29 May
2010
29 May
'10
1:11 a.m.
On Fri, May 28, 2010 at 09:31:03PM +0100, Folderol wrote:
An Optima or other AGM car/boat battery would work well, but they are pricey and HEAVY.
There are large Li/Ion batteries available that might work, designed for electric bicycle
applications, but they tend to run at 24v or 48v or some odd voltage.
Or, you could just buy a Crate busking amp. Those things are A/B amps (I think) can run
forever on a few D batteries.
-ken
On Fri, 28 May 2010 11:13:46 +0200
Jörn Nettingsmeier <nettings(a)folkwang-hochschule.de> wrote:
v>
On 05/27/2010
06:36 PM, Bob van der Poel wrote:
not really recommendable for a permanent setup. with an ups and standard
mains equipment, you will waste battery (and carry dead weight) twice:
in the inverter that generates grid voltage from the battery, and in the
PSUs of your gear that will re-transform the precious grid voltage back
into low-voltage DC. throw out the middle man.
the nice thing about car equipment (as a previous poster has suggested)
is that all the gear is standardized to work at 12 volts dc. many car
radios have line ins these days (for file players etc.). it's easy to
hook up a small mixer here - you should be able to find a cheap one by
the Brand That Shalt Not Be Named or one of the other manufacturers they
steal their designs from - i've seen a few that take 12v dc.
How much sound output power do you actually need? In bridge mode an
amplifier running off 12V can deliver a maximum of 18W RMS into 4ohms.
Here in the UK Maplins supply a suitable power module (they call it 40W
- that's peak power) very cheaply - 15.99ukp
http://www.maplin.co.uk/Module.aspx?ModuleNo=37737
It's actually a Kemco product. I don't know how available that would be
in other countries.
At 500mV sensitivity it will probably be a pretty good match for
direct connection to most keyboards. If not, a small buffer amp could
easily be patched in.
I don't recommend using a car battery. They are not designed for steady
discharge, but for short bursts and long recharge times. Although
initially more expensive you would do a lot better getting a sealed gel
type lead-acid battery with suitable charger.
A friend
of mine was talking about how he would like to be able to busk with
his keyboard, and I said I would look into the possibility of building him a
battery powered PA for it. Does anyone have any suggestions for good ways of
going about this? We would like to keep the cost as low as possible.
How about an off-the-shelf UPS? Don't know how big you'd need, would
depend on the gig time, etc. There is probably a way to calculate that
:)
The consumer UPS units I've see all have lead-acid (sealed) batteries
and are quite reliable.