- Written by Brian Alvarez
- Published on 28 July 2011
Initial set up of the CM8s proved to be fairly simple. Using the factory terminal jumpers I wired up the CM8s using Kimber 8VS speaker cables to my Myryad MI-120 integrated amp. Signals to this combo were provided by an Audiolab 8200CDQ functioning primarily as a DAC.
The CM8's benefited from toe-in and maintained a consistent tonal balance regardless of toe-in. Toe-in just helped to tighten up imaging. The speakers were not overly sensitive to being placed close to rear walls. Lower mid bass energy was most affected by close proximity to the rear walls. I felt the included dual mode port bungs (fully closed, or a donut to lessen the diameter of the port) contributed little to my particular listening conditions. Fully closing the ports lessened bass extension with no other improvements to the sound. Using the hollow portion of the bung had no significant difference to bass response in my room. I chose to do all my listening with the bungs removed. Having hard wood floors I chose to use the adjustable rubber feet.
Once I found a sweet spot for the placement of the speakers, I set about adjusting the feet to level the speakers. Bowers and Wilkins provided the CM8s already broken in and I heard no changes to the speakers performance over time.
The two stars of the this show are the FST mid-range and the Nautilus loaded aluminum tweeter. Much has been written about Bowers and Wilkins revolutionary FST drivers.
To summarize, the role of a mid-range driver doesn't require substantial travel. The surround of a driver presents several problems. The mechanical movement of the cone is in fact a sum of two parts. The cone and the surround. The energy applied to the cone via the voice coil also generates sound through the surround. For various reasons the surround in fact colors the sound the cone produces. Human hearing is most sensitive to mid-range frequencies. Even minute reductions to distortion in this critical region can yield significant improvements. Removing the surround increases linearity and reduces distortion. Interestingly an infinitely rigid material would not work in an FST configuration. Which is where B&Ws expertise with Kevlar plays a role. A Fixed Surround Transducer requires the cone material to have some flexibility. The inherent self damping properties of Kevlar are the ideal material for an FST driver.
The next leading player is the 1" aluminum dome tweeter. Housed in a Nautilus tube, the tapered housing helps to cancel standing waves behind the dome. Essentially focusing the back wave down the tapered tube causes the energy to dissipate and also cancel itself out. The more energy that can be removed from the back wave of driver the purer and more accurate the reproduction. Drivers are semi-transparent (acoustically) and standing waves inside a cabinet are both transmitted through the cabinet and also out through the cone. Removing as much energy within the cabinet is critical. The Nautilus tube accomplishes this very well.
The combination of the FST mid-range and 1" aluminum Nautilus tweeter make wonderful music. This tweeter is one of the finest aluminum units I've heard. Strikingly fast, detailed, and lacking in distortion. The CM8's tonal balance tips upwards significantly. They're bright speakers. With any other tweeter this could prove a problem. A coarse tweeter would yield a speaker that is harsh or grating. The CM8s tweeter is so smooth, so refined, instead of being harsh or aggressive, the CM8 is gloriously detailed with an abundance of air and separation. Cymbals are embodied with clarity and all the metallic detail that soft dome tweeters usually gloss over. Harmonics extended smoothly into the highest reaches of the frequency domain with absolute clarity and purity of tone.
Combined with the stunning resolution and ease of the FST I've seldom heard a speaker at anywhere near this price posses such engaging resolution and imaging without sounding forced. The FST delves so deep into the mid-range it digs up gobs of detail never previously heard by me on extremely familiar recordings. Female vocals in particular ooze in clarity and intimacy. The subtlest nuance of a singers voice (and interaction with the mic) are rendered so effortlessly as to defy belief. The FST never fails to disappoint and this may be one of the best implementations I've yet to hear.