1 # Whole House Audio System
3 We're designing a completely open hardware and open source solution for
4 whole-house audio distribution. The intent is sufficient audio quality
5 to support a pleasing background music experience around the house... not
6 to be an audiophile-level system.
10 The system proposed by our builder was hideously proprietary, and apparently
11 violated the GPL. Just couldn't do it...
15 Our builder had a sub-contractor install ceiling-mounted speakers in each
16 of 9 zones in our house. Each zone has a local impedance-balancing volume
17 control to allow for local / emergency "turn it down" capability. There's
18 a wire bundle from each zone to the central mechanical room consisting of
19 4 conductors for the stereo audio, and 4 twisted pairs (ala CAT-6) we don't
20 intend to use immediately.
22 The new hardware component Bdale designed is a board containing a USB audio
23 interface and stereo class-D audio amplifier. The USB audio DAC part was
24 designed by Burr-Brown and is now a Texas Instruments part. The class D
25 amplifier is also a TI part, available in 15, 30, or 50 watts per
26 channel. While the PCB layout can handle any of these parts, the 50 watt
27 per channel part needs additional heat-sinking and we just don't need that
28 much power. So we built the system using the 30 watt per channel parts. The
29 circuit board is 2.75 x 1.25 inches and less than an inch thick fully
32 A set of these boards, one per
33 "zone", each attach to the speaker wires, a DC power supply, and a USB hub
34 that is attached to a Debian system in the mech room.
37 system runs software that controls audio stream sources, maps them to the
38 various zones, and volume controls the zones .. all controllable from a web
39 browser or Android application.
41 More details will be posted soon!
projects / web / gag.com / blob