# Infinity Foam Surround replacement



## saMxp (Jun 22, 2007)

I've got a set of Infinity RS625 floorstanding towers that I've had for almost 15 years. I've loved their sound until recently, when I noticed that bass response had gone away. I pulled the grill off and found this rotted foam surrounds. (See attached pic).
I found a foam surround replacement kit:
 8" Infinity Speaker Repair Foam Re-edge Kit but being the DIY(M)A guy I am, I started looking into possibly doing an easy upgrade.
I found a guy that wrote a review for the Dayton ST210-8 8" Series II Woofer that said he actually replaced his 8" Infinity woofer with one of these and it sounded great...


> I used these to replace my 8 Infinity woofers in my RS625, I could not be happier. These are noticeably BETTER than the original. I also put two Dayton RS150S-8 6" woofers in my old Infinity center speaker and replaced the rear speakers with 2 more Dayton RS150S-8 6" woofers. Highly recommend.


Is this a good idea? The RS625's have a nominal impedance of 6ohms. Crossover is 2.8kHz. If you swapped in this 8ohm driver, wouldn't that drop the crossover point and leave a gap? I probably should just try to foam kit before I end up spending hundreds of dollars making this an active setup!


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## chad (Jun 30, 2005)

Re-foam them, and that's the company I was going to recommend to buy from....
See my shirt?












They are good folks!


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## saMxp (Jun 22, 2007)

Yeah, the kit is a bargain. I've never done it before, but I figure it shouldn't be too bad. Looking forward to it, actually.
The speaker upgrade is probably just too big of a project. The two passive radiators add a whole other layer of complexity. Are they weighted properly for the enclosure and the Dayton driver?


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## chad (Jun 30, 2005)

saMxp said:


> Yeah, the kit is a bargain. I've never done it before, but I figure it shouldn't be too bad. Looking forward to it, actually.
> The speaker upgrade is probably just too big of a project. The two passive radiators add a whole other layer of complexity. Are they weighted properly for the enclosure and the Dayton driver?


the dayton retrofit would be a royal PITA that I would only dedicate to a "winter project" May as well rebuild from the ground up.


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## saMxp (Jun 22, 2007)

Yeah, that's a good idea. I went ahead and ordered the kit from Orange County Speaker. 

Tell you what would be interesting with this tower is a MMMT 8" woofer array for super high efficiency!


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## saMxp (Jun 22, 2007)

Oh, I forgot to attach a picture of the carnage in the first post. This is some serious foam rot. I'd never seen anything like it before. They sat in storage last spring for a few months. Might have happened then.


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## Robert_J (Nov 9, 2006)

saMxp said:


> This is some serious foam rot. I'd never seen anything like it before.


 Not serious at all. At least there is some foam still there. I fixed my in-laws old Altec Lansing speakers. There was a frame and a cone. The foam had disappeared.

-Robert


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## chad (Jun 30, 2005)

Yeah that ain't bad, the bitchin thing is that it has a phase plug so you don't have to remove the dust dome to shim up the voice coil!


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## saMxp (Jun 22, 2007)

chad said:


> Yeah that ain't bad, the bitchin thing is that it has a phase plug so you don't have to remove the dust dome to shim up the voice coil!


Yeah, I'm hoping that OC Speakers has some comprehensive instructions because I'm not entirely sure what you mean by shimming up the VC. I'm figuring the cone will still be fairly well supported with the spider, and I won't need to mess with VC alignment, no?


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## chad (Jun 30, 2005)

saMxp said:


> Yeah, I'm hoping that OC Speakers has some comprehensive instructions because I'm not entirely sure what you mean by shimming up the VC. I'm figuring the cone will still be fairly well supported with the spider, and I won't need to mess with VC alignment, no?


It depends, it never hurst to shim it up but 9 out of 10 times you will get lucky.


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## bmaupin (Feb 22, 2006)

I've refoamed quite a few Infinity woofers having owned 5 or more pairs of them. Buy the cheapest ones you can find (on eBay), but do make sure that the dimensions (outer and inner diameter) are such that enough of the surround will sit on the frame and cone. I use the basic white kraft glue (from Joanns or any kraft store) and have never had it come undone - even with a rubber surround that came loose from a car door woofer.

Here's how I do it:

1. Use some mineral spirits or xylene (not acetone!) and remove the remaining foam from the woofers and frames. Grab your box of q-tips and apply the thinner with them - throw them away when contaminated with foam bits. Apply only enough thinner to wet the areas where the foams are still attached and re-wet when dry. Best to let the thinner loosen the glue for an hour or more. Work on all of the woofers at the same time so this step doesn't take all day. Use a cloth, your fingers, or a non-metal tool that will not scratch the cone or frame to remove the old foams - this is not critical, but the final results look better if you let the thinner do the work.

2. Before glueing surrounds, the voice coil must be centered. Grab a magazine with somewhat stiff pages - the front or rear of most magazines is perfect. Cut many (15 or 18 per speaker) 1/2" or so wide strips about 1 1/2" long - be sure to make them the same length (more important than width). At 3 places 120 degrees apart, insert the paper shims until you cannot insert any more, being sure to insert the same number at each point. You will notice that the cone can be moved in and out and will hold its position.

3. Raise the cone so that the foam will not rest on the frame (the paper strips provide enough friction), place the foam on the cone and eyeball how much of the foam sits on the cone from the rear so you know how much of the foam lip to glue. Apply glue to inner lip only, center on cone, and then let dry - hour or so.

4. Glue outer lip, apply to frame, and let dry.

5. Remove shims. You're done.

- Brad

ps: Here's something strange. I went to PE to get these instructions since I had posted them there a while ago. I had posted a link to an auction and when I clicked on the auction link it came up, but the auction is 21 months old. ??? His current auction for them is still cheap: $3.95 + $2.50 shipping.

http://cgi.ebay.com/8-in-FOAM-SPEAK...9714942639QQcategoryZ3276QQrdZ1QQcmdZViewItem


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## saMxp (Jun 22, 2007)

Thanks for the writeup! The OC Speaker kit came in today so I'm gonna give it a whirl tonight. I removed the original foam last night and it literally crumbled in my fingers when I ran my thumb across it. Serious degeneration!
The one trick is gonna be that the surround mounts to the backside of the cone. I'm guessing I'll glue it to the basket first, and then rest the cone on the surround and glue the backside?


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## bmaupin (Feb 22, 2006)

saMxp said:


> The one trick is gonna be that the surround mounts to the backside of the cone. I'm guessing I'll glue it to the basket first, and then rest the cone on the surround and glue the backside?


I recommend glueing to the cone first since that is the tricky part and is probably most important to be centered on. How the surround sits on the basket does not matter much. Put the surround under the cone w/o glue first to see how much of the lip to apply glue to. I have done two sets of woofers that had the surround to the rear of the cone - one from an EPI speaker and the other was a Dynaudio 30W100.

- Brad


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## saMxp (Jun 22, 2007)

Good point. I'll center it to the cone and glue it down before the basket. 
Good tip on using paper shims, too!


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## saMxp (Jun 22, 2007)

Man, it worked great! I actually think the voicecoil is centered better than it was. At extreme limits of travel (probably further than max excursion, but still) I hear a little bit of rubbing. Now I can bottom the VC out on the backplate and no rubbing! 
The passive radiators are cooking again! Hadn't seen much movement out of them for a while.
Thanks guys!


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## chad (Jun 30, 2005)

Good job man! It ain't so bad is it?


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## saMxp (Jun 22, 2007)

chad said:


> Good job man! It ain't so bad is it?


Not bad at all. Just a little tricky getting the surround behind the cone once the glue is applied. But with the cardstock as a shim, I wouldn't even hesitate to recone a driver in the future, with how well it aligned. 
One thing I did notice is that the new surrounds are much stiffer than the originals. I'm sure a huge part of this is the fact that the originals were dry rotted, but I can't help but wonder if this will affect the driver's Qms? 

Regardless, they sound great once again. Can't be off by much.


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