All demos

RhPf Electronics Mostard

Mar 7, 2026

The Mostard by RhPf Electronics is one of those boost pedals that instantly makes your guitar feel more alive and present, like switching from a 15-watt practice amp to a cranked Marshall stack. At its core, the Mostard delivers up to plus 30dB of ultra-clean gain, but it’s the way it enhances your guitar’s natural character that makes it special. This isn’t just a volume knob; it’s a sonic magnifying glass that brings out the attack, clarity and harmonic content you didn’t even know was hiding in your signal.

What I love about the Mostard is how it handles different pickup types and playing dynamics. Single coils get that shimmery, articulate boost that cuts through any mix, while humbuckers maintain their warmth but with added punch and definition. The circuit design is beautifully transparent: it doesn’t color your tone so much as reveal it. Whether you’re pushing a clean amp into sweet overdrive or boosting an already cooking tube amp into singing sustain, the Mostard responds to your touch and playing style rather than imposing its own character.

Controls

The Mostard’s panel is refreshingly simple: three tone knobs across the bottom (Low, Mid and High) with a smaller Gain knob mounted above them, and a single footswitch with a status LED. Low tightens up the bottom end, Mid smooths out boxiness or adds clarity depending on which way you turn it, and High adds sparkle or softens harshness. Gain is the boost engine itself, dialing in that plus 30dB of clean headroom. In the demo above I’ve set up sweeps for the Low, Mid, High and Gain knobs, so you can hear each one working on its own before you start stacking them together.

How It Sounds

The presets show how differently those three tone knobs can shape the same clean boost. Mid Riffer leans on a healthy Mid setting with the Gain pushed high for a boost that sits forward and cuts through a riff-heavy mix. Beefy Boost flips that around: Low cranked, Mid and High pulled way back, for a boost that thickens up the low end without getting muddy. Cutting Boost splits the difference with more High and Mid dialed in for an articulate, present push. Chug Boost pairs the Mostard (Low and High both maxed, Mid at zero, Gain in the middle) with a Big Muff for a scooped, chunky front end feeding the fuzz. Across all of them the boost stays clean rather than gritty, doing its job by reshaping frequency balance and adding headroom rather than adding its own grind.

Mostard vs Lava Booster Mk2

The Lava Booster Mk2 is the other Class A MOSFET boost worth comparing here, but the two take different approaches. The Lava is a single-knob design that runs from transparent buffer at unity gain into warm, tube-like overdrive when you push it hard, so its whole job is gain staging along one axis. The Mostard splits that job across four knobs, giving you Low, Mid and High tone shaping alongside the Gain control, so you’re sculpting frequency balance as much as you’re adding volume. If you want one knob that takes you from buffer to breakup, the Lava is the simpler tool. If you want a clean boost you can voice to sit right in front of your amp or the rest of your board, the Mostard gives you more to work with.

Who It’s For

The Mostard suits players who want their existing tone bigger, brighter and more present without the boost itself becoming a character. It works equally well as an always-on tone shaper ahead of an amp or as a way to punch up a chugging riff into a Big Muff, as the Chug Boost preset shows. If you want a boost that also adds its own grit or saturation when pushed, look toward something like the Lava Booster Mk2 instead. For players who just want more of their own guitar, in a more useful shape, the Mostard delivers.

Specs

  • Circuit: clean dynamic boost with MOSFET technology, up to plus 30dB of gain
  • Controls: Low, Mid, High, Gain
  • True bypass
  • Power: 9V DC, under 30mA, 2.1mm center-negative connector
  • Enclosure: standard 125B size
  • LED and DAVIES 1900H knobs finished to match the pedal’s yellow colorway

Signal Chain

Get detailed specs on RhPf Electronics' website

Similar Pedals

<div data-loopydemos="rhpf-electronics-mostard" data-title="RhPf Electronics Mostard | Loopy Demos" data-width="400" data-height="610"></div>
<script src="https://loopydemos.com/embed.js" async></script>

To embed this demo on your website, copy & paste the code above or customize your demo widget