LaScala and Q of driver

[drboar]

I had the impression that the lower the Q the better for a horn driver

I have "Kuben" something that looks simlar to a La Scala but with in my case 12" drivers.

The drivers were measured using Omnimic at 50 cm distance with the horn on a chair in the middle of the room. Same voltage in all measurements

Black trace is a Beyma G320. A real horn driver with a Q of below 0.25 and Fr of about 60 Hz

Red trace is a Eminence driver Q of 0.5 and Fr about 50 Hz

Brown trace is vintage Gamma LA1232. Fr 25-30 Hz Q 0.4 and Vas = 300 liter it should be unsuitable as a horn driver and have a mass rollof above 150 Hz or so.

In a PA setting the Beyma is vastly superior to the Gamma with 10 dB higher sensitivity and better power handling as well. Hower, if we compare the -10 dB point relative to the averege 200-1000 Hz output the Beyma reach -10 dB at 90 Hz while tha Gamma has this point at 55 Hz.

It does appear that suitable Q in horn is a matter of application and that mass roll off and bass horns not allways match up

[djk]

The mass corner affects the upper response limit.

A driver with a lower mass corner generally has the same LF (which is determined by the mouth area and taper rate), but will have more maximum output due to its greater x-max.

The D130 is at least 3dB more efficient than the 2226, but only in the 500hz (mass corner region).

Pick the lowest efficiency driver that will go high enough to meet your mid driver.

The 2220 is about the same as the D130, the 2225=2226.

Note how the more efficient driver is only more efficient at the higher frequencies. The 2235 is the least efficient, but will have the highers maximum output below 50hz due to its higher x-max.