I wanna new sub, one that will make the earth quake, and my heart jump.  My current home theatre setup uses a pair of Velodyne MiniVee 10″ sealed subwoofers.  They aren’t too bad, but I never felt they did an adequate job of the last half-octave in the 20-80 Hz LFE range.

So how to proceed?  I have always liked sealed subwoofers.  That requires moving a lot of air, so why not an 18″ driver, the big boy?  I also thought the approach of Bagend to use a professional driver with electronic equalization was an interesting approach.  The sensitivity of pro 18″ woofers is in the 95-99 dB range compared to the 84-92 dB range for home theatre products.  The box size is kept reasonable by tuning to relative high frequency.  Electronic equalization is used to make up the difference.  In the case of Bagend, they equalize down to 8 Hz !!!  That’s really low, and from reviews I have read requires at least two 18″ drivers for a home theatre setup.  My goal is more modest, say 16 Hz would be nice, 20 Hz more realistic, with one 18″ sub.

So I started to poke around Parts Express and see what they had in the pro 18″ department.  The target was a box size of 2 cubic feet and a sealed Qtc of 0.707.  That put the cut-off frequency of 75-85 Hz for the candidate drivers suitable for a sealed enclosure (many pro drivers are designed for vented or horn enclosure designs).  A sealed enclosure rolls off at -12 dB for each octave, so the amount of equalization required would be expected to be +12 dB at 40 Hz and +24 dB at 20 Hz for a 64 Hz target cut-off.  That’s a lot!  Assume a 97 dB efficiency, then to operate at 100 dB would require about 2 watts above 80 Hz, and around 512 watts at 20 Hz by these numbers!  Assuming of course that the driver has enough Xmax.  That is around 8 mm of driver excursion for an 18″ driver.

One of the candidate drivers was on sale, the PVR Audio 18SW2000.  It would achieve a 82 Hz box tuning in 2 cu ft (actually a little less).  Xmax looks good.  Power handling more than enough.  The frame is cast, not stamped.  And did I mention it is on sale?