Electro-Harmonix Big Muff Pi 2

The Electro-Harmonix Big Muff Pi 2 is a fuzz pedal from Electro-Harmonix, released in 2025 in a nano-sized die-cast chassis¹. What makes it unusual is where its circuit came from: a hand-drawn schematic by Bob Myer, the designer of the original Big Muff, sketched in the late 1970s and never built. It sat in Myer's files for decades until Josh Scott of JHS Pedals and EHX archivist Daniel Danger found it while researching the history of Electro-Harmonix, and Scott decoded it and brought it to production¹².

The circuit is a Big Muff variant that runs on two dual op-amps instead of the transistor gain stages of the classic Big Muff Pi¹². Electro-Harmonix describes the result as similar to the classic Big Muff Pi but with a unique fuzz tone, with singing sustain, gobs of gain, a crispy top end and booming lows¹.

The dual op-amp circuit and the Bob Myer schematic

The story starts with a loose sheet of paper labeled "BIG MUFF USING (2 DUAL OP AMPS)" found among Bob Myer's old notes⁴. It was Myer's own attempt to reimagine the original transistorized Big Muff circuit using the op-amp technology that had emerged later in the 1970s⁵. The design did not make the cut back then and was stashed away¹. MusicRadar reports that EHX boss Mike Matthews never released it because he felt it strayed from the traditional Big Muff voicing⁶. Its existence only came to light when Josh Scott was interviewing Myer for the book Made On Earth For Rising Stars: The Electro-Harmonix Story⁶.

Guitar World's reviewer notes that Bob's design is unique compared with the famous late 70s Op-Amp Big Muff designed by Michael Abrams⁷. The JHS product page details the differences: a different clipping arrangement, an extra gain stage, and various other elements⁴. A Guitar.com circuit analysis adds that the Big Muff 2 puts an extra pair of back-to-back clipping diodes in the first gain stage, where almost all other Big Muff variants only clip in the second two of their four gain stages⁸.

On sound, the JHS page describes the two dual op-amp approach as pushing into more aggressive, cutting territory, with a sharper edge, more volume, and the most pronounced low-end and midrange of any EHX Big Muff ever⁴.

Controls

The Big Muff Pi 2 uses the classic three-knob Big Muff array².

The footswitch is a first for a Big Muff: silent true bypass switching with latching or momentary action¹. Press and hold for more than half a second and the pedal acts momentarily, so you can get a burst of fuzz for as long as you hold it; the momentary action can be disabled¹⁶. MusicRadar's reviewer found this dual-action footswitch one of the pedal's clever features⁶.

JHS x EHX Big Muff 2

Before the nano EHX version, the circuit first appeared as the JHS x EHX Big Muff 2, an official collaboration between JHS Pedals and Electro-Harmonix⁹¹⁰. It shipped in a big-box wedge enclosure, limited to 5,700 units, priced at $249⁷. Guitar World reported the announcement in December 2025, noting the schematic had spent 50 years buried in dust¹⁰.

The JHS version runs on 9VDC center-negative at 18mA and carries the same Volume, Tone and Sustain controls⁴. A yellow Third Man Hardware version, 300 units, was sold in a deluxe book bundle⁹, and Jack White played one of the early prototypes⁹. Guitar.com describes the EHX nano Big Muff Pi 2 as the compact follow-up to that large folded-metal first release².

Deluxe Big Muff Pi 2

In 2026 Electro-Harmonix released the Deluxe Big Muff Pi 2, which the maker calls its most versatile Big Muff ever, giving the dual op-amp circuit the same deluxe treatment as the Deluxe Big Muff Pi¹¹. It is available now at a US street price of $188.20¹².

The Deluxe keeps Volume, Tone and Sustain and adds¹³:

• BLEND knob for wet/dry mix, from 100% dry to 100% distorted¹¹
• GATE knob setting the noise gate threshold; fully counterclockwise disables the gate¹¹
• 3-way WICKER switch: OFF is the standard Big Muff Pi 2 sound, HALF adds a touch of high frequency, FULL opens up the high-frequency bandwidth¹⁴
• Footswitchable parametric MIDS section with FREQ and LEVEL knobs, and a Hi/Lo Q resonance switch¹²
• EXP input for sweeping the MIDS FREQ with an expression pedal (1/4" TRS) or control voltage from 0 to 5V on a TS plug¹¹

MusicRadar notes the mids frequency range runs approximately from 310Hz to 5kHz, and that hooking up an expression pedal to control the mids by foot is "pretty cool"¹³. Premier Guitar suggests the EXP input enables real-time control over the mids frequency for "freaky fuzz wah effects"¹². Unlike the nano version, the Deluxe uses buffered bypass rather than true bypass¹¹.

Power and connections

The Big Muff Pi 2 ships with a 9V battery included, with an adapter optional¹. An optional 9VDC center-negative supply can be connected to the power jack instead; the pedal requires 15mA at 9VDC, and the maker's limit for the power jack is 12VDC¹. Input and output are standard 1/4" jacks, mono, with input impedance of 117kΩ and output impedance of max 2.7kΩ¹⁷.

The Deluxe Big Muff Pi 2 draws more current, 45mA at 9.0VDC center-negative, and a 9.6VDC-200mA power adapter is included in the box¹¹. It adds an EXP jack alongside its audio input (2MΩ) and output (500Ω)¹¹.

Price

Electro-Harmonix lists the Big Muff Pi 2 at $122.00¹, which matches the US street price Bass Magazine reported at launch in December 2025 and the $122 launch price Guitar World and MusicRadar list¹⁵⁷⁶. Thomann affiliate listings tracked by Gearnews have shown a lower street price of $93.00 in December 2025¹⁶. The JHS big-box version was $249⁷, and the Deluxe Big Muff Pi 2 lists at $188.20¹¹.

What reviewers said

Guitar World's review of the nano version awarded five stars for build quality, calling the construction "tip-top" with the silent momentary/latching switching an added bonus⁷. MusicRadar's reviewer called it a valid choice, particularly for players who value something heavier and more aggressive⁶. Guitar.com rated the Big Muff 2 8 out of 10, concluding:

On the Deluxe, MusicRadar's Jonathan Horsley wrote that "the core sound is fantastic" and that with the Wicker switch, expanded EQ, footswitchable mids, onboard noise gate and Blend control it "might well be worth an upgrade" over the three-knob version¹³. Gearnews called it possibly "the ultimate dual op-amp Muff for shoegaze and beyond"⁵.

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