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Speaker Rot

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33 replies to this topic

#1 of 34 OFFLINE   Michael Harris

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Posted March 30 2003 - 09:28 AM

I have a pair of Infinity Kappa 9s and have had them for over 10 years. For those of you who don't know them, the are almost six feet tall and have seven drivers; five that face forward and two that face rearward. Two of the seven drivers are 12" woofers and there lies the problem. I was getting them ready for the movers and I removed the grill and noticed how dirty the rubber gasket between the cone and frame was and when I tried to clean it, it crumbled into dust (shades of "Andromeda Strain"). I was crestfallen. Before I touch the others and have them crumble, is there anyway to rejuvenate the rubber? Is the one woofer toast? Can I just replace it with another 12" woofer? How much would just a thing cost? I love these speakers and see nothing wrong with the mids and tweeters.

#2 of 34 OFFLINE   Michael Bailey

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Posted March 30 2003 - 10:48 AM

A friend of a friend had the same thing happen. He took it to an electronics repair store in houston where they ordered replacements persumably from the speaker manufacturer and reinstalled them for much less than the cost of a new speaker. Sorry I dont know more details than that.

#3 of 34 OFFLINE   Mark Zimmer

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Posted March 31 2003 - 03:46 AM

There are a number of folks who sell replacement kits for the foam surrounds on eBay for pretty reasonable prices--$20 or so. I got one and gave some old speakers a new lease on life and they sound good as new. I'm no DIY guy and found it to be easy enough to accomplish.Posted Image

#4 of 34 OFFLINE   RobWil


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Posted March 31 2003 - 07:20 AM

Unfortunately you will not be able to rejuvinate the foam. You can get kits to re-foam the exsting drivers or you can order new drivers. They may not be as expensive as you might think. The 8 inch driver for my Velodyne sub is only around $50 shipped.
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#5 of 34 OFFLINE   Michael Harris

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Posted March 31 2003 - 09:04 AM

Thanks for the input. Since I've been out of the country for six years, what is a good on-line source for drivers?

#6 of 34 OFFLINE   Phil Iturralde

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Posted March 31 2003 - 09:22 AM

You may want to contact Infinity Product Support and email them. You must choose your product first (Kappa 9.1 ?), then you can "Contact" them via email.

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#7 of 34 OFFLINE   Michael Harris

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Posted December 06 2003 - 03:38 PM

Its been a while but I now have my speakers in my new apartment after being in storage for over a year. Until I read the inputs and did some Google searching I never considered "refoaming". Well, I bought four foam surrounds and after over three hours I now have speakers that sound like new. Considering that I paid over $1000 1990 dollars for them it was worth the time and money ($54). Thanks.

#8 of 34 OFFLINE   Chu Gai

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Posted December 06 2003 - 04:36 PM

Good job Michael!!

Here's a bit more information regarding speaker rot for those who are interested.

Foam surrounds, which have been around for 3 decades or so, are still used. Some individuals have reported rot or degradation while others haven't. To make it even seem more perplexing, given a particular speaker, some have discovered this degradation while others have not. This begs the questions how does it occur and why.

There are two primary ways that rot can occur. First one has degradation that occurs as a result of exposure to UV and ozone. Secondly, degradation can also occur as a result of biological mechanisms. Essentially the foam becomes a source of food for a variety of microbes. With regards to the latter mechanism, storing your speakers in basement or somewhere that's cool and dry can actually exascerbate this problem.

As to why this sometimes does and doesn't occur, the answer lies in the sort of materials the foam is constructed of. It turns out that foam that incorporates ester type compounds is enormously susceptible. Although this general information was generally known as far back as the 70's, ester based foams were still used as they are today. Occasionally we can blame the manufacturer of the speakers when they know what they're using. However, given that the price of the ester vs non-ester based surrounds are the same, or nearly so, often the manufacturer of the speaker who buys his drivers from a number of sources, is never told that these surrounds are frequently interchanged. Hence, unless specifications which include the nature of the foam surround are given to their suppliers, and unless the speaker manufacturer has a lab that can routinely analyze the foam for the presence of ester material, it can be a bit of a crap shoot.

If your drivers use other sorts of materials such as polybutadiene, polyvinylchloried (PVC) modified polystyerenes, rubber or sythethic elastomer modified cloth surround, you're pretty much guaranteed that your surrounds won't fall apart. Of course, if you're the sort of person who cleans their surrounds with chemicals that can leach the plasticizers out, then you'll certainly find that they'll become brittle after time.

In any event, you saved a pretty substantial investment in speakers for very little money. My kudos to you.

#9 of 34 OFFLINE   Michael Harris

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Posted December 07 2003 - 09:38 AM

Chu: You may be right about the "cool and dry". Before storing the speakers I had them in my apartment while I was living in Southern Spain for five years. Very dry. As for the cool part, my apartment was on the side of the building that did not get direct exposure to the sun. Great in summer since I had no AC but terrible in winter. I discovered the rot while packing them up for my transfer back to the US of A. I removed the covers and noticed how dirty the surrounds were. I went to brush them off and found my finger through the material. I was in shock. I am quite certain that UV did not play a role since they were never exposed to the sun. Unlike my friend whose pair of Magnaplans are dead because UV broke down the glue used inside. Unrepairable. Guess tried but true technology is the best. Since I am pretty sure that the dirt build up had something to do with it, what is a good way to clean the surrounds? Any good chemicals? Fortunately all the other drivers, while dirty, are in good shape and I've now cleaned them. I'll soon pop them out of the enclosure to clean the coils, check the connections, etc as I did see some oxidation on the woofers but it was cosmetic.

#10 of 34 OFFLINE   Chu Gai

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Posted December 07 2003 - 10:31 AM

I'm pretty sure also that UV wasn't the main culprit and anyone whose seen 'dirt' under a high power microscope quickly comes to realize that there's thousands of interesting creatures. I don't know about you, but they look hungry to me!
Posted Image
I really don't know what the best material to use for cleaning the surrounds is. You could always contact the manufacturer if it bothers you a lot. I'd certainly stay away from anything that didn't list water as the first ingredient and many people clean their surrounds, rubber based, not foam, with ArmorAll or an equivalent. Myself, I'd just do a periodic vacuuming and if they rot in 10 years, maybe it'll cost you $70 to redo everything. Sounds cheap to me.

#11 of 34 OFFLINE   John Wes

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Posted December 07 2003 - 11:16 AM

This place probably has what you need, and as stated above, it's not that hard to replace them. Just paying attention to detail is about as hard as it gets.

A lot cheaper than replacing the drivers.


#12 of 34 OFFLINE   Richard Boughn

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Posted December 07 2003 - 11:16 AM

If you don't want to do it yourself try a search for speaker repair. Many shops advertise the ability to cheaply repair such damage. Near Portland, Fred's Sound of music web site lists repairs to many brands of speakers. Suspect this type of shop everywhere. Richard

#13 of 34 OFFLINE   Michael Harris

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Posted December 07 2003 - 02:27 PM

It only took me three hours to replace so once every ten years is a bargain.

#14 of 34 OFFLINE   Mike Veroukis

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Posted December 07 2003 - 02:36 PM

[quote] Since I am pretty sure that the dirt build up had something to do with it, what is a good way to clean the surrounds? Any good chemicals? [quote]Well, I'd try using compressed air to clean out any dust buildup every few months. Don't see why you'd need any chemicals, it's just dust really. If you're a heavy smoker, however, I could see some build up forming in which case you may need something to clean it off. Pure water is probably good enough.

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#15 of 34 OFFLINE   Michael Harris

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Posted December 08 2003 - 12:35 AM

Last night I put my newly repaired woofers to the test by playing the new "Pirates of the Caribbean" DVD. I figured the sounds of cannons firing would rock the woofers. Sure enough, they did and the repairs held and there was no rattle. Maybe I'll do one more test with "Gettysburg" which has one heck of a long cannon volley....of course that could get me evicted. With 400w being pumped into each speaker, I've never put up to "11".

#16 of 34 OFFLINE   Jason.Soko


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Posted December 08 2003 - 09:47 AM

I actually found a refoaming kit for the old ESS Model 5's. 27 years old and they still sound beautiful after the restoration.
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#17 of 34 OFFLINE   Elizabeth S

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Posted April 19 2007 - 04:18 PM


A little help please. I'm going to try to replace the foam surrounds on my speakers and have been reading up. This page at speakernet.com explains that there are angled edge and flat edge surrounds.


I don't quite understand the drawing. . .

Could someone tell me from looking at this picture which I have?

Posted Image

I've watched the video on the same site, and it looks like something I could do. . .I think. Posted Image

#18 of 34 OFFLINE   MaxL


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Posted April 19 2007 - 06:12 PM

it looks like it is angled and attatched to the cone from underneath.
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#19 of 34 OFFLINE   Wayne A. Pflughaupt

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Posted April 20 2007 - 03:37 AM

Elizabeth, Parts Express sells these re-foam kits for around $20, that have a pair of both types. It will be self-explanatory once you see them in person. Like Max said, it looks like these have the surround glued to the rear of the cone, which is a bit unusual. Regards, Wayne A. Pflughaupt
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#20 of 34 OFFLINE   Gary Seven

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Posted April 20 2007 - 03:52 AM

I have the Kappa 7's and have the same problem. Although nothing has crumbled (since I didn't touch them for fear), obviously though, they need to be replaced. I called Infinity over a year ago for replacement drivers and of course, they are not available any more. However, refoaming is something that never occurred to me. Do you just glue the foam to the cones? Does someone have a link as to step by step instructions? I really loved these speakers. When they were new, they were the best sounding musical speakers I ever heard.

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