"Arny Krueger" wrote in message
. ..
I have a 500 mW transistor radio with 3" speaker that "blows you out of
the
room".

Narrow bandwidth, high efficiency speaker.

Actually the main speakers have higher efficiency. Barry Mann hit the nail
on what I was alluding to.

Yet my Hi-Fi needs 100 times that much to do the same :-)

Broad bandwidth, low efficiency speaker.

Nope, mains are 93 dB/watt/metre.

Of course the actual measured SPL in the latter case is about 20 dB
higher.

But, one is shaped to fit over the parts of the audio spectrum where the
ear
is most sensitive.

Maybe it has no bass or treble, but you already allow for that pretty much
in the measurement weighting curve.
You could do a very narrow band measurement, and the transistor would still
be nearly 20 dB lower.

Isn't the human brain an amazing thing!

Actually, this one is settled in the ear.

Call it the auditory system maybe, but the brain is definitely the main
factor here.

MrT.