Electrical Engineering - Paging Don K.

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Paging Don K.

northstar

2008-02-27, 5:25 pm

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

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