Bass Modded Big Muff

I modded this pedal for Matt, the bassist/guitarist in local Sydney post-punk band Hira Hira. He would use the Muff as his fuzzed bass sound, and whilst liking the sound, wanted something more bass-friendly. The Big Muff is a great fuzz for bassists looking for a heavier tone so I tweaked this one for use with bass and now offer it as the cubisteffects T-34 Big Muff Bass Mod.

Bassists seek out one Big Muff in particular – the Green Sovtek Russian Big Muff, or “The Tank”. The nickname is apt as it is rumoured to have been built with scrap pieces of tank plating. One of the most formidable weapons in World War II, the T-34 Soviet medium tank blitzed its way through the German forces. Known for its combination of ruggedness and firepower, the T-34 and the Green Sovtek Big Muff have a lot in common.

The tone of the Russian fuzz is similar to the Civil War Sovtek Muff but has more gain, is less smooth sounding and has a touch more aggression. This is ideal for the percussive attack of bass players. A number of selected components are responsible for the bass friendly bottom end the Green Big Muff produces. I have used this pedal as a template, and inspiration, to come up with a number of modifications to tailor the pedal for bassists - to emphasise the depth of a bass’ tone whilst creating a high gain Muff sound. All of this for a fraction of the cost of a vintage Russian Muff. The Green Sovtek Big Muff shares many similarities to the current Big Muff products and these modifications are offered for the NYC Big Muff (as pictured) or the current Black Russian Big Muff.

The T-34 Big Muff Bass modifications also improve on the original hardware and bypass design. What you get in the end is a pedal with a bass sound that has some clean tone mixed with fuzz and a flexibility not seen in any standard Big Muff. This flexibility allows you to pull a number of sounds from the pedal; smooth long synth-like sustain or a splattery loose tone, a mid-frequency EQ’d fuzz for a better place in the mix or a +6dB volume boost.

The T-34 Big Muff Bass Mod has a number of standard, and optional, modifications to transform your standard Big Muff into a unique bass tone monster.

The T-34 Big Muff Bass Mod involves three hardware changes:

  1. TRUE BYPASS – The pedal will have a 3PDT switch installed for true bypass.
  2. DC POWER JACK – The stock 1.35mm DC power jack will be removed for the industry standard “Boss-style” 2.5mm DC jack. This allows daisy chaining  a multiple pedal setup easier.
  3. LED – The stock LED is replaced with a high quality, superbright, waterclear red LED.

The T-34 Big Muff Bass Mod also includes several component replacements. These are to emphasise the low end of the pedal to make it bass friendly. Some ceramic capacitors values are increased to let through more bass. Also, the stock transistors are replaced with Fairchild SE4010 silicon transistors, which gives the pedal a vintage-like bite. I found that these transistors, within a certain Hfe range, complement the bass fuzz sound.  They come in the epoxy dot package, like the Sovteks, and are hand-sorted to ensure the correct current-gain is provided to the circuit. Another modification is done to the diodes in the first stage. This modification “opens up” the distortion, allowing more bass and volume to push through. Also, as you increase the Sustain, the bass response also increases.

Two more mods are also included. These mods have become legendary in the DIY community and are the handiwork of Jack Orman.

  1. TONE BYPASS – A toggle switch is wired to the Tone circuit of the pedal and allows the choice of having the Tone circuit ON or OFF. This switch was found on the late 70′s Op-Amp Big Muff. By bypassing (or turning OFF) the Tone circuit, the pedal has an additional +6dB output. Using this in the bass mod, the tone sounds a touch brighter or has increased treble. It has a great raw fuzz sound that is great on bass. As the Sustain is increased, the attack gets more loose and Fender Blender-esque tones can be achieved.
  2. MID CONTROL MOD - By altering the tone circuit, a pot can be used to control the amount of mids. This provides a better standing in the mix if turned up, or can provide a cut if turned down. Like the Tone Bypass, it alters the original sound of the pedal but does provide more flexibility and ability to achieve a different tone.
    NOTE: The Tone and Mids Control pot will not function when the Tone Bypass mod is engaged as it has been…bypassed.


There are a number of additional options that are offered in the T-34 Big Muff Bass Mod. These added options incur an additional fee and can be seen in the Pricing page.

  • The Diode Mod can be switchable (with a toggle switch as in the picture above). This gives flexibility between the Stock clipping and Modded clipping.
  • The Tone Bypass Mod can be made footswitchable (the pedal would have two switches, ON/OFF and Tone Bypass) instead of a toggle switch. This setup allows the mod to act as a volume/treble boost.
  • A Blend circuit can be installed, with a knob placed aside the Mid Control pot (as seen in the picture above). The blending of a dry signal with fuzz is an important option for bassists and is offered as an extra. A secondary circuit board will be installed in the pedal with a pot controlling the mix of the blend.

Below is a demo of the T-34 Big Muff Bass Mod.
Clip Details: Fender Jazz Bass > T-34 Big Muff >DOD FX-17 Volume Pedal > Fender Bassman
Settings: Rhythm 1 played clean with neck/bridge pickup 50%/50% and Rhythm 2 with neck/bridge pickup 50%/50% and T-34 Big Muff (V: 12 o’clock, T: 11 o’clock, Mid: 12 o’clock, S: 12 o’clock)
Lead 1 with neck pickup 100%, bridge pickup 0% and T-34 Big Muff (V: 12 o’clock, T: 11 o’clock, Mid: Max, S: Max) and cut in/out with volume pedal.
Lead 2 with bridge pickup 100%, neck pickup 0% and T-34 Big Muff (V: 12 o’clock, Tone Bypassed, S: 2 o’clock)
Recording: SM57 > Mbox2 > Reaper

T-34 Bass Big Muff Mod by cubisteffects

Also, here is a recording from local Sydney band Hira Hira. Matt’s T-34 modded Big Muff features in the latter half of the track. Nice work boys!

Children’s Letters to God by Hira Hira. Uploaded by cubisteffects


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