Sunday 31 January 2016

Ace Tone FM-3 Fuzz Master

   Another Japanese Big Muff variant, this one has some substantial modifications. This has a footswitch to select between boost or fuzz, but you can't use both at the same time. The boost mode has it's own volume and tone pots. There are also other differences in biasing, filtering, as well as the location of the volume pot (in this circuit it is moved pre Q4) making this an interesting take on the Big Muff.


  1. what nomenclature is the boost switch. I see it DP??. On/On, On/Off, On/Off/On, On/On/On.

  2. Oops. That would be good to know. It is a DPDT footswitch, I've updated the layout.

    Keep in mind this isn't a boost that stacks on top of the fuzz, you get either fuzz or boost. Not both

  3. This is now verified. Awesome pedal

  4. Hi!
    I made my own version of this pedal and it works fine otherwise, but the Fuzz volume is really low. Has anyone here had anything like that with this layout?
    I changed the Fuzz volume pot to 500k and that didn't help. I also tried lifting the 100k pulldown resistor at the Output but that didn't do anything either. Everything should be as it is on the schematic (dated 28-06-2009). For transistors I used 2N3904's.

    1. And after writing the above I saw the FM-2 Beaker Mod here :D
      So, nevermind the mystery above, I think I'm able to modify my FM-3 with Beaker's mods, atleast at some extent.

  5. I just bought one of these, and compared it to Kit Rae's published schematic. There is a resistor missing. I went nuts for a while trying to figure out why Kit's schemo was showing one less part than what I was counting on my board, but I eventually found it. The original has an additional 100K resistor, directly at the input to ground (between INPUT, and the 8k2/3n3 junction). Also, all the 250p caps in mine are 270p.

  6. Also, the 2SC1000's are the GR gain range (200 - 400).

  7. Voltages, from input to output - all controls at minimum, no input, battery @ 9.51v;

    E = 3.7mV
    B = 0.554V
    C = 3.277V

    E = 47.8mV
    B = 0.668V
    c = 4.72V

    E = 33.1mV
    B = 0.647V
    C = 4.48V

    E = 1.168V
    B = 1.769V
    C = 5.20V