MobileSound is certainly not a newcomer to the car audio industry; it has been around for over ten years. While the vast majority of speaker manufacturers in the industry buy their drivers from large Original Equipment Manufacturers (OEM) - sometimes doing their own engineering, sometimes not - Crystal MobileSound is among the few that actually builds their own woofers. This applies only to subwoofers, however, as Crystal buys its small drivers such as coax and component products from a driver OEM, like most of the other speaker companies. While there is no inherent advantage to this, it does give a mid-size company like Crystal a lot of flexibility. In fact, Crystal not only makes their own drivers, but also manufactures as an OEM themselves and builds custom car audio subwoofers for other speaker companies.
The company has four main product lines: CXE, a line of coax drivers; CPE, a component line; CSE, a line of stamped from subwoofers; and CMP, the top of the line cast frame subwoofers. This month's review is of their latest high-end subwoofer release, the CMPx212, which is a fundamental departure from the current CMP line.
Up until the release of the CMPx212, the CMP subwoofers all used an underhung voice coil and a massive 30 mm thick front plate. In this application, underhung does not refer to the degree of woofer masculinity, but to the voice coil being shorter than the magnetic gap. The vast majority of woofers on the market have overhung voice coils, which is the opposite voice coil height-to-gap relationship with a voice coil longer than the gap dimension. However, the x212 departs from the previous CMP lineup by using the same gonzo 30 mm front plate but with a long overhung voice coil.
Built on a cast aluminum frame, this subwoofer is a compendium of trick features, as you would expect from any $499 car sub. The cone assembly starts with a fairly unusual cone that may look like a standard paper cone, but it's actually a honeycombed kevlar mixture that is extremely stiff (which is where you want to be with a high powered sub cone). Crystal actually builds this in-house; that's unusual since even manufacturers who build their own woofers most generally buy all the parts from speaker parts OEMS (the next level back from the OEM driver makers). The cone is terminated on the inside diameter by an injection molded (with a slick 3-D CMP logo), inverted 5.5-inch diameter dustcap.
This unusual cone is suspended using a 1-inch wide Santoprene heat formed surround. The same material is used to form the mounting gasket "boot" that acts both as a rear sealing gasket, and a front mounting gasket. A 7-inch diameter three-layer flat cloth type spider that has the voice coil lead wires woven into the surface of the spider supplies remaining compliance. Having the voice coil lead wires woven into the spider is becoming rather popular with manufacturers of car subs. Voice lead wires woven into the spider cloth is a good trick and ends the worry about the voice coil leads bouncing off the cone during high excursions, which can be audibly distracting. Another common solution to the lead wire noise problem is to put foam pads on the underside of the cone just above the lead wires, which also works.