JL Audio Fathom IWSv2-SYS-213 In-Wall Subwoofer System

Wolf in Sheep’s Clothing

Equipment report
JL Audio Fathom IWSv2-SYS-213 In-Wall Subwoofer System

When an audio journalist asked loudspeaker designer Richard Vandersteen if his company would make an in-wall speaker, Richard replied, “I’ll make an in-wall speaker when Steinway makes an in-wall piano.”

That brilliant retort perfectly sums up the high-end’s antipathy toward in-wall speakers. In-walls have a much-deserved reputation for providing substandard sound quality—triumphs of convenience over performance that are antithetical to high-end values.

So why did I choose in-wall subwoofers for my new home-theater room? Because the in-wall subwoofer is made by JL Audio, a company that in my experience has never introduced a product that was less than stellar. The company holds 43 patents (with six more pending) related to subwoofers (and amplifiers) and is seriously geeky on the subject. Moreover, JL Audio’s new in-wall subwoofers are decidedly different in design than conventional in-walls—the company appears to have applied its formidable technical chops to the challenge. Finally, my theater room is quite small (in contrast to the separate music listening room described in Issue 294) and in-wall subwoofers freed up scarce floor space. Perhaps in-wall speakers, done right, have a place in a discriminating listener’s system. We’ll find out.

I went for the Fathom IWSv2-SYS-213, a moniker that describes its configuration (in-wall system, version two, and two 13.5" woofers in separate enclosures) yet doesn’t quite roll off the tongue. I’ll call it the IWS in this review, with the understanding that it refers to the 13.5"-woofer/dual-enclosure version. A single-woofer model is also available, but dual woofers in different locations in the room provide smoother bass because each one drives the room’s resonant modes differently. Two woofers also reduce by half the demands placed on each driver (and on the amplifier) for a given output level, expanding the system’s dynamic range and ability to deliver bass impact without strain. The company also makes a version with an 8" woofer for about half the price ($2300 vs. $4900 for the single-woofer version, $3500 vs. $7800 for dual-woofer models).

JL Audio’s solution to the challenge of making a good-sounding in-wall subwoofer starts with a large and solidly braced enclosure along with a novel mounting method for that enclosure. Most in-wall speaker enclosures attach right to the studs, a recipe for amplifying cabinet vibration by coupling the box to the wall structure. Rather than use this compromised industry-standard method, JL suspends the enclosure inside the stud bay from a vertical rod that attaches to a horizontal bar. This clever single-point ball-and-socket arrangement decouples the enclosure from the wall. Spacers and padding around the enclosure, along with a gasket that fits on the stud edges, give the enclosure a snug fit inside the stud bay and reduce the chance of rattles. 

The IWS is installed before the drywall goes up, leaving its entire large enclosure buried inside the wall, except for a 16.5" x 16" opening to access the driver-mounting hole. The driver is shipped separately from the enclosure, and is installed toward the end of construction. The opening is covered by a protective panel that is discarded when the driver is installed. The panel also serves as a template for cutting the surrounding drywall. A sturdy metal grille covers the driver, yet attaches to the wall rather than to the enclosure, again to keep the enclosure decoupled from the wall. Three different grille depths accommodate different wall thicknesses. I painted the grilles my wall color.

The sealed enclosure measures 13.75" wide and either 70" or 55" tall. Five enclosure sizes are available depending on the stud depth. I opted for the 5.5"-deep enclosure as I have 2x6 exterior walls. The three narrower enclosures designed for 2x4 walls are taller than the two for 2x6 walls so that both provide approximately the same interior volume and driver loading. The enclosures are made from CNC-cut birch plywood, a much stiffer and less resonance-prone material than MDF. 

The 13.5" woofer that fits in the enclosure is a home-theater version of JL’s ultra-thin TW5 platform, a woofer that has been successfully used in a range of JL products. This woofer bristles with technical innovation, from the magnet structure, to the cone material, to the surround and just about every other aspect of the design. For this new in-wall driver, JL developed a mechanical structure to provide greater cone excursion within the space limitations of the shallow woofer, which it calls Concentric Tube Suspension. This new woofer, when mounted in its in-wall enclosure, is specified as extending flat to 25Hz (-3dB).

The subwoofer is powered by one of two available freestanding amplifiers that go in your equipment rack. The amplifier model is dictated by whether it is driving one or two woofers, and whether the amp is driving the enclosure that fits in a 2x6 wall or a 2x4 wall. The single-woofer amplifier delivers 1000W, and the dual-woofer model 2000W. Matching the amplifier to the enclosure type is necessary because the equalization curves built into the amplifiers are specific to the enclosure.