Floorstanding loudspeakers — ATC SCM40A

The SCM40A is the active three-way floorstander of the ATC Entry Series and the powered counterpart of the passive SCM40. ATC, the Acoustic Transducer Company, is a British firm that designs and builds all of its drive units in-house, and this model adds a tri-amplifier pack to the tower. The UK price was GBP 7,750 per pair.

Key specs that matter

The driver line-up is a 25 mm dual suspension soft dome tweeter, a 75 mm soft dome midrange and a 164 mm short coil bass unit with a central dust cap. Crossover points are 380 Hz and 3,500 Hz. The grounded source Class A/B tri-amplifier delivers 242 W in total - 150 W to the bass driver, 60 W to the midrange and 32 W to the tweeter. Response extends from 48 Hz to 22 kHz at -6 dB, the pair match is plus or minus 0.5 dB and peak level reaches 112 dB. Coherent dispersion is rated at plus or minus 80 degrees horizontally and plus or minus 10 degrees vertically. The XLR input accepts 1 V for full output. With foot plinth and amplifier included, each cabinet measures 980 x 370 x 344 mm and weighs 36 kg, and spikes add 25 mm to the height while the grille adds 34 mm to the depth. ATC supplies four M8 x 1.25 mm spikes per cabinet and covers the speaker for 6 years.

Engineering and use context

All three drivers use large, optimised motor assemblies, and the tweeter sits in a precision alloy waveguide. The enclosure is sealed and built from braced 18 mm MDF, while the curved side panels are a laminate of three 6 mm MDF layers - the curvature cuts down parallel surfaces that support internal standing waves. The active crossover uses fourth order Linkwitz-Riley filters with additional all-pass sections at both crossover points, and it feeds the power amplifiers at line level. Each amplifier channel runs a pair of MOSFET output transistors, and there are three separate secondary power supplies. Momentary gain reduction through an active FET stage handles overload, and DC fault protection with a thermal trip is signalled by an LED on the rear panel. Buyers can order the cabinets in real wood veneer, cherry or black ash, or in a satin paint finish in white or black.

Pairing

Signal comes from any line-level component that has balanced outputs and its own volume control - a preamplifier, a streamer with volume or a DAC with a digital level stage. No power amplifier or speaker cable is required, since every driver already has its own amplifier channel. Each cabinet needs its own mains connection plus one balanced interconnect.

Alternatives

The ATC SCM19A is the two-way active tower in the same Entry Series, using a 150 mm SL mid and bass driver and 182 W of onboard power.