log vs linear

[{ antonio }]

is there really a difference between a log and a linear pot?

and if a schematic doesnt say what it is, then what is the default?

thanks.

[RDV]

Hey there, check this out!

http://www.diystompboxes.com/cnews/FAQ.html

RDV

[Mark Hammer]

Is there really a difference?  Sometimes yes and sometimes no.

My rule of thumb is this.  If you ever have to know where the "middle" is (e.g., tone boost/cut control, blend control), use a linear pot.  If it has anything to do with volume (e.g., envelope sensitivity control, mixer mic level), use log.  

For everything else, the need to use log or linear will depend on what part of the range you are most interested in.  For example, suppose you want to select a pot to control the LFO speed on a phaser or chorus.  What partof the speed range are you going to be most finicky about?  Do you tend to ignore faster modulation and only really use speeds of 1hz or slower?  Do you normally use that pedal to sync the modulation to the song tempo so you need to have the ability to dial in many variations between 1.5hz and 4hz?  The key issue here is how many degrees of pot rotation do you need to have the settings of interest to you spread over?  Sometimes this will dictate a log, sometimes a linear,sometimes a custom taper, and other times nothing less than a range-switch-plus-pot or even 10-turn pot will do for the needed precision.