Hey Elephant,

Last week I was having a similar discussion with one of my professors about
speaker design. He said that speakers (and microwaves for that matter) are
one of those "hidden sciences" that are more or less presented but not
thuroughly taught. Anyway, we went up to his office and he had a
poly-planar speaker that they took out of the ceiling. It has a red,
plastic frame with five spokes. The diaphragm was flat styrofoam as you
described. This is the first time I have ever seen anything like this!
Quite interesting!

Ernie


Elephant wrote in message ...
Ernie Werbel wrote:

Greetings again. I am cleaning up my shop for a move, and in packing up
some speakers I came across some interesting ones. These are your normal
cone speakers, albeit smaller, ranging from about 1-1/4'' to 2'' in
diameter. Quite interesting little buggers these are, miniature versions
of
the larger, black paper cones.

Interesting enough? Well I came across a few more that had flatter
magnets
inset into the cone such that there was minimal protrusion outward from
the
back of the cone. While most of the small speakers that I come across
have
magnets about 5/8'' to 1'' deep on back of the cone, the most these
extended
was 1/8''!!!

These speakers do work quite well, with ratings up to one half watt, and
I
must say the frequency response is quite satisfactory for general radio
reception.

I have to wonder, with such a marvel of mechanical engineering as these
speakers are, it remains a mystery to me that they are so uncommon.

Ernie


Back in the early 70's, I had a pair of speakers that were only about
1/8" deep. Truely flat speakers. The sound quality was exceptional.
The weirdest thing was that the "cone" was made of styrofoam.
They were called "Poly Planar" speakers. Don't know what ever happened
to them, but would love to have another pair. Have done a search on the
popular engines, but can't find anything.

Being that they were flat and had such good sound, I don't know why they
didn't become popular. Very inexpensive at the time, too.