At 04:06 PM 2/3/2005 -0500, Steven C. Barr wrote:
>...but don't the audio taper and loudness controls attempt to
>for the way the ear/mind works by varying the signal in non-linear ways...
>either by varying only the signal level to approximate what is heard as
>the control is adjusted, or varying the actual frequency response to
>the response of the ear? If you used only a straight potentiometer...no
>would you wind up with most of the volume variation at the lower end of the
The loudness control is altering the frequency response of the system
(i.e., output is not just a scaled version of input) while the audio tape
pot is just a human interface convenience so that rotation approximately
corresponds to the level difference you're hearing. You can use a linear
pot, it's just fussier to adjust.
With linear or audio taper pots, the frequency response of the output is
exactly the same as the input in a properly designed circuit. Either pot in
an improperly designed circuit can show some high-frequency rolloff, but
that is poor design, not intent.
With the loudness control, the bass and treble are boosted more and more as
you turn the level down...or that's how it should be to match the
Fletcher-Munson curves I sent the link to yesterday. So, turn the level
down and you're turning down the midrange more than the highs and the lows.
So, no, I still don't see the similarity. You could use a gear train and
cam arrangement or a 10-turn pot to change the human interface on the
linear pot. The audio taper pot is just a simple, cost-effective
implementation for hand-to-control interface. Nothing to do with the
electrical signal except scaling it up or down.
Richard L. Hess email: [log in to unmask]
Media web: http://www.richardhess.com/tape/
Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX