Refoaming Speakers. How to do it instructions.

[TLS Guy]

Squishman recently bought some older Infinity speakers. Both foam surrounds were rotted out, and he brought them to me for repair.

So, I took photographs of the job.

These are the drivers with the cone edges and chassis at the beginning of clean up. You need to be patient. The glue has to be denatured with denatured alcohol. DO NOT USE ACETONE EVER.

The dust cap is now removed. These drivers had a weight placed over the top of the voice coils which presented a difficult problem, as it had to be removed to place the voice coil shims.

With patience these weight were removed.

You need loudspeaker glue, I had black and clear. If you have a compressor then compressed air is handy for blowing away dust and debris.

At this stage you need to glue the surrounds to the cones, and leave for 24 hours with shims in place.

Here is one of the drivers with the voice coil shims in place. These drivers had a very narrow VC gap, and I had to ease the shims in with a little smear of piston ring lube, that I had on hand.

After the glue has dried and cured, which is 24 hours you can glue the surrounds to the chassis You need to wait 24 hours between stages, so the whole process takes several days. It is important to glue the surround in place without tension. You place the pegs opposite as you go round.

After 24 hours you can remove the clothes pegs and remove the shims.

Now you can replace the weights and dust caps.

At this time you also replace the fiber outer gasket over the area where the foam is glued to the chassis.

After 24 hours the drivers are ready to be tested.

I put them on my signal generator one at a time and carefully listened to each throughout their bandwidth. I head no buzzing or distortion.

Then I placed them on the Dayton woofer tester, connected to my laptop. This has various programs available one of which is the buzz and gap tester program. I am glad to report I got a pass flag from both drivers.

There will be variations form driver to driver, like that surprise I had after removing the dust caps, and finding I could not place the shims without removing that weight.

I did measure the T/S parameter and these are high Qts drivers. So they did this to get a lower F3 form these drivers in small sealed cabinets.

 

[Eppie]

Thanks for posting this Mark. Worth bookmarking. Is that testing software commercial software or freely available?

 

[TLS Guy]

Thanks for posting this Mark. Worth bookmarking. Is that testing software commercial software or freely available?

It is a DATs V3.

 

[-Jim-]

The easiest way to re-foam speakers that I found, was to take my then girlfriend's (now wife of many years) pair of JBL L36s to Vancouver Audio Clinic in Kitsilano (now called Vancouver Speaker Audio Clinic)

When I went to pick them up the owner said they were in such excellent shape, he'd like to buy them from me. Of course that didn't happen. They were retired about 7 years ago after very light use into the Basement Storage Area. My wife wouldn't let me sell them to one of my Brothers who desperately wanted them a few years back. So they sit there all covered up with towels to prevent scratching.

 

[TLS Guy]

The easiest way to re-foam speakers that I found, was to take my then girlfriend's (now wife of many years) pair of JBL L36s to Vancouver Audio Clinic in Kitsilano (now called Vancouver Speaker Audio Clinic)

When I went to pick them up the owner said they were in such excellent shape, he'd like to buy them from me. Of course that didn't happen. They were retired about 7 years ago after very light use into the Basement Storage Area. My wife wouldn't let me sell them to one of my Brothers who desperately wanted them a few years back. So they sit there all covered up with towels to prevent scratching.

You lazy Devil!

 

[Eppie]

Not as lazy as me. I still have a pair of Electrovoice Interface I Series II speakers that have needed refoaming for years. The kits come from Simply Speakers in FLA but if I order anything from the U.S. right now I will never hear the end of it from my wife.

 

[TLS Guy]

The glue that you use- does it remain somewhat tacky, or dry hard? I remember the infinity people saying that when the original speakers were built with polypropolene cones, they had to find new cements that would hold- many cements don't stick to poly very well and if it's a bit flexible, it has to hold without creeping.

It sets hard after 24 hours when fully cured. The glue is designed for this job. Those speakers have as new performance now.

 

[Steve81]

Please try to keep the temperature down folks. This isn’t the steam vent.

 

[TLS Guy]

Please try to keep the temperature down folks. This isn’t the steam vent.

Please explain where the temperature is high? As far as I can tell we have just had a pretty straightforward discussion about repairing a pair of speaker drivers. There was one dash of humor. I see nothing out if line here and actually not even close to any line.

 

[Trell]

Please explain where the temperature is high? As far as I can tell we have just had a pretty straightforward discussion about repairing a pair of speaker drivers. There was one dash of humor. I see nothing out if line here and actually not even close to any line.

A couple of posts where deleted in this thread and now this thread is on topic again.

 

[Steve81]

Please explain where the temperature is high? As far as I can tell we have just had a pretty straightforward discussion about repairing a pair of speaker drivers. There was one dash of humor. I see nothing out if line here and actually not even close to any line.

What Trell said

 

[TLS Guy]

What Trell said

I must have missed those.

 

[Steve81]

I must have missed those.

Just as well; it’s not relevant to the good work you’re doing here.

 

[Squishman]

Interesting to see these photos and the details of the process. I hadn't seen this thread until now after Mark had pointed out to me that he posted it. Those speakers are a great addition to my two-channel room thanks to him!
BTW, he refused payment for this work. But I bought him and his wife a nice box of chocolates, which I imagine they enjoyed.

 

[Eppie]

Are the voice coil shims a must? I've seen suppliers produce videos on gasket replacement where they do not remove the dust caps and just replace the outer gasket. If the wire is copper then the coil would not be self-centering. You can push on the cone to see if the coil is rubbing but you won't know how far off centre it might be.

 

[TLS Guy]

Are the voice coil shims a must? I've seen suppliers produce videos on gasket replacement where they do not remove the dust caps and just replace the outer gasket. If the wire is copper then the coil would not be self-centering. You can push on the cone to see if the coil is rubbing but you won't know how far off centre it might be.

I have never heard of or come across a self centering speaker. The VC suspension is soft, and once the surround is gone, there is no way that I know of the center the VC in the gap without shims.

In the speakers above the VC air gap was very narrow and you would never have centered the VC without shims. If you tried to avoid shims you would have VC rub and a loud buzz for sure.

Removing a dust cap is no big deal and the new one can be glued back in place in seconds, after you have assured yourself there is no gap rub before replacing the dust cap.

 

[Squishman]

Do you soften the glue around the cap with alcohol for several hours before you remove it? I imagine a guy could damage the cone if that was haphazardly removed without proper preparation.

 

[TLS Guy]

Do you soften the glue around the cap with alcohol for several hours before you remove it? I imagine a guy could damage the cone if that was haphazardly removed without proper preparation.

Correct, and that is why you must use alcohol and not acetone. This is a protracted process.

 

[highfigh]

Are the voice coil shims a must? I've seen suppliers produce videos on gasket replacement where they do not remove the dust caps and just replace the outer gasket. If the wire is copper then the coil would not be self-centering. You can push on the cone to see if the coil is rubbing but you won't know how far off centre it might be.

It's best to remove the dust cap- the spider is only one part of the alignment and in speakers with extremely narrow gap between the pole piece and magnet, it's easy to think it's aligned properly and find that its rubs, but only after the cement sets.

 

[TLS Guy]

It's best to remove the dust cap- the spider is only one part of the alignment and in speakers with extremely narrow gap between the pole piece and magnet, it's easy to think it's aligned properly and find that its rubs, but only after the cement sets.

Yes, you must remove the dust cap. Shims are not optional!