Electro-Harmonix Pico Atomic Cluster Spectral Decomposer

The Electro-Harmonix Pico Atomic Cluster Spectral Decomposer is a compact glitch and synth pedal in Electro-Harmonix's Pico Series of mini pedals, released in 2025¹. Where most synth pedals generate new notes from your playing, the Atomic Cluster takes your existing signal apart: Electro-Harmonix says it "breaks down your signal and interpolates it into a variety of musical and whimsical" sounds, using "a unique algorithm to reduce the frequency resolution of your instrument"¹. The result, depending on settings, ranges from rhythmic lo-fi glitch and auto-arpeggio tones to ambient synth pads².

Pedal of the Day's reviewer called it "unlike any effect Electro-Harmonix has made before," a pedal for players who want to experiment rather than dial in a familiar sound².

What it does to your sound

The core of the pedal is the Atoms control. It sets how many simultaneous resonant oscillations the algorithm produces at any moment, from a full spectrum of your input down to a single note. Electro-Harmonix says lower settings create a more pixelated, glitchier sound¹. In practice, that is the difference between a smeared, pad-like version of your chord and a choppy, arpeggiated scatter of tones.

Guitar.com's reviewer described the pedal's job in similar terms: the mode switch "decides whether the transitions between the frequency bands are sharp and choppy or smoothed over"⁶. The effect is built entirely from your own signal, so what you feed it, single notes, chords, or even a synth, shapes what comes out.

Controls and how it is laid out

The control set is small, in keeping with the Pico format. Guitar World lists the full panel as Volume, Speed, Blend, Atoms, a Sharp/Smooth Mode button and a bypass footswitch⁴.

Speed, modes and tap tempo

Speed is the control that determines how the effect sits in a part. Premier Guitar describes its range as running "from more rhythmic effects to complete random chaos"⁷. Pedal of the Day's reviewer put it in playing terms: "Slower settings can mimic the sound of a rhythmic step filter while, faster settings create a more chaotic random feeling effect"².

The rate can also be set by tap tempo¹. Pedal of the Day notes that you "press and release the footswitch to seemlessly enter into Tap Tempo mode, for more hands-free operation"², so you can sync the refresh rate to a tempo without bending down mid-song.

The two modes shape how the oscillations hand over to each other:

• Speed control: slower settings mimic the sound of a rhythmic step filter, while faster settings create a more chaotic, random feeling effect, in Electro-Harmonix's description¹.
• Tap tempo: SPEED can also be set by tap tempo; pressing and releasing the footswitch enters Tap Tempo mode for hands-free operation¹.

Pedal of the Day frames the pair as a choice of "oscillation transition envelope shape"², which is a fair way to think about it: same decomposed signal, different edges between the pieces.

Power and what is in the box

The pedal runs on the included 9.6VDC 200mA power adapter, which comes in the box¹. Guitar World lists the power requirement as a 9V DC adaptor, supplied, drawing 100mA⁴, and Guitar Pedal X also lists 100mA at 9V DC⁵; the maker's own figure is 9.6VDC at 200mA¹. Connections are a TS input and a TS output⁵.

Price, origin and where it fits

The list price on the Electro-Harmonix product page is $129.00 USD as of October 2026¹. Guitar World lists the price as $129, £129 or €119 depending on region⁴, and Gearnews reported it at €129.00 at Thomann in November 2025³. Guitar World lists the pedal's origin as the USA⁴.

Within the Pico line, the Atomic Cluster stands apart from utility pedals. Guitar.com's reviewer noted the benefits of the Pico platform generally⁶, but the Atomic Cluster is an original design rather than a shrunken version of an existing EHX effect, which is what Pedal of the Day singled out². For players comparing it against other signal-mangling synths, it sits alongside pedals like the Hologram Electronics Infinite Jets Resynthesizer or the MXR Textures Granular Synth Engine in the broad category of pedals that rebuild your input rather than add a conventional effect to it.

What reviewers said

Guitar World's review, by Trevor Curwen, was positive on the basics, listing compact size, tap tempo, the two modes and the range of sounds as reasons to buy⁴. Pedal of the Day's verdict leaned on the pedal's character:

That is the honest summary of the pedal's appeal: it is not a subtle tone-shaper, and reviewers did not treat it as one. It is a small-format tool for players who want glitch, chaos and synth-like textures from their own signal.

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