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Butyl rubber surrounds

C

coonmanx

AK Subscriber
Subscriber
I have a pair of Speakerlab two way speakers that I got as a kit back in 1980. They have butyl rubber surrounds on the 8" woofers and they still work very well after thirty years. I even had to "readjust" the magnet on one of the woofers with a hammer when I accidentally dropped one of them while moving. I know that sounds pretty crazy but it worked.

Anyway, why do so many speakers come with foam surrounds when the butyl rubber surrounds seem to be superior and not break down over time. I was watching an older pair of Yamaha speakers on Ebay (very similar to my Speakerlabs but with 10" woofers). They also had butyl rubber surrounds and looked like they were in great shape. I was going to post the link to them but I have already deleted it. Do they use foam because it is cheaper? It seems to break down after time.
 
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Sometimes foam is used because it is cheaper but the main reason is that rubber is a lot heavier than foam, and you cannot get certain parameters with a driver with rubber surrounds.
 
coonmanx said:
Are there high end speakers that use the butyl rubber surrounds?
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90% of modern hi-end speakers use rubber or synthetic/treated fabric or treated paper surrounds

the few that still use foam are special treated foam that lasts much longer then foam from the 70's or 80's
 
Just a note: Nearly all high-end subwoofers use foam surrounds, which have inherent advantages that Butyl can't even begin to provide.

Best Regards,
TerryO
 
I wondered why(though i guess some would be hard pressed to call it a high end sub) the Velodyne DLS 5000r used foam. All i can say is i have eargasms wwhen listening to movies...emmmhmmmm!
 
There are typically higher SPL advantages with foam over rubber, as well as other "QMS" factors to consider with either. True enough rubber has the longevity in the right circumstances, but foam has even more advantages like cost & flexability for openers. Rubber has worked in many good designs and help make them timeless like some EPI & others.
DC
 
I had a roommate in college at Iowa State University that paired up a set of EPIs with a Carver cube. Man those things were loud. We lived across the street from some dorms and once a guy came over and asked us to turn it down. The cabinets sucked but they did produce some decent sound. Oh the days of seven keg parties and the Carver Cube. Good stuff. I don't really recall what his speaker surrounds were however.
 
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B&W always used rubber surrounds

At least with British high end speakers - a lot of them used butyl rubber surrounds - KEF too? And if not grossly abused they will last almost forever (eventually crossovers will need cap service - long time out).One of the challenges was when polyprope cones were all the rage - gluing two plastics to each other wasn't a straightforward thing and some manufacturers had problems with rubber surrounds not staying glued to the plastic woofer or mid.
But in general - on older speakers (say 15 or more years) I'm only interested in those using butyl rubber surrounds.Quality wise - almost all speakers with butyl rubber surrounds are high performance products - it's a mixed bag with foam rolls - which run the gamut from junk to very high performance.
 
LIke every other surround choice, butyl rubber is not the "Be-all and end-all".

My EPIs, bought new, had butyl surrounds, and lasted about 35 years, before they suffered catastrophic failure, and needed replacing. The rubber stiffened with age, and cracked. I replaced them with new surrounds, and, for about $20 for the pair, and my hour of time, I figure the speakers will now outlive me. Think of surround replacement, foam or butyl, as preventative maintenance.

BTW, fabric surrounds often need re-sealing, as the material can migrate, due to gravity. Paper pleated surrounds can stiffen and crack, or get mushy from a humid environment, and lose compliance.

Figure that, no matter the material, your surrounds are going to need some attention after a couple of decades or more.
 
butyl or butyl over cloth ?

Spent decades servicing stereo equipment - never remember replacing a butyl rubber surround driver for aging problems - now I've been out of that trade for about 15 years now - so it's entirely possible that really old butyl surrounds are failing.What a number of companies did was use a "rubber" coating on a cloth surround. From the outside - these looked like rubber surrounds - but weren't exactly. These seemed much more durable than foam surrounds - but once in a great while I'd run into a cracked surround made out of this combination.Obviously once you've got a hole - replacement is required - but I never saw the type of catastrophic failure that's common with foam rolls.
 
luvvinvinyl said:
LIke every other surround choice, butyl rubber is not the "Be-all and end-all".

My EPIs, bought new, had butyl surrounds, and lasted about 35 years, before they suffered catastrophic failure, and needed replacing. The rubber stiffened with age, and cracked. I replaced them with new surrounds, and, for about $20 for the pair, and my hour of time, I figure the speakers will now outlive me. Think of surround replacement, foam or butyl, as preventative maintenance.

BTW, fabric surrounds often need re-sealing, as the material can migrate, due to gravity. Paper pleated surrounds can stiffen and crack, or get mushy from a humid environment, and lose compliance.

Figure that, no matter the material, your surrounds are going to need some attention after a couple of decades or more.
Click to expand...

I agree completely. I've seen plenty of Butyl surround become "work-hardened" and eventially crack or split.

Best Regards,
TerryO
 
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