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Nightmare refoam

Update 03/09/06

The new surrounds are here (ordered by mail from wooferrepair.com), and I will begin the removal process this weekend. I didn't see any point in handling the speaker until I had the goods to finish the job. I'll post pics and keep you UTD on progress!

One thing I'm interested to see, MarkAnderson and Fotno tell me the speaker has a cloth "shell" over the frame to keep the speaker stuffing off the cone. I'm curious about how hard it will be to duplicate the weight/weave of the fabric when I re-assemble the speaker?
 
Round 1

I decided to start with the rotted surround (Call me a wuss!) instead of the packing foam version. Once I got the grille off, I could see what MarkAnderson was talking about: there is a fine mesh screen glued to the outside of the basket, presumably to keep the speaker stuffing from interfering with the cone.
 

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The Tweeter

As I removed the wooger, I noticed a chunk of black plastic floating around in the cabinet, and discovered the tweeter frame is busted! Oh well, one more repair while we're at it, eh? (Someone has also been playing "oooh, what's that?" with the dome)
 

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Cleaning up the old

The surround basically fell off it was so rotted. The glue that was left behind is somewhere between elmer's and that "snot" they use to stick inserts in magazines. It had a stiff layer of surround embedded in it and required some scraping, but it peeled up in long strips and was quite easy to clean off the basket. The type of Xacto I used was much easier to handle on the basket than the small-handled wedge blade style.
 

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Ready for Foam!

The surround residue rubbed right off the cone (the cone is more durable than I expected) but the glue-y stuff was stubborn. I ended up leaving some of it on the cone. I tried a LITTLE alcohol, and the cone does NOT like to be wet! Dry it felt tough, damp it felt like it was gonna fall apart in my hand. The new surround is drying on the cone, when I finish this post it should be set enough to start glueing to the basket. Here's the clean speaker, with the dust cap cut out.
 

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Round 2

Gonna give the glue a few more minutes, so I thought I'd go ahead and post the "refoamed" tear-down. The packing foam lifted right off, with very little pressure. The glue used is hard and kind of "crystalline". It looks like doughnut glaze. It is a b!tch to get off the basket, and there is a TON of it on the cone. This will take hours of careful scraping to clean up.
 

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Holy Cow, I revise my estimate!

After the last 20 minutes of scraping, I have to say this will take DAYS unless I find something to cut the glue, even though I don't want to wet the cone. Alcohol is a no go so far, I'll try AndyMan's suggestion tomorrow, if they have the stuff at Lowe's. Oddly enough, they aren't open at 2:40 a.m.

Those Slackers!
 
The Next Morning...

Fired up the one completed speaker, and the midrange is not working. I'm gonna assume the L-pad is shot, and I had planned on doing the L-pad and recap anyway. Just couldn't wait to try it out!

The wooger responds well, and the OEM tweeter (even with the crumpled dome) sounds great! Funny, the AR wooger is bringing enough midrange to the party that I did not notice the lack at first glimpse - though in all fairness, the first listen was at VERY low volumes before the WAF were out of bed this morning! At higher volumes it is immediately apparent.

I did not glue the dust cap on yet - the smallest one in the kit is still about twice the diameter of the original, and is made of much stiffer paper. I'm gonna cut it down when I get home, didn't have an appropriate tool at the house last night.

I've also attached a close-up of the "doughnut glaze" glue residue on the other wooger. It's almost like over-kill Super Glue, but the places where it puddled on the basket are too thick for that to be what was used.
 

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VC shims

I have read a lot of opinions on VC shimming on AK, and I have to say I'm glad I decided to cut the dustcap and shim the coil. Held everything solid while I worked, made glueing the surround to the basket dead easy (shims held the cone in a "raised" position while I applied glue) and the cone moves like silk after the repair.

My vote? SHIM!
 
oz - so, the kit you bought came with paper caps? Hmm. I'm just wondering if there'll be any ill effects from replacing the original felt with paper. I've got some felt caps here if you want them. Or you might just find a small sheet of felt somewhere and cut new ones. BTW, it actually looks like you just might know what the heck your doin' :D . - Mark
 
First off, thanks for posting this, I am following along eagerly! I am in the midst of my first re-foam...

ozmoid said:
I have read a lot of opinions on VC shimming on AK, and I have to say I'm glad I decided to cut the dustcap and shim the coil. Held everything solid while I worked, made glueing the surround to the basket dead easy (shims held the cone in a "raised" position while I applied glue) and the cone moves like silk after the repair.

My vote? SHIM!
Click to expand...

I have been agonizing about this, but I don't think I will be removing these "dust-caps" -- they are "way down in the valley", so to speak, and I don't want to cut them. These are 10" woofers from Infinity RSb units, so the poly cone was a blessing as far as glue clean-up, much more rugged than paper cones. I think I will do a shim-less refoam and see how it goes.

--Bob
 

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BobE, that cone looks a lot like a "horn" shape in the pic! That makes feel the same way - timid about cutting it off ("way down in the valley", indeed). One thing I found inside the AR though, is the voice coil is literally a tube around a cylindrical magnet. It did not completely fill the space under the dust cap - I was able to leave a little bit of the original cap attached around the glue seam. The shims stick straight out, parallel to the "thrust" of the speaker. That was not what I had envisioned under there. Still, once it's cut, it's cut! Good luck whichever path you decide to take.
 
Bob E. said:
I think I will do a shim-less refoam and see how it goes.
Click to expand...

Just be aware that the voice coil must be centered by some means, whether by using a test tone, or the "battery trick", or whatever. I've found that once the surround is glued to the cone, it usually tends to help center things up by itself. I'll clamp the surround to the basket in four places equally spaced and check for v/c rub by applying pressure to the center of the dust cap...if that checks out, then apply pressure to the cone adjacent to the cap (you are trying to force the cone slightly off-center) in even increments around the cap. If you get no rub (or equally amounts of rub in some cases) at all points around the cap, I'd call it pretty well centered. With clamps still in place, carefully apply glue between the clamps and let cure, then remove the clamps and work the glue into the remaining ......well, you get the idea, I think. Good luck! - Mark
 
Thanks, Mark. Yes, I see the need for other centering techniques. I have an old HP 200CD signal generator I may use for this.

And Oz, yes, it is a curved trumpet-shape. I used acetone to dissolve the glue off, and it did not seem to touch the plastic, which is good. Don't know how that would work on your job, though. One other advantage of shim centering is that you can get the voice-coil centered fore-and-aft as well as coaxially with the magnet pole. When the speaker is laying on its back, like in the picture, it sort of sags the centering spider slightly towards the back of the basket/magnet assembly. With shims, you would be able to postion the cone so that the centering spider is "flat", which is what I assume we want.

By the way, I have some AR-3a's that I was given, and the woofers look different than yours, they seem to have cloth surrounds (and some sort of "stiffener" glued to the cone). No refoaming these, thank goodness! See pic.

--Bob
 

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ozmoid said:
I have read a lot of opinions on VC shimming on AK, and I have to say I'm glad I decided to cut the dustcap and shim the coil. Held everything solid while I worked, made glueing the surround to the basket dead easy (shims held the cone in a "raised" position while I applied glue) and the cone moves like silk after the repair.

My vote? SHIM!
Click to expand...

My vote? Don't shim! Does that cancel the vote? :D

Should an opinion be offered unless one has actually done both or all possible methods for a proper comparison? Successful refoams have been accomplished by the shim, the shimless (with the test tone and the by Feel and by F..k method (Marks and the one I use myself)). There may be more.

I have not done a shimming job myself, so I am in the same boat as far as offering an informed comparative opinion :sigh:

But, here is my reason;

The fear of messing with the dustcap and changing the original sonic character of a driver is the major consideration. It also seems like more work


If the dustcap is to be sacrificed, I think it should be replaced with as exact a replacement as is possible. Even to the point of weighing them and making sure they match. Porous or non porous is probably important to keep the same as well. Whatever the original design was, it was done for a reason.

Also, this dustcap thing is being discussed in a separate thread.... FYI. http://audiokarma.org/forums/showthread.php?t=62735


YMMV.
 
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Bob E. said:
........By the way, I have some AR-3a's that I was given, ......
--Bob
Click to expand...

WOW....given. That is the ultimate score for sure. These are my search list. Tryed a few auctions today but...not this day.

:thmbsp:
 
Bob E. said:
When the speaker is laying on its back, like in the picture, it sort of sags the centering spider slightly towards the back of the basket/magnet assembly. With shims, you would be able to postion the cone so that the centering spider is "flat", which is what I assume we want.
Click to expand...

This is really a non-issue, as far as re-foaming is concerned. A little shift one way or the other won't hurt anything. Oh, and just for the record, I prefer shimming when it's practical. In your case, it just ain't. - Mark
 
I've never shimmed a woofer. I have always managed to get the job done, but I did have a very hard time with a pair of Ohm C2s. But who would cut those cool dust caps that say "Ohm" on them. Wouldn't be the same.

Ed
 
Kencat said:
WOW....given. That is the ultimate score for sure. These are my search list. Tryed a few auctions today but...not this day.

:thmbsp:
Click to expand...
That's how I got started on AK - I gave a pair of (non-working) 3a's to a friend in need of audio (neither of us knew the first thing about what we had!), and they led him here... and I ended up being gifted a restored pair of 2ax's, in the end. Liked 'em enough to buy another pair to restore myself!

And as far as the 3a's go, if I ever get an amp big enough to REALLY drive them (I am told 250 WPC+ is recomended to really "shake 'em up") I'll look for another pair, or try to work out a trade back (maybe a pick-up truck load of Dynacos would entice him?).

Never regretted letting them go, and lovin' every minute that I'm here.
 
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