Muir Audio Design Silicon Steel Boost

The Muir Audio Design Silicon Steel Boost is a boost pedal built around a transformer-based gain stage, announced on 31 October 2024. It provides up to +21 dB of clean level, active Bass and Treble EQ, and a Heat control that adds subtle harmonics without pushing the signal into overdrive breakup¹².

Guitar Pedal X's Stefan Karlsson reviewed it as a high-headroom, high-fidelity tone enhancer: "It delivers high-headroom clean boosting, subtle harmonics, sparkle, and active Bass and Treble EQ"¹. Delicious Audio's Paolo De Gregorio described the transformer-based gain stage as giving the pedal "a unique warmth"².

A clean boost with up to +21 dB

The Silicon Steel Boost is designed to raise your level cleanly rather than to clip your amp or the pedal itself into breakup. Guitar Pedal X describes it as a "Super Hi-Fidelity High Headroom Tone Enhancing Boost" that never induces overdrive breakup, with the Boost control delivering up to +21 dB of level¹. Delicious Audio calls it over +21 dB of gain and notes it "brings a fresh take on the boost stompbox format with a transformer-based gain stage"².

On power, the pedal runs at 9V, where Guitar Pedal X found headroom and volume already substantial, and offers an 18V input option for even higher headroom¹. That makes it a fit for players who want to hit the front of an amp harder, or drive long pedalboard chains, without the boost itself running out of clean level.

The controls

The pedal has four controls¹³:

The Heat control is the one that sets this apart from a plain level boost. Guitar Pedal X explains that "Heat uses soft Asymmetrical clipping for subtle Low Order Harmonics, without overdrive breakup"¹. Delicious Audio puts it in plainer terms: "the 'Heat' knob lets you dial in just the right amount of saturation for a clean yet rich boost with a touch of transformer character"². So Heat is a seasoning control, not a drive control: it thickens the boosted signal rather than turning the pedal into an overdrive.

Because the Bass and Treble controls are active, they cut as well as boost, which lets you reshape your tone at the same time as you raise your level, for example trimming bass before pushing an amp, or adding treble for a solo lift¹.

What it shares with the Silicon Steel Overdrive

The Silicon Steel Boost is not a stripped-down version of Muir Audio's overdrive. Guitar Pedal X is explicit that it is "a totally separately originated circuit," developed to deliver ultimate high headroom, and that the only hardware it shares with the Silky Smooth Saturating Overdrive sibling is the same Audio Output Transformer¹. Delicious Audio frames it slightly differently, saying the Boost is "based in part on the company's Silicon Steel Overdrive, but a brand-new circuit optimized to work as a boost"². Either way, the circuit is its own design, built for clean level rather than saturation.

The Silicon Steel Overdrive itself is a transformer gain stage overdrive pedal, which Delicious Audio says makes low strings resonate with chords and gives higher gain a distinctive overdrive with a unique harmonic profile⁴. Guitar Pedal X's 2023 roundup characterized it as a "Superb silky smooth overdrive heavily reminiscent of the Carlos Santana 'Europa' sound," with the combination of superior components and the hi-fidelity audio output transformer delivering superior results⁵.

The two pedals now sit in a three-pedal Silicon Steel Series that Guitar Pedal X calls "The Silicon Steel Series Trifecta!": Boost, Overdrive and Distortion⁶. The distortion model carries Output, Drive, Bass and Treble controls⁶.

What reviewers said

Guitar Pedal X's review was positive on build and intent as well as sound¹:

Stefan Karlsson, Guitar Pedal X¹

The Silicon Steel Boost also drew a positive verdict from reviewers, with one describing it as "a proper pro studio grade tool" that "exudes high quality overall" and rating it highly recommended¹.

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