The Subdecay Prometheus 3 Dual Super Filter is a filter pedal built around two analog filters, a high pass and a low pass, that Subdecay describes as inspired by "our favorite 1970s monophonic synthesizer classic," the Korg MS-20. Like that synthesizer, the two filters are controlled separately, which is what gives the pedal its range of moving, vocal, synth-like filter sounds12.
What it does
At its core the Prometheus 3 is a dual resonant filter in the filter pedal family, but Subdecay has built a deep editing system around it. The pedal offers 40 editable parameters, including 3 LFOs, envelope shapes, overdrive, tremolo and even the LED color, and any combination can be saved to 11 user presets2. Subdecay's own buying guide notes that the pedal "can get very synthy with its built in octave down envelope," which puts it in synth pedal territory as well as the filter camp3.
For players comparing it within Subdecay's range, the Prometheus 3 sits alongside the Prometheus DLX and the Prometheus V2 as the maker's resonant filter line, with the Proteus series (Proteus, Proteus Auto Filter) and the Vocawah covering other filter approaches.
Controls and editing
The pedal's parameter knobs change what they do depending on which filter bank you are editing1:
| Bank | What the knobs control |
|---|---|
| Envelope filter bank | Envelope depth, filter cutoff frequency, resonance1 |
| LFO filter bank | Modulation depth, filter cutoff, resonance1 |
The envelope controls live in rows 1 and 3 of the editing layout, according to Subdecay's online user guide4. Presets are organized into eleven categorized banks, reached with the Preset and Select knobs, and factory presets are accessed by flipping the Preset/Select switch to BANK mode1.
Auto Sets
The AUTO SET positions in edit mode are not ordinary knobs. Instead of setting a value, they send preset values to each parameter in that row. Two positions have specific jobs1:
- AUTO SET 0 recalls the original settings from before you began editing1
- AUTO SET 1 generally sets things to default or "off"1
Subdecay's product page listed the standard Prometheus 3 with a shipping time of up to 1 week as of December 7, 20231. The maker also lists a B-stock version of the same pedal2.
What reviewers and players say
Published comment on the pedal is thin, but the filter community follows it closely. In a Guitar Pedal X news post, Stefan Karlsson wrote, "I have and love the Prometheus, but I really quite want the Moof too!"5, placing the Prometheus among the rarefied filter pedals players collect alongside the Audio Kitchen Moof.
Videos
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Questions
How many presets does the Prometheus 3 store?
The Prometheus 3 stores 11 user presets that you can save your own settings to. Beyond those, the Preset/Select switch can be flipped to BANK mode to reach factory presets, and the Preset and Select knobs give access to eleven categorized banks of sounds.
What do Auto Sets do on the Prometheus 3?
In edit mode, the AUTO SET positions send preset values to each parameter in a row rather than acting as ordinary controls. Setting the AUTO SET to 1 generally sets things to default or off, while AUTO SET 0 recalls the original settings from before you began editing.
Are the two filters controlled separately?
Yes. Like the MS-20 it draws on, the Prometheus 3's analog high pass and low pass filters are controlled separately, so each filter can be shaped on its own terms.
Is the Prometheus 3 analog or digital?
The heart of the pedal is analog: Subdecay describes it as an analog high pass and low pass filter pair inspired by a 1970s monophonic synthesizer classic. The preset and editing system around those filters is what stores and recalls your settings.
What is the B-stock version of the Prometheus 3?
Subdecay also lists a B-stock version of the Prometheus 3 Dual Super Filter, sold through the maker's own product page. It carries the same MS-20 inspired dual filter design and the same 40 editable parameters and 11 user presets as the standard version.
Sources (5)
- Prometheus 3 Dual Super Filter, Subdecay, 2023-12-07
- Prometheus 3 Dual Super Filter B Stock, Subdecay, 2026-09-26
- Which Synth Pedal is for Me?, Subdecay, 2024-08-15
- ENV-CONTROLS, Subdecay, 2022-12-23
- Guitar Pedal X, Guitar Pedal X, 2026-09-02
