 |
The TRS polarity switch is the feature that does the compatibility work. Expression inputs are not wired the same way across all makers, and the TRS +/- button lets the pedal match either convention. Electro-Harmonix describes it as a "polarity switch for maximum compatibility with a wide range of gear"1.
To connect it, plug a 1/4-inch TRS cable into the output jack and run the other end to an expression input on the device you want to control1. Because the pedal needs no power, it adds no current draw to a daisy chain and there is no battery to worry about.
The Range knob sets the heel-down minimum of the sweep. If a connected device does not reach the values you expect at either end of the travel, the Range knob and the REV and TRS +/- buttons are the three things to work through.
Single, Dual and the rest of the EHX expression range
The Single is one of several expression pedals Electro-Harmonix makes. The closest relative is the Dual Expression Pedal, which controls two devices at once2. The company's other expression options include the Cntl Knob3 and the Next Step Expression Pedal.
For a player choosing between them, the Single is the one to reach for when one expression destination is all you need, and the Dual when you want one pedal to move two parameters at the same time1.
Videos
Pair of Pandas
Sweetwater
Questions
Does the Electro-Harmonix Single Expression Pedal need power?
No. Electro-Harmonix lists the Single Expression Pedal as requiring no power at all. It is an analog, passive-style pedal that sends the expression signal from its 1/4-inch TRS output jack to the device you are controlling, so there is no power supply, battery or current draw to plan for on your board.
What does the TRS +/- button do on the EHX expression pedal?
The TRS +/- button reverses the polarity of the TRS jack. Different makers wire their expression inputs differently, and this switch lets the pedal match either wiring, which Electro-Harmonix describes as expanded compatibility with other devices and maximum compatibility with a wide range of gear.
What does the REV button do on the EHX Single Expression Pedal?
The REV button reverses the sweep direction of the expression pedal. With it engaged, rocking the pedal forward does what rocking it back would normally do on the connected device, so you can set the pedal up to feel the way you want without rewiring anything.
What does the Range knob do?
The Range knob adjusts the minimum setting of the expression pedal. In practice it sets the floor of the sweep, so the heel-down position does not have to go all the way to zero on the device you are controlling.
What is the difference between the Single and Dual Expression Pedal?
The Single Expression Pedal has one output and controls one device. Electro-Harmonix also makes the Dual Expression Pedal, which controls two devices at once. Both share the same basic idea of an affordable analog expression pedal with a range control and reverse function.
What size is the EHX Single Expression Pedal?
Electro-Harmonix lists the dimensions as 9.92 x 3.4 x 3.0 inches, so it is a full-size rocking pedal with a footprint similar to a standard wah or volume pedal rather than a compact mini enclosure.
Sources (3)
- Single Expression Pedal, Electro-Harmonix (ehx.com)
- Electro-Harmonix doubles up with affordable Dual Expression Pedal, musicradar.com, 2017-07-18
- Electro-Harmonix reveals its… Cntl Knob?!, musicradar.com, 2020-07-10
