[hum4god]

hi

i am looking for the formula for first dipole peak again.
what is the relationship between baffle width and first dipole peak frequency ?
i did some sims in edge for two 12" drivers on a 620x320 baffle which gave me a baffle peak at 900hz ,but still would like to get the formula.

is it safe to crossover right at dipole peak freq. to maintain polar pattern if crossover slope is very steep ?

i am thinking of using two 12" baffle/driver per side up to 1000hz , or if that is too high employ a 6" driver for this range.

[Rudolf]

i am looking for the formula for first dipole peak again. ...
i did some sims in edge for two 12" drivers on a 620x320 baffle which gave me a baffle peak at 900hz ,but still would like to get the formula.

It is safer to simulate the peak in edge. Notice how the peak is wandering with different positions of a driver on the OB. Any simple formula will be less exact.

is it safe to crossover right at dipole peak freq. to maintain polar pattern if crossover slope is very steep ?

Scientifically exact would be one octave below the peak. But that would force you into a four-way-system. Crossing near the dipole peak would be a good compromise IMHO. But you don't think of 12 dB/oct as "very steep", don`t you?

i am thinking of using two 12" baffle/driver per side up to 1000hz , or if that is too high employ a 6" driver for this range.

The biggest problem is the distance to the next driver for anything above 1 kHz. The distance should be no more than half the wavelength for 1 kHz: 17 cm. You hardly can achieve that for the upper driver - no way for the lower one. So expect hearing voices from the floor.
To put it into perspective: I feel very adventureous when I dare to cross at 500 Hz from a 15" to the next driver.

Rudolf

[hum4god]

thanks Rudolf
as always , good advice.
i will stick with the edge for dipole peak .
 when i say steep crossover  i mean 96db linear phase or so.
distance of driver no more then half the crossover frequency , damn , i forgot about that .
does that mean center to center of drivers?
if i use the 12" in mtm configuration i would at least have both of them close to the tweeter.
but i might end up with a four way, i was just hoping i can keep it a little simpler . i will try and let my ears decide .