B&W CM9 Speaker System Page 2
The full-range CM9 speakers have a number of common features. They all employ B&W’s woven Kevlar cones, which the company has been using and continually refining since it first introduced them in the DM6 in 1976. The 6.5-inch woofers in the CM9 employ composite paper and Kevlar cones. The cones in the CM9, the midrange driver in the CM Centre 2, and the woofer cone in the CM5 are all Kevlar.
If you’re familiar with B&W’s recent speakers, you’ll recognize the CM9’s 6-inch FST midrange driver. It’s the direct descendant of the midrange that B&W first developed for its flagship 800 Series speakers. It’s still used in that line and in a number of other B&W models—all the way down to the 683. Since midrange frequencies don’t require much cone excursion, the FST cone has no surround. Instead, a ring of foam simply terminates it and keeps it centered. The foam ring is said to match the mechanical impedance of the cone better than a conventional surround. The intent is that the foam largely absorbs any bending waves that travel up the cone. This ostensibly prevents the waves from reflecting back down the cone where they can produce distortion.
The new kid in town here is a smaller, 4-inch FST driver in the CM Centre 2. This smaller midrange facilitates a domestically acceptable center speaker designed the way I like it—as a true three-way design. While the optimum center-channel speaker is always identical to the front left and right models, this isn’t always practical. The next best approach employs a vertically oriented midrange and tweeter that are flanked by one or more woofers. This usually, but not always, results in a more uniform response as the listener moves to the left or right and away from the center axis.
The tweeter that B&W uses in all of the CM speakers is another trickle-down descendant of the 800 Series designs. No, it doesn’t have the diamond dome that graces several 800 Series models (you wish!), but the rear of its aluminum dome is loaded into a tube to better dampen the rear wave and keep it from reflecting back and reradiating through the diaphragm.
The crossovers in the CM models are said to be the simplest B&W has ever used. This is made possible by the drive units’ inherently linear mechanical design. For example, the high-pass filter to the tweeter is just a single high-quality capacitor.
A First Listen: Music
I began my evaluation, as I usually do, with two-channel music and just the CM9s driven full range. The speakers were located a minimum of 3 feet from any nearby walls. I listened for hours without fatigue. Still, I was less than satisfied in a couple of respects. First, while the top end was by no means soft or obviously rolled off, it lacked the open airiness that can help recorded music come fully to life. Also, the mid and upper bass region was too prominent. This resulted in a balance that was pleasing and easy to listen to, but it didn’t tickle my audiophile fancy nearly as much as the less expensive B&W 683s did.
Further down the review road, I blocked the CM9s’ ports with the foam plugs that B&W pro- vides. This somewhat reduced the speakers’ extreme bottom-end reach, and it tightened up the bass to the point where the high end came back into perspective. The speaker no longer sounded too polite and forgiving. I still missed that last bit of sparkle that enhanced the 683’s overall balance, but I’d returned them by that time, so they weren’t available for a direct comparison. Nevertheless, the CM9s sounded considerably more alive and real than before. What happened here? Balance. Just as a rolled-off bottom end can make even a flat top end sound bright, an uptick in the bottom end, particularly through the midbass and upper bass, can make the top end sound recessed—even if it’s reasonably flat with respect to the midrange.
The CM9’s top end was now clean and delicately detailed, and the FST midrange was exceptionally natural and uncolored. Imaging was precise, but I’m fortunate since most speakers image well in my setup. It provided as much depth as the program material required. The bass was also surprisingly extended. On music, I only felt the need for a subwoofer on the most difficult material that features an organ or synthesizer. However, through the midbass, the CM9 was a bit richer than life for my taste.
But when I added the B&W ASW 10CM subwoofer to the mix, with the main speakers now rolled off below 80 Hz, that sealed the deal. The sound was now firmly in the “wow” range. While I still couldn’t completely eliminate a bit of excessive upper bass (often as much the fault of the room as the speaker), and I would have liked just a bit more air at the very top end, those criticisms became minor. In any case, they may be unique to either my expectations or my room.
If a speaker can do right by music, it almost invariably does the business on movies too. Of course, this is provided that the added pieces (subwoofer, center channel, and surrounds) handle their jobs without mucking up the total sound. And it also assumes that the system has enough inherent grunt (a technical term for clean output capability) to handle many soundtracks’ high dynamic range demands.