Kove Z-12
Of all the subwoofers in this test, the Z-12 is the only one that is recommended to be used only in a vented box. As well, a large, square port is suggested for high power applications. So that's exactly what was cooked up - a 2.7 cubic ft. box with a square vent. Like the Massive, I had to pop out the passenger seat to get the box in the extra cab.
As the only single voice coil woofer in the test, the Kove was at a disadvantage because of its nominal 4-ohm rating. Max power from the Rockford Fosgate amp comes at 2 ohms, but the 1500.1 was certainly able to run the Kove at its 750 watt continuous rating.
Starting with sound quality and the "Folon" track from Salif Keita, the Kove was a little flat. The kick drum beats kind of ran into each other with audible overhang. Same for the Nirvana track, but output was better.
A switch to bumpy bass was in order. Turn on the radio. Now you're talking. Instantly the Kove came alive. A turn of the volume knob to the right and everything in the truck was vibrating.
The Kove was at its best, however, on the Outkast CD. "Spaghetti Junction" worked so well that I was encouraged to sample other tracks. The whole mix on the "Stankonia" just seemed to suit the Kove. The only thing I wished for was a dual voice coil version of the Z-12 in order to achieve a 2-ohm load and work the BD1500.1 for everything its got.
The Kove Z-12 excels at big boomy bass. It will do some regular listening and is pleasant at low levels, but you're best to just know that this woofer was meant to thump.
Crystal Mobile Sound CMPx2 12
This is kind of the dark horse of the bunch. At $499, it's the least expensive of four very expensive woofers. Oddly enough, the CMPx2 12 is the heaviest by far. Visually, it appeared to have the smallest surround of the bunch (though it is still huge) and a machined top plate and t-yoke that get good visual marks.
The CMPx2 12 got stuffed into a 1.7 cubic ft. vented box for our tests. This is a very reasonable size for a ported enclosure. The port recommended was four inches in diameter, possibly a little small for a woofer that is capable of moving massive amounts of air. To my surprise, no vent noise was noticed during our test.
First track through was Salif's "Folon." The CMPx2 12 initially seemed a good match for the Massive in terms of sound quality. Things were fairly tight with considerably less overhang than any of the other three. But with such a low tuning frequency, you should almost expect this. Switching to Nirvana, things got even better. The bass and the kick drum were distinct and had great impact, though I wished for a little more SPL here at mid and low volumes. I found it on Cheb Mami. Here the synthesized bass notes were pumping the sub to big excursion levels with some overlap of the high bass notes.
On Yello's "Rubberband Man," the CMPx2 12 got the best results of the bunch at accurately hitting the cascading frequencies of bass notes. Again, output was a bit shallow at low volumes, but from a musical standpoint, the response was exceptional.
Like the Kove woofer, the Outkast CD produced the best results with the CMPx2 12. In the first 30 seconds of the CD there is a repeating bass line that, as it turns out, changes frequencies. None of the other woofers were able to reveal this, but right off, with the Crystal CMPx2 12, I could hear the bass note change frequency midway through. You know a speaker is doing its job when it reveals things others do not.
While the output at mid and low volumes may have lagged slightly, the CMPx2 12 was able to produce some serious sound quality. The Crystal is likely on the same level as the Earthquake and the Crossfire subs from the previous tests in sound quality, yet with a bit more output.
All Told
After all the testing was done it was simple to draw a few conclusions. For the most part, all of these subs are purpose built. They're like dragsters, dB dragsters. Forget about sound quality. The only one to hit a home run in that ballpark was the Crystal CMPx2 12.
Each of these heavyweights is big and expensive. You had better be dedicated before buying a few of these subs -- or have a lot of credit on your card. You're also going to need a serious system to build around them. Big amps, high current power delivery system and a fairly large box.
This group was the best matched of the three tests. They all fit the SPL bill and they all could take a serious beating from one of the biggest amps in the industry. The Eclipse seemed to suffer somewhat from its fairly small cone, while the Crystal, Kove and Massive woofers were pretty much an equal match, but only when you played them with big bumping bass music -- forget the rest.
Save your pennies boys and girls because all these subs mean business and a small farm of them will cost you as much as a winning scratcher ticket.