Electro Harmonix Bass Mono Synth Bassguitar Effects Pedal

EHX Bass Mono Synth — Eleven Mono Synth Engines in One Pedal

The Electro-Harmonix Bass Mono Synth turns an electric bass into a monophonic synthesizer without instrument modifications, special pickups, or MIDI. Eleven onboard synth types — Growl, Wub, Unison, Twin, Spectre, Oblivion, Laser, X-Fade, Acid, Cosmic, and Sub — span vintage emulations, stacked voices, and sub-octave textures. Playing dynamics directly shape the synth voice via pre-tuned oscillators.

Per-Type Control and Eleven User Presets

Each synth type exposes its key parameter via the CTRL knob — Laser shapes the filter envelope attack and decay, Sub sets the sub-octave volume, Oblivion sets the modulation rate. A PRESET footswitch saves and recalls one custom preset per type.

Knobs, Footswitches, and Trigger Response

The top panel gives direct access to every parameter without menu diving.

• Dry Volume: Sets the untreated bass level at the Synth Output — blends the original tone into the mix
• Synth Volume: Sets the synth voice level at the Synth Output — balances the wet layer
• Sensitivity: Adjusts input gain before the trigger block — tunes how dynamics engage the synth
• Type Selector + Control: Picks one of eleven engines and exposes its key parameter — the core sound-shaping pair

Digital Mono Engine

A digital circuit runs the synthesis with oscillators pre-tuned per type. The monophonic engine handles one note at a time and behaves unpredictably with chords or two-note intervals.

• Preset Footswitch: Toggles Preset and WYSIWYG live modes — also saves a preset to the current type
• User Presets: Eleven slots, one per synth type — factory presets can be restored

I/O, Power, and Physical Specs

Buffered bypass topology runs on the included adapter. A dedicated Dry Output always carries the untreated bass signal.

• Inputs: Mono instrument + Expression pedal (TRS)
• Outputs: Mono Synth Output + Mono Dry Output — split dry and wet paths
• Power: 9.6 VDC, 200 mA adapter (125 mA draw) — battery operation not supported
• Dimensions: 121 x 102 x 57 mm, Weight: 599 g