Electro-Harmonix Slammi Plus

The Slammi Plus is a pitch shifter you work with your foot: the treadle bends the pitch of whatever you play by up to three octaves, upwards or downwards. Electro-Harmonix released it in 2017 and has listed it as discontinued since 2026. It is fully polyphonic, so chords stay intact while they move.

The main choice is made with the direction switch: up, down or both at the same time. A rotary switch with eleven positions sets how far the treadle reaches. The first position is called Detune, a seventeen-cent offset that sounds like chorus or doubling; the other positions are fixed intervals. The Pitch Mix knob decides which interval the heel position starts from, in semitones up to an octave. A second switch chooses between bending and X-Fade. In the latter the interval stays put and your foot moves between the dry and the shifted signal. Pick both directions at once and two shifted notes sound side by side, so you can play two-part harmonies. The Blend knob sets how much dry signal and how much effect you hear, from all of one to all of the other.

The pedal is digital and mono, with buffered bypass. The housing is light but sturdy, with a traditional rack and pinion under the treadle. A 9V battery comes with it; a 9.6-volt adapter is bought separately. At just over 25 centimetres long it takes up the space of a full-size expression pedal.

If you want dive bombs, bends and harmonies from one pedal and are after more than a fixed octave on top, there is a lot to explore under one foot here. If you only need the odd octave, a smaller pedal will do.