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  The Gathering Room unit is the most complex device in the system. It contains both the active crossover for the main system, plus the line drivers for the low level wiring distributed throughout the house. The schematic shown here contains only the auxilliary filter and active crossover sections. The line drivers are simply non-inverting unity gain circuits, connected to the output lines with 10uf caps and 100 ohm resistors. There is a buffer amp with 20dB gain and a volume control feeding all the line outputs.

  There is a "drone" line amplifier box in the downstairs movie room, containing one input and five outputs. This unit is wired into the A/V surround sound receiver in the video system such that it can either re-distribute the audio coming down from the main unit upstairs, or use the other inputs on the A/V unit downstairs. This allows the entire downstairs of the house to enjoy a different audio program from the upstairs - done on purpose, of course, with kids & grandkids running around. It consists of simply the basic power supply and five line driver circuits, with a selector switch on the input line.

  The nook speakers have their very own line amplifier built into the wall behind the volume control. There is sufficient line length from the volume knob up to the wall-mounted speakers that any sort of resistive volume control will cause nasty hum in the speakers. Thus, a low-output-resistance amplifier follows the volume control, allowing the speakers to be controlled from a single knob mounted on a wall plate. The power supply for this amplifier is stashed inside the HVAC intake around the corner, with the wires run up the wall along with the signal lines. There is an on-off switch that allows the speakers to be turned on and off without moving the volume control.

The same power supply schematic shown at right is used for all three devices in the system.