If I were asked to pick the winner of the "2006 Subwoofer Juggernaut" award, certainly JL Audio would be looking good on the short list of companies I think really shine as subwoofer manufacturers. This company has been specializing in car audio products since 1975 (national distribution of their subwoofer line started in 1992), and has long been considered a serious competitor among subwoofer manufacturers. JL Audio has earned an outstanding reputation for not only building high quality car subs, but also for their constant striving to elevate the art of car subwoofer design. They were among the earliest companies to use layered voice coil windings beyond four layers, and their patented vented reinforcement collar (VRC) that greatly strengthens the critical bond between the voice coil former, spider and cone is impressive. I know a lot of car audio companies and a lot of engineers and I would have to say that JL Audio is certainly among the group of manufacturers I consider to be gonzo professionals at what they do (for more about JL Audio, check out their website at www.jlaudio.com).
This month we are reviewing the new JL Audio 13W3v3-4. JL Audio's W3 woofers have a fair amount of history. This line of affordable high-performance stamped-frame subwoofers was originally introduced in 1998, and, according the company, was immediately successful for its combination of output capability, sound quality and compact enclosure optimization. All models featured the company's patented VRC technology, long-excursion capability and dual voice coils.The following year, JL Audio introduced the 15" 15W3 and 18" 18W3 subs and both of these were the first in the company to use the JL's new FEA (Finite Element Analysis) "Dynamic Motor Analysis" technology. The 15W3 and 18W3 motors were proof-of-concept products using their new design technologies and ultimately led to the development of JL Audio's flagship W7 subwoofer motors.
In the summer of 2002, the W3's underwent a significant revision that included a patented Elevated Frame Cooling Technology, a new dished cone/dust cap design and a silver powder coated finish to distinguish the new versions. These were designated W3v2's. This brings us to the new W3v3's, which unlike their predecessors, are not a revision of the previous designs but are a complete from the ground up new design, sharing no parts with previous W3's. All of the new W3 models incorporate the JL Audio DMA motor design technology, FEA-optimized suspensions and several new patented technologies. In fact, the company actually set up a completely new state-of-the-art production line engineered specifically for W3v3 production at JL Audio's Miramar, FL, factory.
The 13W3v3-4 is the single voice coil, 13" (actually 13 1/2") version of the W3 lineup. Thirteen-inch diameter woofers aren't too plentiful in the world of car subs since most manufacturers offer 12" and 15" drivers only. The thinking behind this odd size was that a 12" doesn't quite have the Sd (i.e., cone area) for "extreme" high SPL performance and 15" drivers are really big for most small to mid-size cars, so a 13" cone seemed like the right compromise. Compared to the 12" W3 series, the 13" W3 does offer more cone area, which translates to less excursion for a given SPL (or more SPL at the same excursion), but the boxes are also larger (1.1ft3 compared to 1.5ft3 for a similar F3 and Qtc sealed box), so as usual, no free lunch.
Starting with the frame, the 13W3 incorporates their traditional six-spoke stamped metal frame and, like the previous version, has a silver finish. Adding to the strength of this frame is a 3d treatment for the spokes created in the stamping process (check out the cutaway drawing). The bottom of the frame shapes the six 1.5" x 0.125" cooling vents that send accelerated air across the front plate and is the subject of JL Audio's Elevated Frame Cooling patent #6,219,431, a very simple, but effective heat dissipation tool. Because of this feature, JL Audio uses six bolts to attach the frame to the motor assembly.
So "what's under the hood" you ask? The motor structure uses two 145mm x 23mm ferrite magnets. These are sandwiched between a milled and polished front plate and T-yoke (single piece pole and back plate). Noticeably lacking from the motor design is any kind of pole vent ... this is a good thing. Large pole vents do not make effective cooling devices. A better system is to not use a pole vent and force air more directly across the voice coil and front plate, which is what is going on with this sub (if you are feeling like punishing your brain with some serious loudspeak techy stuff, go to the Klippel web site at www.klippel.de, click on the Know-How button and look at Dr. Klippel's paper titled Nonlinear thermal modeling, AES Amsterdam 2003).
All aspects of the motor design are developed using CAD software and then confirmed using a Klippel analyzer, the same tool that Patrick Turnmire, fellow CA&E reviewer, and I use to enhance these subwoofer reviews. JL Audio developed its own propriety modeling software called DMA for Dynamic Motor Analysis. This powerful software is based on an engineering modeling method called FEA (Finite Element Analysis) and is very math intensive to the point that analyzing a speaker at multiple power levels can take up to several hours on a very fast computer. One of the really outstanding things that DMA does is to model flux variations in the magnetic field that are induced by the magnetic field of the voice coil. I should also mention that JL Audio also uses another FEA program called "Cosmos" for modeling thermal dynamics of a woofer. The result of this high performance technology is that JL Audio has done an incredible job of using these powerful computer tools to make woofers that stay very linear up to the extreme volume levels, and this means lower distortion, higher accuracy and better transients.
The cone for the 13W3v3 is similar to the W7 cone and is a mineral-filled polypropylene type that is actually two cones combined: a shallow profile single-piece cone (kind of like a inverted dust cap that covers the lower cone) with a more conventional profile cone that has a small dust cap covering the voice coil former. This does not have the additional bracing the W7 "W" cone, but even without this feature, is very stiff. The lower cone also has two trough indentations just above the voice coil lead-out wire that give the voice coil wires more room to bounce around and not make those annoying noises from hitting the cone. The cone attaches to the voice coil and spider using another patented technique called Floating Cone Attachment Method (FCAM). This allows production to assemble and center the voice coil and spider assembly and then attach the cone in a way that keeps normal manufacturing tolerance variations from off-centering the voice coil; this can happen if the cone, spider and voice coil are assembled as a unit and then installed (JL patent #6,501,844). The attachment point is at another patented JL device, the Vented Reinforcement Collar (VRC, patent #5,734,734). Made from a high-temp composite, the collar provides and attachment point for the spider, voice coil former and the FCAM joint for the cone, plus makes the entire joint extremely rigid and prevents neck joint deformity that can occur with high-powered excursion. The other slick trick is a series of 11 small vents on the peripheral of the collar that channel air from the inside of the voice coil former straight down over the voice coil, an extremely clever and effective cooling device.
Attaching the cone to the frame and providing a portion of the speakers compliance is a 28mm wide and 17mm tall NBR rubber composite surround than incorporates yet another JL Audio patent pending technology titled Surround Stress Relief. The one-piece surround and gasket fit into a sort of molded cup at the cone edge which incorporates a radius in such a manner as to cause less stress on the surround/cone joint on long excursions. Most surrounds "pucker" when you push the cone inward as far as you can, which indicates uneven "stress" on the attachment point. Next time your at a JL dealer, wait until he isn't looking and push the cone as far down as you can (OK, maybe you better ask first). No pucker. Remaining compliance is provided by a flat progressive Nomex-poly-cotton spider that is insert molded onto a composite carrier (also patent pending). The carrier also is the mounting point for the two chrome, color-coded push terminals and provides stress relief for the voice coil lead wires. Lead wires are looped over the spider (not stitched into the spider as is often seen) and into the VRC. The 1 1/2" diameter voice coil is wound on a Kapton former with six layers of round aluminum wire.