3-4 inch drivers:Most systems operate at a lower crossover point because of this important consideration: they ARE USING 6-7 INCH MID RANGE SPEAKERS. For off axis performance,and for the ability to adequately handle the frequencies between 1200 and 3000, having a lower crossover is very important. However if your mid range units are 3 inchers, then off axis performance is less of an issue(especially in you average living rooms anyhow) and coverage in the upper midrange is already assured.
see:(using 34 3-inchers per side, and 30 domes with a c-to-c of