Electro Harmonix Bass Mono Synth review

Setting the standard

  • £115
  • €125
  • $165
(Image: © Future)

MusicRadar Verdict

High-value unit for synth fans to treasure.


  • +

    Great value, fast tracking, wide effects range.


  • -


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Many bassists have dipped a toe into the murky waters of bass synth pedals, and although many offer a reasonable interpretation, there are often issues with tracking, tonal quality and ease of use. 

Fiddling around with pedal controls on a gig, with something as temperamental as a bass synth, when the sounds you’ve spent hours mastering just aren’t working onstage, can be a major pain in the butt. The passing of time has seen more and more players taking to keyboards to get the sounds required. 

Perhaps things are about to change with this new pedal. EHX’s Micro Synth, with its array of sliding controls, was a benchmark for many years, and the new Mono Synth is typically rugged, with a metal chassis and well-sized controls, clearly labelled and intuitive. The pedalboard footprint is very modest too.

With 11 synth types and voicings to choose from, there is inevitably some experimentation required before you find the sounds you’re looking for. Various modulation and filter settings contribute to distinctly different synth sounds, and the control set allows the player to extensively tailor the voicings. Bear in mind that the ‘Mono’ reference means that only one note can be played at a time; as a multi-oscillator monophonic device, only one note per oscillator can be played, so the unit can’t cope with chords.

The sound quality is quite stunning - possibly the most considered and thorough synth sounds we’ve heard using a bass guitar as a trigger

The first two controls determine the volume of your Dry (in other words, uneffected) signal and your Synth (effected) signal. With outputs for both, bassists will love the fact that whether recording or playing live, they no longer have to suffer effected bass synth sounds with no bottom end. Now a perfect blend is easily achievable. The Sensitivity control adjusts the gain of the input signal, which in turn affects how the synth effect is triggered, responds and sounds. This is also affected by your playing style, technique and string attack. 

An LED indicator gives you a visual reference as to how ‘hot’ your signal is. If your playing isn’t triggering the synth, turn the control up - but if you’re hearing ‘false’ triggers and resonance, turn the control down a touch. The Sensitivity control also has an effect on the sweep ranges of several synth effects. 

The CTRL control has a different interaction with each synth setting, from decay and attack times to envelope filter resonance, sweep depth, oscillator volume and modulation rate. The manual gives you an easy-to-understand breakdown for each synth setting. The Bypass switch turns the effect on and off, while the Preset switch allows you to store a preferred sound for easy recall; set the pedal as you require, press and hold the preset switch for three seconds and your control settings are stored. When you want to recall it, simply press the switch. 

The sound quality is quite stunning - possibly the most considered and thorough synth sounds we’ve heard using a bass guitar as a trigger. Each synth setting is notably different from the last, so there are plenty of interesting options available to the player, all of which sound highly usable to these ears. 

The Sensitivity control works wonders when it comes to dealing with glitches based on your instrument’s responsiveness (or lack of it). Naturally, active basses raise certain issues based upon the strength of their active circuitry and pickup output, so adjustments need to be made depending on your bass. 

The tracking is fast, which is a relief. The lower register notes offered by five-string basses are a challenge for units like this, but with some experimentation we found that there were certain synth types that this pedal tracked well with, even when grooving all the way down to the bottom of the B string. 

The best bit about the Mono Synth is the price. At £115, we can see many bassists getting plenty of gig mileage from this pedal - and having followed the anticipation for this unit online, we think many synth-hungry bassists’ prayers may have been answered.