All this talk of 15" and 10" and power into each driver is all very well. These are 'nominal' impedances and power ratings. Using ohms law and DC is OK but in reality the impedance of each speaker varies at different frequencies. The impedance of the 10" is unlikely to be the same as the impedance of the 15" for any given frequency so the power distribution will be much more complex than just saying 225watts and 4x56.25watts.
But all they give us is nominal figures so fag packet drawings and schoolboy physics are the way to go, and are ok if all you are interested in is whether your speakers or amp will blow first.
E.G. say the 10"s were 25ohms at 40hz and the 15" was 15ohms at 40 Hz, what happens to the power distribution then? How much of that amp power is going to get used at 40Hz and where will it go?
Since the 15" is more likely to have a lower impedance for a given frequency than the 10s, a good deal of your power is likely to go in the direction of the 15".
That's just electrically, never mind what then happens acoustically.
This is why mixing drivers doesn't always sound good, even 2x15" from different manufacturers. Regardless of what you think the specs say, your ears are your friend.
