The Pigtronix Dual Expression is a passive expression pedal built to drive two effects at once. Where a normal expression pedal has one output, this one has two isolated TRS jacks, so a single treadle movement can control the parameters of two pedals with expression inputs at the same time1. Pigtronix developed it together with Mission Engineering and released it in November 20111.
The idea is simple: one foot, two parameters. Delicious Audio's review of the Pigtronix Rototron noted that the Dual Expression "has the ability to speed up one rotor while simultaneously slowing down the other," which is exactly the kind of coordinated control the second output and its polarity switch make possible2.
What it does: two expression outputs from one treadle
An expression pedal is a treadle you connect to a pedal or rack unit so you can sweep a parameter, such as delay mix, filter cutoff, or rotary speed, with your foot. The Dual Expression splits that job across two outputs. No Treble described it as "a unit with two outputs to simultaneously control the parameters of two pedals with expression inputs"1.
Because the two TRS jacks are isolated, each output carries its own expression signal without the two connected devices interfering with each other. That opens up pairings a single-output pedal cannot do: sweeping the speed of a rotary simulator on one output while opening a filter on the other, or, with the polarity switch engaged, raising one parameter while lowering the other2.
The Dual Expression was introduced alongside the Pigtronix Rototron rotary speaker simulator, and the two make a natural pairing: the Rototron's two rotors can be driven in opposite directions from one treadle2.
The controls and jacks
The pedal is built around a small set of parts, all reported at release:
| Part | What it is |
|---|---|
| Dual Isolated TRS Jacks | Two expression outputs, each wired with standard TRS cables3 |
| Precision Machined Dual Potentiometer | The treadle-driven pot that generates both expression signals3 |
| Polarity Reversal Switch for Output #2 | Inverts the sweep direction of the second output3 |
Because the circuit is passive, there is no power input, no battery, and no current draw: the treadle simply turns the dual potentiometer, and each half of that pot feeds one jack. Standard 1/4" TRS cables run from each jack to the expression input of the device you want to control3.
The chassis measures 10" x 4" x 2.5" and wears a green "automotive grade" finish3.
Compatibility with other makers' pedals
The Dual Expression uses standard TRS wiring and presents a 20K impedance, which No Treble reported was chosen "to allow for use with devices from most manufacturers"3. In practice that means any pedal or rack unit with a conventional TRS expression input is fair game, not just Pigtronix products.
The polarity reversal switch on output 2 matters here too. Expression inputs are not all wired the same way, and some devices respond in the opposite direction to others. Flipping the polarity of output 2 lets you match a device that sweeps backwards, or deliberately set two effects to move in opposite directions, which No Treble described as "controlling effects in opposite directions"1.
A related pedal: the Custom Shop Active Dual CV
In August 2014 Pigtronix announced a follow-up, the Pigtronix Custom Shop Active Dual CV Expression Pedal. Unlike the passive Dual Expression, it is an active design aimed at control voltage (CV) gear: it has dual outputs to control two CV parameters at once, Neutrik jacks, a polarity reversal switch on one output, and the same automotive-grade textured green finish. Guitar World reported it is eurorack-friendly and can control gear with 1/8" CV inputs, including the Arturia MiniBrute and MicroBrute, Studio Electronics BOOMSTARs, and Tom Oberheim SEMs4.
How it compares with other dual expression pedals
Pigtronix was not the only maker to see the value in two outputs. Source Audio's Dual Expression Pedal likewise offers two isolated TRS expression outputs for simultaneous control over multiple effect pedals or rack systems, and Electro-Harmonix's Dual Expression Pedal gives both EXP outputs a polarity switch for maximum compatibility with a wide range of gear, plus independent range and reverse controls on each output. The LEHLE Dual Expression, made and tested in Germany, is another passive two-output option. The Pigtronix unit's distinguishing features are its passive dual-pot design, its 20K impedance aimed at broad compatibility, and its USA manufacture3.
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Questions
Is the Pigtronix Dual Expression passive?
Yes. It uses a passive circuit with industry standard TRS wiring, so it needs no power of its own. A precision machined dual potentiometer driven by the treadle sends the expression signal to both outputs.
Does the Pigtronix Dual Expression work with pedals from other makers?
Yes. It uses standard TRS wiring and a 20K impedance, which Pigtronix specified to allow use with devices from most manufacturers. Any pedal or rack unit with a TRS expression input is a candidate.
What does the polarity switch on output 2 do?
The polarity reversal switch on output 2 inverts the direction of that output's sweep. With it engaged, pushing the treadle forward raises one parameter while lowering the other, so two effects can move in opposite directions from one movement.
Where is the Pigtronix Dual Expression made?
It is made in the USA. Pigtronix developed it together with Mission Engineering, and it shipped in a green automotive grade finish at a street price of around $159 when released in November 2011.
Sources (4)
- Bass Gear Roundup: Old School Fender, Roland Field Recorder, Arium 050, New Pigtronix Pedal and The Bass of the Week, No Treble, 2011-11-26
- Pedal Review: Pigtronix Rototron (Rotary Speaker Simulator), Delicious Audio, 2014-05-16
- Pigtronix Releases the Dual Expression Pedal, No Treble, 2011-11-18
- Pigtronix Announces Custom Shop Active Dual CV Expression Pedal, Guitar World, 2014-08-13
