KSR Custom Shop Isosceles Pi - 1970-1971 Big Muff Pi Clone


KSR Custom Shop

The Isosceles Pi

The Isosceles Pi is an exact copy of an original Triangle Big Muff PI that was made around 1970-71. It is a clone of a 1st version, second edition Triangle Big Muff known to be one of the best sounding Triangle Muffs. It is described on kitrae’s website as a “V1 Triangle Big Muff 66#11. I have posted two links so you can check it out. All though I have not owned this particular version, I used my experience with various other triangle & Ram’s Head versions such as transistor (Hfe) gain stages and applied it to this clone. This is a unique version of a Triangle Muff as related to component selection and values. It does sound spectacular for sure! See below for more info…..


  • True bypass wiring for both circuits.
  • Cloned 1970-71 V1 Triangle Circuit Board
  • Contains 2N5133 NOS transistors just as the originals came with.
  • DC Power Jack: The standard size 2.1mm Boss style connector for power adaptors.
  • Heavy duty battery clip.
  • Highest quality Alpha brand pots of the correct value.
  • Neutrik jacks.
  • Highest quality resistors and capacitors.
  • Contains the unique 1970-71 Triangle 66#11 Big Muff PI circuit.

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Where to find one?

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