Kove Audio Armageddon Z-12
Kove Audio was founded fairly recently in 1997, but the company owners have been in the car audio business for over 27 years, having founded at least one other well known company. With an imposing name like "Armageddon," the Z-12 was an all-out project for Kove, with Gary Kovner's instructions to his chief engineer to build the best woofer possible, and never mind the cost (for more about Kove Audio, visit www.koveaudio.com).
The Z-12 is built on a cast aluminum frame that has a substantial 40 mm (1-9/16") of reward travel for the spider (this includes a sizeable mounting ring for the spider), painted with a good looking grey wrinkle finish. The motor structure for this woofer features dual stacked 190 mm x 25 mm ceramic Y33 ferrite magnets sandwiched between some very serious metal. The front plate has been milled and polished and finished in a black coating to increase its heat dissipation ability (the black body radiation effect). The back plate is a CNC machined T-yoke (pole piece and back plate are a single piece of metal) that has been milled and polished with the Kove logo engraved on the back, but without the black coating. Magnets and plates are covered by a black rubber magnet "boot." Like most woofers in this class, the pole piece includes a 10 mm extension to improve the linearity of the forward magnetic fringe field. For cooling, the pole has a 35 mm (1-3/8") diameter vent with radiused edges to prevent turbulence noise and improve air flow. Incidentally, the engineers at Kove use all my favorite tools for design, LEAP, LMS and SpeaD (SpeaD is a fairly new program from Red Rock Acoustics that allows a speaker engineer to input the specifications of all the parts in a woofer and have the program give the T/S parameters).
The cone assembly for the Z-12 is also impressive. Subwoofers that handle this much power need very stiff cones, and the Z-12 achieves this with a thick-coated fibrous pulp (paper) cone with a integrated Kevlar mix. Finishing off the cone is a 4.75" diameter, heat-formed 3-D concave shaped dustcap. Connecting the cone to the frame, Kove used a dual density heat pressed foam surround that measures about 35 mm wide and 21 mm high. Kove uses a black Santoprene mounting gasket that covers both the front and rear of the frame mounting area.
Remaining compliance is provided by a pair of black 7.125" diameter poly-cotton blend progressive spiders. Kove primarily intended this high powered sub to be used in vented enclosures, hence the progressive spider (the two spiders are mounted in reverse direction back to back). While the woofer will work into a sealed box, and I did include simulation of this woofer in a sealed box just for comparison purposes, its stiff progressive suspension causes a fairly high rolloff. Still, it is capable of producing tremendous SPL. Like the other three woofers in this review, the Kove uses the new type of spider with the tinsel leads woven into the body of the spider. Industry consensus seems to be that this is definitely a superior way to handle the tinsel-to-connector path. The tinsel leads are terminated to a single set of color-coded chrome push terminal designed to accommodate large wire gauges. All parts in the cone assembly are held together with a high temperature "aerospace" epoxy. The shuttle doesn't fly apart and neither will this woofer!
Powering the cone assembly is a 3" diameter voice coil wound with aluminum round wire onto a black anodized aluminum former. Using the aluminum wire cuts the assembly weight giving the woofer greater sensitivity and acceleration. As mentioned in the beginning of the review, this woofer uses a single 4-layer voice coil, so it has a DCR roughly twice that of the other three DVC woofers. When looking at the comparison data chart, keep in mind that the other woofers take less voltage for a given output because both coils are parallel driven in the simulation.
Massive Audio DMx-12
Massive Audio is a fairly new name to car audio and was introduced about two years ago. However the parent company has been in the pro audio speaker business for about 14 years, which is good experience if you want to build high power car audio subs and component systems. The model submitted for this review is the new DMX-12. This model represents the first in Massive's new high performance DMX line of subwoofers and speakers. You can find out more about Massive Audio at www.massiveaudio.com.
The DMX-12 long excursion subwoofer is built on a new frame for Massive. This cast aluminum black painted frame has 12 narrow support "spokes" and 12 vents below the spider for cooling. I've never seen this frame used before, and it really is a well-designed frame for both mechanical support of large heavy motor structures and cooling across the front plate. There is a substantial 45 mm (1.75") from the spider mounting shelf (a plastic mounting ring is used to support the spider).
The motor structure is built around dual stacked 190 mm x 25 mm ferrite (Ceramic 5) magnets. Holding these to the frame are a set of machined plates. Both front and back plates are machined and coated with a black emissive coating to improve heat transfer (if you remember high school physics, then you know about Planck's Constant [h] and the black body radiation effect and how it was the first step in the field of quantum mechanics?). The back plate is a single piece T-yoke type with a chamfered top that reduces magnetic losses and maximizes air flow from the pole vent. The pole vent is 35 mm (1-3/8") diameter with a radiused exhaust hole to improve air flow and decrease noise. Along with the hollow pole piece vent, the pole is extended above the front plate by 5 mm, again to help linearize the magnetic fringe field in the forward moving direction of the cone assembly, and to improve cooling around the voice coil. Pole piece extensions also act to provide a path guide for the voice coil on extreme excursions. Finishing off the motor system cosmetic is the customary black rubber magnet cover.
Like the Z-12 and the CMPx212, the DMX-12 uses a fibrous pulp cone (paper) that has had Kevlar fibers added to the slurry to increase the stiffness. Obviously, this type of composite cone is pretty popular with manufacturers and this is due to its light weight and stiffness, an all around good performer that's hard to beat. The dustcap is a 4.75" diameter concave injection molded type with a 3-D Massive logo. Connecting the surround to the frame is a vacuum-formed Santoprene surround (Santoprene is a great material for surrounds, less expensive than rubber, but with most of the good edge damping characteristics, and better long term stability than foam) that measures 37 mm wide and 21 mm tall. Massive uses a black Santoprene mounting gasket that covers both the front and rear of the frame mounting area.
The remaining compliance is provided by a 7.125" diameter dual black poly-cotton blend spider arrangement. These linear configured spiders have their roll geometry reversed to cancel out odd-order non-linearity's (trust me, it just works better than one spider alone). Like the other three woofers in this review, the tinsel leads are stitched into the body of the spider.
Driving the DMX-12s cone assembly is a 3" diameter, dual 2-layer winding voice coil (4 layers total) that uses aluminum wire wound on a black anodized 5 mil thick aluminum former. The black adds to the heat dissipating ability of the voice coil and the aluminum wire makes for a lighter assembly for greater overall sensitivity.
After reading all the woofer descriptions you would probably guess that the comparison of these four woofers represents a fairly level playing field, and you would be right. Looking at the data chart pretty much tells the story. If you look at the T/S specs for these woofers, the CMPx212 has the lowest Qts and the Eclipse the highest. However, the range is such that they are can be placed in both vented and sealed enclosures. Starting with the sealed box computer box simulation the first thing I noticed (see the introduction) was that each of these manufactures recommends box volumes considerably greater than you might get from the numbers and a calculator. I decided to follow my usual procedure and first compare all four woofers (again, remembering that Kove does not recommend their woofer for sealed boxes) in the same Qtc=0.7 (box "Q") design, which means for this group, four different sealed box volumes ranging from 0.25 to 0.7 cubic ft. As can be seen, this also means box volumes so small you couldn't build a box that would be both this volume and deep enough to mount the woofer inside of it. Despite that little problem, the comparison shows the only woofer that really has much low-end performance in a small sealed box is the Eclipse 88120Ti, but even they don't recommend a box this small. The second box volume I used was 1 cubic ft. for all four woofers. The results showed the CMPx212 to have a very low Qtc (box "Q") and the Kove a very high F3 (and also the highest linear SPL). However, all four box Qtc's were low (over damped); but as I said in the beginning, once these bad boys warm up, the Qtc's will come up considerably, so it's not so much of an issue unless you listen at maybe 80 dB and never louder (but, then you probably wouldn't be reading this magazine).
Next I did computer simulations in a 1.75 cubic ft. vented box. Here, the playing field was much more level. While the box tuning had to be adjusted to work with the individual driver parameter sets, all but the CMPx212 were in the 30 Hz range; so they were at least similar in this respect. All four woofers produced F3's in the vicinity of 30 Hz with the CMPx212 having the lowest rolloff at 22.5 Hz. It terms of maximum linear output, Kove at 120 dB walked away with that honor, but not really significantly in terms of what I hope is reality for users of these products. All four of these woofers are easily capable of SPL's that exceed 110 dB without any hint of distortion, which means you'll be messing up your hearing before the woofer gives out. About the only place the high SPL number might count is in a dB Drag type of competition, and even then, a lot of other factors are involved to make a winning design, not just the absolute numbers in the data chart. You should also be aware that these numbers are computer simulations based on sine wave analysis and that the actual level before the onset of distortion depends significantly on the program material content. Figures could be as much as 3-4 dB higher or several dB lower depending on conditions.
Bottom line, I don't see any clear standout winners in this group, they all appear to be great performers and at this price range, all have extremely nice build quality. If space was a problem and you really wanted to use a small sealed enclosure of some kind, the Eclipse is probably the best choice. However, this excludes the most important judgement to be made, the subjective one. So how do they sound? Ask Tim.