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  • Electro-Harmonix Bass Mono Synth

    By Chris Loeffler |

    Electro-Harmonix Bass Mono Synth

    When you need to throw down some low down!


    by Chris Loeffler



    True synthesis has existed of the periphery of stringed instruments in large part because the complexity of the polyphonic signal rendered mono that stringed instruments create tends to be more than the typical analog synthesizer can handle. Roland’s approach to this was to push a new pickup for decades that allowed synthesizer engines to create each string as a monophonic signal, and recently digital technology and processing has hit a point that, with ingenuity, processors can take a stringed signal and mostly synthesize it through extraction.


    Electro-Harmonix, ironically the biggest (and first?) company to introduce total, tech-free polyphonic synthesis with their 9 Series, launched two monophonic synthesizers at 2019 Winter NAMM, one for guitar and one for bass. The Electro-Harmonix Bass Mono Synth takes EHX’s proven digital synthesis and moves it back to the mono world, where careful and clean playing are king and the pedal plays the player. The Electro-Hamonix Bass Mono Synth features eleven synthesizers, volume controls for Synth and Vol, CRTL and SENS controls, expression out, a pre-set footswitch, and is powered by a standard 9v power supply.


    What You Need to Know


    The Electro-Harmonix Bass Mono Synth uses digital technology to create eleven unique, analog-based synthesizer sounds in response to a mono input signal. While this at first seems curious given their proven record with other pedals (Synth 9, Mel 9, etc) in converting guitar and bass signals into synthesizer and keyboard sounds, in practice the limitations of mono lead the player closer to approaching their playing style and composition to something truer to the original analog synthesizer sounds it taps into.


    The pedal shares three global controls (Dry Volume, Synth Volume, and Type) and two controls (Sens and CTRL) that do slightly different things for each synth type. The Sens control is essentially shared in functionality as it adjusts the moment of attack based on input signal, but the behavior and waveforms of the various types are different enough that it isn’t a set-it-and-forget-it control between settings. The CTRL knob, however, does something different for every setting. The Expression jack, too, allows for a deeper level of control than is available through the knobs.


    Walking through the eleven synthesizers-


    LASER is a pulsating synth whose rise and swell is dictated by the CTRL knob, from staccato blips to sustained, synth-string like drones. Think early 90’s Depeche Mode. The expression pedal controls the filter frequency to add animation and movement independent from the synth envelope.



    X-FADE is a multi VCO synth that blends dry signal added to the filter sweep for a sound like early synth attempts at organ sounds, from dark and moody to horn-like stabs. CTRL sets the decay time for the filter, and the expression pedal sets the frequency cutoff.


    ACID is a fast decaying synth modeled after the TB-303, with deep, percussive sounds that would be at home in early Aphex Twin recordings or 90’s West Coast rap. CTRL adjusts sweep depth and filter envelope in sync for what EHX feels (and I agreed) was the optimal interaction.  The expression pedal controls the decay time of the envelope.


     COSMIC has a more aggressive edge that, despite the EHX description of being bright, seemed brooding and dark to me in its decay. The CTRL adjusts the decay time of the envelope, and the expression pedal controls the depth of the modulation.  



    SUB can be the least synthesized sounding of the modes, with a simple sub-octave synth for adding low end that can sound natural or like an 8-bit soundtrack. CTRL adds on-the-fly adjustments to the sub oscillator and the expression pedal tweaks the frequency cut-off to blunt the sub-octave stab a bit.


    GROWL is percussive, vocal synth that features a vowel-like climb (E-O-W) as it decays and the filter sweeps to close the envelope. CTRL sets the decay time of the filter and the expression pedal sets the sweep depth and frequency range.

    WUB is a flabby synth with a lazy open and close synched to a LFO for hypnotic pulses. CTRL sets the speed of modualtion and the expression pedal sets the center frequency of the filter.


    UNISON is a stacked set of synths running in parallel for a wall of synth sound. Each note played sounds like an electronic choir. CTRL sets the decay time of the filter envelope and the expression pedal sets the cutoff frequency of the filter and the base of the filter envelope sweep



    TWIN is a throaty synth with a paradoxically wet and dry sounding chirp to its decay like falling down a hole with mechanical crickets (man, that was fun to write). CTRL adjusts the attack and decay times of the filter envelope and the expression pedal controls the filter envelope’s sweep depth or frequency range.



    SPECTRE is multi VCO synth with an added adjustable pitched note that sounds like a robot invasion with laser guns and a bizarre clang in the decay. CTRL adjusts the filter’s cutoff frequency and the expression pedal sets the pitch of the added note in half-step increments from -1 octave to + 4 octaves.



    OBLIVION is to me the most “synth” sounding of the group, with wide, thick warmth animated with a throbbing modulation effect. CTRL sets the rate of modulation and the expression pedal adjusts filter resonance.  

    Being raised on analog versions of “synth-style” effects for stringed instruments, the limitations of mono weren’t as big for me as they might be for someone who has never tackled a bass octave or MXR Blue Box, and I found the attack to respond similarly. I did find points in certain settings where the “glitch” when playing complex chords (which isn’t what the Mono Synth was made for) was less musically pleasing to me than an analog counterpart, in that it seemed to jump too cleanly between the notes it was guessing I was trying to play. I’d liken it to the difference between a CD and vinyl skip.


    The challenge with a pedal with so many sounds is getting to them quickly, and EHX deftly tackles with an allowed preset for each synth type, effectively giving you access to 22 synths (11 FYSIWYG, 11 presets). Saving a preset is as simple as holding down the preset switch for two seconds. Once saved, the preset is accessible by choosing the appropriate synth type and hitting the preset switch. The pre-loaded presets are a good starting point, and you can tweak and edit from there.




    The pedal is monophonic, so don’t expect it to take chords well.




    The anachronism of using modern technology for mono synthesis may seem like a miss to some; I completely disagree. The Electro-Harmonix Bass Mono Synth is designed to encourage an intentional musical approach and honor the sonic roots of synthesis. There are enough synth models in the Bass Mono Synth to create an album’s worth of music without ever using the same setting twice, and the deep, rich tones defied my expectations of what a digital emulation of analog synthesis could sound like without ever becoming a glitchy mess.




    Electro-Harmonix Bass Mono Synth Product Page




    rszchrisphoto-21e10e14.jpg.f84542bf21c2a7296f0e8ee7aaf551fd.jpgChris Loeffler is a multi-instrumentalist and the Content Strategist of Harmony Central. In addition to his ten years experience as an online guitar merchandiser, marketing strategist, and community director he has worked as an international exporter, website consultant and brand manager. When he’s not working he can be found playing music, geeking out on guitar pedals and amps, and brewing tasty beer. 

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