The Keeley Synth-1 Reverse Attack Fuzz Wave Generator is a synth pedal from Keeley Electronics that makes your guitar sound like a fuzzy synthesizer1. It is a guitar-triggered, single-note wave generator: you play one note, and the pedal produces a synth wave from it2. Keeley says it is capable of sounds ranging from "unnatural fuzz noises to pseudo-harmonic, random glitchy counterpoint"2.
The pedal first appeared as a standout in Keeley's NAMM 2019 line-up and was rolled out shortly after, with pre-orders at $1792. MusicRadar and Guitar World both listed the price as $179 when it became available in March 201934.
What it does to your sound
The Synth-1 takes a single note from your guitar and generates a synth wave from it, then distorts it through hard clipping depending on the mode2. A reverse volume swell shapes how each note arrives: the Attack knob governs the swell, with a range from 1500 ms down to 4 ms, so the lead-in time of each note is set by where you put the knob24. Because it is a single-note generator, it is built for lead lines and single-note playing rather than chords1.
Controls
| Control | What it does |
|---|---|
| Attack | Governs a reverse volume swell effect, 1500 ms to 4 ms2 |
| Filter | Sculpts the fuzz wave's EQ and tone; controls the cutoff frequency of the square waves25 |
| Blend | Sets the mix ratio between the dry signal and the wave generator2 |
| Level | Sets the overall effect level2 |
| Wave Shaper | Three-position rocker switch selecting a waveform: square, sawtooth or sine67 |
| Chaos switch | Changes the type of input detection used2 |
The Filter knob pairs with an expression pedal for wah-like control2. There is a TRS expression pedal jack on the side of the pedal, allowing hands-free operation of the Filter control56. MusicRadar noted that the expression pedal input makes the pedal extra performance-friendly4.
Normal and Chaos detection modes
The Chaos switch changes the type of input detection the pedal uses, and the two modes behave quite differently2.
Normal mode uses positive and negative peak detectors, similar to the Boss OC-2, resulting in a stable and consistent output2. Pedal of the Day found that in Normal mode it sounds similar to the classic Boss OC-2, but with more stability and consistency5.
Chaos mode opens up the possibilities, using zero-cross detection to obtain octaves, harmonics, distortion and even a bit of flanging modulation5. The behavior depends on the waveform you have selected:
- With sine waves: a standard octave down is employed alongside another slightly detuned octave to generate a flanging-like modulation, then distorted through hard clipping2.
- With saw or square waves: zero-cross detection is used to obtain the wave's pitch, resulting in a more unstable output2.
Gearnews described the Chaos switch as adding octaves and something Keeley calls "dimensional triggering"8. Pedal of the Day put it more bluntly: the Chaos switch "gets nice and nasty, adding to the complexity of the Synth-1 by changing dimensional triggering and octaves"5.
"the Chaos switch gets nice and nasty, adding to the complexity of the Synth-1 by changing dimensional triggering and octaves"
Where it came from
The Synth-1 is described by Keeley as capable of some far out sounds, ranging from "unnatural fuzz noises to pseudo-harmonic, random glitchy counterpoint"27. Its Blend knob sets the mix ratio between the dry signal and the wave generator, letting the player dial in how much of that generated sound sits under the untouched guitar signal27.
Keeley has since continued in the fuzz and synth-adjacent space with pedals like the Keeley Moon Fuzz and the Keeley OCTA PSI Transfigurating Fuzz, an all-analog fuzz with pitch shifting and octave generation.
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Questions
What does the Chaos switch do on the Keeley Synth-1?
The Chaos switch changes the type of input detection the pedal uses. In Normal mode it tracks like a Boss OC-2 with positive and negative peak detectors. In Chaos mode it switches to zero-cross detection, which adds octaves, harmonics, distortion and a flanging-like modulation, at the cost of a less stable output.
Can you use an expression pedal with the Keeley Synth-1?
Yes. There is a TRS expression pedal jack on the side of the pedal. It controls the Filter knob, which sculpts the fuzz wave's EQ and tone, so you can get wah-like control of the filter frequency hands-free while you play.
Does the Keeley Synth-1 work with chords?
No. The Synth-1 is a guitar-triggered, single-note wave generator. It is designed to track one note at a time and turn it into a fuzzy synth wave, so chords do not produce the stable, consistent output you get from single notes.
How much did the Keeley Synth-1 Reverse Attack cost at launch?
It was priced at $179. Guitar.com reported pre-orders at $179 in February 2019, and both MusicRadar and Guitar World listed the price as $179 when the pedal became available in March 2019.
What does the Attack knob do on the Synth-1?
The Attack knob governs a reverse volume swell effect, with a range from 1500 ms down to 4 ms. It dictates the lead-in time of each note, so you can set how long the swell takes before the synth wave hits full volume.
Sources (8)
- Keeley Electronics Unveils New Synth-1 Pedal, Guitar World, 2019-03-18
- Keeley debuts Synth-1 Reverse Attack Fuzz Wave Generator, Guitar.com, 2019-02-22
- Guitarists can live out their electric dreams with Keeley Electronics' Synth-1 pedal, MusicRadar, 2019-03-18
- Electro-Harmonix String9 String Ensemble review, MusicRadar, 2023-01-03
- Keeley Electronics Synth-1 Reverse Attack Fuzz Wave Generator, Pedal of the Day, 2019-05-02
- Review: Keeley Synth-1, Guitar.com, 2019-04-10
- NAMM 2019: Keeley announces new Synth-1, DDR, Fuzz Bender and Eccos, gearnews.com, 2019-01-24
- Keeley Synth-1 Reverse Attack Fuzz Wave Generator: Synthesizer tones for your guitar, gearnews.com, 2019-03-17
