
"I've devised a simple four step modification to the Plan B Model 12 that adds a switch-selectable overdrive which in effect puts the M12's jewels in a vice - adding a ton of filth, angst, resonance and vinegar to an otherwise pensive filter.
In short, I think you'll love it. So much so that all stock currently at our dealers will be updated in the next couple of days. It will be called the Model 12 Mark II.
It's a very simple modification which requires a single resistor to be bridged across the first vactrol. I strongly recommend this be done via a panel switch because it will keep the filter permanently angry otherwise. Any 'pretty' sounds previously associated with the Model 12 will be gone for good without that..
The resistor value I recommend is a 330 ohm (bands are orange - orange - brown). This gets it nice and pissed off. For the cavalier among you, you may wish to be more aggressive with your selection. A 100 ohm resistor will through it into self oscillation when the res pot is fully CCW. Warning - It'll be shrill and LOUD. Before you opt for the 100 vs. the 330 possibly you'd like to test them both first to see which you like best. I felt a 330 ohm was sufficient.
A step by step (there's only three) list of directions with photos can be found on the Plan_B_analog_blog yahoogroup here
Go to the photos section and open the 'Model 12 Modification' folder. Everything you need is there. It's quite easy. It requires a single DPDT switch, a single 1/4 watt resistor, about three inches of wire and (optional) heatshrink tubing to cover the resistor body and switch terminations.
enjoy.
- P"