Pigtronix Resotron is a multi-mode filter that brings the analog sounds of '70s era synthesizers to the world of envelope pedals for guitar, bass and beyond. Resotron is the first envelope pedal that can be made to follow the pitch of the notes you play. This pitch-following ability causes the filter to move around based on what notes you choose to play, just like an old-school analog keyboard synthesizer. UP and DOWN envelope modes are also included to perform the more traditional, velocity-sensitive filter movement that responds to how hard you hit the strings.

A push-button OSCILLATE function turns the Resotron into an analog synthesizer pedal. This mode shorts out the PEAK knob, effectively setting it to 100% while simultaneously activating a voltage-controlled amplifier (VCA) in the output stage. With the OSCILLATE function turned on, the CUTOFF knob sets the tuning of the synth effect while the VCA instantly follows the volume of your input signal. The synthesizer sounds created by the Resotron can also be radically altered by switching between the LPF, BPF and HPF modes, each of which has its own distinctive waveform and modulation characteristics when overdriven by the onboard compressor.

The multi-mode filter at the heart of the Resotron can be set to Low Pass (LPF), Band Pass (BPF) or High Pass (HPF) modes. Each of these voices has a distinctive character which can be manipulated by adjusting the PEAK knob to emphasize frequencies below, at or above the position of the CUTOFF knob. As the PEAK is increased, the resonance or “Q” of the filter becomes more extreme, up to the point of self-oscillation. A SENSITIVY control sets how dramatically the pedal will respond to playing dynamics in the UP and DOWN envelope modes, while a GLIDE control allows you to set how long it takes for the filter to move between notes in the PITCH mode.

Before the signal from the input of the pedal hits the filter inside the Resotron, it passes through an optical compression stage derived from the Philosopher’s Tone pedal. The increased volume and punch from the compressor can then be mixed into the audio signal using the BLEND control without affecting the SENSITIVITY of the envelope. Resotron accepts active CV and passive TRS expression pedal inputs for foot-controlled filter sweeps and outboard modulation which is mixed in parallel with the onboard pitch-following and amplitude tracking systems. The Resotron also features a TRIGGER (aka Sidechain) input which enables the musician to use an external audio source to modulate the filter.