Electro Harmonix Pico Swello Effect Pedal

Pico Swello Attack Envelope — Polyphonic Swell from the POG2, Now in a Pico Stompbox

The Electro-Harmonix Pico Swello is a dedicated attack envelope pedal that lifts the polyphonic swell circuit from the POG2 into the ultra-compact Pico chassis. Every note receives its own envelope, so single-note lines, arpeggios, and chords swell smoothly. This pedal fits POG2-style swells into a stompbox sized for crowded pedalboards.

What Sets This Envelope Pedal Apart

Unlike most auto-swell pedals that operate on the overall signal, this unit applies the envelope polyphonically, treating each note independently for natural, multi-voice swells. A built-in low-pass filter with two resonance settings adds further movement, and the modulation depth is tied to the Attack knob.

Controls and Signal Flow

Four knobs and one button cover every parameter. Attack sweeps from quick, gentle swells to slow, long swells and reverse-style effects. Volume compensates for the perceived drop in level during long attack times, while Freq and Mod drive the low-pass filter.

• Attack: envelope time — sets how quickly each note swells in
• Volume: overall output — compensates for low volume during long attacks
• Freq controls the LPF cutoff to set the maximum filter frequency.
• Mod: filter modulation depth/direction — sweeps the LPF up or down
• Filter button: engages LPF and selects resonance — Green off, Orange low, Red high

Inputs, Outputs, and Power

It runs on mono 6.3 mm TS connections on both input and output, with the required power adapter shipping in the box.

• I/O: 6.3 mm TS mono in and out
• Power: 9.6 VDC adapter included, 100 mA draw — no battery operation
• Package contents: power adapter and owner's manual

Circuit, Bypass, and Build

The unit uses a digital circuit with buffered bypass, which keeps the signal intact when the effect is off. The chassis keeps the footprint small enough to slot into dense boards.

• Circuit: digital with buffered bypass
• Audio: mono in / mono out
• Dimensions: 92.7 x 50.8 x 50.8 mm