
Key Points
Drunk Beaver’s Pedal Drop #37 — the Bashtanka Muff — is a mostly faithful OpAmp take on the EHX Big Muff 2, released on Pi Day (3.14). Key changes include moving low-end filtering from ~0.7 Hz to 15 Hz, a tone switch that toggles between the Big Muff tone stack and a simple low-pass (resulting in louder, no-mid-scoop voicing), MC4558 op amps for higher fidelity, NOS TFK SAL41 dual silicon diodes for clipping, and a Motorola MC1478 used to buffer a virtual ground. Thirty units are available for $150 / €150 / 559 PLN on the Drunk Beaver Rocks webstore. No dedicated demo was made for this rapid-prototype release; Big Muff 2 reference samples were used instead.
The Bashtanka is a mostly unadulterated take on the recent EHX Big Muff 2 circuit. Vitalii wanted to explore the potential of that circuit, with additional fixes for Low-end filter (e.g. 0.7Hz filtering in the original gain section looks odd for an audio circuit and might cause issues); Vitalii moved those to 15Hz.
The key mod is a tone switch which sits between the Big Muff tone-stack and a simple Low Pass Filter (louder, no mids scoop). On the components side - Vitalii deployed MC4558 OpAmps (supposed to be more high fidelity than RC4558 or JRC.NJM4558). Those were used in older Nobels ODR-1 batches.
Also deployed are NOS TFK SAL41 dual Si diodes for clipping - housed in an unusual package that looks like a transistor!
Finally, for a PSU virtual ground buffering a vintage Motorola MC1478 OpAmp is used.
So all-in-all this is a relatively faithful copy - distinct for its Filter / Muff EQ toggle-switch.
There will be 30 units of the Bashtanka Muff which go for $150 / €150 / 559 PLN on the Drunk Beaver Rocks Webstore.
This will be the 3rd Big Muff 2 take in the collection. I have the original Nano EXH variety, a one-off Gigahearts take (a gift), and one of these Bashtanka’s is on the way now too!
Of course, as a rapid prototyping release there is no demo for this pedal. While it should be very famlari territory - I’ve used one of the Big Muff 2 demos for sound-sample purposes.

