X-Git-Url: https://git.gag.com/?p=web%2Fgag.com;a=blobdiff_plain;f=electronics%2Faudio%2Fwholehouse%2Findex.mdwn;h=5b30105690a969ad82537b5c83e71763a4dc90c7;hp=e56801440127636b12c1fb57a87cedb625106d5d;hb=9eba2eafbe4db22256041e9b0fc10572d65fa160;hpb=0361164098d0859b16b2a1d43070639b26c16090

diff --git a/electronics/audio/wholehouse/index.mdwn b/electronics/audio/wholehouse/index.mdwn
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--- a/electronics/audio/wholehouse/index.mdwn
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 # Whole House Audio System
 
 We're designing a completely open hardware and open source solution for
-whole-house audio distribution.
+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 key hardware component is a board containing a USB audio interface
-and stereo 50 watt class-D audio amplifier.  A set of these boards, one per
-"zone", get wired to speakers in the various rooms.  A 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.
+## Motivation
 
-More details will be posted soon!
+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 href="usbclassd-v0.1.jpg"> <img src="usbclassd-v0.1-thumb.jpg"></a>
+
+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.
+
+## Artifacts ##
+
+The prototype hardware design current gEDA files are available from 
+[git.gag.com](http://git.gag.com) in the project 
+[hw/usbclassd](http://git.gag.com/?p=hw/usbclassd;a=summary).  
+
+Bdale gave a [talk](http://youtu.be/gMTKyW6MXME) at Linux Conf Australia
+in January 2016, [slides here](http://gag.com/bdale/talks/2016/lca), which 
+led to [an LWN article](http://lwn.net/Articles/674191/) 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!