Bass: GBS Fuzz

This is the GBS, it developed from a chat with JSA Effects (1) about adding some buffering in front of the Bazz Fuss, a simple but powerful-sounding fuzz circuit. I ended up adding a passive Muff-style tone control plus gain recovery stage for some EQ as I had an unused half of an opamp. Fatter coupling caps also make it more appropriate for bass frequencies.

1. The buffer is standard Klon-style (2) but the gain stage uses a BC549C instead of the 2N5088 seen in many Bazz Fuss builds and is biased by the 3.3M R5 resistor. This gives the fuzz more "growl" and saturation to my ear. I borrowed this from a Brazilian company called Epider Sound and their Heavy Metal pedal (3). The addition of the R5 doesn't seem to work with BC549Bs, so make sure you have the right transistor.

2. D1 can be swapped out with other types of diodes for different textures - other silicon (1S1588) or BAT41/46 are good starting points for more open vs compressed gain.

3. Right now, the gain recovery stage is set at 10 dB (470K/47K for the non-inverted second amp). A B500K pot could replace the 470K (R11) if you wanted the option to dial it back. I will definitely try this on the breadboard again, since this fuzz can get really saturated.  

4. The tone control has corner frequencies of 1540 and 800 Hz, but these are easily modified with standard BMP tone stack values (4).   

5. You may want to socket the 47nF cap C12, it's what worked best for a bass fuzz but can be customized for your own tastes. This cap has a big impact on the amount of background hiss.

Fig. 1, GBS Schematic

 

The perfboard layout is pretty straightforward and I managed to get it all together without any jumpers. As of right now, this exact layout is unverified. The one I used for the pedal build needed a few fixes so I worked in changes to clean up the wiring for this layout.

 

Fig. 2, Perf Layout and Mask (Reversed)

 

Here's a few pics of my build, since I used a DPDT switch there is a daughter board with the Millenium 2 bypass for the indicator LED. A 3PDT switch means you don't need this tiny board. 

 

Fig. 3, GBS Build Apr 2023

 

Demo vid:

 

Fig. 4, It's only 1 minute