ATC SCM40A - Pair of Active Floorstanding Speakers

The tweeter is a 25mm soft dome with neodymium magnet and features a unique doped polyester double suspension design, which reduces oscillation modes, thus avoiding the use of ferrofluid damping found in most tweeters. This design also allows for a smaller magnetic gap, in order to offer greater power handling than conventional designs.

They boast a 242W Class AB tri-amp module embedded within each speaker, split into 32W for the tweeter, 60W for the midrange and 150W for the bass driver. Two MOSFET transistors are dedicated to each channel, equivalent to four identical output stages driven by three separate secondary power supplies to “scale” the power according to the frequency band and driver requirements.

The active crossovers are fourth-order Linkwitz-Riley type at 380 Hz and 3.5 kHz with built-in phase compensation, and are connected directly to the drivers: the result is lower distortion, more accurate management of the crossover points and better control.

Why have an amplifier for each driver? There are two main advantages. First of all, each amplifier does not need to handle the entire audio spectrum: so each stage has an easier job of covering a smaller bandwidth. But most importantly, the passive crossover is eliminated, reducing the amplifier load to only the voice coil of each driver, not the complex combination of coils, capacitors and resistors of a passive crossover.