Bowers & Wilkins CM4 Loudspeakers 
Home Theater Loudspeakers Floorstanding Loudspeakers
Written by Brian Kahn   
Monday, 01 October 2001

The CM4 ($1,500) is the top-of-the-line speaker in B&W’s new moderately-priced CM line. The CM line consists of three speakers: the stand-mounted CM2, the CMC center channel and the floor-standing CM4 reviewed here. The CM4 speaker weighs in at 40 pounds and is fairly compact at 35.8 inches high, 7.8 inches wide and 11.5 inches deep. The CM4 has a very compact, clean and modern appearance. The well-executed cabinet comes with a real wood veneer of either maple or rosenut. The review samples were a light maple. Upon first glance, it is immediately evident that the design team paid attention to aesthetics. The speaker starts out as a tall, narrow, well-finished maple box with a simple black cloth grille. Once the grille is removed, things get exciting. Beneath the grille is an aluminum baffle with three drivers. The tweeter is on top. Directly beneath the tweeter is the telltale yellow Kevlar midrange with a gray, cone-shaped dust cap. Below that is an aluminum-coned driver with another gray cone-shaped dust cap. The surrounds for the two lower units are a light gray rubber. This speaker, contrary to popular belief, may actually be more aesthetically appealing in a modern design environment with its grille removed. A close review of the speaker will reveal that, despite the moderate price, B&W has not relaxed their standards for superior fit and finish.

The driver complement consists of a one-inch metal dome tweeter, a 6.5-inch Kevlar bass/midrange unit and a 6.5-inch aluminum bass driver. B&W considers this design to be a "two- and-a-half-way" speaker, due to the overlap between the two 6.5-inch driver units. The speaker can be bi-wired if desired. The frequency range is stated as 38Hz to 20Khz and the recommended power range is 50 – 150 watts per channel. The binding posts have plastic plugs that prevent the use of banana plugs, but a determined listener could potentially remove the plastic.

The technological highlights of the CM4, and indeed of the entire CM line, include Nautilus-type tube-loaded tweeters, Kevlar cone midrange and "flowport" porting. The Nautilus tube design reduces the chances of unwanted radiating sound waves from reaching the back of the tweeter, resulting in cleaner highs. The Kevlar driver allows for a stiff and lightweight driver, capable of handling a large bandwidth accurately. Lastly, the "flowport" uses golf ball-type dimples and flared port ends to reduce port turbulence.

I placed the CM4s in my two-channel system, which also includes a Krell 300iL integrated amplifier, a McIntosh Labs MC602 stereo amplifier, a Sunfire Subwoofer Jr., a Yamaha TX-950 tuner, a Theta Data Basic CD transport and Perpetual Technologies DAC, connected with Audio Analysis interconnects. I also experimented with both Audioquest Gibraltar and Monster Cable Z2 Reference bi-wire speaker cables. I found the CM4s need several days of break-in before reaching their sonic potential. My collection of subwoofers were used during set-up but not during any critical listening, as I found subwoofers to be unnecessary after the initial break-in period.

Ultimately, my CM4s were placed close to two feet from the rear wall and exactly six feet apart. I experimented with varying degrees of toe-in. I ended up with only a slight toe-in, perhaps less than one inch.

The Music
The majority of my listening was with the CM4s and the Krell integrated amp. I also spent some time with the smaller CM2s, as well as utilizing the MC602 amplifier driven by the Krell’s preamp section. While using the smaller CM2s, I also used the Sunfire Jr. subwoofer, employing the CM4s in a stand-alone configuration. I found the sonic qualities of the CM2s and CM4s to be very similar to each other from the midrange up.

The B&Ws were slightly relaxed, with a very liquid midrange. The depth of the bass astounded me, given the cabinet’s small appearance. I found the highs to be very smooth, without a hint of harshness at any volume. During my listening sessions with the B&Ws, I used much of the same material as with my review of the Krell 300iL integrated amplifier.

The bass performance was solid and detailed throughout my listening sessions. I noted that, in general and especially with the bass, the Krell amplifier was a bit more analytical in quality than the McIntosh Labs MC602 amplifier. I began with Holly Cole’s "Train Song" from the It Happened One Night (Metro Blue) album. The acoustic bass is very low and detailed. The smaller CM2s had problems with this track at high volumes, but the CM4s were able to play extremely loud without bottoming out. I continued to evaluate the low-end performance of the B&Ws with Crystal Method’s "Busy Child" off of their Vegas (Outpost Recordings) album. "Busy Child" prominently features a fast, sharp and deep synthesizer line throughout the track. The B&Ws were able to reproduce this bass line without any significant delay or smearing. The attack remained fast and the decay clean. I was able to easily differentiate between the notes. To downplay the effect of a fantastic front end and resolute electronics on this system set-up would be an oversight, especially considering that many of these speakers will be configured with a high-powered AV preamp or receiver. A receiver shouldn’t be a problem, but with any good speaker, the better the amplification and front end get, the more real and exciting the music sounds.

At first, I was a bit anxious about the CM’s ability to portray an accurate soundstage. My concern was based solely on the low elevation of the tweeter, as past experience has demonstrated that speakers with low tweeters generally have a vertically compressed soundstage. I was pleasantly surprised to find that the vertical dispersion characteristics of the drivers have greatly reduced this phenomenon. The soundstage as a whole was solid, with great depth and good width extending out beyond the boundaries of the cabinets.

The CM4s handled male vocals extremely well. I was particularly impressed while listening to Nat King Cole’s Love Is The Thing album (Capitol/DCC). From the first track, "When I Fall In Love," it was immediately apparent that the B&Ws would have no problem in musically bringing Nat back to life in my listening room. This ability with male vocals was also notable on other albums, such as Robbie Roberton’s epononymously titled album (Mobile Fidelity), which features both Robertson and U2’s Bono on vocals. While the CM4’s performance on female vocals was more than competent, it didn’t grab me quite the way its performance with male vocals did.

I utilized two of my favorite albums, Robertson’s self-titled release and Bill Berry’s For Duke (Realtime Records), for evaluating soundstaging. Both albums produced deep and wide soundstages. The For Duke album was on a more intimate level, while Robertson album was on a larger scale, with a greater dynamic range as well. The B&Ws had no problems with either setting, small and intimate or large and dynamic. The B&W’s imaging was not as exact as the electrostatic speakers I have recently had in my system.

The Downside
My complaints about the CM4 are fairly limited and do not involve sonically intrusive items. The CM series gives the listener a taste of a truly high-end system, but they don’t quite go all the way. Looking back at my listening notes, the CM4 performed very well across the board, often nearly as good as a speaker costing as much as twice the sticker price here, yet there were instances when the speaker did not quite match the highest standards imaging and transparency reserved for the most expensive high performance speakers.

I believe the imaging and female vocal performance may be related to a very slight vagueness in the upper midrange. This is just enough to prevent the rock-solid imaging that I have heard in B&W’s top-of-the-line Nautilus speakers. The speakers handle the remainder of the frequency range so well that this otherwise good midrange became noticeable.

The new B&W CM line, and the CM4s in particular, offer great performance at their price point. They have a well-executed, aesthetically pleasing design, capable of providing a sonic performance that you would expect to come at a much higher price. The ultimate lack of detail and transparency as described above will most likely not be noticed in a system of components priced in the range of the CMs. It would take spectacularly resolute and amazingly expensive electronics to see this. The CM4 does a lot more than its simple clean appearance would indicate, and what it does, it does very well.
Manufacturer Bowers & Wilkins
Model CM4 Loudspeakers
Reviewer Brian Kahn

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