ATC (Acoustic Transducer Company) Loudspeakers of Britain has begun shipping its SCM19AT active loudspeakers in the U.S. consumer Hi-Fi and CI markets.
The new SCM19AT system is an active version of the company’s SCM19 driver/amp pairings in a floor standing design.
Identical acoustically to ATC’s passive SCM19 2-way system but using the 19 liter volume in a slim tower format, the SCM19AT combines aesthetic appeal with the benefits of active design.
The SCM19AT’s cabinet, which is finished in cherry or black ash wood veneer, provides a rigid and damped environment for the SH25-76 soft dome tweeter and 150mm super-linear mid/bass driver. Drive units are individually powered by a proprietary amp pack comprising ATC’s discrete MOSFET Class A/B modules, providing 32W of continuous power to the HF section and 150W to the bass.
The 19AT’s tweeter employs a dual suspension system, designed to suppress rocking modes even at high power output levels. The ATC configuration of a short edge-wound voice coil in a long, narrow magnetic gap ensures low distortion throughout the tweeter’s operating band and removes the need for Ferro fluids, which can dry out over time, compromising performance. A soft-domed diaphragm extends high frequency range and offers a smooth off-axis response. The tweeter’s 15,000 gauss (1.5 tesla) neodymium magnet has a black heat-treated top plate, which dissipates heat away from the voice coil to maintain high power handling and low power compression. A precision-machined 5.5mm rigid alloy waveguide provides optimum dispersion with a flat on-axis frequency response and resonance-free operation.
The SCM19AT’s 150mm ATC SL mid/bass driver uses a weighted, doped fabric cone with a 75mm soft dome. The cone is driven by an ‘under-hung’ (short coil/long gap) motor using a proprietary 9kg ‘Super Linear’ magnet system. The 75mm ribbon wire voice coil is meticulously milled and wound in-house by ATC. ATC’s familiar under-hung motor topology maintains linear coil force and inductance, even at high drive levels, keeping distortion low.
The 19AT’s proprietary two-way on-board amp pack design has been revised to reduce noise and distortion (a further -10dB @ 10kHz), while achieving a lower operating temperature for improved reliability. The design includes protection circuits for both DC offset and thermal overload. ATC’s Grounded Source output stage modules are fed by a two-way active crossover section featuring 2nd order modified Butterworth circuitry with phase compensation for each crossover point. The advantage of active crossovers is that their response remains unaffected by variable voice coil impedance, while the use of phase compensation enables phase coherency at the crossover points, improving the SCM19AT’s tonal balance and enhancing imaging for a pin-point stereo field. As usual system input is via balanced XLR.
The ATC SCM19AT – the first active 19 in the company’s history – is designed for optimum performance with the grille attached, although the difference in performance without the grill is minimal. Finished in anthracite grey, the metal grille fixes to the cabinet via hidden magnets. As with all ATC products, the SCM19AT is backed by a six-year warranty.
Lone Mountain Audio is the exclusive U.S. distributor for ATC Loudspeakers.
“The new SCM19AT’s are incredibly powerful loudspeakers for the home,” said Brad Lunde, president of Lone Mountain Audio. “The power amplifiers built-in were designed to seamlessly enhance the systems low frequency performance while not interfering with high frequency output and systems to deliver precise details, clarity and pure music reproduction.”
