You did say you where a soundman didn't you ?

Not heard of watts equal v squared over r ?

eg an amp powered off 9v battery into an 8ohm spkr will give almost 10w
providing it can draw enough current and can drive rail to rail. Does your
outboard have a generator that can charge a car battery ? you could mount a
cheap car radio cd player that supports mp3's or even has an input for an
ipod which would be good for 20w/channel.

Pete

Pete Cross wrote:
You did say you where a soundman didn't you ?

Not heard of watts equal v squared over r ?

eg an amp powered off 9v battery into an 8ohm spkr will give almost 10w
providing it can draw enough current and can drive rail to rail. Does your
outboard have a generator that can charge a car battery ? you could mount a
cheap car radio cd player that supports mp3's or even has an input for an
ipod which would be good for 20w/channel.

Pete



Sounds like you have mistaken 9v DC for 9v AC. Quite a difference. An
amplifier running off a 9volt rail can output 8v p-p at best (2xVbe have
to be taken off the maximum rail voltage). 8v p-p is 2.83v rms which
into 8 ohms is 1W. There are techniques used involving DC-DC converters
which can increase the rail voltage, bridge connection and/or output
transformers which reduce the load impedance as seen by the amplifier,
but for a straight single-ended transistor amplifier driven from a 9v
rail, 1W is the best you'll get into 8 ohms.

S.

In article ,
Pete Cross 1@2 wrote:
eg an amp powered off 9v battery into an 8ohm spkr will give almost 10w
providing it can draw enough current and can drive rail to rail.

You jest? The most you can get into a 4 ohm speaker from a car battery at
13 odd volts is approx 5 watts. Unless you go for bridge outputs.

--
*When you've seen one shopping centre you've seen a mall*

Dave Plowman London SW
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