The OPFXS Dig Deep is a sub-harmonic generator octave pedal from the maker OPFXS. Pedal of the Day called it "as unique an octave pedal as we've ever come across"1. The pedal's Dry knob, used in secondary mode, offers 8 different tracking options, adjusting to fit your specific guitar and pickup types and moving from the low frequency register up to the higher end1. The reviewer found that adding depth and presence to any guitar signal is always key, and that the Dig Deep excels at just that, with a low-end that goes from faint and barely audible to powerful and booming, with a nice range in between1.
Pedal of the Day called it "as unique an octave pedal as we've ever come across"1. It sits in the wider field of octave and pitch pedals, most of which track full chords rather than a single bass note.
What it does to a signal
The Dig Deep is a monophonic octaver: it only does one note at a time, which Guitar Pedal X's Stefan Karlsson described as perfect for delivering basslines, so a player can supplement melodies with simultaneous bassline action2. Delicious Audio's Paolo De Gregorio, covering the Mk3, described it as an octave-down pedal that "generates a rich, monophonic bass line from your guitar signal"3. Pedal of the Day found that the low-end goes "from faint and barely audible to powerful and booming, with a nice range in between," and concluded that "Adding depth and presence to any guitar signal is always key, and the Dig Deep excels at just that"1.
gearnews.com also noted that the unit can be used as a pitch-shifter as well as an octaver4.
The controls
On the original Dig Deep, operation uses only two primary controls: Volume for Clean and Volume for the octave tone4. Each knob hides a secondary function, reached through the F micro button.
| Control | Primary function | Secondary function |
|---|---|---|
| Dry | Clean volume | 8 tracking options, fitting guitar and pickup types, from the low frequency register up to the higher end1 |
| Sub | Sets the level of the lower octave1 | Sets the Tone of the sub octave, with 12 options from dark to bright1 |
| F micro button | Toggles Fast and Slow attack modes1 | Held down, enters secondary mode; also switches Mono and Split output1 |
In Split mode, a Y-cable splits the Dry and Sub signals and routes them to two different places, so the clean guitar and the sub-octave tone can go to separate destinations1.
The Dig Deep Sub Octave Mk3
The Dig Deep Sub Octave Mk3 carries the same core design as the original Dig Deep: a sub-harmonic generator octave pedal from OPFXS135. As on the original, the Dry knob in secondary mode offers 8 different tracking options, adjusting to fit your specific guitar and pickup types, moving from the low frequency register up to the higher end1. Pedal of the Day's description of the low-end applies across the design: it goes from faint and barely audible to powerful and booming, with a nice range in between1.
Pedal of the Day's review describes the Dig Deep's controls in detail, including the Dry knob's 8 different tracking options, which adjust to fit your specific guitar and pickup types and move from the low frequency register up to the higher end1. The same review sums up the pedal's purpose: "Adding depth and presence to any guitar signal is always key, and the Dig Deep excels at just that"1.
Videos
Guitar World
OPFXS
Carl Wockner
Questions
Which strings does the OPFXS Dig Deep affect?
The Dig Deep works on just the lower three strings of the guitar, leaving the higher strings untouched and clean, according to Pedal of the Day. Guitar Pedal X describes the same behavior on the MK3: the lower strings receive octave processing while the upper strings remain unaffected. That lets a player keep playing melody on top while the pedal supplies a bass line underneath.
What does the F button do on the OPFXS Dig Deep?
Pedal of the Day explains that the F micro button toggles between Fast and Slow attack modes, and that holding it down enters a secondary mode where each knob controls something different. The same button is also used to switch between Mono and Split modes of output.
What is Split mode on the OPFXS Dig Deep?
Split is one of the pedal's two output modes, alongside Mono. In Split mode, a Y-cable splits the Dry and Sub signals and routes them to two different places, so the clean guitar and the sub-octave bass tone can be sent to separate amps, effects chains or recording inputs.
How many tracking options does the Dig Deep have?
The Dry knob, in its secondary mode, offers 8 different tracking options, adjusting to fit specific guitar and pickup types and moving from the low frequency register up to the higher end, according to Pedal of the Day. The Sub knob in secondary mode adds 12 tone options for the sub octave, from dark to bright.
Is there a newer version of the OPFXS Dig Deep?
Yes. The Dig Deep Sub Octave Mk3 was released in October 2025, reported by Delicious Audio. It adds five primary knobs, four assignable controls via a dedicated editor, 3 user presets, full MIDI and a USB-C editor, and is compatible with everything from 6-string to baritone guitars.
Sources (5)
- OPFXS Dig Deep Sub-Harmonic Generator, Pedal of the Day, 2020-10-30
- Guitar Pedal X, Guitar Pedal X, 2025-09-02
- New Pedal: OPFXS Dig Deep Sub Octave Mk3, Delicious Audio, 2025-10-22
- OPFXS Dig Deep: The best octaver pedal of 2019 so far?, gearnews.com, 2019-10-26
- Dig Deep with OPFXS' new sub-harmonic generator on the latest episode of Cooking with Sound, Guitar World, 2020-01-03
