The Electro-Harmonix Synth9 is a digital synth pedal that converts what you play on guitar or bass into vintage synthesizer sounds, in real time and with no extra hardware. Electro-Harmonix calls it the Synthesizer Machine, and describes its range as covering "searing lead synths to spacey synth pads and deep, funky, synth bass grooves"1. It carries nine presets that the maker says were "precisely tuned to emulate the most sought after, vintage synthesizer sounds"1.
It was released in 20171 and, unlike many guitar synths, it needs no special pickup, no MIDI connection and no modifications to your instrument: you plug into the input jack and play1. It is polyphonic, so chords as well as single notes get converted1.
Nine vintage synth sounds from guitar or bass
The core of the pedal is its preset knob, a white numbered dial that selects one of nine preset sounds1. Each preset emulates a different vintage synthesizer voice, and the two CTRL knobs change what they do depending on which preset is loaded1. At launch, Premier Guitar's press coverage noted the pedal "features DRY volume, SYNTH volume, CTRL1 and CTRL2 knobs that provide precise control over each preset's parameters"2, and MusicRadar likewise reported "dry volume and synth volume, plus control 1 and control 2, which adjust type-specific parameters"3.
The pedal is polyphonic, so it tracks chords, not just single lines1. Its usable range has limits worth knowing before you buy: tracking extends up to about the 23rd fret on the high-E string of a standard guitar, and down to the open A string on a bass guitar2. Notes above or below that window are outside the reliable conversion range.
The controls
| Control | What it does |
|---|---|
| PRESET knob | Selects one of the nine preset sounds1 |
| DRY VOL knob | Controls the volume of the untreated instrument signal at the synth output jack1 |
| SYNTH volume | Adjusts the synth volume2 |
| CTRL 1 knob | Makes adjustments based on the selected preset1 |
| CTRL 2 knob | Preset-dependent parameter control2 |
| BYPASS footswitch | Toggles between buffered bypass and effect mode; status LED lights in effect mode1 |
The CTRL knobs are the shape-shifting part of the panel. Because each of the nine presets is a different synth voice, the parameters the CTRL knobs adjust change from preset to preset, rather than being fixed functions like a modulation speed control1.
Outputs: synth, dry, and what each does
The Synth9 has two output jacks, which is where it differs from a simple one-output pedal1.
- SYNTH OUTPUT jack: outputs the mix set by the DRY and SYNTH volume controls1. This is the main output, carrying your blended dry and synth sounds.
- DRY OUTPUT jack: outputs the signal present at the input jack through a buffer circuit1. This gives you your clean, untreated instrument sound on a separate line.
The two-output design lets you send the synth sound to one amp or mixer channel and your dry guitar signal to another, keeping the clean tone independent of the synth blend1.
Power: 9.6V, 200mA adapter included
The Synth9 runs on the EHX 9.6DC power supply, a 9.6VDC, 200mA adapter that comes in the box12. Its actual current draw is 100mA1.
The Synth9 uses a 9.6VDC supply rather than the 9V standard of most pedalboards. It is powered by the included EHX adapter, not a battery, and its 100mA draw means a daisy chain output rated below that will not run it reliably.
Built on the B9, C9, KEY9 and MEL9 technology
The Synth9 is the synthesizer entry in a family of EHX "machine" pedals that all convert a guitar signal into another instrument's sound. Premier Guitar's launch coverage described it as "using the same innovative technology that powers the award-winning B9 and C9 Organ Machines as well as the KEY9 Electric Piano Machine"2.
The line started with the B9 Organ Machine in 20144, which Guitar Interactive Magazine reported could "deliver classic organ sounds without a special synthesizer pickup or extra equipment"5. The C9 followed in 2014 with nine more organ and keyboard sounds6, then the KEY9 Electric Piano Machine in 20157, and the MEL9 Tape Replay Machine in 2016, which emulates tape-replay keyboard sounds8. MusicRadar's review of the C9 noted that "like the B9, tracking is superb"9, the quality that made the format practical.
| Pedal | Year | Sounds |
|---|---|---|
| B9 Organ Machine | 2014 | Organ4 |
| C9 Organ Machine | 2014 | Organ and keyboard6 |
| KEY9 Electric Piano Machine | 2015 | Electric piano7 |
| MEL9 Tape Replay Machine | 2016 | Tape-replay keyboard sounds8 |
| Synth9 | 2017 | Vintage synthesizers1 |
The Synth9 applies the same no-special-pickup approach to synthesizer voices, where most competing guitar synths of the era, such as MIDI-based systems, required a divided pickup or a MIDI converter. Within EHX's own range, players who want a single synth voice rather than nine presets also have options like the Mono Synth and Bass Mono Synth12.
Videos
EHX
The Bass Channel
Reverb
Questions
Does the Synth9 work on bass?
Yes. Electro-Harmonix says the Synth9 works on guitar or bass without modifications, special pickups or MIDI implementation1. Its usable tracking range extends down to the open A string on a bass guitar2.
Does the EHX Synth9 need MIDI or a special pickup?
No. The pedal works on guitar or bass without modifications, special pickups or MIDI implementation1. One retailer, Microdesignum, sells a version with an installed MIDI control module for players who want full control of all functions via MIDI10, but that is a third-party modification, not something the stock pedal requires.
How high up the neck does the Synth9 track?
The usable tracking range extends up to about the 23rd fret on the high-E string of a standard guitar2.
Is the Synth9 true bypass?
No. It uses buffered bypass, toggled by the bypass footswitch, with a status LED that lights in effect mode1.
What does the Synth9 dry output do?
The dry output jack outputs the signal present at the input jack through a buffer circuit, giving your untreated instrument sound on its own output1. The synth output jack carries the mix set by the dry and synth volume controls1.
Sources (10)
- SYNTH9 | Synthesizer Machine - Electro-Harmonix, Electro-Harmonix
- Electro-Harmonix Introduces the Synth9, Premier Guitar, 2017-02-21
- Electro-Harmonix reveals Synth9 Synthesizer Machine pedal, MusicRadar, 2017-02-21
- B9 | Organ Machine - Electro-Harmonix, Electro-Harmonix
- Electro-Harmonix Unveils the B9 Organ Machine, Guitar Interactive Magazine, 2014-06-19
- C9 | Organ Machine - Electro-Harmonix, Electro-Harmonix
- KEY9 | Electric Piano Machine - Electro-Harmonix, Electro-Harmonix
- MEL9 | Tape Replay Machine - Electro-Harmonix, Electro-Harmonix
- Electro-Harmonix C9 Organ Machine review, MusicRadar, 2015-12-03
- EHX Synth9 with MIDI control, Microdesignum
