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Spatial Audio Lab X2 Loudspeaker

Spatial Audio Lab X2 Loudspeaker

In all my years as an audiophile I’ve never been captivated by the allure of horn-based loudspeakers. I admired their dynamic abilities, but they never made me want to own loudspeakers based on horn technology. However, during the past three years I’ve gradually altered my opinions about horn-based dipole designs. Why? Because my primary listening room changed from a room built from the ground up to hold my longtime reference Dunlavy SC-VI loudspeakers to a smaller one, located in the basement, that was definitely not built originally with audio reproduction in mind. In my current primary listening room, some speakers that sounded fine in my open-concept living room had too much midbass bloom when I relocated them into my basement listening room. In short, my new room is not an “easy” one to place speakers into.

At first, I was disappointed that my current listening room was not as flexible, friendly, and forgiving of loudspeakers as my old one was. But then, since I prefer lemonade to raw lemons, I decided to take on the challenge to find loudspeakers that would work successfully in my new room. I’ve tried conventional box-enclosure designs with omnidirectional bass propagation, as well as designs with more controlled dispersion and less room interaction. So far, the most elegant solution for my problem room has been Spatial Audio and its open-baffle dipole designs.

Spatial Audio’s loudspeaker designer Clayton Shaw’s first company, Emerald Physics, began in 1978 as a “project company,” where Shaw worked on prototypes for clients. In 2006 Shaw took his latest design to the Rocky Mountain Audio Show, where he met the owner of Underwood Hi-Fi, Walter Liederman, who was so impressed by Shaw’s work that he encouraged Emerald Physics to build what came to be the Emerald Physics CS2, which debuted at the 2007 Rocky Mountain Audio Fest. In 2010 Shaw sold Emerald Physics and all its intellectual property to Underwood Hi-Fi and agreed to continue designing Emerald Acoustics loudspeakers for three years under a non-compete clause. The models 2.3 and 2.7 were Shaw’s last Emerald Physics designs.

Spatial Audio Lab X2 Loudspeaker

In 2010 Shaw created Spatial Audio, whose first products were computer-audio installations using Mac Minis and a software suite that combined sophisticated EQ with the ability to handle multiple channels of crossovers. I reviewed the Spatial Audio computer system for The Absolute Sound in 2012. In 2014, Shaw released the first Spatial loudspeakers, the M1 and M2, followed in 2015 by the Lumina, M3, M4, and flagship X1. His newest design is the X2.

The first Spatial Audio loudspeaker that I had personal experience with was the M3 ($2495/pr.). It was the original loudspeaker I installed in my new room. I kept the M3 for approximately three years, during which time I tried a couple of more conventional loudspeakers in the same room. I quickly learned that some, such as the Studio Electric FSX, had a more refined treble and smoother midrange, but I could not get the midbass under control, so I went back to the Spatial M3s. When Spatial announced its new X2 loudspeaker ($9600/pr. in black, red, or white; $13,900/pr. in Baltic birch) based on the X1, but with an Air Motion Transformer (AMT) instead of a compression tweeter, a 15″ woofer, and a modular design, I let Clayton know that I wanted to hear what the X2 could do. After the 2017 Rocky Mountain Audio Show, the demo pair that had been at the show, came back to my “problem” room. 

After I’d lived with this pair for almost four months, Clayton Shaw revisited my room and replaced the original crossover circuit with the current production one. The loudspeaker went from 94dB sensitivity to 91dB. All listening notes were made using this current production crossover, which I much prefer to the original one, not only due to its improved linearity, but also to its decreased sensitivity, which makes amplifier noise less of a problem. The Digital Amplifier Company’s Cherry MEGAschino power amplifier that produced hiss at 94dB was dead quiet at the lower 91dB sensitivity.

 

Technical Details
The X2 is a modular, two-way, two-piece, open-baffle loudspeaker design that employs a 15″ bass driver coupled to a midrange/tweeter Air Motion Transformer (AMT) mounted in a horn/waveguide. This waveguide, manufactured by Beyma, is specifically designed for this wider-band “pleated diaphragm,” as Beyma calls it, that covers frequencies from 1kHz up. The waveguide system is designed to deliver a controlled dispersion pattern similar to what is produced by the open-baffle design used with the X2’s woofer.

While its relatively easy to understand how a waveguide controls a midrange and tweeter’s dispersion—its shape affects and limits the dispersion pattern to a particular angle—an open baffle’s effects on bass dispersion is not quite as obvious. A box speaker, regardless of whether it is sealed or ported, generates omnidirectional bass below a particular frequency dictated by the box’s physical design and crossover. It doesn’t matter whether the box is wood, metal, carbon-fiber, or even solid rock; due to its propagation characteristics, it will still generate an omnidirectional bass.

How does an open-baffle design change the bass from omnidirectional to controlled dispersion? The answer in one word is cancellation. The sound generated by the woofer goes both forward into the room and backward in the other direction. The forward and the backward waves generated by the woofer meet at the edges of the open baffle and cancel each other out. This means that the low-frequency energy generated to the sides of the open-baffle loudspeaker is vastly reduced. If you were to draw a picture of an open-baffle dispersion pattern it would look like a lopsided figure eight, with a much larger lobe generated to the front of the loudspeaker while a smaller lobe comes out the rear. At the sides almost no energy is present.

What does this mean in terms of perceived sound? With less low-frequency information being thrown to the sides of the room (and less bass energy overall), the room’s resonances are energized to a far lesser degree and the room does not try to “sing along” or amplify certain frequencies while attenuating others.

Another advantage of controlled and similar dispersion patterns for both the bass and the midrange/treble drivers is greater harmonic consistency at the optimal seating position. Even several feet to either side of the ideal position, the harmonic balance remains the same. Outside of the controlled dispersion area the output over the entire frequency range also drops evenly so that reflected energy off the sidewalls is not bass or treble-heavy and does not affect the frequency balance at the listener’s position.

Ergonomic Details and Setup
The heaviest section of the two-part X2 only weighs 45 pounds, which makes it an easy carrying weight for your average semi-fit audiophile, even if he must place the loudspeakers in a room upstairs or in a basement. The two-piece configuration also reduces other potential issues. Less weight in each box often means an easier trip for the contents and fewer shipping damage issues. Also, the unboxing is much easier. The only tricky part of the assembly is fitting the two units together—you must line up three points of contact, which really isn’t too tough.

As with any top-performance component, the X2 loudspeakers require careful setup and placement to perform optimally. Although the X2s can create a listening position sweet-spot large enough for a sitting human to never bounce out of; to achieve optimal imaging with the X2 requires taking the time to make sure that both loudspeakers are positioned so they are exactly equidistant from the primary listening position and front wall boundaries. And I do mean “exactly.” Even a deviation of as little as an inch will affect imaging precision. I set up the X2s three separate times in my room—once when they first arrived, a second time when the crossovers were changed, and a third time about two weeks after the change-over because something wasn’t quite right. I found one loudspeaker was 1½ inches closer to the back wall than the other. Retriangulating made a noticeable improvement in the X2’s imaging precision.

 

I used two power amplifiers with the X2s—the Pass Labs X150.8 and the Digital Amplifier Company’s Cherry MEGAschino. Neither had any issues driving the loudspeakers at what I consider normal listening levels. When pushed hard the lower-powered Pass displayed some slight signs of strain on especially punishing material. Much of the time the amps were tethered to the Mytek Manhattan II DAC/pre. Other front-end sources included a Mac Mini connected to the DACs via USB, the Lumin X-1 streamer/DAC, the Aqua La Voce II DAC, and my analog rig—a VPI TNT III W/Graham 1.5 arm and Clearaudio Victory II cartridge. Speaker cable was the latest Audience Au24SX, and interconnect was Wireworld Eclipse 7 for the long preamp-to-amp run and Audience Au24SX for the shorter analog cables.

My primary listening room also hosts a pair of JL Audio Fathom f112 subwoofers. They were set for a 45Hz crossover point with a 12dB-per-octave slope. Both the X2 and f112 received full-range signals which allowed the X2 to roll off naturally, while I used the f112’s internal crossover to limit its upper-frequency response.

Sound
My first good pair of loudspeakers were the original ProAc Tablettes, recommended by Harry Pearson many years ago. One area where they really excelled over other loudspeakers available at the time was in their ability to produce a palpable three-dimensional image and disappear in the process. So, to some degree I have always been “an image freak,” who values a loudspeaker’s ability to vanish and produce a convincing three-dimensional soundstage. And while the Spatial M3s, with their coaxial tweeter/midrange compression drivers, imaged well and could produce a stable and believable 3-D soundstage, the X2 do an even more credible and complete job of disappearing. When they were optimally set up, it was virtually impossible to tell where the speaker’s drivers were located. The X2s simply produced the mix, clearly laid out in three dimensions. Whether I played one of my own purist single-stereo-microphone recordings or the latest multi-tracked pop confection, the image was solid and dimensional. The Spatial X2s were all about easily decoding the mix. 

The X2’s ability to define the soundstage with greater clarity wasn’t because the overall size of the soundstage was any larger than that of other loudspeakers, but because the spaces between the instruments and voices, where the music was not, were quieter. Cue the “blacker blacks” cliché. But to my ears lower noise translates into a more lucid presentation that is simply easier to listen to and listen into because there’s less noise to confuse your ear/brain.  

Reviews of multi-driver loudspeakers often, justifiably, devote a great deal of time and verbiage to the degree to which the loudspeaker integrates its drivers to produce a coherent full-range transducer. Due to their combination of only two drivers, similar dispersion patterns between treble, midrange, and bass, lower-than-usual crossover points, and quasi-point-source tweeter/midrange configuration, the X2 proved to be among the more coherent loudspeakers I’ve experienced. And not only was the X2 coherent within its own range, but its low end rolled off evenly and smoothly and made it easy to integrate the X2s with the JL f112 subwoofers.

I mentioned earlier that my main room has some bass overload issues. With conventional box loudspeakers the corners of my room, even with bass traps, had far more bass energy than I heard at the listening position. And while the bass was excessive in the corners, it was somewhat leaner than optimal at my ears. The X2s (and the M3s before them) changed that. With the X2s the bass in the corners was vastly reduced while the bass at my listening position not only increased in level, but also in coherence, with reduced room interaction around 70Hz. 

Another aspect of the sound that is related to the improved bass response and lower amount of room interaction was that with the X2s the system had the ability to poke you in the chest with its lower-midrange and upper-bass dynamics. This is one area where dynamic-driver-based loudspeaker designs usually have an advantage over planar designs. And while the full-range Apogee loudspeakers and Sound Lab A3 with side panels could deliver this amount of impact, smaller planar designs, such as the original Quad ESL 57s, could only do this occasionally when placed into the exactly right-sized room with the right electronics.

 

While I’ve always admired an electrostatic dipole’s speed, delicacy, and ability to retain low-level detail, many times I‘ve found the ethereal and shimmery additive colorations of their sound to be less than ideal. The X2 combines the best aspects of a dipole design (its dispersion pattern) with a more dynamic sound signature that doesn’t add additional shimmer to the original harmonic character of the music. The AMT tweeter/midrange is as fast as an electrostatic panel, but it has better linearity and more controlled dispersion.

As we humans age our hearing goes through changes. For many older audiophiles, as their ability to hear frequencies above 10kHz wanes, their sensitivity to non-linearities below 10kHz increases, so they are actually more aware of anomalies within their perceptible hearing range than before. My own hearing tops out at 13kHz, but I’ve noticed that, especially around 3kHz, I’ve become more sensitive to harshness, electronic hash, and distortion. With the Spatial M3 I was aware that the tweeter/midrange was not as smooth as some well-designed dynamic driver-based loudspeakers, such as the Studio Electric FSX. The X2’s tweeter/midrange was as smooth and non-fatiguing as the Studio Electric FSX, especially around that 2.5kHz to 3.5kHz range.

Although the X2 loudspeaker system is smooth through the midrange and into the treble, it does not lack for resolution. When I listened to the new 2018 mix of the Beatles White Album via Tidal and Qobuz, it was easy to hear how different the new recording was. On tracks I’ve heard many times on many different systems I was impressed by how easy it was to listen deeply into the mix. Listening seemed to require less effort. The X2’s resolving power reminded me of my current desktop references, the Audience 1+1 V3, with similar incisiveness and a lack of additive aural distractions.

It’s rare to come across a loudspeaker that doesn’t have some amount of harmonic bias—i.e. variation from neutrality—that pushes it on one side or the other of the bright/dark harmonic balance. Usually I can identify which side of this great divide a loudspeaker falls on easily. With the X2 I was much less aware of any harmonic tilt or bias. Perhaps this was because the room’s reflected sound had less influence on the system’s overall presentation. I was, however, made more acutely aware of how much the harmonic balance varied from one recording to the next. 

There is one performance area where the X2 does not perform as well as more conventional designs—when the listener sits outside the dispersion pattern of the loudspeaker, the sound changes drastically. Not only does imaging collapse completely, but also the harmonic balance changes with lots of upper-frequency roll-off. If you must have a 5.1, 7.1, or 9.1 system designed for group listening, the X2 loudspeakers would not be optimal. In those kinds of setups, where the goal is good sound for all, but great sound for none (in my humble opinion), I would opt for a wider-dispersion design. But if 3.1 or 5.1 with one perfect seating position is your goal, the X2 will work nicely. 

Competition
During the past few years there have been a veritable cornucopia of excellent loudspeakers available around $10,000 per pair. You could even call it the $10k horserace! Golden Ear’s Triton Reference and Focal’s Kanta 2 are just two examples of the excellent loudspeakers out there. In point of fact there are very few high-performance loudspeaker manufacturers who don’t have something available for around $10k a pair. And while there are many fine options, none have the same combination of features and capabilities as the Spatial X2. The closest are some of the late Siegfried Linkwitz designs created for DIYers, but those require far more assembly time than the Spatial X2s.

Summary
Sonically, loudspeakers and rooms are intimately connected. Take a great speaker, put it in a room whose issues interact with it in a negative way, and the result will probably be bad sound. And while some audiophiles have the resources to build a dedicated listening room whose dimensions and materials allow it to work with a wide variety of loudspeakers, the vast majority of us walk into completed, general-purpose rooms that must be adapted to high-quality listening. And sometimes that loudspeaker that measured well and sounded fine at the dealers’ room or an audio show, with nice, even, near-omnidirectional low-frequency dispersion, will not work successfully in a real-world home. That is where a loudspeaker with controlled low-frequency dispersion, such as the Spatial X2 can succeed where many conventional designs fail.

So, if you have a room where you can’t seem to get your bass frequencies under control. And the room, despite your best efforts, continues to try to sing along with your loudspeakers. Perhaps instead of adding more sound treatments, EQ curves, and DSP, the more elegant solution is to find speakers that can work with your room rather than against it. A pair of Spatial X2s certainly did that for me.

Specs & Pricing

Type: Two-way passive dipole
Driver complement: AMT tweeter/midrange and 15″ dynamic driver woofer with composite cone
Frequency response: 20Hz to 23kHz
Impedance: 4 ohms nominal
Sensitivity: 91dB
Dimensions: 18″ x 44″ x 12″
Weight: 90 lbs.
Price: $9600/pr. in black, red, or white; $13,900/pr. in Baltic birch

Spatial Audio Lab
4220W 2200S St. Unit L
Salt Lake City, UT 84120
(435) 640-1294
spatialaudio.us

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