Eventide H9 Harmonizer

The Eventide H9 Harmonizer is a multi-effects stompbox that packs Eventide's delay, modulation, pitch and reverb processing into a single compact pedal, along with a fast, built-in tuner¹²³. Eventide unveiled it in January 2013 as the newest addition to its stompbox line, describing it as featuring a simple, one-knob user interface with stereo audio I/O, MIDI I/O, and expression pedal and auxiliary switch inputs⁴. Guitar World later called it "a complete pedalboard in one stompbox"⁵.

The line has two eras. The original H9, its cheaper H9 Core sibling and the fully loaded H9 Max ran Eventide's Factor-pedal algorithms on a one-knob interface best paired with a companion app. In June 2026 Eventide rebooted the pedal as the H9 Harmonizer Gen 2, built on the same ARM processing architecture as the H90 Harmonizer and carrying the full H90 and H9 Max algorithm libraries⁶.

Eventide algorithms in one pedal

The H9 was designed to consolidate what Eventide had already built into its Factor pedals (TimeFactor, ModFactor, PitchFactor and Space). The full Harmonizer Multi Effects version came loaded with algorithms from those four pedals, including Tape Echo (with delay, saturation, wow and flutter controls), Vintage Delay (delay, modulation and filter controls), Chorus, Tremolo, the H910/H949 pitch-and-delay algorithm, Shimmer, Hall, and the exclusive Ultratap¹¹. Guitar World's review counted access to up to 42 different Eventide effect algorithms from the Factor and Space pedals, spanning delays, modulation, pitch shifting and reverbs¹².

Eventide kept adding to the library after launch. By 2019 the company had announced Harmadillo, the 51st algorithm for the pedal¹³, and the 2020 limited-edition H9 Dark shipped with a "full deck" of all 52 H9 algorithms, including the new TriceraChorus¹³. Algorithm purchases were priced per piece for H9 and H9 Core owners and free for H9 Max owners⁷.

The Gen 2 goes further than any earlier H9. It includes 74+ algorithms covering the full H90 and H9 Max libraries with 1,000+ presets out of the box, spanning delay, reverb, pitch, granular effects, vocal FX, looping and more¹⁰. MusicRadar notes the addition of polyphonic algorithms such as Polysynth, Polyphony, Polyflex and Prism Shift¹⁴.

The controls on the original H9

The original H9's front panel is deliberately minimal: two footswitches labeled Active and Tap with red indicator lights, three buttons labeled X, Y and Z for accessing algorithm parameters, an encoder knob that also depresses as a switch, and a Presets button that changes presets and the operating mode⁸. Guitar World's reviewer described the X, Y and Z buttons and large jog wheel as standing in for dedicated parameter knobs¹².

Two deeper features made the one-knob design workable:

• Master mode: holding the X, Y or Z button makes every available parameter in the algorithm controllable⁸.
• Hotknob: effectively an expression pedal when used with the encoder, allowing grouping of X, Y and Z or any combination⁸.

The pedal holds up to 99 presets, and the user can define how many it holds⁸. Even so, Guitar Pedal X argues the onboard interface was mostly saved by the Bluetooth app: on the original H9 the app was "pretty much an essential," while on the Gen 2 it is a nice-to-have¹⁵.

The controls on the H9 Gen 2

The Gen 2 redesign centers on four core modes: Select, Perform, Presets, and Parameters¹⁰. The control set is a main rotary encoder, three Quick Knobs tied to A/B/C Quick Access Parameters, and button pads, with combinations reaching further functions¹⁵¹⁰.

Connectivity on the Gen 2 includes two 1/4-inch TS inputs, two TS outputs, USB-C for the Eventide Control app, 5-pin MIDI I/O, and an expression pedal input⁹⁸. It supports stereo, MIDI, expression and aux control, with dual instrument and line-level I/O for studio and live use¹⁰. On Premier Guitar's demo, Tom Botwin showed the tuner entry: press down both footswitches to enter tuning mode, press one switch to exit¹⁶.

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Pete Thorn's demo of the Gen 2 emphasizes what changed under the hood: "there's all the algorithms in there from the H90," running on updated ARM processing with an easier workflow¹⁷.

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Power and connections

Both generations of the H9 use center-positive power, which is the opposite polarity of most stompboxes. EarthQuaker Devices' pedalboard guide singles the H9 out on exactly this point: "some require center positive power (like the Eventide H9)"¹⁸.

Both versions carry stereo 1/4-inch ins and outs plus MIDI In/Out and USB⁸. The original also has expression pedal and auxiliary switch inputs⁴, and the H9 Max's tuner function can be assigned to an external switch through that aux jack¹⁹. The Gen 2 is flexible about placement: Premier Guitar's demo notes it can run in an amp effects loop, in stereo in a modeler's effects loop, in a wet/dry setup, or in mixer sends and returns, and with the MixingLink you can run vocals and MIDI keyboards through it¹⁶.

H9, H9 Core and H9 Max

The H9 shipped in tiers: the H9, the H9 Core and the H9 Max⁷. MusicRadar described the Core as delivering "the legendary sounds of Eventide's H910 and H949 Harmonizers"²⁰. The full H9 Harmonizer Multi Effects version carried the complete algorithm loadout¹¹, and the H9 Max topped the range; Guitar.com's review of the Max notes its expression pedal input among the connections²¹. In June 2026, Eventide upgraded all registered H9 Standard and Core owners to the full 52-algorithm H9 Max library for free, ending the tiered model. Eventide also allows algorithms to be synced for free to as many as four H9 or H9 Core pedals registered to the same account²².

What reviewers said

Guitar World's 2013 review of the H9 Harmonizer Effect Processor found it "fully lives up to the company's well-deserved reputation, delivering pristine, noise-free effects with luxurious sheen, depth and detail"¹². MusicPlayers.com's Bruce Sokolovic was equally direct about the sound:

His review rated the pedal 3.6 stars overall, earning a WIHO (Outstanding) Award, and praised the iOS-based editor as thoughtfully laid out and extremely useful, while noting room for improvement in the presets list and update method⁸. Criticisms were specific: some algorithms took nearly a full second to load, and a slight latency estimated between 2 and 5ms was felt in pitch tracking, though tracking itself was spot on⁸. Support was a highlight, with an email answered in hours and a phone call in under five minutes⁸.

For the Gen 2, Guitar World's Matt McCracken notes it carries not only all the algorithms from the H9 Max but all the same effects found on the H90⁹. Pedal of the Day's coverage says the Gen 2 "exceeds all expectations, and features the both the sonic and build quality we've all come to" expect from Eventide¹⁰.

Who uses it

The H9's pitch heritage traces to Eventide's H910 and H949 studio harmonizers, "the prized studio processors used on stage by Frank Zappa, Jimmy Page and Eddie Van Halen"²³. On the pedal itself, guitarist Eric Krasno names the H9 among the pedals he could not live without, using it mainly for a vintage delay setting²⁴.

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