ATC SCM100SE Loudspeaker ATC's Amp Pack

ATC's Amp Pack

Chicken or egg, which came first? In practice ATC's MOSFET power amplifiers were initially developed for its professional (active) loudspeakers before being refined into the 'domestic' 100W P1 [HFN Mar '10] and 300W P2 [HFN Mar '17] models. Naturally there's been some to-ing and fro-ing between the design of the active speaker power packs and its hi-fi stereo amplifiers, so the three-channel system fitted inside the SCM100SE is its most elegant yet, with fully discrete op-amps used in the balanced line input and active filter stages. The crossovers are set at 380Hz and 3.5kHz and employ 2nd-order Butterworth all-pass filters. These offer a flat magnitude/variable phase response – the implementation claimed to offer an improved phase coherence through the crossover regions that could not be achieved with a conventional passive crossover design.


Finally there are the amplifiers themselves, a combination of 50W (treble), 100W (mid) and 200W (bass) Class A/B MOSFET stages with their own rugged power supplies. Separate PSUs, with localised regulation, are employed for the active line and filter circuits, the ensemble adding a full 5kg to each speaker's weight. PM

Loudspeaker Technology Ltd
Gloucestershire, UK
Supplied by: Loudspeaker Technology Ltd
01285 760561