Here's an octave fuzz I've been working on. Q1 and Q2 set up a NPN Fuzz Face. Which is working well on the breadboard at the moment.
Q3-5 create a frequency doubler, which is quite working. I noted the voltages on the schematic. I suspect I need to get the voltages at the collector and emitter of Q3 to around 4.5V by adjusting R6 and R7.
(http://www.super-freq.com/wp-content/uploads/2011/08/Screen-shot-2011-08-18-at-4.35.17-PM.png)
try making r6 a 10k, its just a basic voltage divider. if you get your values equal you should get 1/2 supply.
I think your on to the right idea. But, it's the voltage at the collector of Q3 that needs to get down to 4.5 volts.
I was thinking about placing a pot across +9v and 0v with wiper at the base of Q3 and adjusting from there?
sure a bias trimmer just wire it as a variable resistor youll need like a 100k at least to start you might beable to go lower but that's where i would start.