Types of Fuzz (circuit topololgy?)

Discussion in 'Effects [BG]' started by blindrabbit, Jan 27, 2013.

  1. Tried to do a search on this to no avail, so hopefully the collective wisdom of TB can help out.

    I know a little bit about fuzz. I've had a few and enjoyed them, and I've listened to move videos and clips than I can count of the endless pedals out there - so I know there are hundreds if not thousands of different options. I'm also developing an interest in starting to build some pedals and fuzzes from kits, which had led me to wondering...

    How many different types of fuzz circuits are there?


    What are the general (NOT specific to any given pedal) characteristics of these circuits that may or may not lend themselves to use with bass, or certain applications.

    This is more of an academic interest, so I'm hoping to not get into a debate about one pedal or brand over another, or how one is just "the best". I'm sure they all have their pros and cons, otherwise only one type of circuit would exist, right?

    To start, here is some of what I've read and learned to date (feel free to correct any errors, by no means am I an expert).

    Types and characteristics seem to include:

    Fuzzface (with varieties include germanium and silicon circuits, also the Sunface) - I've read these being referred to as "transparent", but also finicky and sensitive to a lot of factors such as your guitar or amp.

    Muff (endless versions of muff circuits) - more often than it seems that not the mids are relatively scooped, but that can be addressed through component changes

    Brassmaster - originally designed for bass, retains low end relatively well


    Octave fuzz


    I can imagine that there may be all sorts of entirely unique circuits out there that would be interesting to hear about, but it seems like a good list could be generated of the common ones.

    One final point - I'm really only asking about fuzz at the moment. I know it gets more complex when we start to talk about different types of overdrive or distortion, so how about restricting just to "fuzz" for the time being? :)
  2. Whoops...I forgot Tonebenders, and I've read that these tend to not retain much low end.
  3. jetofuj


    Jun 16, 2008
    When it comes to Tone Benders there are at least few versions:

    MkI, Mk1.5 (circuit topology is very similar to Fuzz Face), MkII (long board version, short board version), SupaFuzz MkI (similar to MkI, but with tone control instead of attack), MkIII and IV (esentially the same circuit, but with different transistors and values), Jumbo TB, Supa TB...

    + you've also get Fuzz Tone (3 or 4 versions), Fuzzrite (ge and si + Rosac Nu Fuzz), Fy-2, Fy-6 (there are many variants of SuperFuzz with small tweaks like Ibanez Super Fuzz or Ace Tone Fuzz Master), Octavia, Jordan Bosstone (at least 3 versions), and many, many others :)
  4. ...perhaps there are more than I thought there would be. I was thinking maybe 6-10 types (with permutations within), but is that an underestimate?
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  6. How about Gated fuzz like a mammoth? :bag:
  7. I was wondering if "gated fuzz" was a type of circuit in and of itself, or just a modification to an existing circuit type. However, as best as I can tell, it does appear that the Mammoth is its own beast, so to speak.
  8. grygrx

    grygrx Lookout! Here comes the Fuzz! Staff Member

    Dec 24, 2003
    Columbia, MO
    Mammoth appears to be a majorly tweaked fuzz face.
  9. Plucky The Bassist

    Plucky The Bassist Bassist for Michael "Epic Mic" Rowe Supporting Member

    Jul 30, 2010
    Houston, TX
    Which ones are you talking about? The ones they are pumping out now retain quite a bit of low-end, especially compared to most of the big muffs.
  10. I have a monster fuzz by pro tone, and it's not made to replicate anything. I never really wondered about circuitry. :confused:
  11. The circuit topology doesn't really affect whether a fuzz will be "good" for bass or not...the main thing seems to be sizing the coupling capacitors to pass bass tones (or not as the case may be). There are coupling capacitors at the input and output of the circuit, and often a "bias bypass" cap (for transistor fuzzes) or a feedback filter cap on op-amp distortions that controls what frequencies get distorted. Fuzz circuits with multiple gain stages like the Big Muff also have caps to connect the stages together.

    There is no "right" value for these coupling caps, they are a compromise, a trade off. For guitar use, fuzz pedals often intentionally limit the bass frequencies because distorting the bass frequencies makes a "muddy" or "flubby" distorted tone. If the coupling caps are too small, the fuzz tone can sound thin or weak. It's possible to build a fuzz circuit and have sockets where you can test and experiment with different caps in a circuit without having to solder them in and out of the circuit board every time.

    Basic fuzz pedal circuit topology summary:

    Two-transistor, direct coupled stages:
    Fuzz Face, Woolly Mammoth, ect. The Woolly Mammoth is very similar to the original Fuzz Face circuit except it uses silicon transistors, a passive tone control, and a variable bias feedback (the 'bite' control).

    Three-transistor fuzzes
    (most) Tone Benders. There's a couple of variations, one design uses a 1-transistor boost/buffer stage feeding a fuzz face circuit, another uses a fuzz face stage and feeds a final output buffer/booster stage. The ancient Maestro FZ-1 and rare Burns Buzzaround are also 3 transistor fuzzes.

    Big Muff: 4 transistor multistage fuzz
    The most complex fuzz circuit so far, it has a buffer/boost stage, then two clipping stages that use a transistor amplifier but limit the signal with diode clipping, then a final buffer stage for the tone control.

    RAT, Tubescreamer, OCD ect: op-amp based distortions
    There are many varieties of the same basic circuits. The RAT is probably the simplest of these, electronically. The RAT uses clipping diodes tied to ground after the op-amp to clip the signal, the tubescreamer uses clipping diodes in its feedback loop to 'softly' clip the signal. Again there are one or two capacitors in the feedback loop that control the gain vs. frequency, and therefore the 'voice' of the distortion. The "Ruetz Mod" for the RAT removes one of the feedback capacitors. But like the transistor fuzzes, the coupling capacitors will affect how much bass gets into and out of the circuit.
  12. Thanks Crater! I may chatter on more later on this topic, but in the few seconds that I have right now, you've hit on exactly the kind of information I was looking for. I did know that caps values and the like had substantial impact upon the appropriateness of a given circuit for bass, but I had also read in a number of areas that other aspects of the nature of the circuit did too. I'd not read before anything distilling it down to 2, 3, and 4 transistor descriptions. I'll give this a closer read later on.
  13. I think clipping method would be a major factor, though honestly the EQ (pre/post) makes the biggest difference.

    Diodes (to ground or in feedback)
    Saturation (pushing an active element past its limits)
    With each, component choice affects how the signal is clipped. Gain is important, since it affects how much of the signal is clipped off.
  14. johnk_10

    johnk_10 vintage bass nut

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    some designs also use diode clipping, mosfet clipping or use multiple stages of fets (with no diode or mosfet clipping) for the overdrive/distortion.