The Pigtronix Resotron Tracking Filter is an all-analog envelope filter pedal from Pigtronix. Where a standard envelope filter sweeps its filter in response to how hard you pick, the Resotron also introduces pitch tracking: a mode where the effect follows the actual notes you play rather than your playing dynamics1.
MusicRadar's reviewer, Trevor Curwen, describes it as a pedal that covers traditional envelope filter territory on one hand, with both up and down envelope behavior, while opening up pitch-following sounds on the other1.
A filter that follows the notes you play
The core idea is the pitch-following mode. Instead of the filter sweep being driven by your attack, it is driven by pitch, so the filter tracks the notes you play. A Glide knob sets how long it takes for the filter to move between notes in this mode, letting you choose between an instant jump to each new note and a slower slide between them1.
The filter itself can be set to work as a low-pass or high-pass filter, or in band-pass mode for typical wah tones. Standard Peak and Cutoff knobs adjust the filter voices, and Curwen found that combination offered "loads of sonic potential"1.
In use, Curwen reports you can dial in several subtle variations on the auto-wah experience for funky riffing, reggae rhythms and Jerry Garcia-style leads, plus tones you would expect from a phaser or flanger1.
Controls and expression
| Control | What it does |
|---|---|
| Peak | Adjusts the resonance of the filter voices1 |
| Cutoff | Sets the filter cutoff point1 |
| Glide | Sets how long the filter takes to move between notes in Pitch mode1 |
Plugging in an expression pedal allows foot control of the filter cutoff if you would like a more conventional wah experience from the pedal1.
Circuit and power
The Resotron's 24dB/oct filter circuitry is based on the SSM2040 chip as found on some vintage synths, and the pedal is all-analog throughout1.
The Resotron runs on 18 volts, which Curwen points out could tie up two outputs on some power distributors. Check your power supply's capacity before building it into a crowded board1.
What the reviewer made of it
MusicRadar's review highlighted the pedal's "huge range of envelope filter sounds" and its compact size as strengths1.
"+ Huge range of envelope filter sounds."
For players comparing filter pedals, the Resotron sits alongside Pigtronix's other filter and modulation designs such as the Ringmaster Analog Multiplier and the Tremvelope, but its pitch-tracking mode is what sets it apart from a conventional envelope filter or wah1.
Videos
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Questions
Does the Pigtronix Resotron run on 18 volts?
Yes. The Resotron uses 18-volt operation, which MusicRadar's reviewer notes could tie up two outputs on some power distributors, so plan your pedalboard power supply accordingly.
Can you control the Resotron with an expression pedal?
Yes. Plugging an expression pedal into the Resotron gives you foot control of the filter cutoff, which MusicRadar's reviewer describes as a way to get a more conventional wah experience from the pedal.
Is the Resotron analog?
Yes. MusicRadar describes the Resotron as an all-analog pedal, with 24dB/oct filter circuitry based on the SSM2040 chip, the same chip found in some vintage synths.
What is the difference between pitch tracking and an envelope filter?
A conventional envelope filter responds to your picking dynamics, sweeping the filter based on how hard you play. Pitch tracking instead follows the actual notes you play, so the filter position is tied to pitch rather than attack strength. The Resotron does both.
Sources (1)
- Pigtronix Resotron Tracking Filter review, MusicRadar, 2019-05-28
