Electronics III: Week 3

For my plan of attack for this project I am building two audio amplifiers and a passive crossover that will drive a 2 way speaker with a midrange speaker and a tweeter. I ordered the first audio amplifier kit supplied by Parts Express. The amp is a 2x15 Watt class d amp. After some more research I found this kit and the reviews I saw were good. It was in my price range and now I can't wait for it to come. Next I'm going to work from the schematic to breadboard the prototype. I also chose the tweeter and the midrange driver that will be powered by the amps.

Schematic

Class D amplifiers

Class D amplification it refers to a switchig amplifier that uses pulse-width modulation. The input signal is compared with a triangular waveform and the signal from the comparator switches the output stage to the positive or negative supply voltage. This is done using a very swithing frequency which is usyally ten times or more than the audio bandwidth (200kHz or above). As the output stage only has to switch, its efficieny is very high. However, there are also a number of drawbacks to this approach. It is rather difficult to keep the signal waveform free of distorsion, a hefty output filter is required and drastic measures must be takes to limit radiated interference. For low-distorsion amplification, it is always necessary to use negative feedback.

Tweeter:

Midrange Driver

Amp #2 for the Midrange Driver