Tannoy Dimension surround speaker system

Founded in 1927 by Guy Fountain, Tannoy was the first company to develop a moving-coil speaker with DC-energized magnets. During World War II, Tannoy speakers became so common on RAF airfields and in British railway stations that the word "Tannoy" became synonymous with "speaker." Your average high-tech company is considered old after 10 years; to reach the age of 75 makes Tannoy positively prehistoric.

Tannoy has retained its youth through its continual research and innovation in creating high-value products. Their new Dimension series is a case in point. These speakers combine Tannoy's well-established Dual Concentric design with a new SuperTweeter to create a speaker designed to cope with the latest demands of digital sound reproduction. Will the Dimension system keep Tannoy competitive into their 76th year? Could be.

Reproducing Sounds Only Dogs Can Hear
Since the average middle-aged videophile is lucky if he can hear up to 15kHz, you may wonder what the point is of making a speaker capable of reproducing sound up to 100kHz. Blame it on those new, higher-resolution audio formats, DVD-Audio and Super Audio CD. Both provide an upper-frequency limit far beyond the measly 20kHz of conventional CDs. The 20kHz "brick-wall" digital filter employed by CD players can cause phase shift and group delay. These anomalies vanish when your high-frequency filters are up at 100kHz. And while their audible consequences are controversial, in theory, at least, even upper-frequency-challenged males over 40 may be able to hear an improvement in high-frequency definition and detail when the upper-frequency limits are raised. My experience with SACD confirms that its upper-frequency reproduction is more lifelike than conventional CD's. Unfortunately, most speakers begin to roll off their upper frequencies near 15kHz.

Enter Tannoy's new SuperTweeter, which comes in three standalone models and, for the Dimension series, a permanently attached version. Housed in a spherical cabinet, the SuperTweeter's titanium-dome driver uses a copper-clad voice-coil of aluminum and a neodymium magnet system. Inside the cabinet you'll find: high-purity, solid-silver wiring with a PTFE-coated dielectric; noninductive planar thick-film resistors; and high-quality polycarbonate capacitors. The ST100—provided here for use in the rear channels—has a third-order compensated highpass crossover filter with a clever multi-tap connection system that permits three different crossover frequencies (14, 16, or 18kHz) at five different levels (-3dB, -1.5dB, 0dB, +1.5dB, or +3dB). Tannoy's unique Performance Platform provides three-point support so you can precisely adjust the tweeter's angle and position. The SuperTweeter's delicate titanium dome is protected by a removable grille held on by magnetism. Critical listeners can remove the grilles; owners of pets and parents of small children should probably leave them in place.

Tannoy has invested many years of research and refinement in their Dual Concentric drive-unit, a coaxial design they have used successfully in a wide range of speaker systems. Rather than abandon it for the Dimension series, Tannoy's designers came up with the idea of mating it with the ultra-high-frequency SuperTweeter to extend the DC's frequency range, and thus create a full-fidelity speaker that retains the original advantages of an already proven design.

Here's what makes the Dual Concentric design unique: With the tweeter in the same physical plane as the midrange/ woofer—actually, inside it—subtle location and spatial cues in music and soundtracks are said to be better preserved. A coincident acoustic point source provides constant symmetrical directivity, unlike a conventional speaker with its tweeter in a different part of the cabinet from the midrange and woofer. Coincident driver placement generates a truly spherical wavefront that provides a more linear phase response, and creates symmetrical dispersion in the horizontal and vertical planes. The result: a larger listening window.

Tannoy's coincident design has separate magnets for each transducer. A twin-magnet design produces optimum magnetic flux shaping, since each magnet assembly is designed for a specific diaphragm. Tannoy's Tulip CAD (Computer-Aided Design) Waveguide creates a large throat area for the tweeter, which, with the precision injection-molded woofer cone and surround piston, produces a driver with low coloration but high efficiency. The tweeter also features a shaped pole-piece to control the compliance of its diaphragm, a nitrite rubber surround, and magnetic liquid cooling. An internal diffraction ring between the midrange/woofer and high-frequency driver blends their acoustic wavefront into a harmonious sonic unit.

For this review, Tannoy sent their TD10 for the front left and right speakers (a smaller TD8 and larger TD12 are also available), the TDC center speaker, and a pair of Saturn S8LR speakers, coupled with two ST100 SuperTweeters for the rears. Since the line's TDSub subwoofer was not yet in production, Tannoy's PS 350B 15-inch subwoofer was also included to complete the system.

Rather than the usual rectangular box, the TD10's birch plywood cabinet is rhomboid, a shape that minimizes internal resonances and external reflections. The front baffle is covered with black velvet. This not only looks elegant, but offers the advantage of reducing high-frequency reflections off the front baffle surface. Instead of a conventional grillecloth, the TD10 has a rather thick, velvet-covered plywood plate with rubber strings running vertically in front of the Dual Concentric driver. It looks stylish, but its 1/2-inch-thick plywood edges had a negative effect on imaging—I consigned the grilles to the back of my storage closet for the duration of the review.

The TD10 has two rear ports stuffed with removable foam plugs. A sixth-order Linkwitz-Riley crossover system with a 1.2kHz crossover unites the midrange/ woofer with its tweeter, while a third-order highpass filter set at 14kHz blends in the SuperTweeter. Speaker-terminal connections are mounted on an unusual circular plate. Five connectors allow for not only biwiring or biamping, but also provide a dedicated ground terminal. This particular connection's function is to eliminate any RF getting back to your amplifier's feedback nodes. Tannoy has found that speaker components often act as radio-frequency receivers, dumping RF hash back into the power amplifier. The dedicated grounding terminal siphons off and neutralizes this RF energy. I did not, however, use this feature in my listening tests.