On February 6, 2018 at 12:07, Ernie Gilman said...
I saw something new when I looked at this again:
I see why it's tempting to conceive of speakers as drawing power from an amplifier, but here's a parallel situation: if a pipe connects a lake of one elevation to a lake of a lower elevation, does the lower lake draw water, or does the upper lake feed water? It's definitely the latter.
The difference in elevation provides a force to move the water to the lower lake: the force of gravity. With amplifiers and speakers, the voltage at the amplifier output provides the force to move energy into the speakers.
The diameter of the pipe and the difference in elevation of the lake determine how much water will flow. The impedance of the speaker and the voltage of the amp determine how much energy will flow into the speaker.
Which causes water to flow depends on the original water level at the lower body of water. If it was below the low end of the pipe, it couldn't have drawn the water to it and even then, if the upper lake was already spilling into the pipe, the lower one won't affect flow until its level creates enough back pressure that the flow from above is resisted.
Speakers are presented with voltage. What happens after this is up to the speaker's resistance/impedance. If the impedance is extremely high, not much current will flow but the power is still only determined through calculation and it's neither constant, nor is it due to anything more than the fact that a connection between the amp and speaker has been made.