DaveD Posted January 20, 2006 Report Share Posted January 20, 2006 A little off topic here, I am, but still in the family. The driver experts here can probably answer this for me.On the 8 inch woofers of the Kloss Cambridge Soundworks Ensemble, the original examples have a butyl rubber surround. It is dull black in appearance. This surround also appears in some examples of the final version of the speaker, the New Ensemble, constructed in China-- although the original ones are in a basket with 4 screw holes (probably cast) and the final ones are in a basket with 8 screw holes (probably stamped). This 8 screw hole driver with butyl surround is also used in some examples of the Powered Subwoofer II.In the middle period, some examples have a surround that is black and very shiny, also in a basket with 8 screw holes. The same driver is used in some examples of the Powered Subwoofer II. What is this shiny surround material? It is not foam, but has a smooth surface like the dull surfaced butyl. Is either one of these materials more resistant to ozone than the other one?Is the dull butyl more resistant to ozone than the modern foam surrounds? Link to comment Share on other sites More sharing options...
Carlspeak Posted January 20, 2006 Report Share Posted January 20, 2006 >A little off topic here, I am, but still in the family. The>driver experts here can probably answer this for me.>>On the 8 inch woofers of the Kloss Cambridge Soundworks>Ensemble, the original examples have a butyl rubber surround. >It is dull black in appearance. This surround also appears in>some examples of the final version of the speaker, the New>Ensemble, constructed in China-- although the original ones>are in a basket with 4 screw holes (probably cast) and the>final ones are in a basket with 8 screw holes (probably>stamped). This 8 screw hole driver with butyl surround is>also used in some examples of the Powered Subwoofer II.>>In the middle period, some examples have a surround that is>black and very shiny, also in a basket with 8 screw holes. >The same driver is used in some examples of the Powered>Subwoofer II. What is this shiny surround material? It is>not foam, but has a smooth surface like the dull surfaced>butyl. Is either one of these materials more resistant to>ozone than the other one?>>Is the dull butyl more resistant to ozone than the modern foam>surrounds?>>I personally don't think either one is significantly different from the other. It's probably more a function of the "smoothness-of-finish" on one butyl die vs the other. Butyl rubber is the generically the same stuff used for years to make tire inner tubes. It'll stretch a mile before it will tear an inch. There is no known research in support of ozone affecting butyl as much as it does foam. However, there has been some posts on this web site from folks concerned about the aging affects affecting the stiffness characteristics. I wouldn't worry about the difference in finish.CarlCarl's Custom Loudspeakers Link to comment Share on other sites More sharing options...
DaveD Posted January 20, 2006 Author Report Share Posted January 20, 2006 Thanks, Carl. This is good news and from somebody who must have the experience to back it up. I doubt that any stiffening of the butyl would be enough to provide meaningfully more resistance than the acoustic suspension resistance itself. Now, on a vented cabinet, things might be different. Link to comment Share on other sites More sharing options...
DaveD Posted January 20, 2006 Author Report Share Posted January 20, 2006 ...or,Maybe I am wrong about that. Is the concern about butyl stiffening in regard to acoustic suspension cabinets? There certainly are a lot of those as topics in this forum! Any thoughts and actual experiences would be appreciated. Also, links to those strings where this is discussed. Link to comment Share on other sites More sharing options...
Carlspeak Posted January 21, 2006 Report Share Posted January 21, 2006 >...or,>>Maybe I am wrong about that. Is the concern about butyl>stiffening in regard to acoustic suspension cabinets? AS or vented, it doesn't make any difference. What I was writing about is the T/S parameters getting altered over time by the rubber's hysterisis characteristics changing with age. I don't know if they do on woofers with butyl surrounds. I suspect it's minor and in the overall frequency spectrum we hear and sense during music playback, it's so minor, it's insignificant. My suggestion is, be less concerned about the bass and more concerned about the mids and highs. They are what you hear most and are most sensitive to. If a speaker's characteristics are altered here ever so slightly, you're more likely here it in the 1 kHz to 5 kHz range because your hearing is much more sensitive here. Check out Robinson and Dodson's equal loudness countours published in their 1956 seminal work (British Journal of Applied Physics). The curves can be found in F. Alton Everest's Master Handbook of Acoustics, 2nd Ed. published by Tab Books. There>certainly are a lot of those as topics in this forum! Any>thoughts and actual experiences would be appreciated. Also,>links to those strings where this is discussed.CarlCarl's Custom Loudspeakers Link to comment Share on other sites More sharing options...
Pete B Posted January 23, 2006 Report Share Posted January 23, 2006 >...or,>>Maybe I am wrong about that. Is the concern about butyl>stiffening in regard to acoustic suspension cabinets? There>certainly are a lot of those as topics in this forum! Any>thoughts and actual experiences would be appreciated. Also,>links to those strings where this is discussed.It has to be taken on a case by case basis how much a shift in T&S parameters matters for a give system. I've not yet found a trend, some report rubber edges cracking in a fairly short time, I've seen some stiffen by about a factor of 3 or 4 in 10 or 20 years, this *does* matter. I've seen others over 25 years old with little if any shift. Here's the link: http://www.diyaudio.com/forums/showthread.php?threadid=71420Pete B. Link to comment Share on other sites More sharing options...
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