KSR Custom Shop Haggis Pi Deluxe - 1973 Big Muff Pi Clone


KSR Custom Shop

The Haggis Pi

The Haggis Pi is an exact copy of an original 1973 Ram’s Head Muff that I own. This pedal was dissected and analyzed thoroughly. I have played through so many muffs. I truly love them! I’ve had ones that were awesome and some that were poor. I kept this one because it was… well, just incredible. It sits here with me forever. All of the original components were measured; transistor gain stages (Hfe) were analyzed. See below for more info…..

The Haggis Pi Deluxe Version

The Deluxe version of the Haggis PI has an added Linear Power Booster (LPB) added to the circuit. Ever put a booster before a muff for that lead solo break through? It adds extra volume and sustain to cut through the rest of the band. The booster is not just an EH LPB circuit. It is voiced to give a slight treble boost which is really tasty. Much time was spent to optimize the boosters sound and how it reacts when engaging the Big Muff circuit.

Slightly close to what I’ve seen others recently offer (such as a switch to set the volume pot to full volume...not really the same thing; limited). So I added a LPB style circuit to the board, a pot to control the volume of the booster and an additional stomp switch so either MUFF or LPB circuit can be used alone or TOGETHER! Awesome!

Basically this one pedal is two individual pedals in one enclosure. The booster or Big Muff can be used individually or together. The booster is staged before the muff of course. You can adjust the volume of the booster to where you like it as a booster and then you can adjust it again for your taste when using it in combination with the Big Muff.

Both circuits sound awesome. The Muff just absolutely rips, you have the duplicated circuit from my original ’73 FS39666 transistor big muff. Voltages of the replica are extremely close to my original.

So enough of my rambling, if you have questions feel free to ask.


  • True bypass wiring for both circuits.
  • Cloned 1973 Ram's Head Circuit Board #3003
  • Contains 2N5133 NOS transistors which have the same characteristics as the original famed FS 36999 Transistors that came with these pedals.
  • 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 a LPB (Linear Power Booster) styled circuit. Can be used by itself or together in front of the Big Muff circuit.
  • Contains the famed 1973 Ram’s Head Big Muff PI circuit. Can be used by itself or together after the LPB circuit.

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