Somewhere in the last month, your band has probably had this conversation. There is a song you want to play, and it has an organ part, or a string pad, or a synth line running underneath the whole thing — and nobody in the room plays keys. So you either skip the song, or you play it and quietly accept that it sounds thin compared to the record.

There is an entire shelf in our store that solves this, and most guitarists walk straight past it. These are pedals that turn a guitar into an organ, a Mellotron, an analog synth or something that has no acoustic equivalent at all. Some of them are older technology than you think. Some of them will handle a full six-string chord without blinking, and some will fall apart if you let one extra string ring. This article explains what each one actually does, how the technology inside decides what it can and cannot do, and which one solves your particular problem.

Before any product names, understand this, because it will save you from buying the wrong pedal.

Every pedal here works in one of a few fundamentally different ways, and the technology decides whether you can play chords through it. This has almost nothing to do with price. A RM749 pedal will happily take a strummed chord while a RM5,600 unit needs special hardware to do the same thing.

Here are the families.

Capture-and-sustain. The pedal records a tiny slice of audio and loops it seamlessly, creating infinite sustain. It never asks "what note is that?" — it just replays what it heard. Because it does no pitch detection at all, it works on absolutely anything: chords, feedback, a vocal, a snare drum. The catch is that it can only sustain what you already played. It cannot invent a new sound.

Pitch-tracking resynthesis. The pedal works out what note you are playing, then reshapes your own string signal with filters and pitch-shifting into a different timbre. This is how the organ and Mellotron pedals work — and it is worth knowing that there is no sample of an organ inside them. It is your guitar, filtered into something else. Chord-capable, but only up to a point, and only if you feed it a clean signal.

Polyphonic octave stacking. No note detection either. The pedal shifts your entire signal up and down by octaves and mixes them back together. Stack enough octaves and the ear reads it as an organ. Completely chord-safe.

Analog frequency division. Old-school and entirely analog. The circuit squares your signal into a hard square wave, then halves the frequency to make lower octaves. Division only works on one repeating waveform — feed it a chord and the circuit genuinely cannot decide what to divide. Monophonic by physics, not by choice. The upside is zero latency; it responds instantly because there is no computer thinking about it.

Phase-locked loop, or PLL. A self-correcting oscillator that constantly asks "am I in step with the incoming signal?" and chases your pitch until it locks on. Once locked, that oscillator can be divided or multiplied into harmony voices. It needs one unambiguous note to lock to — give it two, or a muddy low signal, and it hunts, jumps octaves and screams. Monophonic, and the instability is the entire point.

Divided pickup, per-string tracking. The only real solution to the polyphony problem. A special pickup gives the unit six separate signals, one per string, so it tracks each string independently and never has to guess which note you meant. This is why proper guitar synths need extra hardware.

Keep those in mind and every product below explains itself.

This is the capture-and-sustain family, and it is the easiest place for most guitarists to start.

Press the switch and the Superego grabs a snapshot of whatever you are playing and holds it, forever, underneath you. Then you take your hands off that chord and play a melody over the top of it — over your own pad, live, with one guitar. Because it never analyses pitch, it is genuinely polyphonic on anything you feed it. Chords, feedback, a bass, a vocal, a drum.

The controls are simple. Speed/Layer sets how quickly the frozen sound fades in and out. Gliss sets how it slides between frozen notes — turn it up and each new freeze glides into the last like a synth portamento. Dry and Effect balance your live playing against the held sound. Three modes: hold the switch to freeze momentarily, freeze automatically as you play, or latch it hands-free.

The feature that makes it special is the effects loop on the original Superego, which processes only the frozen signal. Put a reverb and a delay in that loop and your held pad drifts into an enormous ambient wash while your dry guitar stays completely clean in front of it. That is a sound you cannot get any other way without two amps.

The Superego+ is the bigger version: four modes, an adjustable attack and decay, a threshold control, and eleven built-in effects — detune, delay, echo, flange, phase, mod, rotary, two tremolos, pitch shifting and a filter — so you no longer need external pedals in a loop. It also takes an expression pedal.

Best for: ambient and post-rock, worship pads, solo performers, anyone who wants to accompany themselves. Not for: creating sounds you did not play. This is a sustainer, not a synth voice.

If you came to this article because your band has no keyboard player, these two are the answer.

They share an engine. Both track what you are playing and reshape your own guitar signal into a different instrument — and it is worth repeating that there is no organ or Mellotron sample inside either of them. It is your strings, filtered and pitch-shifted in real time. Both are polyphonic, so chords work, and the MEL9 handles up to five notes at once.

The B9 gives you nine organ sounds: Fat & Full, Jazz (smooth, Jimmy Smith territory), Gospel, Classic Rock (straight "A Whiter Shade of Pale"), Bottom End for organ bass lines, Octaves, Cathedral for enormous pipe-organ psychedelia, Continental for that 1960s combo-organ jangle, and Bell Organ. Beyond volume, you get Mod for the speed of the vibrato and rotary character, and Click — which adds the percussive key-click of a real organ and is the control that sells the illusion.

The MEL9 gives you nine Mellotron sounds: Orchestra, Cello, Strings, Flute, Clarinet, Saxophone, Brass, Low Choir and High Choir. Its two key controls are Attack, which sets how slowly the sound swells in — turn it up and every note blooms like a volume pedal — and Sustain, which sets how long the sound rings on after you stop playing. That combination is what makes instant string pads possible without a keyboard.

Both have separate dry and effect outputs, so you can send the organ to one amp and your guitar to another. And both track fast enough to keep up with quick passages.

One warning that applies to both, straight from the manuals: do not put distortion or overdrive in front of these pedals. It muddies the input and the tracking falls apart. Dirt goes after. If your pickups are weak, a clean boost or compressor in front will improve things noticeably.

Best for: worship teams, covers bands, prog, psychedelia, anyone who needs a keyboard part and has no keyboard. Not for: playing after a fuzz pedal, or very percussive picking — both are sensitive to how evenly you attack the strings.

A different route to a similar destination, and the one to reach for if you strum hard.

The Organizer has no organ voices at all. It generates an octave above and an octave below your signal, and lets you blend them against your dry sound. Stack those and your ear hears a drawbar organ. The Choir control takes a mix of the up and down signals and regenerates it, adding two octaves up, two octaves down and a slightly delayed direct signal — the church-organ layer. Note that Choir only does anything if both Up and Down are in play.

Tone rolls off the top end. Lag adds a very short slapback delay to the wet signal, which is what creates the swelling, slightly Leslie-like smear as chords bloom in.

The important practical difference from the B9: because it is doing octave shifting rather than pitch analysis, it tracks chords beautifully — reviewers note it holds up even on the harmonic complexity of a 12-string, and it follows bends and finger vibrato cleanly. It is the pedal here you can strum freely into.

Its limitation is the flip side of the same coin. It has one basic voice. There are no organ presets and no harmoniser intervals — no thirds, no fifths. It does one thing extremely well.

Best for: big chordal organ washes, drones, ambient beds, players with a heavy right hand. Not for: anyone wanting variety or specific organ voicings. Also worth knowing: it responds best to a light touch — very heavy strumming can overwhelm the effect.

Fully analog, no digital processing anywhere, and it sounds like 1978 in the best way.

Four blendable voices: Base (your signal squared into a hard square wave), Sub (two octaves down), Down 1 (one octave down) and Up 1 (one octave up). Plus Level and Filter for overall volume and brightness. That is the entire pedal.

Because it works by analog frequency division rather than digital analysis, it has absolutely zero latency — it responds the instant you pick, which no digital pedal can quite match. The trade-off is equally absolute: it is monophonic, and true chords are essentially impossible.

It also glitches, and you should know where. Tracking gets volatile below about the seventh fret, producing stuttering and sputtering. Notes cut off abruptly rather than fading. Weak-output pickups make the bass strings sound flubby. Reviewers who like this pedal — and most do — treat all of that as character rather than fault, because the glitch is genuinely part of the sound.

Best for: chiptune and 8-bit leads, octave fuzz, faux-baritone, single-note riffs that need to sound enormous and broken. Not for: chords, low-register playing, or anyone who wants things to behave predictably. Use the neck pickup and stay above the seventh fret.

This is the most extreme thing in the article and the one people fall in love with fastest.

The PLL inside it is an oscillator that chases your pitch until it locks on, at which point that locked signal gets divided and multiplied into harmony voices. What comes out is an aggressive, full-frequency blare that cuts through absolutely anything.

Three sound sources, blended on the Voice Mixer: the Master Oscillator, the Subharmonic, and a square-wave Fuzz. The Master Oscillator has a toggle for which octave it references — unison, one down, or two down — and an eight-position rotary selecting the output interval, reaching up to three octaves above what you played. The Subharmonic has its own eight-position rotary going up to three octaves below. And the Frequency Modulator offers Glide, for smooth synth-style portamento between notes, or Vibrato, for sci-fi laser sweeps.

It is monophonic and it demands precise playing — neck pickup, light touch, bare fingers. Overlapping notes produce genuine anarchy. There is no dynamic response and no envelope control: it is on or it is off.

And unlike most pedals in this article, this one has a documented track record. EarthQuaker's own artist coverage credits it on Idles' Joy as an Act of Resistance, Boris's LφVE & EVφL, and in Poppy's industrial guitar work.

Best for: industrial, noise, heavy riff doubling, EDM-style monophonic leads, anything that needs to sound genuinely hostile. Not for: subtlety, chords, or clean-up.

Bass players get their own entry, and this is by some distance the easiest synth pedal here to actually use.

Eleven voices, each with its own preset slot: Laser (deep and pulsating), X-Fade, Acid (fast-decaying TB-303 territory), Cosmic, Sub (a round sub-octave purely for adding weight), Growl, Wub, Unison, Twin, Spectre and Oblivion. Four controls — Dry Volume, Synth Volume, Sens for input sensitivity, and CTRL, which does something different on every voice, usually envelope decay or filter behaviour. Pick a voice, turn one knob, done. It also takes an expression pedal.

The one thing you must know: it is emphatically monophonic. EHX's own manual is blunt — it does not work properly when chords or even two-note intervals are played, and behaves erratically when it receives more than one note. In practice that means single-note lines only, and clean muting matters more than you think — an open string still ringing under a fretted note counts as a second note as far as the pedal is concerned.

That is not a flaw. Every classic bass synth works this way. But if your parts involve double stops or chordal playing, this is the wrong pedal.

Best for: synth-bass lines, sub reinforcement under a heavy riff, acid and dub textures, and live playing where recallable presets matter. Not for: chordal bass playing, or players with loose muting technique.

If the pedals above are single dishes, the C4 is a kitchen.

It gives you the building blocks of a modular synthesiser in a small enclosure: four independent voices, eleven envelope followers, twenty-five filter effects, fourteen LFO shapes, and two programmable sixteen-step sequencers. Pitch shifting extends nearly four octaves in either direction. Six presets are reachable from the pedal itself; 128 more are addressable over MIDI. It runs in stereo, does USB-MIDI, and syncs to MIDI clock.

The honest answer to the chord question is: it depends on your patch. Each of the four voices can be set as a polyphonic pitch block — which handles chords — or as a monophonic pitch shifter or oscillator, which does not. So the C4 is chord-capable when you build it that way, and monophonic on most of the genuinely synth-sounding oscillator patches. This is the single most misunderstood thing about the pedal and worth being clear on before you buy.

The other thing to know is that the real editing happens in the Neuro app, on desktop or phone. There are only four knobs on the pedal. Reviewers consistently find the app well designed and the tracking excellent, but if the idea of editing sounds on a screen puts you off, this is not your pedal.

Best for: sound designers, players who want sequencer patterns, anyone building specific sounds rather than reaching for presets, stereo rigs. Not for: players who want to plug in and immediately hear a classic vintage synth. Reviewers note it skews modern and digital rather than warm and analog.

Everything above tries to solve the polyphony problem with one guitar cable. The SY-1000 solves it properly, and the difference is worth understanding.

With a GK divided pickup fitted to your guitar, the SY-1000 receives six separate signals — one per string — and tracks each independently. It never has to guess which note you meant, because it can hear all six at once, separately. That is genuine polyphonic tracking, and it is why nothing in the families above can match it.

Three synthesis engines: the Dynamic Synth, which follows your envelope and dynamics with ten oscillator waveforms; the OSC Synth for analog-style oscillator synthesis; and a recreation of the Roland GR-300, the 1979 unit that defined what "guitar synth" meant for players like Andy Summers and Pat Metheny. On top of that you get modelled guitars and basses, alternate tunings, a full modelling amp and effects rig, three simultaneous instrument parts, and 400 patches each in guitar and bass modes.

Two practical things to get right before you buy. First, the normal quarter-inch input works, but it does not unlock everything — through a standard cable you get the amps, cabs, effects and the Dynamic Synth, but the OSC Synth, the GR-300 and the modelled guitars all require the GK pickup. Second, check your pickup compatibility. The older GK-2A, GK-3 and GK-3B connect directly with a GKC cable, but the newer GK-5 and GK-5B need a GKC-DA converter. That is an easy and annoying mistake to make.

Best for: players who want real synth capability with no compromises, alternate tunings, studio work, and anyone tired of pedals that cannot handle chords. Not for: casual curiosity. It is a significant investment and it requires modifying your guitar to get the most from it.

1. Distortion goes AFTER, never before. This is the single biggest reason people think these pedals are broken. Overdrive and fuzz smear the harmonic content that a tracking pedal relies on to identify your note. EHX's own manuals say it outright. Put your dirt after the synth pedal, not in front of it.

2. A compressor in front will transform the experience. Almost every pedal here is sensitive to how evenly you pick — reviewers repeatedly note uneven note levels and tracking that comes and goes with your attack. A compressor evens that out and makes the whole thing dramatically more reliable, especially live.

3. Pickup choice matters, and it is not consistent. The Data Corrupter and the Bit Commander both work best on the neck pickup with a lighter touch. But the B9's manual specifically recommends the bridge pickup. There is no universal rule — check the manual, and if in doubt, try both before you decide the pedal is at fault.

4. Mute everything you are not playing. For every monophonic pedal here, a still-ringing open string counts as a second note. If a mono synth pedal sounds like it is malfunctioning, nine times out of ten it is your left hand, not the pedal.

"We need organ parts and we have no keys player." → B9 Organ Machine for specific organ voicings, or Organizer V2 if you strum hard and want big chordal washes.

"We need string and choir pads." → MEL9, with the Attack control turned up. Or the Superego if you would rather freeze your own chords than emulate strings.

"I play alone and want to accompany myself." → Superego or Superego+. Nothing else here does this.

"I want a synth bass line." → Bass Mono Synth. Single notes only, but it is the fastest route from plugging in to sounding right.

"I want my riffs to sound genuinely brutal." → Data Corrupter for chaos, Bit Commander V2 for retro square-wave glitch.

"I want to build my own sounds from scratch." → Source Audio C4 Synth.

"I want to actually play synth on a guitar, properly." → Boss SY-1000, with a GK pickup. Nothing else here comes close, and nothing else here costs as much.