OD trim/pot with 346k - a must have!

[hans-jörg]

Hi Gents,

very, very interesting replys.
Dont hesitate ...

Thank You.

Hans-Jörg

[martin manning]

Another part of the equation to this would be when selecting a value pot for OD trigger...Consider where the wiper is set in the trace..Lower settings of the pot you have larger series resistance, which effects the high end frequency response...100k set 50k will be brighter than say the 346 set the same being darker or some might consider it smoother.. Thought I would mention..

Another good thing to consider... it's amazing how many implications a simple voltage divider can have, eh?

If I'm not mistaken it's the parallel combination of the series and shunt resistances of the 220k series resistor and the trimmer, plus the 68k grid resistor that you need to look at. In this case the result is similar, since the corner frequency is 10.6kHz for the 220k w/ 350k trimmer, using a 100p input capacitance for OD1, and it'd be 11.6kHz for a 220k w/ 100k trimmer, with both set at a "worst case" 100k to ground. A 100k trimmer set at 25k would be up at 17.5kHz.

edit: forgot the 68k grid resistor, so I corrected my figures... the series 68k really moderates the difference with the larger trimmer resistance, but brings the knee down into the upper audio range for the 100k to ground settings.