The Supro Resotron Tracking Filter is a filter pedal made by Supro, shown at the 2019 NAMM Show1. It belongs to the family of tracking filters: instead of an envelope filter that reacts to how hard you pick, it introduces the concept of a pitch-following filter, with the effect based purely on the actual notes you play2.
What it does
The Resotron's design sets it apart from a conventional auto-wah or envelope filter. Where those pedals listen to your picking dynamics, the Resotron tracks the pitch of the notes themselves, so the filter response follows what you play rather than how you play it2.
The circuit behind it is a 24dB/oct filter based on the SSM2040 chip, as found on some vintage synths2. It can be set to work as a low-pass or high-pass filter, or in band-pass mode for typical wah tones, with response to your playing set by the Sensitivity knob2. MusicRadar's reviewer Trevor Curwen summed up the range of the design as a "Huge range of envelope filter sounds"2.
The published review of this design covers the Pigtronix Resotron Tracking Filter, the closely related version of the same circuit. The Supro-branded Resotron was shown at the 2019 NAMM Show1.
Resotron vs a wah pedal
| Resotron Tracking Filter | Wah pedal | |
|---|---|---|
| What drives the sweep | The pitch of the notes you play2 | Your foot on a rocking pedal |
| Modes | Low-pass, high-pass or band-pass2 | Typically band-pass |
| Sensitivity control | Yes, via the Sensitivity knob2 | No |
Videos
Bass Gear Magazine
Questions
What is a tracking filter?
A tracking filter is a filter effect that responds to the pitch of the notes you play rather than to how hard you pick. Most envelope filters open and close according to your playing dynamics, while a pitch-following design like the Resotron bases the effect purely on the actual notes, which changes how the filter moves under your fingers.
How is the Resotron different from a wah pedal?
A wah pedal is worked by foot, rocking a pedal to sweep a band-pass filter by hand. The Resotron sweeps itself: it can run in band-pass mode for typical wah tones, but the filter movement comes from the notes you play, set by the Sensitivity knob, rather than from a pedal.
Sources (2)
- Supro Resotron Tracking Filter at 2019 NAMM Show, Bass Gear Magazine, 2019-03-14
- Pigtronix Resotron Tracking Filter review, MusicRadar, 2019-05-28
