It took a little longer than anticipated, but we now have Round 2 of the Subwoofer Comparison Test. This time we review the next price range of cast frame, 12-inch monsters that went all-out in a battle of SPL versus Sound Quality. The four speakers in Round 2 each have their own strengths and weaknesses in terms of their utility. There is no clear winner here. Bear in mind that if you are in the market for a subwoofer such as one of these, it is important to know what your preferences are. Your preferences play an important part in determining "the winner" for you. So using the charts here as guidelines, relate the performance of each subwoofer to your own musical style or taste. We hope that you will be able to make use of the opinions within this story to help you make a buying decision on your next car audio shopping spree.
Four 12" Long Excursion Subwoofers
This month's speaker review looks at four more dual voice coil long excursion subwoofers. Priced between $309-$499 they represent a class of woofers that vary from $10 to $200 more than the last four 12" long excursion subwoofers reviewed. The subs submitted for this comparison test were the Ultimate ACW1200, the Earthquake DBX-12, the Audiobahn AW1205X and the MA Audio SYW12K.
The price range for this group is greater than those subs seen in previous reviews; however, they do fall fairly neatly into two categories. The Earthquake and Ultimate subs are the lower priced pair ($310-$349) of the four woofers and have similar construction and power handling ratings. Audiobahn and MA Audio's subs are both more expensive ($399-$499) and exhibit substantially heavier construction and commensurately higher power handling ratings. All four woofers were recommended for both sealed box and vented box use, however two of them, the Audiobahn AW1205X and the MA Audio SYW12K, can be mounted in a fairly small sealed enclosures while the Ultimate and Earthquake subs required somewhat larger box volumes for the same level of damping. More importantly all four of these long excursion woofers are easily capable of undistorted SPL in excess 110 dB!
Testing was done using the same procedures as the previous subwoofer test. The LinearX LMS analyzer (Win9X software) was used along with the LinearX VIBox to produce separate voltage and current curves (sometimes referred to as admittance curves) in an abbreviated frequency range of 10 Hz-10 kHz with a 550-point resolution. These two curves were then mathematically divided (V/I=Z) and the data converted from voltage to Ohms to produce high-resolution impedance curves. This data was then imported into the LinearX LEAP CAD program (a Win9X version of LEAP is due out in a few months). Once the LMS data was copied into the LEAP software, box simulations were created at 2.83V and at a voltage level high enough to produce cone excursion that was equal to the Xmax of the voice coil plus about 15%. This method describes the woofer's linear operating envelope. Linear Operating Envelope is just engineer-speak for approximately how loud the woofer will get before it starts creating noticeable distortion.
Audiobahn AW1205X
Audiobahn was founded in 1997 and so is relatively new to the car audio business. The company actually was a spin-off from a Los Angeles car audio retailer, although the story is a bit more complex than that. However, despite the short time in business the company has managed to grow over 600% and been able to field some very impressive products such as the AW1205X subwoofer (check out their web site at www.audiobahninc.com).
The AW1205X Ultra High Excursion subwoofer is at the upper-mid part of the Audiobahn subwoofer lineup. They actually have a couple of other models with more magnet and higher power handling and maybe even more chrome! When the woofer arrived and I removed it from the cardboard shipping carton, I was surprised to find the driver further packed in a slick imprinted wood box with a hinged lid and clasp. It's obvious that a lot of attention to detail went into this product right from the start.
Audiobahn started with a new and very heavy frame design that has six thick spokes and six vents below the spider area for cooling. The edges of the spokes have been polished and the whole frame chrome-plated. There is a substantial 47 mm beneath the spider to the front plate to allow for the very long rear excursion potential.
The motor system is really outrageous looking from the outside. When you first check this woofer out, the first thing that strikes your eye is the magnet cover. The polished and shaped T-yoke and front plate are bolted together and finished with bright chrome plating. Instead of the usual rubber magnet boot, Audiobahn chose a chrome-plated screen. This accounts for my first impression that the back of this woofer looked more like the air breather on a Holly four-barrel carburetor, but, hey, this is car audio. All this chrome hides a double stacked set of ferrite magnets. For cooling the T-yoke has a 46 mm (1.81") diameter pole vent (no debris screen is used) which, along with the frame venting, a vented voice coil former contribute to the 1000 W RMS published power handling rating on this subwoofer. A 10 mm pole extension (hollowed out at the top to minimize magnetic losses) provides additional cooling and increased fringe field linearity. Driving the AW1205X's cone assembly using the magnetic flux provided by this rather large motor structure is a 3" (diameter) four layer (2 two-layer coils) voice coil wound on a black anodized and heat-treated aluminum former. Both voice coil tinsel leads are terminated with some impressive looking heavy-duty terminal blocks that accept large gauge cable and that loosen and tighten using a hex wrench. The AW1205X's cone assembly starts with a laminated glass fiber composite paper (pulp) cone. Cosmetically, the under side of the cone looks like a standard thick paper cone, but the top has a woven black glass fiber texture that, like the Earthquake DBX-12, resembles woven carbon fiber. The 5" diameter flat dustcap is made from injection molded styrene plastic and includes a 3D Audiobahn silk-screened logo. Connecting the cone to the frame is a 38 mm (1.49") wide (20 mm height) UV treated pressed foam surround. This is capped off with a chrome plated mounting ring with the Audiobahn logo in embossed letters instead of the usual paper, or Santoprene mounting gasket. The remaining compliance is provided by a 7.25" diameter Nomex spider. This spider is described by Audiobahn as a "slightly progressive linear" type and has the voice coil tinsel leads stitched into the spider surface to prevent lead slapping against the rear surface of the cone.