The ALC4 is a combination of a speaker controller and power amplifier. The ALC units are designed to guarantee the best speaker drive, with maximum sound quality and operating reliability. The amplifier stage consists of a 2x 2kW (2 ohms RMS) Class G design. The combination of double conventional power supplies with a massive 400 Joules capacitor bank makes the ALC4 deliver dynamic and sustained very high power output. The controller section consist of several stages; On the input stage the SDP circuit and on the output stage the SIS circuit ensure easy, reliable and optimised speaker response. The SDP circuit can be seen as the “brain” of the amplifier. By means of speaker-specific modules, that are located in 2 front-accessible slots, the characteristics of the connected speaker are loaded into the amplifier. With this, the amplifier is “tailor-made” to the speaker, regardless of the power output specifications of the amplifier. This can be done with either the analogue SDP modules, or the DDP digital drive processor™. By placing the modules in the slots, the SDP circuit is automatically activated, without the need for changing switches/jumpers (“plug&play”). Taking out the modules, bypasses the SDP circuit and converts the ALC into a “standard” stereo power ampli- fier, for use with traditional speaker systems. The SIS circuit extends the control-loop of the amplifier to the input terminals of the speaker, by means of two additional (sense) wires, compensating for the influence of speaker cables. SIS offers cable-length independent damping, resulting in a virtually infinite damping under all conditions (up to an almost immeasurable value of over 10.000). ATCM has a number of sensors within the ampli- fier, that constantly monitor both operating temperature, in and output signal. For the temperature section of ATCM, the input signal stage is regulated when dangerous temperature increase is sensed; In this way, the amplifier stays in operation, instead of switching into “heat protection”.