RAD24
This device adds the following additional capability to a HAL system:
A RAD24 provides one audio output channel that is a one-watt plenum-rated class-D amplifier which directly drives an 8-Ohm loudspeaker. It installs in a U.S. 4-square gang box, or the flanges can be removed and the RAD can be mounted to a ceiling loudspeaker's 70/100 mounting holes (replacing the transformer) or to another flat surface.
See Also