[LAD] Fader mapping - was - Ardour MIDI tracer

Ralf Mardorf ralf.mardorf at alice-dsl.net
Wed Aug 20 20:42:17 UTC 2014

On Wed, 2014-08-20 at 07:37 -0700, Len Ovens wrote:
> However, Mixers don't look like that, the area from plus 10 to -10
> takes up a whole lot more room on the fader travel than anything lower
> than that. [snip]
> It appears that faders do not have linear or log taper, but rather
> some custom taper

"Audio taper

The most used non-linear taper is the logarithmic (log) or audio taper.
This is mainly used for audio volume control, to obtain a more natural
‘linear’ perception in sound intensity change when you adjust the
volume. Because the human ear is sensitive to sound intensity in a
logarithmic fashion, at low sound intensities a small change in
intensity is perceived as a big change in loudness, while at high
intensities a large change is required for the same change in perceived
loudness. To compensate for the ears logarithmic behavior, audio taper
pots were developed. While it is called logarithmic, it is actually an
exponential curve (the opposite of the logarithmic behavior of the human
ear).  Sometimes inverse logarithmic (anti-log) pots are used, for
example in audio controls which turn counterclockwise, but also in some
other specialized applications.

The dashed lines in the graph below show the ‘real’ logarithmic curves.
In practice logarithmic types which are used for audio applications do
not really behave in a correct exponential way, but follow the curve
stepwise."- http://www.resistorguide.com/potentiometer-taper/

"P&G [snip] have a real Logarithmic law.... (Alps is a “Audio Taper”)" -

More information about the Linux-audio-dev mailing list