Floorstanding loudspeakers — ATC SCM50ASLT

The SCM50ASLT is the active three-way model built on the SCM50 cabinet in the ATC Tower Series, sold alongside a passive SCM50PSLT that shares the same box. ATC aimed the pair at home listeners with drivers and electronics that it designs and manufactures in-house. In the UK the active version starts at GBP 17,600, and the North American price is USD 26,999 per pair.

Key specs that matter

Each tower uses an SH25-76S 25 mm tweeter, an SM75-150S 75 mm soft dome midrange and a 243 mm Super Linear bass driver. Crossover points are 380 Hz and 3,500 Hz. Three amplifiers per cabinet provide 200 W to the bass unit, 100 W to the midrange and 50 W to the tweeter. Amplitude linearity is plus or minus 2 dB from 70 Hz to 20 kHz, and the wider response reaches 38 Hz to 25 kHz within plus or minus 6 dB. Pairs are matched to plus or minus 0.5 dB, maximum output is 112 dB and coherent dispersion is plus or minus 80 degrees horizontally and plus or minus 10 degrees vertically. The cabinet measures 1003 x 304 x 470 mm and ATC lists a weight of 51 kg, 5.5 kg more than the passive twin.

Engineering and use context

Every drive unit has its own dedicated MOSFET amplifier, individually matched to it, working in Class A/B. Because the filtering happens before these amplifiers, no passive crossover network sits between amplifier and driver. The active crossover begins with a wide-bandwidth, electronically balanced input stage with high common mode rejection and low distortion, followed by fourth order Linkwitz-Riley filters. The magnet system of the woofer follows the ATC Super Linear Magnet approach, and the current SCM50 towers also received an updated tweeter and a revised reflex port design. Each pair comes with two fabric-wrapped grilles, eight M8 x 1.25 mm spikes with nuts and two IEC power cables. Veneers in walnut, oak, cherry or black ash and satin paint in white or black come at no charge, while burr poplar, burr magnolia, pippy oak, rosewood, crown cut European walnut and gloss finishes carry a surcharge. The passive version is rated at 85 dB for 1 W at 1 m with an 8 ohm nominal load dipping to 5.5 ohm.

Pairing

Signal enters through an XLR connector, so the speakers connect to a preamplifier or source with balanced outputs and volume control. ATC suggests its own CDA2 CD player, preamplifier and DAC or the SCA2 preamplifier as partners for the SCM50 towers, along with its P2 power amplifier.

Alternatives

Within the Tower Series, the ATC SCM100ASLT offers active drive in a bigger cabinet.