On May 30, 6:11*pm, "Phil Allison" wrote:
...snip....
** Ever see a Quad ESL57 ?

The tweeter is a 3cm wide strip, mids come from a similar pair of strips
each side and there are two, fairly large rectangular bass panels outside
them. *Horizontal dispersion is at least 15 degrees at the highest
frequencies but vertical dispersion is much narrower.

Crossovers are simple 6dB/octave and there is some overlapping - *despite
which transient response is near perfect at any frequency.

... * Phil

The man I met had NOT known to make strips and his first units had an
'interesting' effect with that beaming. If you placed a flat panel
ESL on each side of a person speaking into a microphone; the
microphone was in a dead zone so there was no squeal. Then the beaming
effect literally projected the sound straight in front of the speaker
for a great distance with little noticeable drop in sound level. In
other words, perfect as a PA. The person in the front heard about the
same level as a person 100 feet further away in the back. Actually a
strange effect to witness.