The Red Witch Synthotron III is an all-analog monophonic guitar synthesizer pedal that packs three effects into one enclosure: a four-voice synth engine, a filter with sample and hold, and an analog chorus. Designed by Ben Fulton, it converts your guitar signal into synth tones one note at a time, then lets you shape them with a filter section and finish them with a bucket-brigade chorus1. It sits in Red Witch's Synthotron line alongside the earlier Synthotron II and the Synthotron CV.
Red Witch launched the Synthotron III in November 2023 as an expanded, all-analog synth pedal21, with a limited run: a maximum of 100 units produced through the end of 2023, each hand-signed and numbered by Ben Fulton2.
Four voices set by toggle switches
The synth engine gives you four independent all-analog voices with pitch and octave settings across them, each set by the top toggle switch on its channel1. The voices stack in a chain: each one references the note generated by the voice before it, so the intervals compound as you go.
| Voice | Toggle | Settings |
|---|---|---|
| Voice One | Pitch 1 (yellow strip) | Unison, 1 octave up, 2 octaves up |
| Voice Three | Pitch 2 (red strip) | References the note from Voice One and generates 1 octave below, a perfect 4th or perfect 5th below, or a major 2nd or minor 6th below |
| Voice Four | 8ve (dark red strip) | References the note from Voice Three and generates 1, 2, or 3 octaves below |
Because the pedal is monophonic, it tracks one note at a time, so the four voices layer into a single stacked synth tone rather than a chord1. Each of the three effects (synth, filter, chorus) has its own footswitch, so you can engage or disengage each section independently1.
The Flux, filter and chorus controls
The Flux dial controls the "spring" or glissando between notes, which is how the pitch slides from one note to the next rather than stepping instantly1. That single control does a lot to make the synth feel like an instrument rather than a converter.
The filter section offers three modes1:
- Sample Hold Mode, where the filter jumps to randomly held values
- Envelope Filter Mode, which follows your picking dynamics
- Manual Sweep Mode, via an external expression pedal
An external expression jack controls the frequency range in expression pedal filter sweep mode, and an external CV input opens the pedal up to control from other gear1.
The chorus section is all analog, built around a NOS MN3007 bucket brigade chip, and Red Witch says the circuit is based around the Empress Deus Chorus1. Twin voice settings switch between a warm CE-1 styled chorus and a bright shimmery chorus1. Two controls govern it: Mix, which blends the wet and dry signal, and Depth, which sets the depth of the chorus effect1.
Power, outputs and running two amps
The Synthotron III runs on 9V DC from any standard guitar pedal external power supply, tip negative, drawing 130mA1. Inside the pedal, the 9 volts is converted to 18 volts for maximum headroom and stability1.
The 130mA current draw is well above what a battery or a low-current daisy chain output is meant to deliver. Plan on a dedicated 9V DC output on your pedalboard power supply.
The external dry out lets you split the pedal between two amps, one carrying the clean signal and the other carrying the synth1. That is a practical setup for this kind of pedal: the synth voice goes to its own amp while your clean guitar tone stays untouched.
What reviewers said
Guitar Pedal X's Stefan Karlsson reviewed the Synthotron III in his 2023 roundup, calling it4:
"Great sounding updated and upgraded pedal-based analog synthesizer - a little on the pricey side perhaps - but it really does sound superb."4
MusicRadar noted the price as well, describing it at £599 as a premium piece of kit3. Ben Fulton's own framing of the pedal, in Premier Guitar's announcement, was blunt:
"This is the only pedal in the world that can create these sounds. There are thousands of Fuzz pedals, Chorus pedals and overdrive pedals. But only ONE Synthotron."2
How it compares
Against other entries in the synth pedals category, the Synthotron III's distinction is that it is fully analog and monophonic, where most modern guitar synths, like the Meris Enzo X or Boss SY-200, are digital and often polyphonic. Its closest spiritual ancestors are analog monosynths in pedal form such as the Electro-Harmonix Micro Synthesizer and the Pigtronix Mothership2. If you want chords from a synth pedal, a polyphonic digital option will serve better; if you want the glide, stacking intervals and filter behavior of an analog monosynth, that is the territory the Synthotron III occupies.
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Questions
Is the Red Witch Synthotron III fully analog?
Yes. Red Witch describes the Synthotron III as 100% analog, from its four synth voices to its filter and chorus sections. The chorus is built around a NOS MN3007 bucket brigade chip, the same kind of delay line used in classic analog chorus designs.
Is the Synthotron III polyphonic?
No. Red Witch describes it as an all analog monophonic guitar synthesizer, meaning it tracks and converts one note at a time. Chords will not come out as chords through the synth voices, so it is best treated as a single-note instrument.
Can the Synthotron III run two amps at once?
Yes. It has an external dry out that lets you split the pedal between two amps, one carrying your clean guitar signal and the other carrying the synth signal. That separation keeps the clean tone untouched while the synth goes to its own amp.
What power supply does the Synthotron III need?
It runs on 9V DC from any standard guitar pedal external power supply, tip negative, and draws 130mA. Inside the pedal the 9 volts is converted to 18 volts for maximum headroom and stability, so it needs a supply that can deliver its current draw.
What chorus chip does the Synthotron III use?
The chorus section uses a NOS MN3007 bucket brigade chip, and Red Witch says the circuit is based around the Empress Deus Chorus. Twin voice settings switch between a warm CE-1 styled chorus and a bright shimmery chorus.
Sources (4)
- SYNTHOTRON III, Red Witch Pedals
- Synthotron III From Red Witch, Premier Guitar, 2023-10-24
- “This is the only pedal in the world that can create these sounds”: Red Witch launches the expanded Synthotron III, an all-analogue workstation for synth, envelope filter and chorus, MusicRadar, 2023-11-07
- Guitar Pedal X, Guitar Pedal X, 2023-12-19
