Horn centre spacing


2010-07-28 10:47 am
Any thoughts. Many horn based systems have mid/treble horns separated by some vertical distance from the acoustic centres of the drivers, particularly if the mid/treble horn is on top of bass horns, eg, Klipsh, Altec, EV..or even a 2x15, etc.

Pi loudspeakers kindly publish a simple formula for working out the null angles and the greater the distance between driver centres, the narrower the null angle..

Clearly with bass horn (or 2x15 say) beneath them, one is often looking at a driver separation of feet rather than inches? How does this work if you take into consideration most of the horns implemented have narrow vertical dispersion, say+/-20 degrees (40 deg. total) and few can be used much below 800Hz..even 500Hz and you can't get the centres close enough to avoid nulls?

Or perhaps it doesn't matter because the listener/s are much further away??!

Or is there still a benefit in splitting the loudspeaker stack to include, say cone mids, to enable crossover frequencies low enough for each cabinet to fall within the lobe free crossover area?