November 1, 2009
B&W CT SW15 Subwoofer and SA 1000 Subwoofer Amplifier: The New Sub in My House
I have a love/hate relationship with subwoofers. Over the years, Ive owned speakers that had dramatic bass by themselves, such as Thiels CS3.5, KEFs R107, and ATCs SCM50. But during that time I moved often, and never had exactly the right room in which any of those speakers could maximize both imaging and bass. Well, thats not entirely true. There was one room in Boston that measured 35L x 15W x 9H and was built of solid wood and three-ply glass -- there, the KEFs thundered down into the low organ pedals and threw a 3D image. But 18 months later I was gone, left with only a memory of what a perfect room could sound like.
Back in the old days of audiophilia, my solution was to get great-sounding monitors and augment them with a subwoofer. That way, I could place the sub in the best place for bass, and the monitors in the best places for imaging. I tried building a sub myself from an 18" Electro-Voice driver, until I found out that my memories of wood shop were more acute than my hands. My first really great sub was the Entec L2-f20, at the time the most delicate and carefully resolving woofer available. But it had two problems: It couldnt fill a really big room with bottom-octave bass, and it was butt ugly. I know were supposed to suffer for our love of great sound, but the Entec looked like something from a cheap 1940s sci-fi movie.
So when Bob Carvers Sunfire sub came out, with its promise of huge bass from a little box, I decided to sell the Entec and go small. I had a long talk with designer Carver about his woofers, and he assured me that just one would fill with sound my huge and (hopefully) permanent room. But just in case, I asked for two.
Perhaps I drove them a bit too hard. Thats what I thought as I watched them dance across the floor in time with the music. Carver sent me some extra pairs of soft feet, which stopped the disco diving, but I couldnt help thinking that if the feet were soft, I was losing bass. Still, I persisted, even though, in my room, the Sunfires bass dropped off precipitously below 38Hz. I thought maybe I was doomed to a bassless existence.
Then, our esteemed editor sent me a JL Audio Fathom f112. About a week later, I received a Zu Method. Both of these behemoths could pump everything from block-rockin beats to the big war scenes in 300. JLA used a brilliant equalization scheme to achieve their subs deep sounds, while the Zus two 15" drivers could drive a massive amount of air. Both sounded great, and the Zu was even gorgeous to look at. Unfortunately, neither could quite fit the places in the room where I needed them to be. And given the sudden availability of various ingenious DSP room-resonance tamers -- such Anthems ARC and the ubiquitous Audyssey -- I decided I wanted a killer sub that would fit right where I wanted it: under the center-channel speaker and between the left and right front speakers. That meant something with a big wallop and a small footprint.
Of course, the world of subwoofers is now full of little offspring of Bob Carvers original idea. How many manufacturers make small subs that are better than Sunfires? Perhaps a few. But I wanted something a lot better, not just an incremental improvement. I already had the Sunfires.
So, every few months, Id spend the better part of a day cruising websites, checking press releases, looking for anything new that might suit my needs. I kept coming back to B&W, a company whose history of big, accurate bass goes back 30 years, to the introduction of the 801. B&W speakers are used as monitors in recording studios and soundstages all over the world, from Abbey Road to Skywalker Sound, but the subwoofer section on their website offered nothing that fit my criteria. However, I have an indefatigable soul. Like a miner panning for gold, I decided to look through B&Ws dizzying array of speaker lines, most of which are accompanied by their own lines of subwoofers. The model names werent much help. Lets see . . . shall I check out the XT, CM, LM, or VM series? Strikeout.
Then I found the CT (Custom Theater) section. Sounded promising. And then I found this: "Take apart CT800 speakers and youll find technologies derived from our most advanced freestanding speakers: speakers like the groundbreaking Nautilus, or our reference-standard 800 Series." A somewhat invisible speaker that sounds like the 800 series? Intriguing.
The B&W speakers most likely to show up in recording studios are their 800 and 801 models, but the cost of a full five- or seven-channel setup of these easily runs into six figures. More power to you if you can afford it, but I cant. On top of that, think of the floor space all those big boxes would claim. Many who could afford the speakers themselves couldnt spend the hundreds of thousands of dollars for an acoustical engineer and a complete buildout. And even if they could, they probably dont have a spouse who would prefer behemoth floorstanders to hidden speakers. Solution? Speakers in flat-black cabinets that can be built into a wall. Now, if they only had a bombo sub . . .
Thats when I discovered the CT SW15, which stands for Custom Theater SubWoofer 15". That distinctly unsexy handle turned out to be the name of exactly what I was looking for: a plain black box of moderate size but with a massive 15" driver. At 21.7"H x 21.7"W x 10.3"D and a solid 66.1 pounds, the CT SW15 will never be mistaken for a Bob Carver design. But its ability to sit flush with or against a wall is extraordinarily helpful, and its box is plenty big enough to handle the violent in-and-out excursions of that massive cone. And at a price of $1350 USD, the SW15 had started to sound pretty tantalizing.
One of the reasons the CT SW15 takes up as little space as it does is that its a passive design. Thats right -- the amplifier is separate. B&Ws SA 1000 is a class-D amp measuring 16.9"W x 3.9"H x 12.7"D and weighing 14.3 pounds. It costs $1500, which brings the total price of the CT SW15 plus SA 1000 to $2850, or a couple hundred dollars more than either the JLA Fathom f112 or the Zu Method powered subs.
I liked the idea of a separate amplifier. I understand the arguments for the little cubes with their multi-thousand-watt amps and having a big open hose of current available whenever needed. I also know that no one has ever demonstrated that being so close to all those vibrations from a big flapping cone is damaging to a subwoofers amp, yet I've remained a little suspicious. So Im at least intellectually on board with the CT SW15s designers decision to have an outboard amp. Interestingly, rather than develop some tiny, Carver-imitating amplifier, B&W licensed their technology from the current leader in compact amplification, Bang & Olufsen.
Did I say B&O? Dont they make those retro-modern-looking "lifestyle" systems you see in the upscale backgrounds of Architectural Digest, or urban thrillers directed by Michael Mann? The last B&O product I remember creating a stir in the audiophile community was a turntable whose main advantage was its fixed arm/cartridge geometry, which meant you didnt have to use a protractor -- a technology so old it came out about the same time as the B&W 801! B&O, B&W . . . the names are pretty close. Maybe theyve been secret cousins all along and just never told us?
Anyway, B&O developed a diminutive, sturdy, fine-sounding amp and dubbed it ICEpower (ICE=Intelligent Compact Efficient), and thats what B&W has licensed for use in the SA 1000. At 14.3 pounds, the SA 1000 is light for an amplifier, but B&W claims it "produces an astounding 1000W of subwoofer-range power, thanks to its ultra-efficient class-D amplifier design," and that its "equalization is custom-tailored to the CT SW subs, delivering deep-bass extension all the way to 16Hz."
It was time to see if Id at last found the subwoofer that fit all my needs.
The CT SW15 went in the same place I always put my subs. I know, the physicists out there will say Im nuts, but I believe a subwoofer belongs between the two front speakers. Ive tried them all over the room, with steep cutoffs over 40Hz, and I can still hear where the bass is coming from. As I said above, the sub should fit itself into my life, not vice versa.
Hooking up the CT SW15 to the SA 1000 was simple. You can use stripped wires and binding posts or, for an extra-sturdy link, a Neutrik SpeakOn connector. The power switch is three-way: On/Auto/Standby. For the green crowd, the current draw in Standby is a mere 3W. I chose the convenience of Auto.
B&W proposes two different setups: one for home theater, one for two-channel audio. Since this is a home-theater publication, I stuck with that aspect, but you stereo fans are offered some helpful hints about how to integrate a sub into a two-channel system.
B&Ws recommended home-theater settings begin with the volume control at 9 oclock, the Low Pass filter Off, the Phase switch at 0°, and Equalization set to Movie. Theres also a three-position Bass Extension switch: A = -6dB at 16Hz, B = -6dB at 20Hz, and C = -6dB at 25Hz. The CT SW15 plays loudest on C and least loud on A. The Low-Pass Frequency control offers two-channel listeners the choice of matching the rolloff levels of the mains to the sub, but this is switched out of the signal chain for a home-theater setup: your receiver or preamplifier-processor will handle that job.
I started with B&Ws recommended settings and used the Audyssey setup in the Integra DHC-9.9 preamplifier-processor.
Any time a new subwoofer goes into my system, the first thing I try is the opening of "So What," from Miles Daviss Kind of Blue ("six-eye" LP, Columbia 8163; SACD/CD, Columbia/Legacy M64935). The short opening duet of pianist Bill Evans and bassist Paul Chambers can reveal a lot about how a subwoofer handles the tender woodiness of a double bass, but more important, this is one of those treasurable records for which all the musicians were playing together in the same space. That simple method means that, unlike recordings that are assembled track by track, on Kind of Blue you can actually hear the room the music was performed in. Our senses know what a room sounds like, but to have your brain spark and say room, you need deep, accurate bass. The CT SW15 sounded perfectly natural.
Paul Chambers bass has a mighty sound, but its low E string stops at 41.2Hz. Danny Elfmans score for Mission: Impossible (CD, PolyGram 454525) goes much lower, offering snap-fast low percussion, deep synthesizer bass, and a broad dynamic range. The B&W had ample slam, though not quite the simple, elegant realism of the Zu Method. Throwing the Equalization switch to its Music setting brought the B&W back into the race. The Movie setting dried up the signal and was better for explosions, but I was more interested in the quick, accurate bass of Music. For anyone who wants to switch back and forth, theres a 12V trigger on the back that will do the job for you.
A couple of recent Blu-rays that have won five stars chez Marshall have deep bass. Spike Lees Miracle at St. Anna (dont miss the interviews with the actual soldiers in the extras) is a sweet film whose soundtrack makes little use of the LFE channel, but the occasional explosion strikes with all the startling power of real war. I tried re-running a few of them, turning off all my other speakers and cranking the B&W combo up to 6dB above THX reference level. My wife and my house gave up before the B&W did, and there was never a hint of audible distortion.
Our other recent five-star movie is Watchmen. Its soundstage has constant low-frequency rumbling punctuated by deep, loud zaps, wails, and bangs, and the sound-design team uses frequent subtle shifts in bass to keep the viewer off balance. When the effects come, they hit suddenly and hard, and the B&Ws handled everything with suitable grace and enormous power.
That the B&W, JLA, and Zu subwoofers are all superior to the less-expensive Sunfire is as it should be. The JLA might be my choice if I spent most of my time watching sci-fi and fantasy flicks. Since it has room correction built in, I also might pick the JLA if I didnt have Audyssey or one of its cousins -- though anyone with a serious interest in home theater should have a room-correction system. And I might pick the Zu if I spent all my time listening to music.
But for the whole package, the B&W does the best job. Like the JL Audio Fathom f112, the B&W CT SW15 plus SA 1000 sounded imperturbable and unflappable. And like the Zu Method, it loved all sorts of music, from thumping dub to late-Romantic orchestral music. Unlike either, the B&W sub fits my décor as perfectly as it fits my rooms acoustic. It stays.
. . . Wes Marshall
B&W CT SW15 Subwoofer
B&W Group North America