This handy little power amplifier module uses the LM3886 device, whcih is capable of up to 68W into 4 ohms with an appropriate power supply.

This device can be powered from +/-10V up to +/-42V. An unregulated supply consisting of a transformer, bridge rectifier and large reservoir capacitors can be used to provide the DC power rails. A module such as the PSU-13 can also be used for some applications.

The PA-1 requires a heatsink, and the design is such that it can be bolted directly to one with simple mounting for the module. The size of the heatsink will depend on the application and can be calculated using the data sheet for the LM3886 and the thermal resistance of the heatsink.

The module was used with a +/-20V rail in the mono balance check monitor project, driving a 4 ohm speaker.

On-board fuses are present to provide protection due to catastophic failure. The LM3886 has significant protective circuitry contained in it, including short circuit and thermal protection.

PA-1 Circuit (pdf) PA-1 BOM (pdf)
PA-1 PCB (pdf) LM3886 Data Sheet (pdf)

I've used this module in several active speaker systems and bi-amplifier systems and found it to be very robust. Two can be mounted side-by-side on a 150mm heatsink in general hi-fi applications.

Power Amplifier PA-1
















PA-1 Power Amplifier Module













Bank of 4 PA-1 modules used in a stereo bi-amplifier system for a hi-fi loudspeaker.