audio taper vs. linear pots

[gnugear]

I've noticed that dfferent fuzz schematics call for either a linear or log pot ... does it matter or is it just a personal preference?

[gnugear]

Okay, I just found out that it controls the sweep of the pot. Now I want to know why you'd ever want to use a linear pot if the sweep isn't as gradual? Is it best to use audio for all your pots?

[80k]

Okay, I just found out that it controls the sweep of the pot. Now I want to know why you'd ever want to use a linear pot if the sweep isn't as gradual? Is it best to use audio for all your pots?

different functions respond differently.  audio works well with log pots.  linear works better for other functions, like frequency or tone (although i've seen log used for tone)... depends on the circuit and the function.  they both have their purpose, and the goal is generally to have the sweep as gradual as possible.

[MartyMart]

I've started to use linear taper for almost everything, I just prefer the increase.
Log pots seem to have all the change "bunched up" at the top of the pot.

Marty.

[Mark Hammer]

If this isn't an FAQ, it oughta be, because I'm tired of writing it.

"Taper" describes how much you have to change the pot to get a change in resistance at different points along the travel/rotation.  Some audio parameters - volume in particular, and occasionally pitch/pulsation/oscillation rate - are such that our ears will hear things as changing in an unsmooth fashion if the amount of resistance change per degree rotation is constant.  Other things benefit from the pot having an identifiable "middle".  This is most clearly the case for Baxandall-type boost/cut controls and balance/mix controls, where having an identifiable "middle" provides useful information to the user.

Other than that, however, it is often the user's choice as to which they prefer.  For example, if one had a fuzz that was generally used with the distortion amount dimed, but occasionally turned down just a bit to achieve subtgle shades of severe distortion (the low gain range is systematically ignored), it might be wise to use a log pot wired up so that all the low gai settings were squeezed into 20% of the pot's rotation and the remaining 80% was for shades of burn.  Another player might find a use for ALL gain ranges, in which case a linear taper would give roughly equal "dialability" for all settings.

Taper can sometimes be used to cheat.  It was a common strategy years ago to stick in linear taper volume pots in guitar amplifiers.  With such a taper, there would be little actual change in perceived volume beyond a setting of maybe 3 out of 10.  The person in the showroom would think "Wow, if it's THIS loud on 3, imagine what it would be like on 9!"

In general, though, unless otherwise indicated, use log for volume, depth, rate, and sensitivity pots, and linear for tone.  All other uses can be your choice, or rather, the choice of what's in your parts bin.