Pot Value

[Shakey 1047]

I am going to build this circuit in my Ernie Ball volume pedal, the only thing I need to know is, is the pot value at the output of the circuit critical, and should it be "log" or "lin." I know it says "lin" but I just wondered what difference it would make if I used "log" as I have loads of them. Appreciate any help.
Thanks Dave.

[tedmich]

it will sound different and possibly inferior! Trite, I know but I find the choice of log/linear usually requires experimentation.

[Mark Hammer]

The rule of thumb is that if you need to know what "middle" is, then you use linear. So, boost/cut controls are linear. If the control is adjusting level, then log is generally preferred, because that's how our ears work. If the control is adjusting "rate" (i.e., an LFO in a modulation pedal), reverse log is generally preferred, since it spreads out the relevant changes to resistance in a better manner and maks it easier to dial in variations in faster speeds.

In a great many other cases, it is entirely a matter of taste and preferences. One person may find a log pot ideal for changes in distortion drive, while another person may find that it clumps too many degrees of distortion (that are of interest to them) into too small a range of rotation. In those instances, try one taper, and if you don't like it try another. There are no hard and fast rules.

[Ronsonic]

ATMO, that pot is non-critical. The value can be anything from 10-100K. Now the taper may be another issue if you find all the level change bunched at one end or the other of the travel and it's touchy to adjust. If so you may be able to adjust the taper by adding a resistor from one end or the other to the wiper.