Monday, 24 June 2013

Sekova FA-II Fuzz

Check out Tonemachines blog post for this 1969 japanese beauty.
Apparently, this is exactly the same circuit that can be found inside Apollo Fuzz and Crestwood Fuzz boxes...
The circuit uses "positive ground" with PNP Ge transistors. Mind the power supply or use a charge pump.

Now verified. Different transistor models/individuals will affect the output level, so it's recommended to use sockets to find out the perfect set. Or you could tweak the board and replace collector resistors with trimmers.


5 comments:

  1. There is a cut missing on the right side of the emitter of Q1 and a 27k resistor between -9V and the base of Q2.

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    Replies
    1. Good call. Thanks. I'll update the layout once i'm back home...
      Did you build it?
      +m

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    2. Yes, but I need to put in other transistors or use trimpots for biasing to get more output. I used Russian 1T308b (pin-out BCE) PNPs.

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    3. Cool. I'll tag this then with a note...
      +m

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  2. Built a npn silicon version today with silicon diodes and after some tweaking it became quite good, swapped the two 5,6k resistors at q2 to 3,9k to reduce some gating and put a 500 audio taper for volume, could probably go higher because the volulme reaches just above unity. A 2n5088 for q1 and 2n4401 for q2 worked best for me. The attack knob is quite interesting, it pans between the 1nf capacitor and 220nf cap and goes from dirty, skanky, almost FY-2 - like fuzziness to a bassy deep growl. Now it's sounds quite evil, reminds me a bit of a Death by Audio design or something. Just wish the sustain was longer and the volume higher...a post boost is in the works for sure.

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