Floorstanding loudspeakers — ATC SCM50PSLT

The SCM50PSLT is the passive version of the SCM50 tower from ATC, the British maker that also offers this cabinet in an active form as the SCM50ASLT. It belongs to the Tower Series, which also includes the SCM20ASLT, SCM100ASLT, SCM150ASLT, SCM200ASLT and SCM300ASLT. All three drive units are made in-house by ATC, and a pair is listed in the USA at USD 19,999.

Key specs that matter

This model is a ported three-way passive design. High frequencies come from a 25 mm SH25-76S silk dome tweeter, whose neodymium magnet gives a flux density above 2.0 T, the midrange is handled by the 75 mm SM75-150S soft dome, and the low end is taken by a 234 mm bass unit built with ATC Super Linear magnet technology. Crossover points sit at 380 Hz and 3.5 kHz. ATC gives amplitude linearity of plus or minus 2 dB between 70 Hz and 20 kHz, with the -6 dB points at 40 Hz and 25 kHz. Sensitivity is 85 dB at 1 W and 1 m, nominal impedance is 8 ohm with a 5.5 ohm minimum, and maximum continuous output reaches 112 dB SPL at 1 m. ATC recommends amplification of 100 to 1500 W. Each cabinet measures 1003 x 304 x 470 mm (HxWxD) and weighs 45.5 kg.

Engineering and use context

ATC attributes the accuracy of this model mainly to the SM75-150S soft dome midrange, which alone takes the full span from the lower to the upper crossover. It is the S (Super) specification of the dome, with a short coil and long gap motor held on dual suspensions, and ATC cites high power handling and low power compression. The tweeter also runs on a dual suspension and uses no ferrofluid, which ATC credits with long life, and it sits in a precision-machined alloy waveguide. The Super Linear magnet of the woofer is there to reduce distortion. Recent revisions brought the SH25-76S tweeter and a reworked port profile, and the maker states these changes improved all performance parameters. Dispersion is specified as 80 degrees either side coherent across the horizontal axis and 10 degrees either side coherent on the vertical axis. Pairs are matched to within 0.5 dB. Four veneers are standard - cherry, walnut, oak and black ash. Rosewood, pippy oak, burr poplar and burr magnolia, as well as high-gloss lacquer, are available for a surcharge.

Pairing

Cables attach to binding posts that also take 4 mm banana plugs. The modest sensitivity and a power window reaching into four figures point to a high-output amplifier, while the impedance minimum keeps the load moderate. Buyers who would rather not choose amplification separately can select the SCM50ASLT, the same tower fitted with built-in amplification.

Alternatives

The ATC SCM100ASLT is a larger floorstanding model from the same Tower Series.