The Diamond Pedals F-Octave is a fuzz pedal with a switchable analog octave-up mode, made by Diamond Pedals. It was originally launched in 2017 and returned to the lineup in 2025 as an enhanced edition1. At its heart is what RockBoard's PedalPedia describes as "a finely tuned, discrete analog fuzz circuit designed for rich harmonic content and dynamic response"1, and the whole thing is built around the sound of an early-70s classic: the Foxx Tone Machine12.
The two modes are the point of the pedal. With the octave off, RockBoard's PedalPedia says you get "a warm, fat fuzz, full of wooly midrange and smooth compression, perfect for leads"1. Flip the octave on and the pedal produces upper-register harmonics with what RockBoard's PedalPedia calls vintage attitude and a synth-like texture1. Diamond also says the F-Octave "plays beautifully with both guitar and bass"3.
Fuzz with an analog octave-up mode
The F-Octave is a two-in-one pedal: a silicon fuzz on its own, and a fuzz combined with an analog octave-up effect. Pedal of the Day's 2017 review put it plainly: with the octave engaged, "your fuzz pedal turns into a nasty but clear analog octave up effect"2. The same reviewer found it "can easily drive your amp to breakup territory, do octave up and walls of fuzz sounds, and more"2.
Guitar Pedal X's Stefan Karlsson described the 2025 edition as an "Analog Silicon Fuzz and Octave Effects Pedal" that "uses an OCT switch: up selects fuzz only; down engages upper octave"5. Delicious Audio's Paolo De Gregorio framed the sound as "delivering the same high-gain silicon fuzz that defined early '70s rock tones"4.
Controls
| Control | What it does |
|---|---|
| Volume | Overall output level2 |
| Octave toggle switch | Up: fuzz only. Down: fuzz plus octave-up5 |
| LPF | Added on the 2025 edition5 |
The 2017 version had a small touch that players liked: "The LED even changes color to purple when you switch modes, letting you always know which half of the pedal you're utilizing," as Pedal of the Day noted2. The 2025 edition carries that idea into its look, with a purple enclosure and gold yellow accent5.
The enclosure is practical for pedalboards. Pedal of the Day praised the "top-mounted input and output jacks" and the "super-pedalboard-friendly size"2. On build quality, the reviewer's verdict was firm:
"As with all Diamond Pedals, this thing is built like a tank, and should expect many miles to be put on it for years and years to come."
From the Foxx Tone Machine to the reissue
The F-Octave's circuit is based on the vintage Foxx Tone Machine, the funky, fuzzy-coated fuzz pedal produced by Foxx in the early to mid 70s and re-issued in the 2000s26. RockBoard's PedalPedia describes the F-Octave as "crafted in tribute to the legendary Foxx Tone Machine"1. The Tone Machine was the flagship of Foxx's lineup, according to GuitarPlayer's Dave Hunter7, and its fuzzy felt coating became a signature of US-made Foxx pedals.
The Tone Machine itself came from Steve Ridinger Associates8. Its fuzz-plus-octave formula has been copied widely since; General Guitar Gadgets, for instance, sells a clone project of the same circuit, noting "This pedal has a great fuzz sound and Octave sound as well"9. Diamond's take is one of several modern pedals built on that design.
The 2017 F-Octave built a following strong enough that, as Guitar Pedal X reported in July 2025, "the 2017 F-Octave editions were fetching quite high prices on Reverb.com" before the reissue arrived5. The 2025 edition brings the pedal back with the added LPF control and the new finish, and Guitar Pedal X reported it "should be imminently available at leading dealers"5.
Power and setup
The F-Octave runs on a regular 9 to 18V DC power supply with a center-negative 2.1mm barrel jack35. RockBoard's PedalPedia lists its current draw at 10mA1, while Guitar Pedal X gives approximately 20mA5. Either figure is modest, so the pedal sits comfortably on a standard pedalboard power supply alongside other octave and pitch or overdrive pedals.
The maker specifies a center-negative 2.1mm barrel jack and 9 to 18V DC35. The pedal accepts more than the usual 9V, so a supply with a wider voltage range opens up the higher settings.
Videos
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Questions
Is the Diamond F-Octave a copy of the Foxx Tone Machine?
It is a tribute rather than a straight clone. Diamond Pedals describes the F-Octave as crafted in tribute to the Foxx Tone Machine, and reviewers note it is based on the vintage circuit. The 2025 edition adds its own features, including an LPF control, so it is an enhanced take on the original design rather than a reproduction.
What power supply does the Diamond F-Octave need?
It runs on a regular 9 to 18V DC supply with a center-negative 2.1mm barrel jack. Current draw is listed as 10mA by RockBoard's PedalPedia and about 20mA by Guitar Pedal X, but either way it is light on power and easy to run from a standard pedalboard supply.
Can the octave be turned off on the F-Octave?
Yes. An octave toggle switch selects between two modes: up gives fuzz only, and down engages the upper octave. With the octave off you get a warm, fat fuzz with wooly midrange and smooth compression; with it on you get searing upper-register harmonics.
Does the F-Octave use silicon or germanium transistors?
Silicon. Guitar Pedal X describes the 2025 edition as an analog silicon fuzz and octave pedal, and Pedal of the Day found the fuzz tones in the 2017 original were those of classic silicon. No germanium version is mentioned.
Is the Diamond F-Octave analog?
Yes. Diamond Pedals describes it as a finely tuned, discrete analog fuzz circuit, and RockBoard's PedalPedia lists the circuit type as analog. The octave-up effect in the 2017 version was also described by reviewers as analog.
Is the Diamond F-Octave still in production?
Yes. Originally launched in 2017, the F-Octave returned to the Diamond Pedals lineup in 2025 as an enhanced edition. Guitar Pedal X reported in July 2025 that it should be imminently available at leading dealers.
Sources (9)
- F-Octave by Diamond Pedals, RockBoard PedalPedia, 2026
- Diamond Pedals f-Octave Fuzz Octave, Pedal of the Day, 2017-08-16
- F-Octave, Diamond Pedals
- New Pedal: Diamond Pedals F-Octave Fuzz, Delicious Audio, 2025-07-09
- Guitar Pedal X, Guitar Pedal X, 2025-07-09
- TONEHOME, TONEHOME - the World of Vintage Guitar Effect Pedals
- The Foxx Tone Machine Was the Fuzz of Choice for Peter Frampton, Billy Gibbons, and Adrian Belew, GuitarPlayer (www.guitarplayer.com), 2021-11-15
- TONEHOME, TONEHOME
- Foxx™ Tone Machine™ Clone: Octave Fuzz Kit, PCB & Schematic, General Guitar Gadgets, 2014-05-18
