klein@ucbcad.UUCP (Mike Klein) (06/06/85)
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)
mohler@druxu.UUCP (MohlerDS) (06/10/85)
There are many manufacturers of drivers employing these materials. Several stores and basement companies have sprung up selling them along with crossover parts, some of these companies advertise in the back of Audio magazine. Beware, companies new to these driver materials may go through the same delamination hastles that B&W, KEF and Infinity went through early on. As for personal experience I have found the KEF bextrene drivers to be superb and easy to locate. I have used the KEF T-27, T-52, B-110, B-110R, B-200, B-139, B139/2 and all have produced excellent results. David S. Mohler AT&T-ISL @ Denver druxu!mohler