John Fields <starship at freeside.fc.net> wrote in article
<5n6gft$on1$1 at yakuza.fc.net>...
>>> Consider an amplifier with an 8 ohm output impedance feeding 8 volts into
> a speaker with an 8 ohm impedance. The speaker will be dissipating 8
> watts of power and will generate a specific sound pressure level.
>> Next, consider the same amplifier putting 8 volts into a 16 ohm load.
> Since P = E^2 / R, the power being pumped into the load is 8^2 / 16, or 4
> watts, which will yield a lower sound pressure level.
>> The assumption, of course, is that both speakers have the same efficiency
> and are, in fact, identical except for their impedances.
If you assume enough, then specific cases where a general statement seems
incorrect can be contrived.
My problem is that I've seen so many combinations of efficiency and
impedance, and I know a little about where efficiency and impedance come
from in terms of design.
In the end one decides that they are, as a rule, orthogonal to each other.
Which is why most folks specify them separately.