Tannoy AMS-8A
Four thousand dollars a pair for monitors that will tell you the truth about your mix - and you may not like what you hear.
Overview
At $3,995 per pair, the AMS 8A was never going to be an impulse buy for a project studio. It was the smallest member of Tannoy's Active Monitor Series. The AMS line also included the 10A, 12A and the 210A active subwoofer. The 8A carried the company's Dual Concentric design, a driver topology Tannoy had been refining since it began building loudspeakers in the late 1920s. It paired an 8-inch Dual Concentric low-frequency driver with a 1-inch HF compression driver mounted concentrically behind it, using a damped tulip-shaped waveguide. The woofer cone acts as an extension of the HF horn. That is the whole idea of the Dual Concentric: a coincident point source with a constant directivity pattern and linear amplitude and phase response on both the horizontal and vertical axes.
The big difference from a passive studio monitor is the amplification bolted to the back. Each cabinet carried bi-amped MOSFET power modules, 140 watts continuous to the HF section and 140 watts continuous to the LF section. That is a lot of power for an 8-inch nearfield. The amps were Class A/B designs with an op-amp front end and MOSFET outputs, fed by an analog power supply built around a toroidal transformer chosen for its low hum field. Heat came off a massive double-anodized, aluminum-finned back plate, and a blue LED on the front panel confirmed power. The rear layout was well-marked and easy to follow, with switches placed for easy adjustment access. A subassembly beneath the fuse holder stowed spare fuses, and operating voltage was switchable between 100-120V and 200-210V.
The active crossover is where Tannoy's engineering showed. It used high-grade, 1% precision matched components, giving tolerances within 0.25 dB throughout each passband. The shaping, which the company kept to itself, was designed for a tight amplitude response and also for linear phase behavior, avoiding the phase distortion found in traditional passive two-way designs. Owners also got a choice of low-frequency alignment: a 4th-order tuning (Tannoy's factory recommendation) or a 6th-order setting that trades a more gradual roll-off for added extension. Mix (February 1998, p.126) published a field test of the AMS 8A.
The cabinet was built from MDF with an unusually hefty 1½-inch-thick front baffle drilled for two flared "anti-chuffing" bass reflex ports. The remaining sides were ¾-inch MDF with a brace behind the driver. The large ¾-inch radius edges used L-channel wood strips with rubber antiskid inserts, and one-inch-thick open-cell foam lined the interior. The drive unit sat in a charcoal-black cabinet with slate side inlay, built around Tannoy's DMT (Differential Material Technology) twin-laminated space-frame design, heavily braced and decoupled to keep signal from contaminating the enclosure. The woofer used a curvilinear polypropylene cone and rubber surround, materials chosen for stability against humidity and generally higher performance than paper cones with foam surrounds. The cast frame was thin but strong, less resonant than stamped steel and less prone to draining flux from the magnet structure, and its flat spider was reckoned more linear than cupped designs. The chamber behind the spider and magnet was well-vented to lower air modulation and reduce power compression from voice-coil heating.
Not everything about the execution earned praise. In the same Mix lab analysis (February 1998, p.126), Mike Klasco noted that the active crossover had no sub-enclosure, leaving components exposed inside the cabinet. He also found that the heat sink fins resonated audibly when the enclosure was thumped, a resonance that might be audible in a quiet auditioning room under some listening conditions. The speaker was not magnetically shielded. The HF compression driver used a unique low-distortion, low-compression-ratio phase plug, with clay material on the back plate damping driver motion against the enclosure brace.
Measured behavior was strong where it counted. The lab work published in Mix (February 1998, p.126) found distortion - THD+N plus second and third harmonic - well under 1% from 100 Hz upward. A spectral contamination test showed clarity with self-noise roughly 50 dB below input signals, and an impulse response showed tight phase correlation between woofer and tweeter with fast settling. On-axis response carried a notch at 18 kHz that disappeared when listening even a few degrees off-axis. Gehman's listening notes in the same issue described monitors so brutally honest they were "discouraging." His playback of Tracy Chapman's New Beginning revealed bass a little tubbier and a top end less silky than he'd have liked, while Hootie & the Blowfish's Fairweather Johnson came across bright up top but clear in the bottom with a midrange that was right on. His conclusion was that if a mix sounded great on the AMS 8As, it would translate to any speaker a consumer owned. He added that active systems brought consistency, since the monitor, amps and crossovers stayed constant no matter which room or facility they were used in.
That consistency is the practical argument for the AMS 8A today. A powered monitor with matched amplification and active crossover eliminates a whole category of variables, and the Dual Concentric driver gives it a point-source coherence that conventional two-ways struggle to match. The trade-offs are equally real: the exposed crossover internals and the resonant heat-sink fins are the kind of flaws a buyer should know about going in, and the lack of magnetic shielding limits placement near CRT-era gear. Spare fuses stowed in the rear subassembly are a nice touch for anyone running these hard. Collectors and engineers chasing a pair should expect to pay for the Tannoy name and the active topology — and should audition carefully for that fin resonance before committing.
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