Help with fuzz face volume clean up

[BobbyWe]

Hello!
I've recently built a BC108 si fuzz face. Basic stuff, nothing fancy going on. Only deviation from the schematic was increasing the value of to resistors to provide more volume.
I'm actually pretty happy with the result, it sounds as you excpect a fuzz face to sound. Only problem is that it doesn't clean up very smoothly when rolling of the volume on the guitar. Rather, the gain drops very steeply from 100% to 50% when turning the knob from 9 to 8. It's more like an extra on/off switch for the fuzz instead of a useful gain control.
Any ideas what I can do to mitigate this?

Edit: the fuzz is first in the pedal chain. Played through a tele and a strat, whose volume sweeps are smooth and even when the fuzz is off, and with other OD pedals.

Schematic:

[iainpunk]

my guess is that is has imperfect bias. what DC operating voltages are you getting on Q2's collector and base?
the Base should be at 0.7-ish volts and the Collector at about 4 to 5 volt.

cheers

[Steben]

Any low impedance circuit like a fuzz face would normally lead to a very non linear volume sweep.
Personally I don't mind this and frankly I like this fragile trick. It takes practice but that sweep over two point makes for quick control.
Does the signal sound glassy clean when backed off? An improper bias would not sound smooth and nicely.
Swapping the 5.1k with a 10k trimpot would give control over biasing.