The class-D topology uses PWM, that is, pulsewidth modulation, and a suitable filter at the output. As a consequence, the big difference compared to a class-A (or AB, B, etc.) amplifier is the efficiency. For the D-watt amp this amounts to no less than 93% into 8 ohms and 174 watts (these are real Elektor watts as opposed to Chinese watts). This means an extraordinarily low heat dissipation and a much smaller heatsink than what you would ordinarily expect with this kind of power. This type of amplifier is found these days in many places where large powers are required in professional applications, such as theaters or festivals. But they are also becoming increasingly more common in the living room.
The D-watt follows the formidable ‘Q-watt’ and is an excellent alternative for this design from 2013. As a service to our readers, Elektor Labs have put together a kit that contains all the necessary electronic parts, including the circuit board, the heatsinks and the wire for winding the coil. The kit is available now – including the optional switching power supply – from our Store.