So Where I work we have 4 of these used in a large theater, I fell in love with them, so I spent the better part of the day dissecting one and getting all of the measurements from it.
Built mine based on the JBL 4645 THX certified Movie theater sub.
" 800 Watts Continuous Pink Noise, 1600 Watts Continuous Program Power Handling
Usable response to 22 Hz (-10 dB, no EQ), flat to 22 Hz (-3 dB) with External EQ
2242H SVGTM Super Vented Gap Cooled Driver- High Sensitivity- Minimal Power Compression- Highest Maximum-SPL Capability- Extremely Low 2nd and 3rd- Harmonic Distortion- Symmetrical Field Geometry SFGTM- Magnet Structure- Extended Excursion Capability
Approved by Lucasfilm, Ltd. for THX installations
TRANSDUCER: JBL Model 2242H 460 mm (18 in) Low Frequency Transducer
Rated Impedance: 8 ohms
Minimum Impedance: 7.2 ohms
POWER HANDLING CAPABILITY:Continuous Pink Noise: 800 wattsContinuous Program: 1600 wattsPeak Power: 3200 watts
Axial Sensitivity:50 Hz to 500 Hz; 99 dB, 1W @ 1m40 Hz to 100 Hz; 97 dB, 1W @ 1m
Power Compression:At -10 dB power (80 W): 0.6 dBAt -3 dB power (400 W): 2.0 dBAt rated power (800 W): 3.3 dB
So one entire sheet of MDF later and a few days I have this,
~10 Cu ft. box tuned to 30Hz single 18" JBL pro sub weighs in at 131lbs.
At 1,200 Watts program thing rocks the house!
Hard to capture scale in the pic, but it is the size of my fridge minis a few feet in height.
Here is an older pic of my sound rack ( Yes I still rock the tape player )
The lower JBL UREI Amps are the ES600 model, I have one bridged running the single 18'
I used a slightly different driver, I went with the 2241h JBL Driver.
Long story short, I corner loaded it and I am in love! feeling the room shake was a surprise for the low end response of that driver rolls off around 25Hz with a EQ i was able to boost it slightly. but I feel the low end is more than enough.
Just thought I would share, I will be painting mine soon and may even put the JBL logo's on the side... and may even build another in the future...