Originally Posted by Trimlock
How would this setup work with a radian 745 or faital HF144?
Recommended minimum crossover point 800 hz.
10 degree exit angle, 3 inch coil, 100w AES power handling, 111dB sensitivity on their specified horn. If crossing the driver lower than 800 hz, maximum power must be reduced and crossover slope increased. 1w>100 watt = 20 dB. I'd expect to shave 6 dB minimum off it's maximum output when crossing it at 650 hz as in this design. 111+14 dB= 125 dB. One diaphragm to cover 650 hz to 20 khz. The BMS driver has two diaphragms and two coils to cover the same range. Magnetic gap flux density not specified. No mention if the phase plug is annular or tangerine style.
Recommended minimum crossover point 900 hz. 29 degree exit angle, 2.56 inch coil, 80w AES power handling above 900 hz. Dropping the crossover point to 650 hz, Faital recommends cutting the power handling in half to 40w. 108dB + 40w ( 16dB ) = 124 dB. I would expect to cut that by a further 3 dB, for 121 dB maximum.
One diaphragm to cover 650 hz to 20 khz. BMS has two diaphragms driven by two coils for the same range. 1.7T flux density in the magnetic gap. Annular phase plug.
Midrange diaphragm 3.5 inch coil. HF diaphragm 1.75 coil. 300 hz recommended crossover frequency for midrange diaphragm. 150w AES power handling above 400 hz for the midrange diaphragm. 80w AES power handling for HF diaphragm. Flux density of 1.95T in the gap for the midrange. 2.2T for the HF.
From the original post: "Why build this? Well, 135db sustained anywhere above 100hz AND exceptional sound quality in a reasonable size box. That's what 112dB w/m hi's (with 1300w peak handling!
) and 105 db w/m mids gets you!"
The Radian narrow exit angle of 10 degrees may not the best match for a 90 degree horn. At some frequency at high ka values, the driver will be beaming into a 10 degree angle, and only the side lobes "illuminate" or will be loaded by the horn. Just a speculation on my part, but I would bet the Radian would be a better match for the 60 degree horn version of this box with the 18 Sound XT1464. Polar response curves on the horn would be the best indication if it is suitable.
If you are fine with lower output, you could use a different driver, but there are trade-offs. A driver optimized for HF output will necessarily have tight clearances ( around a half mm or so ) from the diaphragm to the phase plug. This is less useful if you want low frequencies from the compression driver which requires more diaphragm excursion.