PowerAmp.asc is the schematic of the power amp I use. The idea behind the design is to have a bullet-proof circuit that runs off of the same voltage as my notebook power brick. That gave me international power capability and a spare notebook supply, which is also replaceable at most field conference sites. I used discreet components over IC's because they were more available, better documented, and more forgiving of the input voltage range of my notebook powerbrick, than the automotive power amp IC's that first caught my attention.
The circuits where build on plated-through hole perfboard. The layout is shown in HandsFreeLayout.asc and PowerAmpLayout.asc. For speakers, I was planning on being able to use a 5 1/2" woofer from my un-used home theater center speaker. But that "woofer" made voice sound like a public address from the movie M.A.S.H. So, instead I used a pair of 4 Ohm car audio speakers in series. This worked out well because (i) they are thin(to mount in car door panels) and (ii) have polypropylene cones to handle adverse environments, like the frozen luggage compartments of commercial aviation.
The box was vented with a 1/4-20 nut that serves as a tripod mount and equalized the sealed speaker cabinet for the air pressure changes of flight.
Now I have a PA system that fits in a suit case. I guess my next project should be a compact teleprompter.
--Mike