Speaker Repair

[d-jones]

I wasn’t sure if this was something that would interest members of this blog or not, but I've seen a number of detailed discussions of home audio equipment break out here, so what the heck, here goes. Way back in 1981 when I was a 17 year old private in the army, I walked into a stereo shop off post with the intention of buying my first stereo system. With my budget being rather limited, the high end stuff was totally out of the question, so I settled for an entry level JVC system, consisting of an amp, a tuner, a cassette tape deck, a turntable, and two speakers. Not long before I was due to be discharged from the military in 1984, all but the speakers were stolen out of the barracks, thus ending my interest in stereo equipment for the next twenty five years. Well, a few years ago I picked up a very nice Pioneer SX1080 receiver and pulled the old JVC speakers out of storage to use with it. Everything was fine for several years. I know the receiver is more than capable of destroying these speakers if I were to crank up the volume, but I’m not really a volume cranking kind of guy, so there’s never been a problem, at least not until the other day when I heard the speakers making an unpleasant sound that had nothing to do with my choice of record. Removing the front covers from the speaker cabinets quickly revealed the cause. After thirty one years the front foam suspension had failed on the woofers in both speakers. So, what to do?

I wasn’t really in the mood to spend money on new speakers, so I thought I’d see if they could be repaired. With that in mind, and one of my damaged woofers in hand, I headed down to a local speaker shop here in Burbank to see what they had to say about it. Well, they said they could make the repair for me for about $70.00 per speaker, or, if I was competent working with my hands they would sell me a kit to make the repairs myself for $30.00 and some change. I bought the kit.

Unfortunately, I didn’t think about getting a photo of the damaged suspension until it was too late, but here it is with the suspension completely removed. The foam curlers were used to lift the paper cone for better access to the rotted out suspension foam.

 

[d-jones]

On this speaker, the foam attaches to the underside of the paper cone, and all of it needed to be removed before the new foam could be glued in place. Fortunately, it was so rotten that it was easily scraped away with my fingernails. Here it is, ready for the new suspension.

 

[d-jones]

This is what the new suspension looks like. Not much to it. It will need to be stretched into place around the paper cone. I’ve also cut away the center dust cover so that paper shims could be installed around the inside surface of the voice coil. You can see them tucked into position.

 

[d-jones]

As you can see in this photo, it’s a pretty snug fit.

 

[d-jones]

Now, by pulling the foam away from the speaker cone as shown, glue was applied to the flat inner surface you see here. Then I simply worked my way around the speaker, pulling the foam and applying the glue, until the entire flat inner surface had a nice relatively even coat.

 

[d-jones]

Now working quickly, foam curlers were tucked into position all the way around the speaker, then the larger pink curlers seen earlier were removed, allowing the paper cone to drop back down and capture the yellow curlers between the paper cone and the metal frame. Then the speaker was propped up and weighted as shown until the glue had dried.

 

[d-jones]

With the glue dry, the yellow curlers are removed and the larger pink ones reinstalled to lift the paper cone up out of the way of the frame. Then glue is applied all the way around the metal frame and the curlers are again removed, allowing the cone to drop back down and bring the outer edge of the foam suspension into contact with the glue. I made sure the paper shims were still in place around the voice coil, and then applied weight to the foam and let it sit until dry.

 

[d-jones]

Once the glue was dry the speaker was ready for an ops check. The paper shims were pulled out and it was hooked up to the receiver where it worked perfectly. So now it was ready for a new dust cover. Since removing it risks damage to the paper cone, the outer edge of the old dustcover is left in place(You can see it in some of the earlier photos). I applied the fresh glue directly to the top of the old dustcovers outer edge and then pressed the new one into place on top of it. Once again, some highly specialized speaker repair tools were employed here to see that even pressure was applied until the glue had dried. The large Tupperware tumbler fit the dustcover perfectly, and the Fire King mug added just the right amount of weight to the affair.[this post was last edited: 12/22/2012-03:15]

 

[d-jones]

Ahhh, that's much better.

 

[d-jones]

So here it is, ready to go for another thirty years. It was a fun little project. Had these been more expensive speakers I may not have been willing to try this, but having done this repair twice now(remember I have two speakers) I don't think I'd hesitate to do it again.

 

[lordkenmore]

Good job! And this is worth talking about here--that surround issue is a problem with many older speakers.

 

[lordkenmore]

I know the receiver is more than capable of destroying these

It's actually safer having too much power than too little. If the amplifier doesn't have enough power, it can start "clipping" which can destroy the speaker in a hurry. Of course, a powerful amplifier turned up to see how loud things can get can also finish off a speaker. Basic rules of thumb: too much power is better than too little, and if things start sounding bad, it's a good idea to drop the volume.

 

[wayupnorth]

I bought my repair kit from a company called Simply Speakers for under $20 for my 30 year old Bose Interaudio SA1000's. The company is very good to deal with and promptly shipped the repair kit with detailed instructions. The speakers sound better than new again.

 

[westie2]

Nice job and great idea using the pink and yellow rollers!!  I like your step by step photos too.

 

[westingman123]

Way cool!

I have the Technics system I bought piece by piece in 1980. This will come in handy, I'll bet! Great tutorial.

 

[fido]

Yes, thanks for posting. At some point I need to test the mains energised speaker in my mid '30s HMV radiogram. That thing is so heavy it has an extra bracket fixed to the base of the cabinet to support it!
My first cassette deck was also a JVC, an odd looking wedge shaped toploader.

 

[kimball455]

Great Information

I have a pair of Advent II speakers that have the dreaded foam rot. Now I know how to fix them.
Harry

 

[hydralique]

Clever . . .

use of the pink and yellow rollers! I've been putting off doing my old Boston A-100s so it's very nice to see such excellent photos of refoaming. If you haven't already found it, Audiokarma.org is a wonderful source of information about all sorts of old stereo equipment.

 

[whirlcool]

Nice report here about how to do a refoaming job.

I have a pair of JBL 4311's from 1977 and still the foam is in good shape and my 1968 AR-3a's used a fabric surround instead of foam.

You can save some big bucks if you find some expensive speakers that just need new foam. A lot of people think that's the end of the speaker if the foam crumbles.

But from what I have heard it takes a special kind of patience to do a refoaming job.

 

[wayupnorth]

Replacing the foam is actually quite easy to do

The hardest part is scraping the bits of old foam from the speaker edges without damaging the speaker itself. A regular screwdriver worked for me on that. The cement is very fast acting and will stick to anything. So you have to work quick and make sure the foam is perfectly placed. I was just about an hour from start to finish on both.

 

[d-jones]

John - The guy at the speaker shop told me the same thing. It's better to have too much power than too little. I'd never heard that before so I learned something new that day.

And I have to agree with Tim. The hardest part of the job was the foam removal. But for me, the most worrisome part of the job was gluing the new foam into place. It's important to get the inside flat edge of the foam to lay flat against the paper cone, and on my speakers it wasn't cooperating. That edge of the foam suspension is formed at an angle to match the slope of the paper cone, but in this case the match wasn't quite perfect. I had to act quickly and raid my wife's curlers again so that they would keep the foam in contact with the paper cone until the glue had dried. Thank heavens it worked.

 

But in spite of any momentary problems I may have had, it really wasn't all that hard to do. And as Allen points out above, most people do seem to think that when the foam is bad the speaker is ruined. Now that I've done this a couple of times I may try looking for a good deal on a pair of quality speakers in need of new foam.

 

Anyways, thanks for all of the comments guys. I'm glad you found this thread worthwhile.

 

[qsd-dan]

Good job, there!

I have 6 vintage Acoustic Research AR-9 speakers that needed all the of the bass drivers and lower mid-range drivers re-foamed. That's a total of 18 drivers (12 bass drivers and 6 lower mid-range drivers). Luckily, I had a buddy do it for me for a fraction of the price that most wanted to charge. I don't think I'd have enough patience to re-foam all of those drivers in the short amount of time he did them.

 

[gansky1]

I have four sets of Advent speakers, two sets found this summer need new foam. I've stared at the pictures but not sure I'm up for the gluing part. I'm horrible at gluing anything but wood, fortunately there is a commercial electronics-audio guy here that will do them for $130 a set. You did a fantastic job on yours, the curlers were brilliant!

Dan, those are some sweet speakers you have. My first ex-husband had a set of these, they were overwhelming in a small apartment but amazing. Sound that can make the hair on your arms tingle!

 

[qsd-dan]

My first ex-husband had a set of these, they were overwhelming in a small apartment but amazing. Sound that can make the hair on your arms tingle!

I bet you guys quickly made a lot of enemies in that apartment complex ;>)

They will throw out more than enough sound if needed, but eat up gobs of wattage for breakfast with an 87 db efficiency rating. A very powerful amp is required for them to openly sing without distortion. Not too friendly in the mobile department either, standing 4.5 feet tall and weighing in at 135 pounds......each.