Whole House Audio System

We're designing a completely open hardware and open source solution for whole-house audio distribution. The intent is sufficient audio quality to support a pleasing background music experience around the house... not to be an audiophile-level system.


The system proposed by our builder was hideously proprietary, and apparently violated the GPL. Just couldn't do it...

System Design

Our builder had a sub-contractor install ceiling-mounted speakers in each of 9 zones in our house. Each zone has a local impedance-balancing volume control to allow for local / emergency "turn it down" capability. There's a wire bundle from each zone to the central mechanical room consisting of 4 conductors for the stereo audio, and 4 twisted pairs (ala CAT-6) we don't intend to use immediately.

The new hardware component Bdale designed is a board containing a USB audio interface and stereo class-D audio amplifier. The USB audio DAC part was designed by Burr-Brown and is now a Texas Instruments part. The class D amplifier is also a TI part, available in 15, 30, or 50 watts per channel. While the PCB layout can handle any of these parts, the 50 watt per channel part needs additional heat-sinking and we just don't need that much power. So we built the system using the 30 watt per channel parts. The circuit board is 2.75 x 1.25 inches and less than an inch thick fully populated.

A set of these boards, one per "zone", each attach to the speaker wires, a DC power supply, and a USB hub that is attached to a Debian system in the mech room.

The Debian (Linux) system runs software that controls audio stream sources, maps them to the various zones, and volume controls the zones .. all controllable from a web browser or Android application.


The prototype hardware design current gEDA files are available from git.gag.com in the project hw/usbclassd.

Bdale gave a talk at Linux Conf Australia in January 2016, slides here, which led to an LWN article by Jon Corbet.

Future Plans

The initial design is working very well. We're pondering the possibility of making enough boards to sell, watch this space for more details!