In the loudspeaker power discussion a few weeks ago you stated:
The 8 ohms is a ficticious value based on V/I (rms) at some
>frequency, including the effects of the back emf and the
>acoustical load at that frequency.
Not true with engineers I have known. Impedance is based on an average of *all* frequencies from 20 through 20,000 Hz.
an amplifier as a source behind impedance (along with
>feedback loops etc) doesn't obey Ohm's Law.
Ohms law may be applied nevertheless in simply form as: P = I^2 Ret where P = power dissipated into the load connected to the amplifier Ret = total resistance of the load, i.e. coil, core, and air load resistance.
ns