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View Full Version : DIY refoam - road to desaster?



Infredible
05-17-2004, 08:00 PM
Hi all,

Over the weekend I became a proud 4343
owner, thanks to Andrew forum member "mr845".

They are almost pristine and of course sounds delightful. Only problem is that the
2231A and 2121 need to be refoamed.

I called my local speaker shop "A Brown soun" and beeing way behind schedule
told me that I will have to wait at least three weeks before anything can be done.
I'm really impatient guy so I'm considering doing it myself using Orange County Speakers refoam kit.
I've never done this before but I read a lot about it on this forum and I'm a pretty handy guy.
Do you guys think it's doable or is it too tricky to the point of messing the drivers?
Any coments are welcome.
Thanks.

Robh3606
05-17-2004, 09:15 PM
Bo wrote a good thread about refoaming. I like Rick Cob in Tampa for surround kits. Goes by Looneytunes on E-Bay. Every kit I have ever used by him has been dead on. They are really not that hard to do but the 10's look like they are harder than a 12 or 15. I would do the 15 first.

mailto:rcobb@tampabay.rr.com


http://audioheritage.csdco.com/vbulletin/showthread.php?s=&threadid=469&highlight=NEW+SURROUNDS

Good Luck

Rob:)

Infredible
05-17-2004, 09:22 PM
Thanks Rob,

I did came across this nice posting and that's what encouraged me to do it myself
I ordered the foam already from Orange County. I'll check with Looneytunes and compair.

Fred.

Paul Joppa
05-17-2004, 09:48 PM
A friend re-foamed an LE8T recently - admittedly, a real challenge. There seems to be only one after-market surround that's the right size; it's available from several vendors. These are respected national speaker vendors, and they sell it as a replacement for that specific driver. My friend's dexterity is better than mine, but he said it was a pretty easy task.

However, even after plenty of break in, the resonance was over 80Hz (spec is around 45Hz)! The foam was probably ten times stiffer than the original. He had to tear it out, get a softer surround locally, and cut it down to the right diameter. Looks strange with the join line (and it's bright red!), but the resonance is now back to 45-50Hz where it belongs, and he has another octave of bass. A fairly frustrating experience, overall.

It's not always easy to get the right part but the wrong part can be a disaster. And don't believe any stories about "this was made by the company that supplies them to JBL, so it must be identical". It probably isn't!

Infredible
05-17-2004, 10:06 PM
Thanks for the advises.

Today I came across a web page describing a refoam with photos and the guy tells you to remove the dust cap in order to center the voice coil with some cut business card pieces.
The question is when looking at Bo's threat there's no mention about centering the coil but to run a 20-30 Hz sine test tone while glue is slowly drying.
Should I be concerned about centering. To me looks like the spider is pretty stiff enough to maintain the coil in the right place.
Fred.

Ken Pachkowsky
05-17-2004, 11:58 PM
Originally posted by Infredible
Thanks for the advises.

Today I came across a web page describing a refoam with photos and the guy tells you to remove the dust cap in order to center the voice coil with some cut business card pieces.
The question is when looking at Bo's threat there's no mention about centering the coil but to run a 20-30 Hz sine test tone while glue is slowly drying.
Should I be concerned about centering. To me looks like the spider is pretty stiff enough to maintain the coil in the right place.
Fred.

The short answer is YES. The reason to run the 30hz sine wave is to help center the coil while the glue is still wet. Cleaning off the old glue completely is important. Patience is the key.

Good Luck

PS: Our bud in Tampa is the best.

Guido
05-18-2004, 03:37 AM
I also use surround kits from Rick Cobb.

Regarding the resonance frequency I had a problem with LE10 surrounds. Couldn't get the Fs lower than 50 Hz on a pair of LE10A. I thought the foam was too stiff.

Rick ensured me that he uses the surrounds that are used with the original recone kit for LE10. So I ordered again.

I hope that I'll be closer to spec with the LE10H I'll do shortly.

delshadowrio
05-18-2004, 10:28 AM
I recently refoamed four 4412's without a glitch. I used a tone through the speakers without removing the dustcaps. They perform beautiful.

The help in this forum took the fear out of DIY. It was alot easier than I expected. As mentioned above, get all of the old glue off and be patient. Its worth every minute spent.

Enjoy

MM

boputnam
05-18-2004, 10:31 AM
Originally posted by delshadowrio
I recently refoamed four 4412's without a glitch. I used a tone through the speakers without removing the dustcaps. They perform beautiful. :thmbsup:

Infredible
05-18-2004, 11:31 AM
So after all the advises I ordered the foam from Rick and I'm going to do it mylsef.
I will be patient and I hope I'm going to be rewarded with a nice speaker to listen to for years.
I will let you know how it goes.
Thanks,

Fred.

4313B
05-18-2004, 11:43 AM
Originally posted by Infredible
Hi all,

Over the weekend I became a proud 4343 owner.
Well that's certainly something fun to do over the weekend! :p

Congrats! :cheers:

Infredible
05-18-2004, 12:36 PM
Thanks Giskard.
I wanted those since I was 12 when I first eard
them. Now 28 years after I finaly have them :D
And the best is that my girlfriend love them too :cool: She says that the JBL blue matches that of our loft :dancin:

Fred.

Regis
05-18-2004, 01:28 PM
I've done about a half dozen of these successfully, except for the last one, an Altec 12" woofer from the Nine II's. These are the ones with the humongous 13.5 inch frames and the very wide foam surrounds. I did the first one awhile back with the 30hz test tone and got the surround right and it's sounded good ever since. The second one, I laid the speaker cabinet on it's back like I've done before, ran the test tone and centered the cone until there was no noise. Retried four times while the glue tried. Perfectly quiet.

Later on that evening (ten hours later) I demo'd them and the latest repaired woofer had total voice coil rub going on. I suspect the large Altec surrounds sag somewhat from gravity and allow the voice coil to touch. Should I have did the final alignment with the speaker in a vertical position? Or just like the others in the horizontal? Going to end up redoing them again and I just want to make sure. Any advice is greatly appreciated!

Regis

boputnam
05-18-2004, 01:42 PM
Hey, Regis...

I'll take a stab at this: If I understand your post, I've personally never done a transducer mounted in the baffle - I always do them separately, on the bench. That way, you're not asking the cone to move any air, per se, during the centering - you're only asking the voicecoil to move (relatively slowly) in the gap to stay centered. With the woofer mounted in the baffle, you're asking it to do some work, while trying to get it to center. Maybe that conflicted with your effort...? I don't know.

I've done a few of those same Altec 12's you're referring to (but did them loose, on the bench...), and they did not suffer the plight you describe.

Regis
05-18-2004, 02:52 PM
I'll try them out of the box. The only reason I did it that way, was because the wires were there for the crossover, but a few alligator clips and extra wire will fix that, or run it directly from the speaker wire (?). With the set, I'll have an extra surround in case this one doesn't come out. I'm tempted to tip it up vertical to make sure. Thanks Bo.

boputnam
05-18-2004, 03:11 PM
Hell, in the day before I had a tone generator, I'd just connect my shop stereo amp leads right to the transducer, keeping the gain quite low. That way, you can still use the speaker cabinets for a candle wax catcher and drink coaster... :spin:

Robh3606
05-18-2004, 03:23 PM
"That way, you can still use the speaker cabinets for a candle wax catcher and drink"

My favorite was always the plant stand and " stick your finger in the cones" for the kiddies :eek: Right up there with pin the tail on the donkey!

Rob :D

Regis
05-18-2004, 03:45 PM
The grills make great cat scratching posts and the dogs are very happy as well, with a lift of the leg!

delshadowrio
05-19-2004, 07:30 AM
Have you ever played darts wit a midget?:eek:

MM

ngccglp
05-19-2004, 03:41 PM
Later on that evening (ten hours later) I demo'd them and the latest repaired woofer had total voice coil rub going on.

Hi, can you actually hear that? Is there a way to test whether the voice coil is centred properly? I have a feeling one of my 2231H was not refoamed properly which caused the bass to be somewhat weaker than the other side. I have checked the cabinet they don't seem to be the problem. I also noticed the foam is not exactly concentric with the frame. But this could be due to manufacturing tolerances of the foam.

Thanks
David

boputnam
05-19-2004, 06:48 PM
Originally posted by ngccglp
...can you actually hear that? :yes: Best way, is to remove the transducer, bench it, and sweep test it. Lower Hz will reveal if there's rubbin' going on. Too, over at Widget's one day, we could carefully press-in the cone and feel a rub, but this is not guaranteed that you're not pushing unevenly. Best is a bench test, in a quiet shop.

ngccglp
05-19-2004, 08:28 PM
Thanks Bo.

Regis
05-20-2004, 10:26 AM
You can hear a voice coil rubbing. It sounds like a hollow grating noise that is different than the musical program you're playing. As you turn up the volume, it usually worsens and becomes a harsh buzz. That's my experience with it, others may have had different experiences with it. If it's very minor, you may have to hold your ear close to the woofer at a reasonable volume level and compare one speaker to another.

GordonW
05-20-2004, 09:24 PM
This is a little bit of a humorous-sounding solution, but believe me, it's worked...

Try taking the problem woofer out, rotating it 180 degrees (where the current top would be the bottom and vice versa) and bolting it back in. Let gravity work "with" you rather than "against" you, in essence.

It may actually take a little experimentation (rotating the woofer around and trying bolting it in in different positions radially), but I'll bet you can get it to work, without noises...

Regards,
Gordon.

ngccglp
05-21-2004, 03:39 AM
It may actually take a little experimentation (rotating the woofer around and trying bolting it in in different positions radially), but I'll bet you can get it to work, without noises...

Interesting...Is there a certain preferred orientation of the woofer i.e. taking the two leads on the edge of the dust cap as reference, should they be up, down or side?

David

GordonW
05-21-2004, 06:03 PM
There's no "preferred" orientation, other than which ever way happens to make the voice coil NOT rub! :D

Really, it's kind of a kludge... but it may make the speaker usable. I've seen it work before...

Regards,
Gordon.

Infredible
05-24-2004, 11:19 AM
Hi gang,

Ok I bite the bullet over the weekend and did my refoaming. It took me about 8 hours over the course of several days.
The result is beautiful and the sound is just astonishing. The low end is there now thanks to Rick's perfect foam and instructions.
Thank you all for encouraging me on doing it, it's not difficult and patience is the key.

Fred.

Infredible
05-24-2004, 11:20 AM
Here's a picture.

Robh3606
05-24-2004, 04:05 PM
Very nice work!!

Rob:)

honist_bob
05-24-2004, 05:23 PM
Where can I get a 30 Hz test CD?

boputnam
05-24-2004, 06:35 PM
:dancin:

Very, very clean - nice. Now, you can amaze your friends and neighbors with just how much quality time you can spend in the garage/shop. Good tunes, some MEK, what else matters?? ;)

And, to "honest_bob", Search for "test tones" "test CD" "BassZone" and maybe "Rick Cobb" and it's all out here in this database we call the LHF... Rick Cobb might sort you out if he has any laying about. Cool cat... :yes:

Infredible
05-25-2004, 11:23 AM
Hey honest_bob, you can PM me your address so I can send you a copy of the 30Hz cd. Since you don't leave to far from me It should arrive fast.

Fred.

boputnam
05-25-2004, 05:37 PM
Another thought: if really in a hurry, I could email a wave file, if your able to take large files. Then you could copy/paste adding to it to extend it's length.

Let us know...

honist_bob
05-25-2004, 08:41 PM
Thanks, Bo. I found a nice tone generator through the search words you listed.
And hey, my polk audio computer monitor speakers don't go down to 30hz like a 15" JBL woofer!
Thanks, RDM