Floorstanding loudspeakers — ATC SCM150PSLT

The SCM150PSLT is the passive SCM150 floor-stander from the ATC Tower Series, made by Loudspeaker Technology Ltd at Aston Down in Gloucestershire. It uses the same cabinet as the active SCM150ASLT but replaces the internal tri-amplifier with a passive crossover and binding posts, leaving the choice of power amplifier to the owner. ATC also offers the SCM150 in stand-mounted Classic form and as a Special Edition.

Key specs that matter

Three drivers share the band - a 25 mm tweeter, a 75 mm soft dome midrange and a 375 mm Super Linear bass driver, divided at 380 Hz and 3.5 kHz. ATC rates amplitude linearity at plus or minus 2 dB between 60 Hz and 17 kHz and gives the minus 6 dB points as 25 Hz and 22 kHz. Matching between the two speakers of a pair is held within 0.5 dB. Sine wave sensitivity is 91 dB at 1 W and 1 m into a nominal 8 ohm load, and ATC suggests amplifiers between 100 and 1500 W. Maximum continuous output at 1 m is 117 dB SPL. Coherent dispersion covers plus or minus 80 degrees horizontally and plus or minus 10 degrees vertically. Cabinet dimensions are 1104 x 495 x 635 mm (HxWxD).

Engineering and use context

The midrange is the company's SM75-150S soft dome, the part ATC credits for most of the SCM50, SCM100 and SCM150 family's accuracy with speech and music, while the bass unit uses ATC's Super Linear Magnet technology. Later updates added a new tweeter and a revised port profile. Two grilles covered in fabric and eight M8 spikes with nuts are included per pair. For comparison, the stand-mounted SCM150SL weighs 67.2 kg and sits in an 884 mm cabinet, and the passive SCM150SE weighs 93 kg. The veneer range covers cherry, walnut, oak and black ash as standard, and satin black or white paint is offered too, with rarer veneers and piano gloss at a surcharge.

Pairing

Wiring goes through binding posts that accept 4 mm banana plugs. With its fairly high sensitivity and benign nominal load the tower is not hard to drive, yet ATC's broad power range also allows very powerful designs. ATC names its own P2 power amplifier, SCA2 preamplifier and CDA2 CD player with preamp and DAC as partner units.

Alternatives

ATC's passive SCM50PSLT tower is a smaller three-way option, with a 234 mm bass driver, 85 dB sensitivity and a 1003 mm cabinet weighing 45.5 kg.