GSUS4 Guides / Creative Pedals
OPFXS Pedals: Creative Tools for Players Who Want More Than Ordinary Effects
OPFXS is not just another boutique pedal brand. The best way to understand it is as a practical creative toolbox for guitarists who need to do more on stage, in loops and in compact live setups.
The clearest example is Dig Deep MK3. With the right Range setting, an electric or acoustic guitar can make the lower strings behave like a bass-style sub layer while the upper strings stay useful for chords, rhythm and melody.
Quick Verdict
Start with Dig Deep MK3 if you want guitar and bass energy from one instrument.
- Set the tracking range around the lower strings so bass notes trigger the sub voice while upper-string parts stay more like normal guitar.
- Use Split mode when the rig has enough inputs: dry guitar goes to the guitar chain, sub goes to a bass DI, bass amp, looper or separate mixer channel.
- For acoustic guitars, High Pass and Low Pass are not afterthoughts. They help remove body thump and top-end noise from the generated sub signal.
- Look at V-UNO X, Gain Box and Twin Boost when the board needs programmable multi-effects, analogue gain variety or repeatable boost levels.
Brand Context
Why OPFXS feels different
OPFXS is an independent effects brand from La Spezia, Italy, founded in 2019 by OP Electronics. The Gsus4 OPFXS collection describes the range around creative sound generation, modulation, octave effects, gain shaping and programmable control.
The important part is the combination. OPFXS is not simply recreating familiar vintage circuits. Across the range, the brand often blends analogue sound, digital control, presets, MIDI and flexible routing in ways that help real pedalboards solve real arrangement problems.
That makes the range especially relevant for players who need one instrument to cover more than one job: solo acoustic guitarists, guitar-and-drum duos, worship teams, buskers, ambient players and anyone building loops live.
Main Feature
Dig Deep MK3: one guitar, one bass-like layer, one smarter rig
The Dig Deep MK3 is an advanced octave-down pedal built to generate a deep, monophonic bass line from a guitar signal without simply covering every string in sub-octave sound. OPFXS describes the MK3 as creating bass presence while keeping upper strings unaffected, with very low latency of about 5 to 7 ms.
The key control for the "one guitar, two roles" idea is Range. It is not best understood as a normal tone control; it is the practical way to decide where sub tracking responds across the fretboard. You dial the response so lower strings such as E, A and D can carry the bass role, then use Sub Mix, -1 Oct, -2 Oct, Low Pass and High Pass to shape how that bass layer sits.
Split is the live feature that turns the idea into a rig. With Split engaged, the dry guitar can continue to the main output while the generated sub signal leaves through the dedicated SUB output. That means the guitar and the bass-like layer can hit different amps, DI boxes, mixer channels, loop tracks or effect chains.
Practical Gsus4 take: The most useful setup is often lower-string bass support plus a separate dry guitar path. For solo and duo players, that can make one guitar feel more like a guitar-and-bass performance rig without turning the whole instrument into a muddy octave effect.
Signal Chains
Detailed Dig Deep MK3 setup ideas
These are starting points. The exact Range position depends on the guitar, pickup, tuning, string gauge and right-hand dynamics. Set it by ear: bring the Range up until the bass strings trigger reliably, then back it down if upper-string chords start pulling too much sub into the mix.
1Solo acoustic guitar with separate bass channel
This is the cleanest setup for a singer-songwriter, cafe player or church acoustic player who wants the audience to hear guitar and low-end support as two controlled sources.
- Acoustic guitarPickup or preamp output. Keep the input clean and consistent.
- Dig Deep MK3Range aimed at the lower strings; Split turned on.
- Main OutDry guitar path to acoustic preamp, EQ, reverb and DI.
- SUB OutSub path to compressor, bass DI or a spare mixer channel.
- PAEngineer can EQ the guitar and sub separately.
Main Out - acoustic guitar
Use normal acoustic tools: notch/EQ for feedback, light compression if needed, then reverb. Do not over-compress if the guitar still needs dynamic strumming.
SUB Out - bass-like layer
Use High Pass to reduce body thump, Low Pass to remove pick edge and a compressor or bass DI to keep the low end steady. Keep the sub level supportive, not dominant.
2Electric guitar duo rig with guitar amp and bass amp
For a two-piece band or guitar-and-drum duo, the point is separation. The dry guitar can stay expressive and effected while the sub stays cleaner, tighter and more like a bass source.
- Electric guitarBridge or middle pickup can track clearly; neck pickup may sound rounder.
- Tuner / light compOptional before Dig Deep if it helps input consistency.
- Dig Deep MK3Split on; -1 Oct as the main bass voice, -2 Oct used carefully.
- Main OutDrive, modulation, delay and guitar amp or modeller.
- SUB OutBass preamp, compressor, bass amp or FOH DI.
Main Out - guitar chain
Put your normal drives and ambience after the dry output so chords and leads still behave like a regular electric guitar rig.
SUB Out - bass chain
Avoid sending the sub through heavy guitar distortion unless that is the intended sound. Bass compression and a focused EQ usually translate better live.
3Loop station setup with bass-first building
This is where Dig Deep MK3 can feel like a second player. Build the bass loop from the SUB output, then keep the dry guitar available for rhythm, melody or ambient layers.
- GuitarPlay simple low-string bass figures first.
- Dig Deep MK3Preset 1 for strong bass tracking; Split on.
- SUB OutLooper input A, bass track or mixer bass channel.
- Main OutGuitar effects into looper input B or guitar amp.
- Preset changeUse another preset with less sub for chords and leads.
Looping workflow
Record the bass line first with clean timing. Then lower the Sub Mix or change presets so later guitar layers do not keep adding unwanted bass notes.
Mixer workflow
If the looper has separate outputs, send the bass loop to a bass DI or full-range PA channel and keep guitar loops on the normal guitar path.
4Simple mono fallback when the venue has one channel
Not every gig gives you two inputs. The MK3 can still work as a mixed effect, but the settings need to be more conservative because guitar and sub will share one output path.
- GuitarElectric or acoustic.
- Dig Deep MK3Split off; dry and sub mixed at main output.
- Preamp / EQShape the full signal before the PA or amp.
- DI / amp / PAFull-range monitoring helps the sub translate.
Keep the sub lower
Start with Sub Mix below where you think it should be. The room will usually make low frequencies feel larger than the pedalboard does.
Filter with intent
Low Pass helps the sub stop fighting the guitar's attack. High Pass keeps the bottom from becoming cloudy, especially with acoustic body resonance.
Gsus4 Table
Which Dig Deep MK3 routing fits your gig?
Use this as a quick decision table before wiring the board. On mobile, each row becomes a stacked card so the content stays readable without sideways dragging.
| Setup | Main Out | SUB Out | Best for | Watch |
|---|---|---|---|---|
| Solo acoustic split | Acoustic preamp, EQ, reverb, DI | Bass DI or spare PA channel with compression | Singer-songwriters, worship, small venues | Body thump and feedback; use High Pass carefully |
| Electric duo rig | Drives, modulation, delay, guitar amp | Bass preamp, compressor, bass amp or FOH | Guitar-and-drum duos, compact bands | Do not overdrive the bass path unless it is intentional |
| Loop station split | Guitar effects or looper guitar input | Looper bass track or separate looper input | Live looping, busking, layered arrangements | Change presets after the bass loop so later parts stay clean |
| Mono mixed output | Combined dry and sub signal to one channel | Not used | Quick setup, limited venue inputs | Keep Sub Mix modest; one EQ has to serve both sounds |
| Studio or DAW split | Interface input for guitar track | Interface input for bass-style track | Home recording, demos, arrangement writing | Edit the two tracks together so the groove stays locked |
Core Controls
The Dig Deep MK3 controls that matter most
OPFXS gives the MK3 five knobs, two buttons and Shift access to secondary parameters. These are the practical controls to understand first.
| Control | What it does | Practical use |
|---|---|---|
| Range | Adjusts where the sub tracking responds across the fretboard. | Aim it at the low-string area so bass notes trigger while upper chord tones stay cleaner. |
| Sub Mix | Sets the overall level of the generated sub signal. | Use it like an arrangement fader. Enough low-end support, not enough to swallow the guitar. |
| -1 Oct / -2 Oct | Controls the one-octave-down and two-octave-down voices. | Let -1 Oct do most of the bass job. Add -2 Oct lightly for size when the system can handle it. |
| Low Pass | Cuts high frequencies from the sub signal. | Smooths pick attack and makes the sub sit more like a bass source than a bright synth layer. |
| High Pass | Controls low frequencies in the sub signal and can reduce unwanted acoustic-guitar noise. | Tightens acoustic rigs, controls body resonance and stops the PA from becoming muddy. |
| Split | Sends dry signal to main output and sub signal to the dedicated SUB output. | The most important live feature for loopers, duos and players using separate guitar and bass processing. |
| DNC / HNC | Advanced tracking functions for dominant-note and high-note behaviour. | Useful when open strings, inversions or chord voicings need cleaner tracking behaviour. |
| Presets / MIDI / USB-C editor | Stores up to three settings and supports deeper setup through editor and MIDI control. | Save one preset for bass-line tracking, one for mixed subtle support and one for no-sub or special parts. |
Beyond Dig Deep
The rest of the OPFXS story at Gsus4
Dig Deep MK3 is the obvious hook, but the OPFXS range is broader than octave sounds. These models show how the brand moves between programmable control, analogue gain and utility pedals with a modern live-rig mindset.
Sub-Octave Routing
Dig Deep MK3
Advanced octave-down pedal for bass-like monophonic support, with Range control, filters, presets, MIDI, editor support and split dry/sub outputs.
Programmable Multi-FX
V-UNO X
A compact programmable creative multi-effect for guitar and bass. It is not framed here as a replacement for a large modeller; it is a pedalboard-friendly box for changing effect roles, presets and MIDI-controlled setups.
Analogue Gain Hub
Gain Box
Fully analogue multi-channel gain with Dry, Fuzz, Overdrive and Distortion channels. It can cover low-gain drive, stacked gain textures and fuzz while keeping dry blend available for clarity.
Precision Boost
Twin Boost
A 100 percent analogue boost path with digital control, up to 24 dB of clean boost and a numerical display. The appeal is simple: repeatable boost levels you can actually see on stage.
Gsus4 Table
OPFXS range snapshot
A fast way to explain the range inside the blog without turning every product into a full review.
| Pedal | Main idea | Why it matters | Good fit |
|---|---|---|---|
| Dig Deep MK3 | Advanced octave-down bass-style generator with split routing. | Can make one guitar cover guitar and bass-like roles in a controlled rig. | Solo, duo, loop station, acoustic or electric live rigs. |
| V-UNO X | Compact programmable multi-effect for guitar and bass. | Loads different effect categories and can serve changing roles on a small board. | Players who want a flexible MIDI-ready utility effect. |
| Gain Box | Analogue dry, fuzz, overdrive and distortion channels with digital control. | Covers low-gain texture through fuzz and distortion without losing dry clarity. | Gain stackers, bass players, MIDI boards and studio rigs. |
| Twin Boost | Digitally controlled analogue boost with visible dB settings. | Makes boost levels repeatable and stage-friendly instead of guesswork. | Solos, amp push, stereo boost or two-position gain staging. |
| Parallel Dimension | Analogue BBD chorus and vibrato. | Adds classic modulation movement inside the same Italian OPFXS family. | Clean movement, synth texture and vintage-style modulation. |
| Electric Vibe | All-analogue phaser and vibrato inspired by Uni-Vibe-style movement. | Brings chewy modulation to players who want more character than a basic phaser. | Psychedelic, roots, ambient and expressive lead sounds. |
| Asteroide | Creative sampler and harmonizer. | Captures and replays notes as harmonic layers for experimental arranging. | Sound design, ambient, indie and experimental players. |
Who It Is For
Who should look at OPFXS first?
- Solo and duo performersPlayers who need more low-end authority without adding another musician or a full extra rig.
- Loop station usersPlayers who want bass loops, guitar loops and live parts to sit in separate lanes instead of one crowded signal.
- Acoustic playersPlayers who want one acoustic guitar to fill more space at worship, cafe, busking and small venue gigs.
- No-bass lineupsGuitarists in two-piece bands or compact ensembles who need controlled low-end support.
- Creative pedal huntersPlayers looking beyond the usual overdrive, delay and reverb choices into more arrangement-focused effects.
- Modern pedalboard buildersPlayers who care about presets, MIDI, editor support, split outputs and repeatable gain staging.
Conclusion
OPFXS pedals are about changing what your instrument can do.
Whether you want to turn one guitar into a guitar-and-bass performance rig with Dig Deep MK3, build complex gain textures with Gain Box, control boost levels with precision using Twin Boost, or explore programmable multi-effects with V-UNO X, OPFXS gives creative players tools that feel genuinely different.
FAQ
Common OPFXS and Dig Deep MK3 questions
Can Dig Deep MK3 replace a bass player?
Not in the musical sense. It can create convincing bass-like support from guitar, especially for simple lines, loops and duo arrangements, but it will not replace the phrasing, note choice and feel of a dedicated bassist.
Does Dig Deep MK3 work with acoustic guitar?
Yes. OPFXS lists acoustic and semi-acoustic guitars among compatible instruments. The practical tip is to control body noise with Range, High Pass and Low Pass, especially when sending the sub path to a PA.
Why is Split output such a big deal?
Because dry guitar and sub bass need different processing. A guitar amp, reverb and overdrive chain is rarely the best destination for low-end bass support. Split output lets each part go where it belongs.
Is V-UNO X the same idea as a large modeller?
No. It is better described as a compact programmable multi-effect workstation for pedalboards. It can load different effects and use MIDI/editor control, but it is not trying to replace every part of a large amp-modelling floorboard.
Why use Twin Boost instead of a normal boost pedal?
The display and digital control make boost levels repeatable. If you need exactly the same solo lift, amp push or stereo boost every set, that is more useful than guessing by knob position under stage lighting.
Sources and Further Reading
Product references checked
- Gsus4 guide reference: The Sound of Springs
- Gsus4 OPFXS collection
- OPFXS Dig Deep MK3 official product page
- OPFXS V-UNO X official product page
- OPFXS Gain Box official product page
- OPFXS Twin Boost official product page
Last checked: 10 July 2026.
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