SPEAKERS AND SUBS
Sony XS-L121P5
By Paul Sonoda
Posted on Monday, Mar 1, 2004

Until recently, woofers have changed very little. Sure, there have been vast improvements in materials, but the basic shape and function has remained constant. Lately, there have been several companies that are trying to break the traditional mold of what we think a speaker should look like. Today, you can buy square- and even triangle-shaped woofers. With the introduction of Sony’s XS-L121P5, you can have a pentagon shaped woofer as well.

First Look
The XS-L121P5 is a 12-inch, 4-ohm woofer that ushers in a new direction from Sony. For those of us who forgot our high-school geometry, a pentagon is a five-sided polygon. It’s in this shape that Sony believes they have created a polypropylene speaker cone that improves rigidity for lower distortion and the reduction of standing waves on the cone itself. By using this unique shape, the Sony XS-L121P5 basket has five pairs of mounting holes, giving you two more mounting holes over standard style woofers. This solid mounting is a nice touch. The Sony XS-L121P5 is designed for small sealed or ported enclosures.

Closer Look
The ruby red color of the polypropylene cone compliments the silver basket frame nicely. The rubber surround incorporates three expansion ribs at five points to control the pistonic motion of the woofer. The suspension system uses dual, "Triple-layer" spiders where the lead wires are embedded into the top spider. This prevents the lead wires from interfering with the movement of the woofer. Connections to the speaker are made through sturdy gold-plated binding posts. The Sony XS-L121P5 uses a four-layer, edge-wound voice coil on an aluminum former, which packs the voice coil wire into a smaller space for improved efficiency. The aluminum former acts as a heat sink to help dissipate the heat generated by high-power operation.

Manuals/Web Support
Information on the Sony XS-L121P5 was available on the Sony Xplod Web site located at www.xplodsony.com. The site is a slick, flash-based portal that contains basic information about the woofer and other Sony car audio products. The site allows consumers to register their products and to ask questions of the technical department of Sony. However, I was not able to find a direct link on the car audio site to download any product literature or information manual. Only by searching Sony’s main site was I able to be finally directed to another one of Sony’s sites, www.iq.sony.com/srvs/sosdocs/ . Here, I was able to download the owner’s manual and Thiele-Small parameters for the XS-L121P5. The owner’s manual provided basic installation information and specifications about the XS-L121P5, but neither the owner’s manual nor the Web site provided any enclosure recommendations (Sony reports that enclosure recommendations are included in the carton of each 8- to 15-inch P5 sub — ed.).

Installation
The Sony XS-L121P5 was sent to me installed in an enclosure. The outside dimensions of the enclosure are 26.5 inches by 16.5 inches by 10 inches (L x W x H). The enclosure was constructed with high-quality marine-grade plywood covered in gray trunk liner material. This ported enclosure uses a 3-inch flared port with a functional length of 8.5 inches located adjacent to the front face of the enclosure. Based on this information, the total enclosure volume was measured at a net volume of 1.67cubic feet, with the enclosure tuned to 34 Hz. The combined weight of the enclosure and woofer is 36.5 pounds. There was no internal bracing, baffling, or acoustical treatments.

Sound Q & Performance
I placed the test enclosure in the back of a Minivan and measured the SPL output with power input of 1 watt, 350 watts, and 1200 watts, respectively. The higher power levels were referenced to the RMS and Peak power ratings of the XS-L121P5.

The enclosure supplied is on the smaller side for a 12-inch woofer at 1.67 cubic feet for a ported enclosure. Even so, the Sony XS-L121P5 generated very good output. The SPL output with 1 watt of power exceeded 105 dB between 40 Hz to 50 Hz with only a 3 dB drop in SPL at 31.5 Hz. In a smaller vehicle, you could easily see an increase of +3 to +6 dB of output. Upping the power to its rated RMS power rating of 350 watts delivered a commendable SPL output of 126.8 dB at 50 Hz down to 121.9 dB at 31.5 Hz. The sound quality of the woofer was good. There was some audible ringing coming from the enclosure which I attributed to the lack of acoustical treatment inside the enclosure. (The addition of some internal insulation would be effective in eliminating these enclosure noises.) The woofer or port did not generate any audible noises.

With 1200 watts applied, the Sony XS-L121P5 delivered a loud 130.3 dB at 50 Hz. With nearly three-and-a-half times more power, the XS-L121P5 increased its output less than 3 dB. Power compression of the woofer was as evident as the audible strain during this test. At frequencies lower than the port tuning frequency, the SPL increase was created by the rattling and bottoming out noises from the XS-L121P5. This baby was angry. For high power applications, I strongly recommend the use of a subsonic filter.

Summary
The Sony XS-L121P5 is a woofer at an entry-level price point with good performance, better sound quality, and really cool looks. With a reasonable amount of power, the XS-L121P5 will deliver good SPL and tonal quality. The XS-L121P5 also matches there pentagon shaped subwoofer amplifiers, allowing for some very cool installation opportunities. In the world of me-too products, the Sony XS-L121P5 offers something different that will satisfy your performance as well as cosmetic needs.