The Electro-Harmonix Bass9 Bass Machine is a digital pedal that transforms a guitar into nine different basses, transposing your playing one to two octaves down with no special pickups, MIDI or instrument modifications required12. Released in 2019, it is the latest in EHX's 9 Series, following the B9, C9, Key9, Synth9 and Mel9 pedals, and relies on the same technology that powers them13. You plug it in like any other stompbox and play4.
The core idea is simple: instead of carrying a bass to a gig or a recording session, you step on the pedal and your guitar becomes a bass. Electro-Harmonix describes the Bass9 as polyphonic, with a new algorithm maximized for transposing one to two octaves down with what the maker calls superior dynamics and tracking1. Independent Effect and Dry volume controls let you blend the bass sound with your dry guitar signal, so one player can cover both parts5.
What it does: bass tones from a guitar
The Bass9 sits in the octave and pitch family, but it does something different from a straightforward octave pedal like the Micro POG or Pitch Fork. Those pedals add an octave-shifted copy of your guitar signal. The Bass9 instead replaces your tone with a modeled bass instrument, complete with the character of specific basses: a Precision-style bass, a Danelectro 6-string, fretless electric and standup sounds, synth basses and a bowed bass145.
Because it is polyphonic, it tracks chords as well as single notes, and Electro-Harmonix says it does so without mods, special pickups or MIDI implementation1. Premier Guitar's announcement put it plainly when the pedal launched in August 2019: the Bass9 "transforms a guitar into nine different basses and requires no special pickups, MIDI or instrument modifications"2.
The Split Bass mode is the standout for solo playing. It makes it possible to play bass on the lower strings (all notes below F#3) and chords or melody on the higher strings at the same time, so one guitarist can lay down a bassline and a chord or lead part in a single pass12.
The nine bass modes
A rotary MODE knob selects the bass patch1. The nine programs are12:
| Mode | What it is |
|---|---|
| PRECISION | Pays homage to the Fender Precision bass2 |
| LONGHORN | Emulates the Danelectro 6-string bass, ideal for baritone type tones15 |
| FRETLESS | Both electric and standup fretless basses15 |
| SYNTH | Channels the Taurus synthesiser4 |
| VIRTUAL | Synth bass type program1 |
| BOWED | Classic bowed bass15 |
| SPLIT BASS | Bass on the lower strings (below F#3), chords or melody on the higher strings1 |
| 3:03 | Polyphonic effect a la the Roland TB-3034 |
| FLIP-FLOP | Ninth program in the set1 |
In Guitar World's review, Trevor Curwen found that "the bowed sounds and various synth bass types offer plenty of opportunity for low-end grooving"3.
The controls and jacks
The front panel keeps the 9 Series layout: a MODE knob, two parameter knobs, two volume knobs and a footswitch15.
| Control or jack | What it does |
|---|---|
| MODE knob | Selects a bass patch1 |
| CTRL1 and CTRL2 knobs | Assigned to various parameters, depending on which bass model you choose5 |
| DRY VOL knob | Controls the volume of the untreated instrument signal at the Effect Output jack1 |
| EFFECT volume | Sets the level of the selected bass patch at the Effect Output jack1 |
| INPUT jack | Quarter-inch jack for your instrument or the output of another effects pedal1 |
| EFFECT OUTPUT jack | Outputs the mix set by the Dry and Effect volume controls1 |
| DRY OUTPUT jack | Outputs the input signal at unity gain, always active17 |
| BYPASS footswitch and LED | Toggles the Effect Output between bypass and effect mode; the LED lights in effect mode1 |
The CTRL knobs change jobs from patch to patch. In Precision mode, for example, Ctrl 1 governs sub-octaves while Ctrl 2 mirrors the original P-Bass's tone control, as Guitar.com reported at launch6.
The Dry Output deserves a note of its own. It outputs the signal present at the input jack at unity gain and is always active, whether the effect is engaged or not17. That makes it useful for feeding a tuner or a second amp with your clean guitar signal while the Effect Output carries the bass sound, and the independent Effect and Dry volume controls let you precisely tune the mix at the Effect Output25.
Power
The Bass9 runs on the standard EHX 9.6DC-200mA power supply, which is included12. Current draw is 100mA13.
The Bass9 uses a 9.6V DC supply rather than the 9V center-negative standard many pedalboards are wired for. It ships with its own adapter, and players running isolated power supplies should check their supply's voltage options before plugging in.
Where it came from
The Bass9 arrived on August 8, 2019, announced from New York City and available immediately2. It is the latest 9-series pedal from Electro-Harmonix, following the B9 Organ Machine (2014), C9, Key9, Synth9 and Mel9 Tape Replay Machine3. The series shares one idea across all its pedals: a rotary switch selects one of nine preset instrument emulations, with no special pickups or extra hardware needed. The B9 delivers organ tones, the Key9 electric pianos, the Synth9 synthesizer sounds, and the Mel9 tape-replay sounds, while the Bass9 applies the format to bass instruments8910.
What reviewers said
Coverage at launch was broadly positive about the concept. MusicRadar's Jonathan Horsley walked through the modes, noting Precision ("no prizes for guessing how this sounds"), Synth ("channels the Taurus Synthesiser"), Split Bass and the TB-303-flavored 3:03, and summed up the appeal: "Just plug it in like all your other stompboxes and you're off"4. Gearnews highlighted the independent Effect and Dry volume controls for blending bass with dry guitar5.
Guitar World's Trevor Curwen reviewed the pedal in March 2020 alongside two other EHX releases, listing its features as buffered bypass and the nine programs, and finding the bowed sounds and synth bass types offered plenty of opportunity for low-end grooving3.
Videos
EHX
Guitarist
Rock Guitar Vibes
Questions
Does the Bass9 need a special pickup or MIDI?
No. Electro-Harmonix says the polyphonic Bass9 tracks well and works on guitar without mods, special pickups or MIDI implementation. You plug in like any other stompbox and play. It is a standard quarter-inch jack input, so any electric guitar works.
Is the Bass9 true bypass?
No. The maker lists the Bass9 as selectable buffered bypass, and Guitar World's review describes it as buffered bypass. The footswitch toggles the Effect Output jack between bypass and effect mode, with a status LED that lights in effect mode.
Can I use the Bass9 on a bass guitar?
The Bass9 is designed to transform a guitar into nine different basses, transposing one to two octaves down. Electro-Harmonix describes it as polyphonic and says it works on guitar without modifications. The maker does not list bass guitar as an input for the Bass9 itself.
What does the Bass9 Dry Output do?
The Dry Output jack outputs the signal present at the input jack, always active at unity gain, whether the effect is on or off. The separate Effect Output jack carries the mix set by the Dry and Effect volume controls, so you can blend bass with your dry guitar signal.
Is the Bass9 analog or digital?
It is digital. Electro-Harmonix lists the Bass9 as a digital pedal, and it uses a new algorithm optimized for transposing one to two octaves down with what the maker calls superior dynamics and tracking.
Sources (10)
- BASS9 | Bass Machine - Electro-Harmonix, Electro-Harmonix
- Electro-Harmonix Unveils the Bass9, Premier Guitar, 2019-08-08
- Electro-Harmonix Mod 11, Nano Operation Overlord and Bass9 Bass Machine, Guitar World, 2020-03-20
- Electro-Harmonix reveals the Bass9 bass machine pedal, MusicRadar, 2019-08-08
- Electro-Harmonix BASS9 Bass Machine: Get nine different bass tones from your guitar, www.gearnews.com, 2019-08-09
- EHX’s Bass9 Bass Machine transforms guitars into basses, Guitar.com, 2019-08-13
- Electro-Harmonix Introduces the Bass9 Bass Machine Pedal, Guitar World, 2019-08-08
- B9 | Organ Machine - Electro-Harmonix, Electro-Harmonix
- KEY9 | Electric Piano Machine - Electro-Harmonix, Electro-Harmonix
- SYNTH9 | Synthesizer Machine - Electro-Harmonix, Electro-Harmonix
