AW: Lin/Log Pots?

[Haible Juergen]

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>CV input amount to a summing node to control CV on VCO,VCF,VCA etc.
>VCF, Filter cutoff, Resonance
>A,D,S,R pots on Env Gens.
>
>Would it also be dependent on the circuit design?

(1) 	Use linear pots where you want to control a small range with good 
resolution. (example: fine tune knob on a VCO)
(2) 	Use log pots where the range is large, and you want to have 
decent resolution in the low part of the whole range as well. 
(Example: FM intensity on a VCO. You'd want very small amounts for 
vibrato, and sometimes you want large amounts for weird effects. 
Standard, i.e. not voltage controlled, ADSR belong into this category 
as well.)
(3) 	Use linearpots where you want large range (as in (2)), but 
already have an expo converter in your circuit (example: Cutoff knob 
on a V/oct VCF)
(4) 	Sometimes you want such a large range, that log pots are just not 
sufficient. Then you would choose Method (3) even if you don't need 
voltage control of the parameter. (example: ENV or LFO times from 
milliseconds to minutes with a single knob)
(5) 	Sometimes you need the higher resolution at the CW end of the 
knob rather than on the CCW end. Then you have the choice: Find a "neg 
log" ("reverse audio") pot, or make a compromise by using a lin pot 
and some additional resistor (bad method, IMO - don't beat me!), or 
use a slider instead of a rotary knob, and use it upside down, or find 
a rotary pot where you can put the axle (sp?) in from the rear rather 
than from the front (they do exist!), or, best of all, use method (4) 
and do it electronically. (Example: Resonance of some 4-pole filters) 

JH.