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LE15-Thumper
04-13-2005, 02:26 PM
Ok, I have seen all the posts (Most) on refoaming and using the 30hz tone method without cutting dustcaps.
One question that is driving me nuts, and keeping me from trying this method. If you are a applying a 30Hz test tone to the driver WHILE the glue is drying. What keeps the foam from lifting off the edge of the basket ? Wouldn't the up/down motion of the cone lift the foam off the basket if the glue is not yet dry ?
What am I missing ??

4313B
04-13-2005, 02:32 PM
You aren't supposed to drive it hard enough to cause the foam to separate from the basket flange. Get a driver, apply some 30 Hz tone to it and note the movement of the surround.

What am I missing ??

Your missing the experience of just doing it. :p All will become clear.

Robh3606
04-13-2005, 02:43 PM
The glue gets very tacky and if you look there is not that much movement where it actually is glued. You are not running them at X-Max like Giskard says when you do it, it will become clear. I have used this method several times and it has worked very well.

Rob:)

LE15-Thumper
04-13-2005, 02:59 PM
What causes the self centering action ?

BTW...A-La David Carradine, "I am very greatful, you have taught a young grasshopper well."

LE15-Thumper
04-13-2005, 03:02 PM
Ok, I got some scrap NON-JBL drivers to try out first.

Robh3606
04-13-2005, 06:24 PM
The flux from the coil and magnet center the coil. What you have to watch is you don't tilt the cone on a long throw driver. Thats why you are running the 30Hz. Not to X-Max but a healthy excursions once it starts to really tack well.

Rob:)

boputnam
04-14-2005, 08:17 AM
The flux from the coil and magnet center the coil. :yes:

The coil oscilating in the magnetic field is "self-centering", so long as it is not obstructed / prevented from doing so.

Use a voltage drive of 1 to 3 v (max) - I stick my ear into the cone as I approach the 3v drive to listen very carefully for any "rubbing" or mechanical sounds. If present, while the glue is soft you can gently reposition the cone - but it's like moving your dog, you push on the opposite direction you want it to move... :rotfl:

Let the glue set at a gentle 1 to 1.5v drive and check every 30-minutes. :applaud:

4313B
04-14-2005, 08:26 AM
And if you use JBL recone glue instead of the supplied glue it will set much faster. I used the supplied glue to attach the foam to the cone because it dries nice and clear and the JBL recone glue to attach the foam to the basket. Still allow the full 24 hours drying time before a power test.

BTW - I like Rick's 12" kit for 2214H's but not 128H's. I think someone else posted the same thing somewhere.

boputnam
04-14-2005, 08:48 AM
BTW - I like Rick's 12" kit for 2214H's but not 128H's. I think someone else posted the same thing somewhere. Cool. Was it a fit, or pliant issue?

And, I agree on the glue. The slow setting stuff has saved a lot newbies from "do-overs". And, that it drys clear (and shrinks a bit) makes the handiwork look great... :)

4313B
04-14-2005, 08:51 AM
It was a fit issue. I did the 128H right after the 2214H and it ended in disaster. The foam fit perfectly on the 2214H and it came out great. A bit of care was required for the 128H I suppose and I evidently had none to spare at the moment. :rotfl:

Robh3606
04-14-2005, 09:31 AM
Yeah I did 128h-1 and 2214's and the compliances were different diameters. Even with the correct kit for the smaller diameter 128 you had to watch the centering to the cone very carefully. The compliance roll edge didn't go up flush to the cone like the 2214.

Rob:)

boputnam
04-14-2005, 09:38 AM
It was a fit issue. I did the 128H ... and it ended in disaster. Good to know!! :dancin:

All this time I thought it was my limited ability or lack of experience...
:homer:

4313B
04-14-2005, 09:47 AM
Good to know!! :dancin:

All this time I thought it was my lack of experience...
:homer:It was Bo. :p Experience matters. I've not done very many refoams at all.
I've done countless recones.
Oh, and I've screwed a few of them up too. ;)

Even with the correct kit for the smaller diameter 128 you had to watch the centering to the cone very carefully. The compliance roll edge didn't go up flush to the cone like the 2214.Right. And I simply didn't give it the attention it deserved. It was a trial anyway so I'm not broken up about it at all. The surround was an extra.

Bill Ding
04-21-2005, 08:06 PM
:yes:

The coil oscilating in the magnetic field is "self-centering", so long as it is not obstructed / prevented from doing so.

Use a voltage drive of 1 to 3 v (max) - I stick my ear into the cone as I approach the 3v drive to listen very carefully for any "rubbing" or mechanical sounds. If present, while the glue is soft you can gently reposition the cone - but it's like moving your dog, you push on the opposite direction you want it to move... :rotfl:

Let the glue set at a gentle 1 to 1.5v drive and check every 30-minutes. :applaud:

I need to refoam a pair of JBL L-50 I recently purchased. Could you explain the source of the 30hz tone? When you refer to the 3v is that from a power supply and if so ac or dc?

Thanks

Bill

Robh3606
04-21-2005, 08:20 PM
Depending on who you get your kit from some will supply a cd with a 30Hz tone. Just drop it in the cd player on repeat and your done. It's simple enough to make your own if you have software. Any kind of signal generator, even a computer sound card will work just fine.

Rob:)

hector.murray
04-23-2005, 07:32 PM
WinIsd has a tone & sweep generator built into it. It works sufficiently so long as you pump it through an amp. Works for me anyway.

Bill Ding
04-23-2005, 07:54 PM
It would be easier for me to use a cd with the 30hz tone than a computer program (I'm running windows 98 1st!!! and lucky to even get on the internet).

I see Partsexpress and WooferRepair among others have refoam kits for my JBL L-50's but all I have seen offer only the plastic shims that require the removal of the dust cap.

Does anyone have a source for the 30hz cd, either alone or with a refoam kit?

Thanks
Bill Ding

mech986
04-24-2005, 01:17 AM
Hi All,

I use an old Heathkit signal generator played right into the driver since I don't need to drive it to high amplitudes.

In terms of not dislodging the surround/cone/basket glue joints, here's a method that I picked up from AA.

After all the cleanup of cone and basket, Apply modest amount of glue to the cone surface and inner edge of the surround on the appropriate surface. Let get tacky and then contact fit. At this point you are just getting everything approximated for fit and cosmetic appearance (perfectly circular).

Then using medium size paper binder clips (black with those T-shaped flip handles) temporarily clip down the outer circumference of the surround to the basket frame without glue. You are looking to get your first pass at temporary alignment. usually 6 to 8 clips will do fine for most baskets, depending on diameter. Do some gentle cone pushing to see if you have any rubbing- consider doing with the driver oriented in a number of positions to see if the spider is weak or vulnerable to sagging. Once you go over it a few times and reset your clips, then try the 30-40hz tone and listen for any distortion or rubbing. You might try a few more iterations of clip adjustment (one side or all around) to check your alignment.

When you are satisfied (and that may require a bit more power like from your generator driven amp now) that significant cone excursion is still clean and clear, then take off 2 or 3 clamps, lift outer edge of surround, glue to basket and then replace clips. I then do a quick recheck with the tone to be sure nothing has altered, shouldn't since 2/3 of cone was still clipped. Going all the way around requires 2 more iterations, and at the end you have checked alignment at least 3 times with glue. I usually then allow 1 full hour of drying time so the surround is fairly well set, and then apply/glue in the carboard or stiff foam outer edge basket filler strips, the 1/4 or 1/3 circumference jobs, and reclip. Then a full 24 hours drying time, trying to resist the temptation of running more tone testing - its really a kick to watch a cone working as you have resurrecting it.

Then it's all clips off, another test while out of the box, then it gets installed, don't forget a new gasket. Once the rest of the box is sealed, then its test tone and music time. If everything is working, then music to break-in-the-surround-by time!!

All this because I don't want to cut off the dustcap and shim? Well, I don't necessarily trust myself well with small sharp instruments and those cones just never look quite right after repair of a tear or puncture. This method has worked for me on 3 full resurrounds so far with 2 12", and 2 10's and 2 8's.

Hope this helps.

Regards,

Bart

jtgyn
04-24-2005, 05:32 AM
G'Day Bill,
If you want a CD of 30Hz, PM me and I will make you one.
Regards Scott

boputnam
04-24-2005, 03:08 PM
Does anyone have a source for the 30hz cd, either alone or with a refoam kit? Hey, Bill...

Sorry - was travelling and missed your post.

Go to the Resurround Step-by-step Thread - there's plenty of resources listed there. Rick Cobb should have the surround you need, and ask for the 30Hz CD, too! :bouncy:

boputnam
04-24-2005, 05:37 PM
When you refer to the 3v is that from a power supply and if so ac or dc? Hey, Bill...
Missed this, too.

I use a signal generator at modest output, sine wave. AC.

DC would give you only one direction of cone movement: OUT on (+) in the case of "other" brands, IN on (+) in the case of JBL (who of course is correct! :D ).

Bill Ding
04-25-2005, 08:02 PM
When we are aligning a cone during a refoaming what are we concerned with exactly to keep from rubbing? Are we trying to center the cone concentriclly or we trying to center the cone in and out or both?

Thanks

Bill

boputnam
04-26-2005, 07:24 PM
Hey, Bill...

Cool avatar!

The idea is to center the voicecoil in the gap - concentrically - so that as the voicecoil moves though the gap (in or out) it will not touch or scrape either the pole piece or the magnet assembly. You want the voicecoil to float in the gap free of mechanical obstruction.

Where the voicecoil rests - relative to in or out - relates to the suspension (combination of the compliance (surround) and the spider) of the cone.

Bill Ding
04-27-2005, 08:10 PM
Bo
Thanks for the response on centering the cone.

The avatar is a picture of one my Bill Dings I made. These are 4 1/2" wooden stackable toy men from the 40's and 50's. I jigsaw them out for the grandkids. At least 20 men can be stacked on one at the bottom, lots of fun for them.

Bill

boputnam
04-27-2005, 08:45 PM
Dood...


Many here stack much things of much less significance - like L100's... :D

Post a pic of the stacked Bills! Who knows where THAT might lead...