Theory Audio Design 5.2 Surround Sound System with 75-inch Soundbar Reviewed

Theory Audio Design 5.2 Surround Sound System with 75-inch Soundbar Reviewed

Theory Audio Design's speaker systems manage the nearly impossible feat of being both lifestyle friendly and unflinchingly high-performance.

Squint hard at the elliptical orbit of the home audio industry and you'll see that it revolves around two centers of gravity: One, the lifestyle-oriented, dominated by companies like Bang & Olufsen, Bowers & Wilkins' Formation line, and the like; The other, the high-performance oriented, lorded over by brands like JBL Synthesis and Pro Audio Technology. Granted, most products we evaluate here at HomeTheaterReview don't fall purely into one category or the other, rather orbiting between those two extremes. But generally speaking, the closer you get to one focus, the farther you get from the other.

And then along comes Theory Audio Design, the brainchild of Pro Audio Technology owner and president Paul Hales. Initially conceived to tap into the existing PRO customer base, to provide an upgraded audio experience for TVs in and around houses in which PRO is used in a dedicated theater room, Theory has grown a bit in scope and intent since it was first designed. Simply put, it's Hales' goal to cater to both the residential and commercial marketplace, serving indoor as well as outdoor applications, surround sound and distributed audio alike, with as few models as possible.


Rather than leaping into all of those pools at once, though, the company is starting in the home theater (or perhaps it would be more accurate to say the media room) with modular, mix-and-match surround sound systems that mostly revolve around three soundbar offerings, each designed to match the width of the most common TV sizes dominating the media room marketplace at the moment. The sb65, designed to match 65-inch displays, retails for $2,000. The sb75 (the logical mate for 75-inch TVs) comes in at $2,200. And the sb85 (you can fill in this parenthetical yourself, can't you?), carries a price tag of $2,400.


All three share the same driver configurations: Six of Theory's 5-inch Carbon Fiber Low Frequency Drivers (two for each LCR channel) and three 1.4-inch Advanced Polymer Compression Drivers. Height and depth are the same across the lineup, at 9.5 and 3.8 inches, respectively. All three have the same power handling capabilities at 200W (AES) per channel. Maximum output is also rated identically across the line at 117dB Per Channel; >124dB Three Channels Driven.

The biggest difference, aside from the obvious disparity in width, is that the sb65 is comprised of three separate sealed enclosures, while the sb75 and sb85 have three separate bass-reflex enclosures, each with two front-firing ports. The result is that while the sb65 has a rated bandwidth of 75 Hz to 23 kHz, the sb75 and sb85 extend from 58 Hz to 23 kHz.

Theory_sb25_grille_on-off.jpgIf you'd prefer to skip the soundbars altogether, Theory also offers its sb25 multipurpose on-wall speaker, which is positioned more as a surround or height- effects channel speaker but can just as easily be configured as LCR channels (or just L&R if you don't want a center speaker). The sb25 is effectively one channel of the sb75 housed in its own enclosure, as it features two of the 5-inch Carbon Fiber Low Frequency Drivers and a single 1.4-inch Advanced Polymer Compression Driver, along with two front-firing ports, and 200W (AES) power handling, with maximum output rated at 117dB.

Theory also currently offers two passive in-room subs (with powered and in-wall versions coming later this year). The sub12 is rated for 500W (AES)/1000W continuous power handling with maximum output of 122dB and low frequency extension down to 22 Hz. The sub15 ups the maximum output to 124dB and features the same rated power-handling and bandwidth specs.

The Hookup
The secret sauce of the Theory Audio Design system is the $3,500 ALC-1809, a fanless 1U loudspeaker controller with nine Class-D amplified channels (three of them 300WPC into 4 ohms, six of them 100WPC into 4ohs, bridgeable to 300W), 96 kHz/32-bit DSP processing, 8x8 matrix bass management, 8x8 matrix mixing capabilities, 20 parametric EQs per channel, and automatic signal ducking capabilities (for intercom and paging).


Depending on your needs, the ALC can be configured to drive everything from a 2.0 system up to a 5.2.2 Atmos system. Future ALCs will feature HDMI switching, Dolby processing, etc., but for now, though, you'll need to bring your own surround sound processor to the equation.

And it needs to be one with balanced XLR outputs for every channel (or you need to use RCA-to-XLR adapters), since the ALC-1809's phoenix-style audio inputs are balanced only. You can opt to do the phoenix wiring yourself or rely on Theory's XLR-to-phoenix adapters.


Speaker-level outputs are phoenix, as well, but I found that the terminals had no trouble whatsoever accommodating my preferred 12-guage speaker wire. Neither did the spring-loaded binding posts on the back of the speakers themselves.

When it comes to configuring and setting up the ALC-1809 to drive a Theory system, your installer will have three options. The most basic and automatic of the three involves using a piece of software called ALC Automator. If you don't need more than nine channels of amplification (which would require at least one additional loudspeaker controller), this is by far the preferable option, since it automates the process of assigning channels, setting delays and levels, dialing in boundary gain compensation, configuring bass management, etc.

More advanced software solutions available from Theory require more manual configuration, but give you access to PEQ and other adjustments and fine-tuning.

But since most installers will likely rely on the ALC Automator, I went that route for my installation of a Theory sys5.2 - 7515 5.2 Surround Sound System. This system is comprised of a sb75 soundbar, two sb25 on-walls for surrounds, and two sub15 subwoofers. The sb75 was chosen to match the width of my Vizio P75-F1 display, and it comes within 3/32 of an inch on each side of doing so perfectly. Hales tells me that it's an even closer match for Sony's higher-end 75-inch displays.

Theory originally pitched me the idea of doing a 5.2.2 system review, but my recent dalliance with Dolby Atmos has come to an end, and frankly I'm tired of distracting overhead speakers for the time being. (Okay, full disclosure: I also didn't want to ceiling mount a pair of 23-pound speakers, however temporarily. I've also heard enough Theory Audio Design Atmos demos to know that the system absolutely excels at object-based audio; I was here to do some hands-on testing with the configuration software, as well as to gauge the system's performance in a room I know intimately, with my own demo material.) Z-CLIP_wall_cleats.jpg

Theory insists that the work of installing the sb75 soundbar is a three-person job. I found it doable with two humans and an American Staffordshire Terrier supervising, but there was some huffing and panting involved. The sb75 weighs in at hefty 68 pounds, largely due to its incredibly inert extruded aluminum cabinet. That bulk, combined with its length, makes it unwieldy. Like the sb25, the soundbar relies on a cleat-mount system for physical installation (dubbed Z-CLIP in the company's documentation), which gives you a little wiggle room in terms of left/right placement, although it should go without saying that the cleats should be screwed into studs.

The sub15s proved a little easier to install and position. Given that they have no internal amps, they weigh a mere 76 pounds apiece -- more than the sb75, true, but given their rather compact dimensions, they're luggable by a solitary Wookiee. They're also only 19.8 inches deep -- no deeper than an RSL Speedwoofer 10S -- although at 23.5 inches wide they're not quite what you'd call "compact." Automator_4_3_2.jpg

With the speakers placed, I fired up the ALC Automator software and connected my computer to the ALC-1809 via the included USB cable. Upon opening the software, I noticed all sorts of funky potential configurations outside the boundaries of the typical 2.0, 5.2, 5.2.2, 7.2, etc. For whatever reason, 4.3.2 particularly amused me, but my sense of humor is weird. Just know that whatever configuration you choose must be supported by your surround processor/preamp.

With my preferred 5.2 speaker setup selected, I then went to the drop-down boxes at the top of the screen and selected which specific speaker models filled each role. I then had to go buy a tape measure from Lowe's, because it's been a minute since I had to use one and couldn't find my old one. The ALC Automator asks you to plug in the distances from each speaker to the seating position, as well as distances from each speaker to the nearest corner, with one-foot increments for the former and choices of in-corner, 1 foot, or >2 feet for the latter. You also tell the software whether the speaker is mounted on the wall, 1 foot away, or more than 2 feet away, then apply your settings and let the software crunch its numbers. Again, Automator calculates levels, delays, bass management, and boundary gain compensation based on the numbers you give it, so there's little else to do after you feed it the relevant measurements.


The software even gives you a handy map of inputs and outputs, shows you how to wire bridged channels, and gives you a legend of which speaker goes where. It also activates lights on the back of the ALC to show you which input channels correspond to bridged outputs.


I uploaded the results calculated by the software to the ALC (which took about two minutes), carried the ALC into my media room, and connected it between the speakers and Emotiva's RMC-1 preamp, then did some quick listening. I decided that I needed an additional couple decibels of gain for the sub channel, so I carted the ALC back into my home office, made that tweak, uploaded the results, then reconnected the loudspeaker controller/amp to my system and dug in for some serious listening.

You probably have some level of expectations for the performance of the Theory Audio Design system simply based on the fact that it's built around a soundbar. Throw those expectations out the window.

Actually, you know what? Strike that. Let's hold onto those expectations for a bit and talk about the shortcomings that most people associate with soundbar systems, because they help shine a light on what makes this such a fantastic speaker system. I think it's safe to say that you would expect an integrated LCR speaker with width matching your TV screen to be somewhat limited in terms of soundstaging, right?

It took only a few minutes with the UHD Blu-ray release of Conan the Barbarian (the ridiculous 2011 reboot starring Jason Momoa) to recognize that this is far from the case with the sb75. In the early scene in which young Conan joins the youth in his village to earn the right to become a warrior, I was struck by just how expansive Tyler Bates' percussive score sounded through the soundbar.

The heart-pounding drumming sounded as if it were coming from a spot at least a few feet beyond the constraints of the cabinet. This avoided the problem inherent to so many soundbar-based surround systems, in which the soundfield forms a sort of wedge -- wide at the rear of the room and pinched toward the front. Throughout the silly sword-and-sorcery adventure, all I heard from the Theory system was room-filling and cohesive surround sound that never felt limited in the slightest in terms of speaker placement. The wonderfully wide dispersion of the speakers leads to a big, cinematic audio experience that's easily on par with the best standalone speakers in this price class.

Given the limited depth of the cabinets across the entire Theory line, you might also expect some limitations in terms of dynamics. There, too, you'd be dead wrong. In fact, the punch and slam delivered by this system don't merely outpace other speakers of roughly the same size; In terms of attack, the system also embarrasses much larger and more expensive speaker systems, as well. During Star Wars: Episode II -- Attack of the Clones, I was particularly smitten with the way the system (subs and speakers alike) handled the seismic charges dropped by Jango Fett into the flight path of Obi-Wan Kenobi at close to the film's midpoint. That moment of silence, followed by that unmistakable PWANG and the shattering of asteroids, frankly blew me away, and not in a "for a soundbar" kind of way. You simply couldn't ask for more in terms of authority, power, impact, control, and sheer SPL output at anything approaching this price.

You want to pick nits about dialogue clarity? You'll have to pick an easier target than the sb75. Like many of you, I'm sure, I've been re-watching Hamilton on Disney+ nearly nonstop since the minute it started streaming, and my only complaint about the presentation is that the lyrics can be a little hard to understand at times (mostly because there's a weensy bit too much of the room -- and not quite enough direct mic audio -- in the mix). But the sb75, quite frankly, handles the dialogue better than my reference center- channel speaker, especially during tunes like "Guns and Ships" and "Satisfied," during which the lyrics sometimes spray like machine-gun fire.

What about bass integration? Most soundbar systems -- and indeed many sub satellite speaker systems -- have issues with a gap or a significant dip in magnitude response somewhere around the crossover point. I generally use Blue Man Group's "Drumbone" from the Audio album to get a sense of how bad this gap is with sub/sat systems, but the Theory Audio Design system simply chewed it up and asked for more. The transition between the lower- and higher-frequency beats (whose fundamental frequencies sound like they run the gamut from 70ish Hz to somewhere in the mid-80s to my ears) is utterly seamless, wholly linear, without a bit of a dip to be heard.

Granted, sub-20 Hz LFE freaks might take issue with the fact that the sub15 subwoofers only extend down to 22Hz. And it's true there are a handful of movie soundtracks out there that dig a little deeper. In the sewer fight between Spidey and the Lizard in The Amazing Spider-Man, for example, I couldn't feel every last inch of those subsonic, bowel-loosening rumbles for which the scene is cherished by home-theater junkies. If you're familiar with the work of Theory Audio Design's Paul Hales, though, this shouldn't come as a surprise. Even his massive, 21-inch, 155-pound Pro Audio Technology LFC-21sm subwoofer barely dips below 19 Hz. It's a focus on clarity, impact, and distortion-free performance above all else that generally keeps his sub designs from attempting to output such ridiculously low frequencies as you'll find in some other subs. And generally speaking, it's an approach I agree with. What you miss out on in terms of the last word in pants-leg-flapping, you get back in the sort of controlled, dynamic, hard-hitting yet pristine (not to mention LOUD) bass that most people have never experienced in their homes.

That wonderfully musical-yet-muscular bass, combined with the excellent coherency, dynamics, and neutrality of the soundbar and satellite speakers, makes for an incredible home theater speaker system, form factor be damned.

The Downside
In terms of audio quality, I have absolutely nothing negative to say about the Theory Audio Design system. Its performance is beyond reproach. What criticisms I do have about the system overall should be read more as a wish list for future upgrades and enhancements of the system.

Firstly, I would like to see a little more in the way of installation flexibility, especially for the sb75 and its sibling soundbars. Given their heft, I understand why using a soundbar mount that connects to your TV isn't an option. But I would like to see some sort of non-wall-mount solution, even if it were as simple as a stand that could be used for placement atop a credenza. [[Editor's note: in the fact-checking process, Theory Audio Design let us know that a table-top mount solution is in development for release later this year.]]

Networking capabilities would also help, if for no reason other than eliminating the need for a USB connection between computer and controller during setup. (For what it's worth, I could have used a laptop to make the setup a little easier, if only my laptop weren't a Mac. For now, Windows is the only OS supported by the software.)

I would also like to see Theory introduce a smaller multiuse speaker. While the sb25 is pretty much a perfect match for my larger main media room, it's frankly overkill for my 12-by-15-foot secondary media room, which would otherwise be a prime candidate for a Theory Audio Design system.

And while we rarely if ever discuss price in the Downside section of our reviews, it should be stated that the Theory Audio Design system represents a somewhat lopsided value proposition depending on your needs, largely due to the fact that the ALC-1809 loudspeaker controller is the most expensive component in the system.

If you're building a complete surround sound or object-based surround system, the system is frankly a ridiculous bargain. Five stars all the way. For just over $10,000, you can have a truly spectacular 5.2.2 speaker system plus amplification. Just add surround processing and a display and you'll be the envy of your neighborhood on movie night (once we can start inviting our neighbors over for movies again, that is). Seriously, you'd have a hard time putting together a component speaker system with accompanying amplification that performs this well for ten grand.

If you just want or need a soundbar, though, the Theory system doesn't make quite as much sense from the perspective of value: $3,500 for the loudspeaker controller plus $2,000 for the smallest soundbar in the lineup puts you at roughly half the price of a complete object-based sound system.

Competition and Comparisons
If you're looking for the exact combination of lifestyle swagger and unbridled performance that the Theory Audio Design system delivers, I think you'll find the competition to be rare, indeed. But you might want to check out Paradigm's Décor on-wall speaker system. From what I've seen, I like its customizability and installation flexibility. I haven't heard the system, though, so for performance impressions you'll have to check out Brian Kahn's review.

Putting together a component home theater system is difficult enough for those of us who live and breathe this stuff on a daily basis. Do your amps match your speakers? Do your speakers match each other? I get emails at least once a month from readers who are baffled about the fact that the auto-room-setup functionality of their receivers seem to think their subwoofers are in a different ZIP Code altogether from their main speakers.

And hey, solving the puzzle that is high-end home theater is half the fun for some people. But it's also a thing that keeps a lot of people from entering our hobby. The Theory Audio Design system solves so many of those problems and it looks dead sexy while doing so. The fact that it just knocks it right out of the park in terms of performance is something of a minor miracle.

There's just so much to love about this system: its musical-but-muscular bass, overall dynamic impact, wonderful dispersion from surrounds and LCR alike, unimpeachable dialogue clarity, excellent imaging, utter lack of distortion, and beautifully neutral sonic signature. That's not even mentioning the gorgeous design of the speakers themselves. Put it all together and what you get with the Theory Audio Design system is a truly world-class home theater audio experience that sounds like it belongs on a mixing stage and looks like it belongs in the sort of luxury Midtown Manhattan penthouse apartment that I could only dream of affording.

Additional Resources
• Visit the Theory Audio Design website for more product details.
• Read Theory Audio Design Speaker Systems Now Shipping at
• Read CEDIA 2019 Report: A Tale of the Haves and the Have-Nots at


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