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From: klein@ucbcad.UUCP (Mike Klein)
Newsgroups: net.audio
Subject: Speaker Cone Materials --- Bextrene and Polypropylene?
Message-ID: <24@ucbcad.UUCP>
Date: Thu, 6-Jun-85 13:28:54 EDT
Article-I.D.: ucbcad.24
Posted: Thu Jun  6 13:28:54 1985
Date-Received: Sun, 9-Jun-85 04:23:21 EDT
Organization: UC Berkeley CAD Group, Berkeley, CA
Lines: 23

Another article spurred by reading Martin Collins's book.  (I may have
mistyped his name in an earlier posting.)  He mentions the many different
cone materials for low frequency drivers as having profound effects on
the sound quality, especially when the cone begins breakup.  Rigid cones
(like aluminum and other hard materials) are good pistons but are
dastardly when they start to break up.  He notes that Bextrene, developed
by accident at BBC and used extensively by KEF and some other mfrs,
has amazingly good self-damping properties.  Even in breakup, the sound
is still quite pure and almost free of coloration.  Supposedly a larger
diaphragm, like 10 inch or so, can be used all the way up to 3 kHz.

He also mentions a newly developed material which he says offers the same
order of improvement of Bextrene that Bextrene offers over conventional
materials like paper-pulp.  This is a family of materials based on
polypropylene.

Has anyone had experiences with these materials?  Are there any driver
manufacturers who offer high-quality units of either of these materials?
-- 

		-Mike Klein
		...!ucbvax!ucbmerlin:klein	(UUCP)
		klein%ucbmerlin@berkeley	(ARPA)