BM2000 saw the appearance of an actual solar-powered sound system. It was a pretty
simple affair: a cheesy Boss car amp powered by a substantial 12V marine battery topped
up by a 40W solar panel. In practice we ended up using two marine batteries and
charging one off the camp's generator while the other one was in use. The solar panel
got some use about halfway through the event. It worked fine but needed attention
every so often so that it was always facing the sun directly.
Here are some pictures of the system being tested in Jonathan Jaffe's loft...
Out in the desert...
"Cheesy" was the name of the game here. A couple of "Q-Power" PA speakers
bought on a whim from EPO in Houston (one of those totally unpretentious hobby outlets where there's electronic
bits everywhere and it's cheap and if you're nice they'll cut you a deal). Total cost: $120 or so for two.
See 'em in the back of my car
on the way
back from EPO.
Again, cheap & cheesy in effect here! A standard used Boss car amp. Nothing special at all.
Cost in the $50 ballpark. The only difficult bit would be finding one that wasn't
knocked off... (thankfully mine wasn't).
A marine battery is like a car battery but designed for continuous usage rather
than just dumping a bucket load of juice for a few seconds cranking a car's motor.
Since an amp is on drawing a more or less constant amount of power a marine battery is
a good fit for this scenario.
Another property of marine batteries is that they're
designed to be fully discharged -- ordinary car batteries really aren't meant to be
Marine batteries can be obtained cheaply from Costco.
They sell a few versions differing in their capacity and minor things like whether
there is a charge level indicator. The high capacity one with an indicator is
pretty good value. Cost: $60
(Costco is a membership-only warehouse. This year it's $45 for a basic membership but
is well worth it for all the other BM stuff you can buy there. The membership fee pays
for itself immediately in a single BM trip.)
The DJ rig with its mixer, CD players, etc, was run from the marine battery as
well. We used a standard 300W inverter which converts 12V to 110V. Beware! These are ultra-expensive from
places like Radio Shack who'll happily charge nearly a $100 for an inferior (100W, 200W)
is the place to go. Buy at least two,
they're easy to fry by connecting the terminals the wrong way around
(as we found out :-)
). Cost: $40
If you run the sound at a reasonably loud party volume you'll be hauling some serious
current (20 amps or more) from the batteries and if you plan on having the batteries any distance at
all from amp make sure you use good quality thick wiring. For purchasing simplicity I just
used speaker cable. It would be cheaper to use 30A wire intended for a house's electrical
system. Cost: 20c/foot or thereabouts for the speaker wire. Best not to buy this from a flashy hi-fi store. Remember:
you're out in the desert, and if you're anything like me every other component will
be at best "OK" :-)
. Even the Hi-Fi mags say house mains wiring provides pretty
adequate sound reproduction quality if you want to go this route.