Jordan O'BrienATC Loudspeakers is hoping to lean on its reputation for reference-quality audio to sell its latest floor-standing speaker, the SCM19 Active Tower.
Boasting a curved floor-standing design and measuring just 370mm wide and under a metre in height, the SCM19 Active Tower is supposedly acoustically identical to ATC’s award-winning passive SCM19 two-way system
The SCM19AT’s braced, sealed and curved multi-layer laminated cabinet, which is precision-finished in cherry or black ash real-wood veneer, promises to provide a rigid and optimally damped environment for the company’s SH25-76 soft dome tweeter and 150mm super-linear mid/bass driver.
Drive units are individually powered by an upgraded bi-amp pack (also proprietary), comprising ATC’s discrete MOSFET Class A/B modules, providing 32W of continuous power to the HF section and 150W to the bass.
SH25-76 Tweeter
Sharing technology with the ATC soft domed mid-range drive unit, the 19AT’s tweeter employs a unique 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 promises exceptionally low distortion throughout the tweeter’s operating band and removes the need for ferrofluids, which can dry out over time, compromising performance.
A complex-shaped, 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 promises to provide optimum dispersion with a flat on-axis frequency response and resonance-free operation.
Bass Driver
The SCM19AT’s 150mm ATC SL mid/bass driver utilises a carefully weighted doped fabric cone with a 75mm soft dome.
The cone is driven by an ‘under-hung’ (short coil/long gap) motor using a huge 9kg ‘Super Linear’ magnet system, which is unique to ATC loudspeaker systems.
The 75mm ribbon wire voice coil is milled and wound in-house by ATC. While the company’s familiar under-hung motor topology maintains linear coil force and inductance, even at high drive levels, keeping distortion low.
Electronics
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. Mid frequency THD is vanishingly low at 93dB/0.002% and a very wide bandwidth of 200 kHz ensures the accurate reproduction of musical transients.
ATC’s Grounded Source output stage modules are fed by a newly developed 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. Designed and manufactured by ATC entirely in-house, the SCM19AT offers the ownership of a hand-built ruggedly engineered speaker system, world famous for musical accuracy and high power output. Like all ATC products, the SCM19AT is backed by a six-year warranty.
Features
• New ATC designed and built dual suspension 25mm soft dome HF unit with precision alloy wave guide
• “SL” spec bass driver with 75mm integral Soft Dome
• 9kg optimised short-coil/long gap motor assembly
• On-board grounded source 182 watt Class A/B Bi-amplifier
• Active filters and overload protection
• Six year warranty
Specification
Drivers: HF ATC 25mm dual suspension Tweeter, Mid/LF ATC 150mm SL
Matched Response: +/- 0.5dB
Frequency Response (-6dB): 54Hz-22kHz
Dispersion: ±80° Coherent Horizontal, ±10° Coherent Vertical
Max SPL: 108dB
Crossover Frequency: 2.5kHz
Connectors: Male XLR
Input sensitivity: 1V
Filters: 2nd Order critically damped with phase compensation
Overload Protection: Active FET momentary gain reduction
Fault Protection: DC fault protection and thermal trip. Fault indication on rear panel mounted LED
Amplifier Output: 150W LF, 32W HF
Cabinet Dimensions (HxWxD): 980x370x344mm (spikes add 25mm to height, grill adds 34mm to depth)
Weight: 31kg
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