How much eq to realize 12 hz extension?
Well, realize, I did not mean I will EQ it flat to 12Hz. I was talking about it's maximum output at 12Hz. In average size room, corner loaded, at 12 Hz, two of these should be able to produce a minimum of 110dB; and likely closer to 115dB. By 25-30Hz, 130+ dB should be easy. This is in sealed 5 ft^3 boxes and powered with 2000 watts. Of course, these units can handle substantially more power.
The specific EQ I will likely use is a parametric band centered at 20Hz with 6 db of gain, and a Q of 1.2 to 1.5. This gives a free field response of -3 at 19Hz, -6 at 16 Hz and -12 at 12 Hz. At no point is excursion close to mechanical limits with a 2000 watt input under these specific conditions. The AXIS 15 has around a 45mm one way mechanical limit, and a linear range of 28mm one way.
I was going to use JL Audio 12W7 drivers, one per channel. But the AXIS 15 is even more capable then 13W7; when it went on 1/2 price for the PE DOTD I had to take advantage.
-Chris
