Source Audio Spectrum

The scale of what is inside is unusual for a filter pedal. Gearnews reported that the pedal contains 25 different filters, dual filter effects, 11 envelope followers, 14 LFO waveforms and 13 distortion effects in total¹. Source Audio describes the dual filter mode as letting you run two different envelope filters simultaneously, each with its own envelope response as well as Frequency, Depth, Direction and Q controls².

What the Spectrum does

At its core the Spectrum is a filter pedal that also reaches into synth territory. By setting the Spectrum's switch and tweaking its four controls you get access to synth sounds, envelope filtering, octave and harmonizer effects⁴. A mini toggle switch chooses between Tron, Dumpling and Crier settings⁴, and the pedal houses a filter effect you can program via an external USB input⁴¹.

The deep editing happens away from the pedal. The Spectrum connects to Source Audio's Neuro editing tools over USB, and Guitar World counted 29 different filter options available through that software, alongside stereo inputs and outputs⁵. Gearnews described the result as "the most flexible and powerful stereo filter effect pedal of all time," which is Source Audio's own positioning rather than an independent verdict¹.

For players who want a simpler filter pedal without USB editing, Source Audio's earlier filter designs such as the Soundblox 2 Stingray Multi-Filter and the Soundblox Bass Envelope Filter cover similar ground with fewer options.

The controls

The Spectrum uses a four-knob control system with a twist: each knob has two functions, so you can adjust up to eight parameters via the ALT (alternate) switch³. Gearnews lists the knobs on the top of the pedal as Input/Sense, Depth/Mix, Freq/Res and Speed/Vol, with the second level of parameters activated by the Alt button on the front¹.

MusicRadar's NAMM report described the control set in plainer terms: Depth, Speed, Frequency and Mix⁶. A mini toggle switch on the pedal chooses between Tron, Dumpling and Crier settings, three named filter voicings⁴. The pedal itself is purple⁴.

The Alt button is worth understanding before your first session, because half the pedal's surface controls are hidden without it¹:

Presets, MIDI and connections

The Spectrum ships with 128 presets pre-installed. Six are accessible via the pedal's own toggle switch, and the rest are reachable via MIDI²¹. For deeper control, Source Audio says to connect the pedal to the Neuro Hub or any MIDI adapter and use MIDI CC messages to control parameters or recall presets². Gearnews confirms the pedal can be controlled via MIDI through Source Audio's own Neuro Hub¹.

Connection-wise the pedal has twin inputs and outputs⁴, and it is operable in both mono and stereo¹. Guitar World likewise describes stereo inputs and outputs⁵.

Power

The Spectrum runs only on an external power supply. As Gearnews put it, "can only be operated via an external power supply, so no batteries here"¹. If your board runs on batteries or a compact supply, plan for a dedicated power feed for this pedal.

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