O/T: Stupid Question: Quick and Dirty Refoaming

[mikejz84]

Okay so I just picked up an old pair of Infinity RS 2001 bookshelf speakers at a thrift store for $40--Of course the foam is completely gone. I don't really feel like spending almost the same amount to get a real kit to reform them--I am wondering if there is any quick-and-dirty method out there. (They are just going in the garage, nothing fancy needed--just something that sounds decent)

[Volenti]

use a strip of cloth with a thin coat of silicone to replace the surround, will be adequate for "workshop" speakers.

[ashok]

I don't know how good your Infinity sounds. From what I have heard of their small units many years ago , I am inclined to believe that they will be good. It would be a shame to trash them. You are relating the surround repair to the price you paid. You should'nt. You should look at overall cost ( with repair) against something that sounds equally good.
Then there is the DIYR ( do it yourself repair) factor to contend with.

Recently we repaired a Dynaudio 12 inch woofer in a very unique way ( I think). The original used a foam surround. We found the Dynaudio repair service Very expensive and we could not find any foam or rubber surround that matched the driver dimensions. Finally the owner , went to Denmark on work and the local speaker dealer said that he can use a rubber surround which was a bit bigger. All you had to do was cut it and reduce the size.
So we took the rubber surround and cut it at an angle along the edge and chopped off a piece so that when placed properly around the cone the cut edge of the surround would overlap by about 5mm. We then glued the edges ( of the surround) together. A butt joint will not do in this case .

The speaker works fine and the Fr went down a bit but most parameters are almost the same. It also looks MUCH better than the original ugly pale blue foam surround.

We found MANY surround suppliers on the web. You can pick them up at I think $15/- . Here in India they cost about $1 for small ones. But mailing it can cost up to $10/- or so!
The process is also explained clearly on some sites. I don't have the URL's now. You can find it using Google - as we did.

The silicone impregnated cloth is a cheap and dirty way to get the speakers going . It will make sound but not music. If you don't care about the speaker sounding good , that solution is probably what you should use. It will just prevent the coil from scraping the pole piece and everything else will go out the window.
Cheers.

[kelticwizard]

Originally posted by ashok
The silicone impregnated cloth is a cheap and dirty way to get the speakers going . It will make sound but not music. If you don't care about the speaker sounding good , that solution is probably what you should use. It will just prevent the coil from scraping the pole piece and everything else will go out the window.
Cheers.

Actually, unless the suround has a decidedly audible resonance, that is really all it has to do.

I have been experimenting with homemade surrounds for some time, with varying degrees of success. I plan to have another go at it, this time using either liquid latex-available from hobby shops for $10-or that "dip it" liquid buyl rubber that you are supposed to use to give hand tools a rubberized coating. The contemplated process is to get a piece of vinyl tubing which cross section matches the distance between the circumferance of the cone and the frame, (generally around ¾" diam), some spray-on cooking oil like Pam, and a piece of cardboard larger than the outside diameter of the speaker. I would cut a circular slot in the cardboard corresponding to the surround size, stick the vinyl tubing in the slot so it pokes up through the slot halfway, spray the Pam on the vinyl tubing, and take a "dollar store" spray bottle to spray the latex or buyl rubber onto the vinly tubing and the surrounding border. Spray one coat, let dry, spray another, etc. However, I have not done this yet.

What I have found to be makeshift but entirely successful, however, is the following. Take a piece of Saran wrap larger than the speaker size. It must be Saran, not plastic. Saran is vinyl, and there are many glues that will stick to it. Nothing sticks to poly film food wraps. So get Saran or any vinyl or PVC wrap.

Put speaker on table so the cone is pointing straight up. Take any glue that sticks to vinyl. There are many, including most epoxies. Spread around the outside of the cone, then stretch the vinyl over the entire cone and press around the cone to make sure the cone sticks to it. Just press enough to make contact with the glue-you don't want to put pressure on the voice coil. Let dry.

The next day, form the Saran in the surround hole so that it makes a concave "half moon" shape. Then carefully lift the Saran and spread the glue around the metal frame. Press the Saran firmly onto the metal frame, making sure to keep the "half moon" shape of the surround, and let dry.

The next day, simply take scissors and snip the Saran covering the cone and the outside edges of the metal frame. It works. The surround will look a little crinkly because it is not formed, but it will will work and apparently is airtight if enough glue is used to fill in the tiny folds where the surround meets the metal frame.

That's cheap, quick and dirty. It might take 3 days to do, but it will only be about 10 minutes each day!

[kelticwizard]

On the other hand,it should be pointed out that Parts Express sells 6½" speaker foam kits for $20 a pair plus shipping. I haven't used one, but I am told they are worthwhile.
http://www.partsexpress.com/webpage....ctGroup_ID=373

Here is a pdf of the manual for your speakers.
http://oellerer.net/infinity_classic...ical_sheet.pdf

As you can see, the suggested retail price for these speakers was $240 back in 1991. While not super high money, the fact is that even at discount somebody paid close to $200 for these speakers. They might be wasted being used for garage speakers you don't care about. It's your choice, of course, but I would be tempted to buy the surround kit from Parts Express, then use the Infinitys in the garage only until I spotted a yard sale or something where somebody had real cheapie speaks for sale for 5 or 10 bucks. Then I would move the Infinitys into a nicer location in the house to listen to them. But of course, the choice is yours.

[dunderchief]

anybody know of a generally universal 10" refoam kit? I need to pull apart some Illusion Audio ND-10's and I'm sure that the surround will need to be replaced. I would just recone the entire speaker but unfortunately they do not offer replacement cones.

[Nappylady]

(Hi, Jack!)

Just one question: why on earth are all the repair places selling *FOAM* replacement surrounds??? The last thing I want to do is put another surround on that's going to die in 10 years (3 if you're in India) and then I'll have to get another... is there anywhere a general supplier of rubber surround replacement kits?

(/Hi, Jack!)

[kelticwizard]

Dunderchief:

http://www.partsexpress.com/webpage....ctGroup_ID=373

This link is the same as the link in post #5. Parts Express sells refoaming kits from 6½" up to 15", all around $20 for the pair.

Nappylady:

I, too, wondered about the use of of foam, a material that has been shown to deteriorate. Why not butyl rubber or any of the other materials that speaker surrounds are made of?

The only guess I can make is that foam might be the best, least resonance-producing surround material out there. If it didn't deteriorate, perhaps most manufacturers would use foam, because some manufacturers still use it even with the deterioration problem. Perhaps the refoam kit people figured that since they make a product that is essentially affordable and sensible for all but the cheapest speakers, the DIYer would prefer to use the best material overall, and do the replacement every decade. That is to say, resonance-wise, perhaps the thinking is that better to switch from rubber to foam than foam to rubber. Go for sound quality and take your $20 loss every decade.

I get the impression that this surround kit company is American. As such, they probably don't think that much about the conditions in India. If they did, they probably would make the surrounds out of another material. I think I came across an Australian company that used leather or rubber. I'll look it up.

[kelticwizard]

Here is an informative thread on the availability of rubber, not foam, surrounds. Thanks for the info, Mr. Feedback.
Foam Surround Kits-Any Good?

Jaycar is an Australian supplier which quotes it's prices in Australian dollars. The Australian dollar equals 68 cents American. So $30 Australian is about $20 American. I don't know what shipping is. Worth checking out, anyway.

[kelticwizard]

Another thread that deals with this:
http://www.diyaudio.com/forums/showt...601#post242601