Re: Passive crossovers
I'm thinking the questions was more along the lines of:
"hey, aren't these speakers in parallel? is the amp going to see a 1ohm load? will the amp drive each speaker as if it were 2ohm?"
in anycase, the simple answer is to assume that each speaker is 2ohm for the case of determining power to the speaker, and assume that the amp is driving a 2ohm load.
the idea is that, for any given frequency, only one speaker is playing. or, put another way, the tweeter is only playing the highs and the mid only the lows. the tweeter provides the 2ohm load only at the highs, the mid provides 2ohm only for the lows, so there are no sounds that can be played that would allow the combined speaker pair to seem like less.
at the same time, some notes could be fully concentrated on "low", and played only by the mid. some could (but won't) be fully "high", played only by the tweeter. so even though each speaker isn't playing as wide a range of frequencies, it can't suddenly work well with a larger amplifier because there are sounds that could focus that power on just one speaker.
there are technical reasons that show that the minimum impedance can be lower then 2ohm for some frequencies near the crossover point, but its largely assumed that the amplifier will be built to handle this -- actual music should not have an excessive amount of content in this small bandwidth. For this reason, I wouldn't worry about it.
The above assumes the crossovers were built in a sane manner.
-- Chris, M. Sci, Electrical Engineering
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