Напольная акустика — ATC SCM100PSLT

The SCM100PSLT is the passive version of the SCM100 tower in the ATC Tower Series, sharing its cabinet, drivers and 12-inch bass unit with the active SCM100ASLT but driven by an external amplifier through a passive network. It is made by ATC (Acoustic Transducer Company), set up in London in 1974 by Billy Woodman, which today designs and hand-builds its drive units in Gloucestershire and supplies both studios and home listeners.

Key specs that matter

Three ATC drivers are used - a 25 mm soft dome tweeter, the SM75-150 S soft dome midrange of 75 mm and a 314 mm Super Linear bass unit. Within 2 dB the response spans 65 Hz to 17 kHz, and the -6 dB points are 35 Hz and 22 kHz, 3 Hz higher at the bottom than the active model. Sensitivity is 88 dB for 1 W at 1 m, nominal impedance is 8 ohm and ATC suggests amplifiers rated anywhere between 100 and 1500 W. The tower can reach 115 dB SPL. ATC quotes coherent dispersion of 80 degrees either side in the horizontal plane and 10 degrees in the vertical, with pairs matched to 0.5 dB. The cabinet is 1167 mm tall, 428 mm wide and 581 mm deep, and one speaker weighs 58.5 kg, 4.5 kg less than the self-powered SCM100ASLT.

Engineering and use context

The crossover points are the same as in the active version, 380 Hz and 3.5 kHz, but here they are realised passively with second-order Linkwitz-Riley filters instead of the fourth-order active slopes. ATC fits the bass driver with a massive motor assembly, and the SL designation refers to its Super Linear magnet technology, which the company combines with underhung voice coil construction to lower distortion at all levels. Connection is through binding posts that accept bare wire or 4 mm banana plugs. Supplied accessories are two fabric-wrapped grilles plus eight M8 x 1.25 mm spikes and their nuts. The finish list is the same as for the active tower, with standard veneers, satin paints and extra-cost special veneers and high gloss options, and ATC gives a 6-year warranty.

Pairing

ATC's own guidance for its passive monitors explains that extended bass comes at the cost of sensitivity and advises a power amplifier of relatively high output, warning that an underpowered one will distort at high levels and may cause damage. The same guidance asks owners of valve or solid-state amplifiers with high output impedance to check whether the reduced damping they give at low frequencies is acceptable.

Alternatives

The ATC SCM300PSLT is the larger passive tower in the series, fitted with two 375 mm bass drivers and tri-wire binding posts.