Electro Harmonix Q-Tron Plus Pedal

Here is an Electro-Harmonix Q-Tron Plus envelope filter, a highly versatile evolution of the classic Q-Tron design, offering expanded creative control and significantly enhanced routing flexibility for experimental and expressive effects work. Retaining the core musical envelope filter response of the original unit, the Q-Tron Plus adds powerful new functionality aimed at sound designers and adventurous players.

This example features the original Q-Tron filter and preamp architecture, enhanced with a built-in effects loop placed between the preamp and filter stages. This allows external effects to be inserted directly into the signal path without disrupting the envelope response, enabling complex sonic interactions with distortion, modulation, or delay placed inside the filter’s control circuit. This opens up a wide range of creative possibilities, from textured synth-like tones to heavily processed rhythmic filter effects. The loop is particularly effective when combining dynamics-based effects with time-based processors, allowing for unconventional signal chains and highly interactive sound design.

This example also features a selectable Attack Response Switch, allowing players to choose between a slow, smooth, vowel-like filter sweep or a faster, more aggressive response reminiscent of the original Q-Tron’s classic envelope behaviour. This significantly expands the pedal’s expressive range, making it suitable for both subtle funk-style filtering and more pronounced, snappy effects.

Condition is excellent with everything fully functional. A powerful and highly creative envelope filter that extends far beyond traditional designs, offering deep flexibility for experimental, funk, and sound-design focused applications.

Specifications: 

Type: Analog filter effects pedal
Bypass: True bypass
Effects Loop: Dedicated FX send/return loop
Controls: Gain knob, boost switch, resonant peak (Q) control, response switch (fast/slow), sweep direction switch (up/down)
Filters: Selectable low-pass, band-pass, and high-pass filters
Sweep Range: Switchable high/low frequency ranges
Inputs/Outputs: Standard 1/4" instrument input and output (implied), FX send/return loop
Power: Power supply included
Construction: Compact pedalboard effects unit
Features: Envelope follower filter with adjustable dynamics and sweep behaviour