[sdiy] Formula for Audio & Log-taper pots?

[Theo]

There are data sheets with taper graphs at the sites of Alps, Bourns and
Taiwan Alpha.
These show some differences in interpretation of what a "audio" taper should
be,
varying from one of the log tapers to tapers with two linear segments that
kind of approximate a log taper.
The claim is that the "two linear segment" tapers offer a more natural
feeling than the log taper they approximate.

Interesting also are some of the "for volume control" tapers,
surprisingly (for me that is) not log but lin except for the first and last
10% forming a steep S.
Still wonder what the intended use is, maybe controlling a log VCA?

Cheers,
Theo



----- Original Message -----
From: Glen <mclilith at charter.net>
To: synth-diy <synth-diy at dropmix.xs4all.nl>
Sent: Wednesday, April 14, 2004 8:38 PM
Subject: [sdiy] Formula for Audio & Log-taper pots?


> I need to explain to a programmer friend of mine the difference between
> linear, log, and audio tapered potentiometers. All the controls on his
VSTi
> are linear taper, and some of them should definitely be either be audio or
> log taper instead. Explaining linear taper is so simple, I don't even have
> to do it.  ;)
>
> I've read that audio taper pots have 15% resistance at the half-way point
> in their rotation, and that log taper pots have 10% resistance at the
> half-way point. Is this generally correct?
>
> Does anyone know of a more precise way to describe the "curve" of either
> the resistance vs rotation, or more importantly, the attenuation vs
> rotation? I would really like to find a formula to calculate the
> attenuation for a given amount of rotation. I'd also be interested in a
> chart of the same data. I need something that will be crystal-clear to
this
> programmer friend of mine. I'm not sure if just specifying the mid-point
> resistance would be enough for him to properly emulate a given taper.
>
> Unfortunately, I don't have any loose pots laying around to make
> measurements of, at this time. So, I thought someone on the list might
> happen to know the answer.
>
> thanks,
> Glen


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