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  • Mosrite Fuzzrite Fun

    I've built pedals [fuzz] for years and I've recently been investigating the many versions of the Fuzzrite [silicon and germanium]. So far I haven't built a germanium version due to finding transistors that would work in the circuit. There are also different versions of the silicon model and I'm not sure which is the "fuzziest"!
    There is also the Rosac Nu-Fuzz but I'll start a separate thread on that..
    I'm posting the most common Fuzzrite schematic but not really sure it's correct.
    Any FuzRite freaks out there?
    Attached Files

  • #2
    Looks reasonable.
    Now just build one and upload some Audio.

    I remember a close friend in the early 70īs (I am in Argentina and way back then any US made stuff was not availble here and very expensive to import) asked his Mother who was visiting some relatives in Miami to buy him a Gibson 335.

    She was flabbergasted by the price (converted to Argentine Pesos) so she gladly accepted shop salesman "second option": a Mosrite "335" , specially after he threw in a Mosrite Fuzz as a "deal sweetener".

    He was VERY disppointed at first, but then the guitar was surprisingly better than he expected, and the Fuzz was quite usable too.

    We didnīt expect a pedal to "imitate an overdriven amp" by any means, it was an "effect" on its own right, and we were pleased by the "violin/mosquito" type sustained sound.

    You gave me an idea, Iīll probably breadboard and try one myself
    Juan Manuel Fahey

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    • #3
      Yup, good place to start!

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      • #4
        Here's an interesting one....
        Attached Files

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        • #5
          That schematic is basically correct for the silicon version of the Fuzzrite. The distortion depth control is marked as 350K, but were often 500K in the original units. The output volume control was the same value pot, but it has a resistor in parallel that reduces the value to somewhere around 33K. I don't remember the original value, I'd have to look it up.

          The pots were the same ones that were used in the guitars at the time of manufacture, so they could be 350K or 500K. The current Caitlinbread version uses 500K linear pots.

          The circuit contains two inverting stages, so there is a certain amount of phase cancellation at different settings of the distortion depth control. In the middle of the rotation there is a point where the pedal will act like an Octavia pedal, giving you either octave doubling with the neck pickup at higher fret positions or sitar like sounds with the bridge pickup at lower fret positions. At higher settings of the depth control the sound will get very thin and as Juan mentioned, "mosquito" like.

          Have fun!

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          • #6
            Originally posted by 52 Bill View Post
            That schematic is basically correct for the silicon version of the Fuzzrite. The distortion depth control is marked as 350K, but were often 500K in the original units. The output volume control was the same value pot, but it has a resistor in parallel that reduces the value to somewhere around 33K. I don't remember the original value, I'd have to look it up.

            The pots were the same ones that were used in the guitars at the time of manufacture, so they could be 350K or 500K. The current Caitlinbread version uses 500K linear pots.

            The circuit contains two inverting stages, so there is a certain amount of phase cancellation at different settings of the distortion depth control. In the middle of the rotation there is a point where the pedal will act like an Octavia pedal, giving you either octave doubling with the neck pickup at higher fret positions or sitar like sounds with the bridge pickup at lower fret positions. At higher settings of the depth control the sound will get very thin and as Juan mentioned, "mosquito" like.

            Have fun!
            Thanx! Guess I'll just have to try some different transistors in the circuit to see which ones fit best.

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            • #7
              I had a run on building fuzz pedals a couple of years ago and a Fuzzrite built with Soviet ex-military Ge transistors gave a really good 'Spirit in the Sky' sound. I forget what type, but the unusual characteristic with some of the Soviet transistors is they give the forward voltage drop you'd expect with Ge but the low leakage of Si.

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              • #8
                I think the germanium version is slightly different. I've built a dozen of them and will post the schematic when I get home.
                Last edited by mozz; 05-10-2021, 01:54 PM.

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                • #9
                  There seems to be a few different circuits for a few different transistors. The Ge version would be more unstable.
                  I wonder if low gain would sound better?? So far I tried the schematic I posted with no luck. I'm real curious about the Guild Foxey Lady circuit..

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                  • #10
                    Not really unstable, more internet false info. Under the right conditions it works fine. It does have a weird sound as you are combining or choosing 2 signals that are out of phase. The Guild foxy lady is a totally different circuit as it's basically a big muff variant , which there are 17 versions of. Click image for larger version

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                    • #11
                      Originally posted by Brian W. View Post
                      There seems to be a few different circuits for a few different transistors. The Ge version would be more unstable.
                      I wonder if low gain would sound better?? So far I tried the schematic I posted with no luck. I'm real curious about the Guild Foxey Lady circuit..
                      The first version of the "Foxey Lady" was what I meant. It has some similarities to the Mosrite.

                      Probably pretty difficult finding the ge transistors for the Fuzzrite. The reason they went to silicon was the affects of temperature on the Ge's.
                      Attached Files

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                      • #12
                        You can find the 2n2613 and 2n408, just takes time. Most any germanium will work if the gains and leakages are close to the original, Q1 is higher gain and leaky, Q2 is lower gain and not as leaky. Just found a dozen 2n5133 so they are out there too.

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                        • #13
                          Originally posted by mozz View Post
                          You can find the 2n2613 and 2n408, just takes time. Most any germanium will work if the gains and leakages are close to the original, Q1 is higher gain and leaky, Q2 is lower gain and not as leaky. Just found a dozen 2n5133 so they are out there too.
                          I just built the Foxey [I had some 2n5133's laying around]. I'm pretty unimpressed.
                          A few years back I built a Tonebender MK 1 [the one that Gary Hurst morphed out of the 3 - transistor Maestro FZ fuzz] and I spent some time getting the gains and leakage right. When I finished I went back to the good old TB MK 2 circuit!

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                          • #14
                            Here is my favorite fuzzrite: The DAM Fuzzrong FR-70
                            I used a Ksp42 in q1 and a 2n4401 in q2 and it sounds excellent!

                            Click image for larger version

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                            • #15
                              I just built this Orpheum Fuzz. Pretty much a Fuzzrite circuit. I didn't have a 10 Meg resistor so I substituted it with a 2 Meg and am wondering how that is affecting the overall sound of the thing.
                              Attached Files

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