On Fri, 05 Nov 2004 18:50:40 GMT, "Fleetie"
wrote:

Put very approximately, you seem to get a half-power beamwidth of the order
of 45-90 deg across when the wavelength is similar to the diameter.

Hmm! 45-90 is a bit of a range. So diameter~=25mm, c~=344m/s, so
f~=13.7kHz.

I'm surprised. I'd have thought at that kind of frequency, the central
lobe would be considerably narrower, but I can't contradict you at the
moment.

That seems not to explain the extremely noticeable "micro-beaming" effect,
but maybe there are other things coming into play. I mean as I said, the
"sweet spot" is 1 or 2 cm at about 3 or 4 metres from the tweeter, which
is considerably less than ONE degree.

Get a copy of Martin Colloms 'High Performance Loudspeakers'. If you
care at all about music reproduction, it's an essential buy, and has
all that classic stuff in it. Akin to the Radiotron Handbook, I freely
admit! :-)
--

Stewart Pinkerton | Music is Art - Audio is Engineering