AXT Systems

PA-3 Stereo 150W Class-D Amplifier
PA-3 Top Side
PA-3 Bottom Side
This class-D stereo power amplifier module was designed and built to replace some old class-AB amplifiers and heatsinks with a far more efficient (and less hot) amplifier. It is based on the TPA3255 class-D amplifier chip, which is capable of 2-channel output of 150W into 8 ohms.

The module requires a +/-12V power supply for the input circuitry along with a power rail for the power amplifier section (+38-48V). I use a PSU-12 module for the +/-12V section and a ConnexElectronic SMPS for the power amplifier rail. This combination provides for a very efficient amplifier that requires very little heatsinking. 
For heatsinking (when running it at reasonable power levels) I have attached a copper bar to the top of TPA3255 chip with thermal paste and attach either the case panel or additional finned heatsink to the copper bar to remove the heat effectively.

The amplifier is fully balanced (line level inputs) and uses a small MCU (PIC12LF1552) for generating the LED indications from the signals provided by the TPA3255 status pins.