Without going into great detail so as to tip off the builders out there..."3-knob Tone-Bender pedals" like the Soul-Bender run transistor #3 (Q3) at near shut-off with regards to biasing, and Q3 depends entirely on a germanium diode that's connected to it to be nearly matched with regards to forward drop. Bottom-line is you actually have to use a bad (leaky) transistor in Q3 spot to get the pedal to sound even halfway good!
Mike pulled out the germanium diode and Biased Q3 transistor in a "non-conventional manner" and named it SB-2 v2.
Some other positive side-affects of this mod include:
1) cleans up VERY well by turning the guitar's volume knob down...something NO "3 knob tone-Bender can do! Just turn the FUZZ knob full clockwise.
2) the SB-2v2 is 3-4 times louder than a normal Soul-Bender or "3 knob" clone.
3) tone control to the rich-sounding full-Bass (full clockwise)
The Fulltone Soul-Bender is based on the legendary Colorsound and Vox Series III ToneBenders made by Sola-Sound/England in the late '60's that was used by Beck and Page on much of their circa 1968-70 recordings.
The Soul-Bender cleans up when you back-off on the guitar's volume control. This pedal has tons of tonal character and even harmonics and of course, true bypass w/ LED.