Potentiometers: what do you suggest??

Christopher_List at Sonymusic.Com Christopher_List at Sonymusic.Com
Thu Jun 12 02:51:34 CEST 1997






> You could put a 1M fixed resistor in parallel with an appropriate
> value of linear pot. I forget the details but the fixed res is
> called sonmething like a 'log-law-faking resistor'.

This works fine when the resistor is placed between the wiper and ground on
a pot set up as a voltage divider. Unfortunately, in this case the pot is
set up as a rheostat. If I put a resistor in parallel with pins 1 and 2 of
the pot, I'd wind up with a log pot (85% of max resistance at 50%
rotation), which is actually the reverse of an audio pot (audio pot = 15%
resistance at 50% rotation).

I've tested this by doing many a chart in Excel plotting things like
resistance vs. pot rotation, output voltage vs. pot rotation for various
pots hooked up to various circuits - you guys should try it and you'll see
what I mean. It's a lot of fun. You put your total pot value and key
resistor values in cells at the top of the page and use 'em in your
formulas - this lets you try different values easily. Best part is that
anyone who walks by your desk thinks you're doing budgets for fiscal '98!

To Gene's question about the popping vs. thumping; It's definitely the fast
attck popping, and yes, it is useful in some circumstances. The problem is
that I can't get a really fast attack without the popping - like the kind
of attack I get with a 800 - 1K resistor - the attack is either poppy or a
little too soft.

- Chris





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