JL Audio Fathom f113 Subwoofer

Equipment report
JL Audio Fathom f113 powered subwoofer
JL Audio Fathom f113 Subwoofer

I first encountered JL Audio at the 2005 CEDIA Expo—the event this respected manufacturer of caraudio speakers and electronics used to launch its entry into the high-end-audio and home-theater markets. To say I walked into JL Audio’s press conference and demo with trepidation would be an understatement. I had visions of onenote- bass “boom” trucks playing rap music at knee-weakening sound-pressure levels. However, once the press was seated, and after a short introduction, the demo began...with a piano trio track!

Although JL did subsequently demonstrate its subwoofer’s brute-force ability to move large amounts of air at very low frequencies, its surprising choice of gentle piano-trio music to start the demo spoke volumes about the company’s aesthetic.

Can a company whose entire experience is limited to mobile audio bring something new to the high-end audio arena? The surprising answer is that the mobile environment presents a rigorous set of engineering challenges and requires build-quality standards that make it the ideal proving ground for developing high-performance audio products. With 15 years of experience building ne plus ultra car-audio gear, JL has accumulated some serious engineering chops, particularly in designing lowfrequency drivers. Take the 13.5" woofer used in the Fathom f113 reviewed here. In development for seven years, the unit is the subject of 7 granted patents. (It’s surprising that a basic technology that’s been around for decades—the movingcoil driver—could be the subject of 7 new patents.) This driver is a serious piece of engineering, with great attention paid to every element of its design and construction (see sidebar). The abuses routinely inflicted on woofers in the caraudio world led JL to develop design techniques that would make its drivers virtually indestructible. Moreover, I’ve recently discovered that at the upper end of car audio, enthusiasts share an aesthetic similar to that of the audiophile (forget about boom cars—I’m talking about a completely different mindset).

JL Audio’s single-minded pursuit of creating high-performance woofers has given the company a different perspective on creating a home subwoofer for highend music reproduction.


The Fathom f113 looks at first glance like an ordinary subwoofer—a 13.5" cone driver in a sealed rectangular black box with front-panel controls and rearpanel heatsinks and input jacks. The unit accepts unbalanced input signals on RCA jacks or balanced signals on Neutrik XLR/.25" TRS jacks. Multiple Fathoms can be connected together, with one acting as “master” and the others as “slaves.” The front-panel controls provide a wide range of useful adjustments. In addition to the usual level, phase, and crossover-frequency controls, the Fathom’s low-pass filter slope is adjustable (off, 12dB/octave, 24dB/octave) to help achieve a better blend between the subwoofer and the main speakers. The ELF Trim (Extreme Low Frequency) control boosts or cuts the signal at 25Hz (up to 12dB of cut, up to 3dB of boost), to prevent room overload at the lowest frequencies.

Note that the Fathom doesn’t incorporate a high-pass filter for rolling off bass to your main speakers. You can high-pass-filter your main speakers with the bass-management settings in a home-theater controller, buy an external line-level crossover, or simply run the main speakers full-range and match the Fathom’s crossover frequency and lowpass filter slope to your main speaker’s natural roll-off. This latter method, however, doesn’t provide the dynamicrange advantage conferred by keeping low bass out of your main speakers. Keep in mind that a subwoofer crossover must be designed and built to the same standards as a high-end preamplifier—any less and the sound from the main speakers will be compromised.

The Fathom incorporates the JLdeveloped ARO (Automatic Room Optimization) program that smoothes the worst room-induced frequency-response peak. You simply connect the supplied calibration microphone and push the ARO Calibrate button. The Fathom outputs a series of tones that are picked up by the microphone and analyzed. An algorithm creates a filter to attenuate the room’s most severe peak. Although ARO doesn’t address frequency-response dips (the correction of which could be a prescription for driver or amplifier overload), it does have adjustable bandwidth to more precisely tame the peak. Note that ARO calculates the filter parameters digitally, but then engages an analog filter in the signal path.

The rear panel and dual heatsinks (which are, thankfully, rounded rather than sharp-edged) are made from a single piece of metal. Even when driven very hard for long periods, the heatsinks were never warm to the touch.

The overall level of design and execution is first-rate. I got the feeling that the Fathom’s designers did everything they could to build in quality rather than look for corners to cut. In addition, the owner’s manual is a model of clarity, and even the shipping carton is well thought out.


I evaluated the Fathom f113 in three widely varying system configurations, each designed to reveal different aspects of the unit’s performance. I first mated the f113 with a pair of Totem Arro speakers, using the crossover in an Arcam AV9 controller to high-pass-filter the Arro and low-pass-filter the Fathom. Mating a 13.5" woofer with the Arro, a 4.5" two-way, is perhaps not a real-world scenario, but one that nonetheless reveals much about a subwoofer’s upper-bass performance.

I’m accustomed to setting a subwoofer’s crossover frequency as low as possible under the assumption that subwoofers are simply not as good reproducers of midbass and upper bass as are main speakers. The higher the frequency a subwoofer is asked to reproduce, the greater the potential for hearing the sub’s weaknesses, as well as its inability to blend smoothly with the main speakers. A low crossover frequency minimizes the sub’s potential to do more harm than good. To my surprise, the Fathom blended extremely well with the Arro, augmenting the Arro’s limited bass extension without calling attention to the fact that the midbass and lower bass were being reproduced by a radically different transducer than was the upper bass. In fact, with some careful tweaking (see the accompanying subwoofer primer this issue for set-up techniques), I’d go so far as to call the match nearly “seamless.”

What this configuration would not reveal, however, was the Fathom’s capacity for delivering high levels of low bass; the Arro’s woofer bottomed out well before the Fathom approached its limits (even with a very high crossover frequency). So I added the Fathom to the mighty Wilson MAXX 2 loudspeakers, crossing the system over at 50Hz. In effect, the Fathom replaced the Wilson’s bass below 50 cycles. This was a different kind of torture test for a subwoofer; the MAXX 2 has an extraordinary bottom end in every respect: dynamic coherence, transient fidelity, extension, ability to play loudly without strain, and resolution of bass detail. Nonetheless, adding the Fathom didn’t degrade the MAXX 2’s bottom end and even extended the system’s response in the very lowest registers (kick drum and pipe organ territory). I was also able to achieve a continuous transition between the MAXX 2 and the Fathom; the bottomend sounded “of a piece,” rather than as if a weight were dragging down the rest of the spectrum. I also ran the MAXX 2s full-range, with the Fathom coming in at 30Hz with the steepest possible low-pass roll-off (24dB/octave).

The Fathom’s remarkable ability to blend with such diverse loudspeakers is, I believe, due to this subwoofer’s tremendous agility, high resolution, and superb transient behavior. Forget the stereotypes of subwoofers—slow, turgid, thick, sounding like a disconnected boom underneath the music; the Fathom can turn on a dime, starting and stopping with surprising precision. In the midbass the Fathom sounded like a fast and tight 8" driver in a sealed enclosure; in the low bass, the sub delivered the full measure of this extraordinary driver’s capacity for deep extension and explosive dynamics. It was the best of both worlds—finesse backed up with seemingly unlimited depth and impact.

These qualities were abundantly apparent in the Fathom’s reproduction of kick drum. How a subwoofer portrays kick drum separates those few subs worth owning from the vast field of alsorans. All subs will deliver a thump in the bottom end, but only a select few will reproduce the sudden impact and equally sudden decay of well-recorded kick drum. If a sub doesn’t faithfully reproduce this dynamic envelope, the result is an apparent slowing of the rhythm, which fosters the interesting perception that the band is a little lazy or sloppy. But when the kick drum, working with the bass guitar to form the music’s rhythmic and tonal foundation, is reproduced with lifelike transient fidelity, music takes on a much more viscerally engaging and upbeat quality. This is particularly true of drummers with rhythmically interesting right feet—Terry Bozzio (Zappa), Peter Erskine (Weather Report, Steps Ahead), Mike Portnoy (Dream Theater), Rod Morgenstein (Dixie Dregs), Steve Gadd (everyone), and Jack DeJohnette, for examples. Drummers who use double bass drums present an even greater challenge to subwoofers; the closely spaced transient attacks tend to smear into each other if there’s even a hint of driver overhang. The Fathom was remarkable in this regard, presenting clearly differentiated attacks even on fast double-bass-drum rolls.

I was also greatly impressed by the Fathom’s resolution of pitch, subtle dynamic shadings, and inner detail. Acoustic bass was rendered with a wealth of information about the mechanism creating the sound, from the attack of the string to the sonorous resonance of the instrument’s body. Passages in which the bass doubles another instrument playing the melody were particularly revealing of the Fathom’s tight dynamic rendering and precise pitch articulation. Electric bass had a satisfying “purring” quality, coupled with a weighty warmth, that made music physically as well as emotionally engaging. All of the Fathom’s qualities were on display when I listened to bassist Abraham Laboriel’s terrific playing on Victor Feldman’s Audiophile on the JVC XRCD label. (Audiophile is a compilation of two direct-to-disc LPs originally released on the Nautilus label and engineered by the great Alan Sides.)

Throughout the audition, I had a real sense of hearing musical pitches, dynamic expression, and timbre—not of a cone flapping back and forth and of air chuffing through a port. In their quest to deliver low bass from small cabinets, many ported woofers end up overlaying the music with artifacts such as port noise, driver overhang (the woofer continues moving after the drive signal has stopped), and the sound of the cone moving in the box. The Fathom didn’t impose a sound of its own, which is why it was so revealing of bottom-end detail.

Although capable of great delicacy and nuance, the Fathom had a bottomend solidity, power, and iron-fisted control in the lowermost octave that was jaw-dropping. The f113 can move a large amount of air at very low frequencies (-3dB at 17Hz) with effortless ease and a feeling of anchored solidity. Even when reproducing the most demanding music at very high volume, the Fathom never gave any indication that it was nearing its limit.

The final system configuration in which I auditioned the Fathom was in a multichannel system that included the MAXX 2s, a Wilson WATCH center channel, four Revel Embrace surround speakers, an Arcam AV9 controller, Anthem P5 multichannel power amp (on the surrounds), and a Mark Levinson No.436 3-channel amp driving the front three speakers. I used a pair of f113s, with one acting as “master” and the other as “slave.” The Fathoms were driven by the AV9’s subwoofer output jack, which is a monophonic mix of the Low Frequency Effects (LFE) channel and the bass from any other channel designated as “Small” in the AV9’s set-up menu.

I might be in the minority of audiophiles, but I greatly enjoy musical performances on DVD in multichannel sound. A great example of the Fathom’s ability to keep up rhythmically and convey a tight, high-energy performance with a rock-solid bottom end is on the John Mayall & The Bluesbreakers DVD of a concert performance on Mayall’s 70th birthday (which reunites Mayall with Eric Clapton after 34 years). This band’s sharp-as-a-tack rhythm section was well served by the Fathom’s combination of agility, quickness, and center-of-theearth solidity. These guys have been playing together for years (the drummer has been in the band for 17 years), and the Fathom locked right into the groove along with the band.

Finally, I drove the Fathom to over-the-top sound-pressure levels with the most demanding bass content I could find and still didn’t hear any signs of distress. Watching the driver during this exercise suggested that the cone didn’t reach its maximum 4" excursion.