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 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. 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 13W3v3 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 3-D treatment for the spokes created in the stamping process (check out the cutaway drawing on pg. 77). 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.
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. The result of this high-performance technology and modeling programs used by JL Audio is that they have 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 mineral-filled polypropylene cone 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. 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 the Floating Cone Attachment Method (FCAM). The high-temp composite Vented Reinforcement Collar provides an 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 speaker's compliance is a 28mm wide and 17mm tall NBR rubber composite surround than incorporates Surround Stress Relief technology. 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. 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.
In the Lab
Part 1 of this objective measurement section consists of large signal analysis using the Klippel analyzer followed by the LEAP 5 parameter and box analysis. Working with the Klippel analyzer (on loan from Klippel GmbH), Pat Turmire, of Redrock Acoustics, ran the large signal analysis on the 13W3v3-4 subwoofer and provided the Bl (x) curve. The black curve is the Bl curve and shows the motor strength of the woofer as it moves in both directions outward from the center rest position. The lighter curve is a type of displacement curve and if both curves were identical, the motor system's motion in and out of the frame would be perfectly symmetrical.
The 13W3 Bl(x) curve shows the woofer voice coil has virtually no offset at its rest position, which is optimal. This Bl curve's symmetrical slope plateau is broad yet shallow. The displacement at operating SPL near Xmax is barely 1mm, so this is about as good as it gets. Bl can decrease to approximately 70 percent of its small signal value and the driver will still function in a satisfactory manner, only with an elevated level of distortion (about 20 percent). The 70 percent of maximum Bl displacement limit for the JL Audio sub is greater than 16.2mm, which is just beyond the physical Xmax of this driver.
This subwoofer's Kms(x), or stiffness of suspension curve, exhibits equally good symmetry in both directions of travel. The offset is a negligible 1.5mm forward at the rest position. The compliance limit for the suspension when it drops to 50 percent of its rest value is also greater than 16.2mm, again just beyond the physical Xmax of this subwoofer. Both "limit" numbers, Bl and compliance, represent the level at which distortion climbs to 20 percent, which is a realistic criterion for subwoofers given the ear's lack of sensitivity to distortion at low frequencies.
Next I generated the T/S (Thiele/Small) parameters using my usual protocol (for more information, see the extended version of this story at caraudiomag.com). The results follow in the Data Chart.
Box simulations were generated for both sealed and vented type enclosures that were specifically recommended in the manual. For your basic sealed box, JL Audio suggests a 1.5ft3 volume with no fill material. For a ported box, a 2.25ft3 tuned to 27Hz is suggested. The vented box alignment works well and yields a very usable response. The LEAP 5 graph curves show the SPL at 2.83 volts (black curves) in half-space (imagine the woofer mounted in a speaker baffle as big as a football field and that would be very close to "half-space"), 2.83 volts in a 154ft3 car compartment (blue curves), and the SPL at a power level required to get maximum linear excursion (red curves, also half-space). The sealed box curves are solid lines and the ported enclosure curves are the dashed curves. The 2.83-volt results produced an F3 of about 40Hz for the sealed box and a -3dB of 33Hz for the reflex enclosure (vented box). Increasing the simulated input voltage for the 1.5ft3 sealed box computer simulation to 53 volts increased excursion to Xmax + 15% (17.8mm for the 13W3) and increased the driver output to a substantial 111.5dB. The 2.25ft3 vented box computer simulation required 60 simulated volts to drive the 13W3v3-4 sub to the Xmax + 15% excursion level, which resulted in an SPL of 114dB. JL Audio puts a little note on page three of the manual that reads "!!CAUTION!!- Prolonged exposure to sound pressure levels in excess of 100dB can cause permanent hearing loss." I like it when audio companies act responsibly, so plaudits and kudos to JL.
JL Audio's 13W3v3 is a well thought out and very professionally engineered product that incorporates a lot of patented subwoofer design technology. All of the objective results indicate a high-performance design, which, all things being equal should sound pretty good. Unfortunately, the speaker gods do not always side with the engineering department, but I am guessing Eric's response was very favorable once he fired it up.-VD
Subjective
"Huh? What the... ? JL Audio has a new W3 line... the v3 (version 3)? And this thing is 13 1/2", not a 12" or 15"? What happened to the v2 stuff? And why is it 13 1/2"?" These were all questions that blurred my mind as my magazine boss Casey Thorson told me to get busy with this new subwoofer. Luckily, Casey was in a rare good spirit. Being very patient with me this day, he did not curse me for all the questions.
Installation
Well, once the surprise of not getting verbally abused and the fog and excitement of having something new to play with cleared, I wanted to get the lowdown on exactly what JL Audio recommends for the best enclosure when using the all-new 13W3v3-4.
I said to myself, "Self, if I'm gonna get the proper info on this sub, I gotta go to the top!" Yes, it was time to find my secret decoder ring and the super secret code numbers to reach the E-Ring at the JL Audio compound in Florida. I picked up the phone and called JL Audio's vice president of marketing and transducer knowledge master, Manville Smith. After getting through all the security clearances and background checks, I finally heard the melodic chords of Master Manville's voice. And after all that work to get to him, he gives me a gentle kick in the head, telling me to just read the owner's manual! "All the correct information is spelled out for each of our speakers in their manuals, Eric." I was dumbstruck. Again, I asked meekly, "You mean, you guys actually print what works in your owner's manual? Hey, what a concept! That's sweet!" Manville nonchalantly tells me "Yep. And that's what we tell the consumers that call us every day with the same question. We really do mean what we say in those manuals."
If you are an avid reader of these tests, you will know how often the enclosures called out in the owner's manuals and the enclosures that I am told by the manufacturers to use do not coincide with one another - some aren't even close. Getting the really skinny up front is great and I have to congratulate JL Audio for doing their homework and putting together a terrific owner's manual.
OK. So my phone call to Manville was completely useless. Maybe next time I will just read the owner's manual first. Unlike Manville, it taught me a ton of good stuff. The manual recommended a sealed enclosure at 1.5ft3. As usual, I had my guys at the Speaker Works assemble the test enclosure. Master installer Patrick Holdaway commented on the fact that the 13W3v3's will need custom enclosures in most installs because of their unusual size. So if you are a DIY'er, you will need to keep in mind that you will have to either modify a pre-made enclosure or build one from scratch. He also commented that he did like the one-piece frame gasket that came packaged in the box.
To power the JL Audio 13W3v3-4, I used two Crossfire VR1000d amplifiers with a bridging module. These two amps running into the 13W3v3's single 4-ohm voice coil will produce over 1,000 watts of RMS power, which is more than enough to cook this 400-watt RMS driver if I get out of control. The front half of my reference speaker system consists of a pair of USD Audio B-72pro WaveGuide separates. I am powering these with a Zapco C2K-4.0X amplifier at 100 watts per 4 channels. The built-in crossovers and subsonic filters were bypassed. The Alpine PXA-H701 processor was used to set levels and to actively divide the frequency range to all of the speakers.