All the amplifiers’ front panels will look familiar to anyone who has set up a freestanding JL Audio subwoofer; they are laid out identically to the panel of a Fathom f112 or f113. Adjustments include: a selectable low-pass filter at 12dB or 24dB per octave (or no filter); a continuously variable crossover frequency knob; an ELF trim (Extremely Low Frequency) knob with a boost of up to +3dB or a cut of up to -12dB at 23Hz that is useful in taming room overload; a continuously variable phase control; a polarity switch; a master level control; and controls for operating JL Audio’s Digital Automatic Room Optimization (DARO) program. As described in my review of JL’s Fathom f113 in Issue 283, DARO measures the response of the subwoofer in your room at your listening location and employs 18 one-sixth-octave digital filters to flatten frequency response. DARO is extremely effective in removing room-induced peaks and thereby banishing the dreaded bass bloat and overhang so common in subwoofers capable of prodigious output. Calibrating the IWS with DARO is simple and fast: Position the supplied measurement microphone at the listening seat, press one button on the amplifier to start the test-tone sequence, and the system automatically does the rest. The difference in sound quality before and after DARO is night and day. (See my f113 review for more detail on DARO.)
The amplifier’s rear panel offers balanced or unbalanced inputs in either stereo or mono, and subwoofer outputs on Neutrik SpeakON connectors. In a system with multiple amplifiers, one of those amps can be designated as “master” and will serve as the single control point for every other amp.
The small theater system in which the IWS was installed measures 13' x 16' with a 9' ceiling. The two subwoofer enclosures were mounted on the wall behind my 65" Panasonic plasma panel at different distances from the adjacent sidewalls. The rest of the system includes the outstanding Anthem MRX 1120 receiver with Dolby Atmos, a pair of PSB T3 speakers in the left and right positions, a PSB Imagine C3 center speaker on a short stand, PSB CS 650 in-ceiling speakers for Dolby Atmos, and four Atlantic Technologies IW-155 surround speakers mounted in the sidewalls and behind the listening seat.
It was with much anticipation that I fired up the system for the first time, many months after installing the IWS enclosures inside the stud bays during my home’s construction. I had expected good things from the IWS but was floored by the quantity and quality of the bass. Most importantly, the IWS gave absolutely no indication that the subwoofers were mounted inside the wall—they sounded like a pair of very-high-quality freestanding subs. I heard no rattling of their structures, no vibrations, and no extraneous noises—just clean, tight, and extended bass. In fact, even when reproducing high levels of low bass, I could feel with my hand very little wall vibration. It was a delight and a surprise to hear such extremely clean bass, free from any in-wall artifacts.
As for the low frequencies themselves, their delivery was classic JL Audio—a combination of an extremely powerful, dynamic, extended, iron-fisted quality on one hand, and a remarkable resolution of dynamics, pitch, and texture on the other. I’ve lived with JL’s superb Fathom f113 freestanding subwoofers (2019 Golden Ear Award and former Product of the Year winner) and was expecting a large step down. No, the IWSes weren’t quite a match for a pair of JL’s Fathom F113v2s, but their performance came a lot closer to those benchmarks than you (or I) would have thought—delivering an overall presentation previously unimaginable from an in-wall sub. On film soundtracks, the IWS reproduced low-frequency effects with explosive dynamic impact along with a suddenness to the start and stop of those effects. I heard no hint of dynamic compression or indication that the system was nearing its limits. Even when testing the system beyond normal listening levels with very deep bass, the room and my ears were the only limiting factors, not the IWS. In retrospect, the 8" version of the IWS would probably have been sufficient for a room of my size, but then again it might not have delivered the extension at the very bottom end that I heard with the 13.5" model.
Film sound effects, however, can only tell you so much. On music, the IWS didn’t sacrifice pitch definition, articulation, and transient agility to deliver home-theater thrills. The IWS was remarkably nuanced in conveying the texture and dynamic shadings of acoustic bass and bass guitar. Bassist Brian Bromberg’s album Jaco (a tribute to Jaco Pastorius) features virtuoso bass playing encompassing lightning-fast runs over a wide register. Every note of Bromberg’s instrument was precisely articulated in pitch and dynamics, with no smearing of the starts and stops of those notes. Significantly, the IWS maintained this clarity and agility regardless of register, in contrast with many subs that sound thicker and more congealed as pitch descends. The bass was extremely flat, smooth, and consistent in amplitude over a very wide range. This combination of powerful muscularity, unfettered dynamics, and taut clarity was extremely rewarding. Another favorite bass test, Ray Brown’s Soular Energy, showed how well the IWS resolved fine texture and tone color. His instrument had body, timbral color, and detail rather than sounding like generic low frequencies. But most importantly, the IWS didn’t dilute Brown’s incomparable sense of swing. Many five-figure freestanding speakers are not this resolved in the bass.
The sub amplifier’s extensive controls, coupled with the DARO room-correction system, allowed the IWS to integrate with the main speakers without audible discontinuity. There was never a sense, with music or film soundtracks, of two disparate elements creating the sound. Moreover, the IWS disappeared when there was little or no bass energy, where many other subs produce a droning sound that’s a constant reminder of the subwoofer’s presence.
JL Audio’s IWS in-wall subwoofer system doesn’t just rival the performance of generic freestanding subwoofers; it rivals the performance of JL Audio’s freestanding subwoofers, which is an entirely different proposition. If you want uncompromised bass performance in a room that won’t easily accommodate freestanding subwoofers, there’s only one game in town.
Specs & Pricing
Frequency response: 26Hz–101Hz, +/-1.5dB; -3dB at 25Hz and 112Hz
Amplifier power: 2000W RMS (short-term)
Amplifier inputs: Stereo or mono on RCA and XLR jacks
Speaker outputs: Neutrik SpeakOn
Amplifier controls: Low-pass filter on/off, 12dB or 24dB per octave; low-pass filter cutoff frequency, 30Hz–130Hz; polarity, 0 or 180 degrees; variable phase from 0 to 270 degrees; ELF trim variable from -12dB to +3dB at 23Hz
Enclosure dimensions: 13.75" x 55" x 4.7" (for 2x6 stud bays); 13.75" x 55" x 2.9" (for 2x4 stud bays)
Grille and wall opening dimensions: 17.64" x 17.14" (grille); 16.5" x 16" (wall opening)
Amplifier dimensions: 17.4" x 3.5" x 17.9"
Amplifier weight: 43 lbs.
Grille finish: White (paintable)
Price: $4900 (13.5" single woofer); $7900 (13.5" dual woofer, dual enclosures, as reviewed)
JL AUDIO, INC.
10369 North Commerce Pkwy
Miramar, FL 33025-3962