Subdecay Proteus

The Subdecay Proteus is an envelope and sample/hold filter in one compact pedal. In its current mkII form it combines two ways of sweeping a filter: an envelope follower that reacts to how hard you pick, and a random sample/hold mode that jumps the filter to random pitches in time with your tempo. Subdecay describes it as their "plug and play filter," a simpler take on the ideas behind their earlier Prometheus pedals¹.

At the heart of the pedal is an analog OTA based filter design similar to vintage Maestro units, with an all analog signal path. The digital side is control only: it handles tap tempo and the switching between envelope and random sample/hold filtering².

What it does to your sound

An envelope filter listens to your picking and opens and closes a filter in response, the effect behind classic funk auto-wah sounds. A sample/hold filter instead jumps the filter's cutoff to random values on a clock, producing the stepped, synth-like burbles heard on records from the 1970s. The Proteus mkII gives you both in one compact pedal, with digital control for switching between envelope and random sample/hold filtering².

Subdecay positions the two modes with distinct characters. On the earlier Proteus Auto Filter, the maker described the envelope mode as "much more 'funk' than 'shoegaze'" and the step filtering as "pure random sample hold"⁴. The mkII keeps that split: envelope mode for touch-responsive sweeps, sample/hold mode for randomized, arpeggiated filter jumps.

The resonance control shapes how much the filter emphasizes its own cutoff point. Subdecay says it "allows the filter to go from subtle to nasty greasy synthesizer grit," and that the control "adds a new dimension to the effect that goes from subtle to greasy gritty synth tones"².

Controls

The dual color LED gives status at a glance: green when the effect is on, red to show the filter's modulation, so you can tell whether you are in envelope or sample/hold mode even when the filter is bypassed².

How tap tempo works

Tap the Tap/Mode switch two to four times in time and the pedal starts a tap tempo random arpeggiator, its name for the sample/hold mode. The filter then steps to random positions on a clock locked to your tempo. Hold the switch down for one second and the pedal reverts to envelope filter mode².

The 1-2-4 control sets the step rate: one step per beat, two, or four, which Subdecay describes as quarter, eighth and sixteenth notes. It affects sample/hold mode only².

On That Pedal Show, Dan and Mick walked through the earlier version's tap function, noting that you have to hit the switch four times to start the random filtering⁵.

Where it came from

The Proteus grew out of Subdecay's Prometheus line. The original Prometheus was a highly regarded analog envelope filter whose step sequencer and random sample/hold features set it apart from more traditional auto-wah pedals⁶, but it was a deep pedal to learn. Subdecay has said the Proteus came "from the ashes of the original Prometheus" and "embraces a very different philosophy," describing it as what many people wished the Prometheus had been: simpler and easier to use on the fly⁴. The filter circuit in the original Proteus was exactly the same as the Prometheus's⁴.

The Proteus was the product of a multi-product R&D effort Subdecay called Project Quasar, designed as an "Anti-Prometheus" focused on ease of use⁴. In Subdecay's company history, Brian Marshall writes that the pedal took over a year from the initial vision to complete and became a big hit, changing the company's direction and its approach to laying out functionality for more complicated products⁷.

The mkII, introduced in 2019, is a redesign rather than a reissue. Subdecay's changes from the original Proteus include a new design closer to the Maestro Filter Sample/Hold and a switchable band-pass and low-pass filter¹.

The Maestro connection

The Maestro Filter Sample/Hold is the pedal the Proteus mkII's new design is described as coming closer to¹². Subdecay says the mkII is a new design closer to the Maestro Filter Sample Hold rather than a copy of the original Proteus circuit².

The Proteus is related rather than a clone. Subdecay says the mkII is "a new design closely related to the original Filter Sample/Hold," built on an analog OTA based filter similar to vintage Maestro units². For players chasing the original, the Maestro's own sample/hold behavior even has a dedicated internal trimmer, R26, a 100k part that affects only the Sample & Hold function⁸.

Power

The mkII can be powered at up to 18 volts for maximum headroom². This is a change from the original Proteus Auto Filter, which ran on an external regulated 9VDC to 12VDC adapter with a negative center 2.1mm barrel plug and had a 1M input impedance⁴.

Versions and pricing

B-stock mkII units have appeared at $135.00, fully functional and covered by Subdecay's standard 3 year warranty¹.

Related Subdecay filters

The Proteus sits in a wider filter family from the maker:

• Prometheus DLX: a resonant filter pedal that also operates at 18 volts for more headroom¹⁰
• Prometheus 3 Dual Super Filter: keeps the random sample/hold filter on the menu among its modes¹¹
• Proteus Auto Filter: the original, simpler version of this pedal⁴

For a broader look at the category, see filter pedals.

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