A bass fuzz

[Gus]

Here is a bass fuzz sim

note the use of C5 and R13 to reduce Q1 closed loop gain, they also can cause an EQ around Q1
the bias
the gain control setup that also limits max gain
the lowpass filter in the Q2 collector section

Suggested cap and resistor values are shown adjust to what you like.  Values shown looked good in the sim

Circuit is R8 and to the right the left of R8 is a bass and cable sim

[Bill Mountain]

Have you given any thought on how to handle low end to keep it from getting "farty" sounding?

[Gus]

Have you given any thought on how to handle low end to keep it from getting "farty" sounding?

Yes you can reduce it some with controlling the gain and highpass filters, this does not have a blend circuit so there is only so much you can do with a two transistor fuzz like this

Note R13 and C5.  R13 with a larger cap will reduce the closed loop gain around Q1 to even lower frequencies.   By AC coupling R13 with C5 you also can adjust the frequency when the gain reduction will start to take place gain will be decreased as you go up in frequency to a min of 100K in parallel with 100K
R6 also helps reduce the max gain.
You could reduce R13 even more
As always you can adjust the input cap value C1 to control the low end somewhat.

I drew the gain bias section a little different for some fun.  Something to take away from it is the 220 ohm if the gain is set to max there is always a 220 ohm in series with the cap to the wiper and this acts to limit the max gain and helps with high beta Silicon FF like builds.  Omit or adjust the value.

It has the output lowpass section I like to use with Silicon FF like circuits

Screen shot of the circuits frequency response, input green and output blue with the above R and C  values.  Note the area around 50Hz to 100Hz you can reduce that with a 1uf for C5. 
Sometimes people want a "farty" sounding fuzz with bass

[mac]

Sometimes people want a "farty" sounding fuzz with bass

... and guitar

GregV_SunFace

mac