At 03:03 AM 2/4/2003, Chris DeLong wrote:
>This part that you stated; was it measured by ear or by a meter or scope of
>some sort. a common misunderstanding about audio potentiometers (your volume
>knob) is that is you have it cranked halfway up you are using half of the
>power the amp has to deliver. This is not correct. Thats why dB's are there.
>every increase in volume by a knob designed for an audio application is not
>linear. It essentially doubles the power for every increase in SPL. I.E. at
>"2" on the knob you might be using .25W. at "3" on the knob you might be
>using .5W. and so on ans so forth.

To clarify a little more, the Bel and tenth-Bel (deciBel) were developed by
Bell Telephone engineers for the purpose of telephone communications, and
they're deliberately designed to reflect the way your ear works.  One
decibel difference produces a volume change that is perceptible to a
careful and/or trained listener; 3 dB is easily detected by anyone, and 10
dB gives a difference in perceived volume of about double or half.  In
terms of actual power in a circuit, or acoustic energy in the air, a 3 dB
change represents double or half power, and 10 dB, or one Bel, is ten times
or one-tenth the power. A dynamic range of 90 dB, easily achieved on a CD,
represents a range of power of 1:1,000,000, but "only" an audible
difference of about 1:500.

david

--
David Beierl -- dbeierl@attglobal.net