ATC SCM 11 loudspeaker

The venerable British company ATC Loudspeaker Technology was founded in 1974 by Billy Woodman, and is famous within the professional community for developing the first soft-dome midrange driver, and for their well-regarded line of active (powered) studio monitors, the user list of which is a veritable Who's Who of mastering engineers. ATC loudspeakers are all still made in the UK, and were a favorite of the late J. Gordon Holt.

I requested a pair of ATC's SCM 11 passive monitors because its price of $1750/pair in real cherry veneer (or $1850/pair in black ash) fit into my quest to find affordable systems in the $2500–$3750 range. I didn't realize until I removed the SCM 11 from its cloth bag that its bass loading is sealed-box; had I known that, I would have requested them even earlier. (ATC's larger designs are ported.)

ATC's lineup of consumer speakers includes one model below the SCM 11, the SCM 7, which has a 5" mid/woofer and costs $1050/pair. The SCM 11 has Constrained Layer Damping (CLD) on its cone but doesn't share the Super Linear magnet technology found in the SCM 19, a superficially similar two-way with the same size woofer in a larger cabinet. The SCM 19 costs $3150/pair, which puts it outside the limits of this hunt for affordable systems (though it looks very tempting). Super Linear technology is claimed to reduce third-order harmonic distortion 10–15dB between 100Hz and 3kHz, which makes me eager to hear it. Nonetheless, the SCM 11's CLD cone is claimed to reduce distortion between 300Hz and 3kHz by an unstated amount.

The SCM 11 is a stand-mounted two-way design with a 1" soft-dome tweeter with a neodymium magnet structure and a waveguide of some proprietary alloy, and a 6" mid/woofer. Although the cabinets of the review pair I received were veneered in cherrywood (with exceptional matching across the pair), the drivers are inset in a baffle board that sits proud of the cabinet face and covers all but its bottom few inches (which are veneered). The baffle is made of some sort of composite, and finished in a soft piano-black semigloss. Black fabric grilles on MDF frames attach to the speaker with plastic pins, but I didn't use them. A recess in the rear panel holds two pairs of sturdy, knurled, non–EC-compliant binding posts of brass, with brass jumpers installed for single-wiring.

ATC's SCM 11 and Aerial Acoustics' 5B (which I wrote about in June) are variations on the same theme—sealed-box, stand-mounted two-ways costing about $2000/pair—so it seemed reasonable to compare them.

The ATC SCM 11's cabinet measures 15" high by 8.3" wide by 9.8" deep, displaces 1220 in3, and weighs 17.6 lbs. The Aerial 5B measures 13" high by 7.9" wide by 10.8" deep, displaces 1109 in3, and weighs 22 lbs. So the ATC's cabinet is about 10% larger. Perhaps more important—and I keep making a point of this because I think it's both nonintuitive and often overlooked by audiophiles while shopping—the Aerial 5B's 7.1" mid/woofer has just about twice the surface area of the ATC SCM 11's 6" cone: 39.59 vs 19.63 in2. (Of course, this does not translate into twice as much bass.) ATC claims a sensitivity of 85dB for the SCM 11 vs Aerial's claim of 86dB for the 5B. Stated impedance is 8 ohms for the ATC vs 4 ohms for the Aerial. ATC claims low-frequency extension for the SCM 11 of 56Hz, –6dB; Aerial, 60Hz, –2dB, and 50Hz, –8dB. I'd have to call the specifications race a tie. In use, both speakers had the well-controlled, reasonably well-extended bass you hope for from a sealed-box design.

ATC Loudspeaker Technology Ltd.
US distributor: Flat Earth Audio
98 Main Street
Seymour, CT 06483
(888) 653-5454