The Electro-Harmonix Intelligent Harmony Machine is a digital harmonizer and pitch shifter pedal released in 2021 that instantly creates matching harmonies to what you play. Set a key and it generates single-note, diatonic harmonies, including two- and three-part harmonies, from the melody line you feed it. It also performs polyphonic pitch shifts, so the shifts you dial up apply to chords as well as single notes1.
The pedal was designed and built in New York, USA, and uses the same technology as the EHX Pitch Fork +2. Its polyphonic pitch shifting descends from the EHX POG and Pitchfork polyphonic technology3. Guitar World noted at launch that it encroaches on similar sonic territory to Boss's longstanding PS-6 Harmonist, but with enough tweaks to entice EHX fans4.
Two modes, plus a momentary option
The Intelligent Harmony Machine has two distinct modes, plus a momentary mode1.
Intelligent Harmony Mode generates diatonically accurate harmonies in both major and minor keys from single-line melodies you play6. You select your key and the pedal generates the harmony notes, with a huge range of two- and three-part harmony options6. The dual-harmony options come as presets, meaning you cannot independently set both voices6.
Polyphonic Override Mode makes the pedal behave like a pitch shifter with multi-voice talents6. The Key setting is bypassed and harmonization is based on the interval selector, so you can play single notes and chords3. Guitar World described this mode as turning the pedal into a conventional polyphonic pitch-shifter spanning an octave up, an octave down, and all harmonies in between, in the vein of EHX's existing effects4.
Momentary Mode lets you instantly change pitch by simply depressing the pedal's footswitch, with an optional user-set sweep time between the dry and effect signal1. The effect is only active while the footswitch is depressed3.
The controls
| Control | What it does |
|---|---|
| KEY knob | Seven-position rotary switch that, with the toggle switch to its right, sets the key in Intelligent Mode; no effect in Polyphonic Override Mode1 |
| KEY toggle switch | Up sets the sharp variation of the key, down sets the natural variation; no effect in Polyphonic Override Mode1 |
| MAJ/MIN toggle switch | In Intelligent Mode, sets whether the key is major or minor; in Polyphonic Override Mode, sets major or minor for intervals 3, 4, 7 and 8 (3rds and 2nds)1 |
| MIX knob | Sets the mix between dry and effect signal; fully dry at minimum, fully effected at maximum1 |
| VOLUME knob | Sets the output volume of the pedal1 |
| POLY-OVERRIDE button | Switches between Intelligent Harmony mode and Polyphonic Override mode; lit means Polyphonic Override Mode1 |
A point Guitar.com's reviewer raised when comparing the full-size pedal with the Pico version: the full-size pedal lists its harmonies on its face and offers dedicated switches for sharp/natural and major/minor, plus a dry output, which solves the problem of remembering which interval is where7.
Power and connections
The pedal comes equipped with an included 9.6VDC-200mA power adapter, and can also run on an optional 9V battery, which is not included. When using a battery, plugging into the INPUT jack activates power, and Electro-Harmonix recommends an alkaline battery. The included 9VDC, center-negative power supply can be connected to the power jack to provide power without a battery1.
Connections and impedances:
- INPUT jack: load impedance 2.2MΩ1
- OUTPUT jack: source impedance 680Ω1
- DRY OUT jack: outputs a buffered version of the dry signal present at the INPUT jack at all times, source impedance 680Ω1
The DRY OUT jack is the routing feature worth knowing about: because it carries your dry signal at all times, you can split your signal, send the dry feed to a second amp or a tuner, and keep the effected output separate. Delicious Audio notes the dry output adds signal routing and control options and flexibility3.
The Pico version
In 2026 Electro-Harmonix released the Pico Intelligent Harmony Machine, which packs the diatonic functionality of the full-size pedal into the company's ultra-compact pico chassis8. It creates two- or three-part harmony in any key, with 10 harmony interval modes8.
| Intelligent Harmony Machine | Pico Intelligent Harmony Machine | |
|---|---|---|
| Released | 20211 | 20268 |
| Chassis | Standard EHX pedal, 4.5 x 2.75 x 2.1 inches1 | Pico-sized chassis9 |
| Controls | Key knob and toggle, MAJ/MIN toggle, Mix, Volume, Poly-Override button1 | Volume, Mix, Key, Interval, Natural/Sharp or Dual button, bypass footswitch10 |
| Intervals | Harmony options listed on the face7 | 10 single intervals, 10 dual intervals10 |
| Bypass | Buffered1 | Buffered10 |
| Power | 9.6VDC-200mA adapter included; optional 9V battery1 | 9.6VDC-200mA adapter included8 |
| Price | $241.501 | $14910 |
On the Pico version, the KEY knob and # button set the harmonic key, and the INTERVAL knob selects from 10 different harmony interval modes; it ships with a standard EHX 9V power supply11. Guitar.com's reviewer found the full-size pedal is not a mega-pedal behemoth, nor substantially more expensive than the Pico, so the size saving is the main argument for the smaller version7.
What reviewers said
Published reviews of the Pico version give a sense of how the harmony engine sounds. Guitar.com's reviewer found it sounds okay and sometimes great, particularly in the octave and fifth modes79:
"I wouldn't want to record with it, but when it's working best it's definitely good enough for live usage7."
Cillian Breathnach, Guitar.com7
Pedal of the Day's reviewer wrote that adding perfect, tight harmonies to your playing has never been easier with the Pico version9. For the full-size pedal, Electro-Harmonix itself describes the result as sweet, musical tone with spotless tracking1, a maker's claim rather than an independent finding.
Where it sits among EHX pitch pedals
The Intelligent Harmony Machine descends from the EHX POG and Pitchfork polyphonic pitch shifting technology3 and uses the same technology as the Pitch Fork +2. Where the POG2 is an octave generator with true bypass1, the Intelligent Harmony Machine is a keyed harmonizer with buffered bypass, aimed at diatonic harmony parts rather than organ-style octave stacks. Gearnews's 2026 pitch shifter buying guide lists the Intelligent Harmony Machine at $189.00 / £175.00 / 205.00€12.
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Questions
Does the EHX Intelligent Harmony Machine run on a battery?
Yes. It can run on an optional 9V battery, activated by plugging into the INPUT jack, and Electro-Harmonix recommends an alkaline battery. A 9.6VDC-200mA power adapter is included with the pedal, so most players will never need the battery option.
What is the difference between the Intelligent Harmony Machine and the Pico version?
The Pico Intelligent Harmony Machine, released in 2026, packs the diatonic harmony functionality of the 2021 full-size pedal into Electro-Harmonix's ultra-compact pico chassis with a simpler control set. The full-size pedal lists its harmonies on its face and offers dedicated sharp/natural and major/minor switches plus a dry output, and is not substantially more expensive.
Does the Intelligent Harmony Machine work with chords?
Yes, in Polyphonic Override Mode. In that mode the Key setting is bypassed and harmonization is based on the interval selector, so you can play single notes and chords. In Intelligent Harmony Mode the pedal generates diatonic harmonies from single-line melodies.
What does the Dry Out jack do?
The DRY OUT jack outputs a buffered version of the dry signal present at the INPUT jack at all times, with a source impedance of 680 ohms. Delicious Audio notes this dry output adds signal routing and control options and flexibility for splitting your signal.
Is the Intelligent Harmony Machine true bypass?
No. Electro-Harmonix lists the Intelligent Harmony Machine as buffered bypass. The Pico version also uses buffered bypass. By contrast, the EHX POG2 lists true bypass.
Sources (12)
- Intelligent Harmony Machine, Electro-Harmonix
- Intelligent Harmony Machine: A new Harmonizer/Pitch-Shifter from Electro-Harmonix, gearnews.com, 2021-10-28
- Electro-Harmonix Intelligent Harmony Machine, Delicious Audio, 2022-04-08
- Electro-Harmonix ups its pitch-shifting pedal IQ with the Intelligent Harmony Machine, Guitar World, 2021-10-28
- The new Electro-Harmonix Intelligent Harmony Machine gives you a twin guitar sound without another guitarist, MusicRadar, 2021-10-28
- Electro-Harmonix introduces the Intelligent Harmony Machine with up to two harmonised voices on tap, Guitar.com, 2021-10-29
- EHX Pico Intelligent Harmony Machine review: impressive yet hampered, Guitar.com, 2026-06-01
- Pico Intelligent Harmony Machine, Electro-Harmonix
- Electro-Harmonix Pico Intelligent Harmony Machine Harmonizer, Pedal of the Day, 2026-03-10
- Electro-Harmonix Pico Intelligent Harmony Machine review, Guitar World, 2026-04-23
- EHX Pico Intelligent Harmony Machine, Premier Guitar, 2026-01-10
- The 5 Best Pitch Shifter Pedals for Wild Sounds and Perfect Tracking, gearnews.com, 2026-03-16
