Class D Audio Amplification

Class-D is an extremely efficient (85% or more of the actual input power is converted to audio), and highly linear (good-sounding) way to amplify an audio signal. The music in this particular video unfortunately does NOT sound good, because of the cheesy mic in the camera that I used to shoot the video with. It does sound excellent to the ears in real-time.

I was able to get better than 3 Watts of average power to the speaker, using only a single TC4428 MOSFET gate-drive IC. The IC itself has dual inverting/non-inverting drivers, and I used both in a full-bridge topology to drive the speakers through low-pass filters, with a cutoff frequency of 25kHz.

The audio is playing through the speaker in the Ibanez amplifier, which has been disconnected from the rest of the amp.

The waveform shown in the beginning of the video is a classic Pulse-Width Modulation signal...where the duty cycle of the square wave varies in proportion to an analog signal (the audio input from a CD player or something). When the high-frequency carrier (200kHz) square wave is filtered out, it leaves the audio waveform which then drives the speakers.

Category:

Science & Technology

Tags:

• class
• audio
• MOSFET
• IGBT
• homebrew
• electronic
• linear
• tube
• amp
• switching
• amplifier
• SMPS
• switcher
• high
• power