Subwoofer Comparison Test: Round 2 (cont.)
by CAE, Feb 24, 2009
MA Audio has been building loudspeakers and amplifiers for the car audio consumer since 1989 (visit the site at www.maaudio.com) and while it's not one of the older car audio companies, it is also not one of the new guys on the block. The company started out manufacturing in the U.S., but now have product built in their overseas plant established in China in 1992.
The SYW12K represents the top-of-the-line for MA Audio and at 32 lbs. that's not hard to believe. Like the Audiobahn woofer, the MA Audio SYW12K arrived in a cardboard shipping box, but inside the box was a very slick cardboard drum with an imprinted wooden lid and a drum locking mechanism, again showing a lot of attention to detail went into both of these products. The woofer is built on a 20 spoke custom designed frame, which, again like the Audiobahn woofer is polished on the edges and chrome plated. There is about 50 mm of rear travel below the spider that include both the depth of the frame and a 1/2" high plastic spacer ring used to mount the spider. Unlike the Ultimate and Audiobahn woofers, MA Audio did not incorporate below the spider venting into the frame as part of the cooling system (this is not a universal feature and its importance depends upon the effectiveness of the other facets of the motor cooling system).
Like the Audiobahn motor structure, the MA Audio SYW12K has a rather spectacular appearance. Both the single piece forged T-yoke (flat and not shaped) and front plate are polished and chromed. Both plates extend over 5/8" beyond the magnet diameter and are held together by four large chrome bolts. The dual stacked Strontium (higher gauss than standard ferrite) magnets are covered by an injected Santoprene ring embossed with the MA Audio logo. The 44 mm (1.73") pole vent in the T-yoke (no debris screen is used on this model) provides voice coil cooling. Last, the pole has been extended by 18 mm and hollowed out at the top (to lessen magnetic losses) for increased heat dissipation and fringe field linearity. The business end of the motor is a 3" 4-layer (2 two-layer) voice coil wound on a black Kapton former. The voice coil tinsel leads are woven in the spider surface and terminated to two pairs of heavy-duty chrome plated binding post located on opposite sides of the frame.
The cone assembly is also a feature laden, as is the motor structure of this woofer. This driver's cone material is described as a partial pressed spruce pulp paper cone. It has a silver painted coating on the front and that thick papiermache feel on the backside with a high degree of stiffness. The dustcap is a flat 5" diameter injection molded polypropylene type with a 3D silk-screened MA Audio logo. Terminating the outside edge of the cone to the frame is a 50mm (1.96") wide (25 mm height) pressed and treated foam surround. This is the widest surround and smallest cone of the group. Covering the outside edge of the surround mounting surface is a injection molded black Santoprene gasket that not only has a logo "look" for the front side of the woofer, but provides a soft mounting gasket on the rear of the frame for normal front mounting. Remaining compliance is provided by a 7" diameter dual front to back spider assembly. Both spiders are made from 4-way cross-weave cotton.
Earthquake products have appeared on numerous occasions in CA&E. The company is a subsidiary of Hohmann International and is the oldest car audio company in this group of manufacturers, founded back in 1985 (check out earthquakesound.com).
The DBX-12 is sort of the mid-line for Earthquake, with their Magma series being the top-of-the-line. Built on a cast aluminum frame that has been painted silver with black speckles, the DBX-12 has about 35 mm of depth below the spider for rearward travel (this includes a standoff ring for the spider). Providing the horse power for the DBX-12 are two stacked ferrite magnets that are connected to the frame with a single piece hot forged and shaped T-yoke and milled polished front plate. The motor system on the DBX-12 was designed using a non-linear FEA (finite element analysis) program called "High Mass" that optimizes the shape and flow of the magnetic field in the motor structure. This type of software is very useful in designing T-yokes and front plates as well as modeling pole piece extensions such as the 6 mm above the top plate pole piece extension in DBX-12. A 35 mm (1.37") pole vent provides cooling and has a debris screen to prevent anything from being sucked up into the gap area. Finishing off the motor assembly is a black rubber "boot" covering the dual stacked magnets.
The cone assembly is connected to a 2.5" diameter dual voice coil (two 2-layer coils) wound on aluminum former. Each of the two-layer coils is terminated to a pair of silver push terminals located on opposite sides of the frame. The cone is a very stiff fiber impregnated Kevlar weave black polymica type with a texture that looks very similar to woven carbon fiber type cones. Likewise made from fiber impregnated polymica, the 4.5" diameter dustcap is injection molded with a 3D Earthquake logo and is slightly concave. Terminating the cone to the edge of the frame is a 35 mm (1.39") wide foam surround (18 mm height). This surround is made from a 1.25" thick piece of foam that is compressed and laminated. For mounting, the DBX-12 has an injection molded black Santoprene (a material similar to rubber) gasket with embossed logo's that fits over the woofer and works as both a front and rear gasket.
The remaining compliance is provided by a black 6.5" diameter progressive spider made from a chill-pressed weave material call Romax. Integrated and stitched into the weave of the spider are both sets of voice coil lead wires. This is a great technique not only for preventing a lead slapping problem against the underside of the cone, but also tends to be less subject to breaking and cracking over time, although tinsel lead failure is generally not a frequent problem in woofers.
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