2ax-attaching surrounds to aluminum woofers

[wilson]

Hi, I just picked up a pair of early 2ax's with the aluminum alnico woofers. On both woofers the surrounds have become detached from the aluminum baskets - one partially and one entirely. What is the best way to reattach? I have some of the white glue used to glue foam surrounds to steel baskets, should I use that or something else?

Also - as the surround is attached to the cone I'm hoping that I can let them center themselves and glue the outside edge

without shimming the voice coils - Yes?

Thanks.

[RoyC]

Hi, I just picked up a pair of early 2ax's with the aluminum alnico woofers. On both woofers the surrounds have become detached from the aluminum baskets - one partially and one entirely. What is the best way to reattach? I have some of the white glue used to glue foam surrounds to steel baskets, should I use that or something else?

Also - as the surround is attached to the cone I'm hoping that I can let them center themselves and glue the outside edge

without shimming the voice coils - Yes?

Thanks.

Aluminum can be tricky, but I have had success with Goop adhesive (any variety. ie "Household", "Shoe Goo", etc), as well as a strong white glue (Weldbond) without shimming. Be careful, however, as these woofers also have a tendency to separate at the spider, which is a more complicated issue.

You may want to wait for a resident driver repair expert, like Carl (Carlspeak), to chime in here.

Roy

[wilson]

Thanks - The spiders are still firmly attached but it seems like I would want to put a bead of something around the fiberboard ring to make sure that they stay that way?

[RoyC]

Thanks - The spiders are still firmly attached but it seems like I would want to put a bead of something around the fiberboard ring to make sure that they stay that way?

I was mainly referring to the more difficult to access inner glue joint, at the spider/cone/voice coil junction. If it looks good, I wouldn't worry about it.

Roy

[speaker dave]

Also - as the surround is attached to the cone I'm hoping that I can let them center themselves and glue the outside edge

without shimming the voice coils - Yes?

I've refoamed without shimming a number of times. It is appealing to try as you won't damage a dust cap or change the appearance. The first question is wether the spider stiffness seems sufficient to hold the cone pretty straight. Also, if there are any glue marks that give a solid indication of where the surround had been, then you chance of success is high. If either of these are the case then you can probably get away with it.

I was doing Bose 901s and found the best thing was to inject a low frequency tone to force a decent excursion (say 1/4"). First I could glue the surround to the cone and let it dry. (Getting to where you are now, surround attached to cone). I would apply the bead of glue to the back of the surround, then with the tone playing, shift the surround a little left then a little right, a little up then a little down. The idea is to note the two extremes where the LF tone causes it to rub and then pick a point half way in between.

Easier to do than to describe, but it worked very well.

David

[Carlspeak]

For the one woofer that's partially attached, simply lift the loose part and apply the glue underneath. I use an MEK solvent based brown glue that will glue almost any two surfaces together. It can be obtained from Orange County speaker repair.

The woofer with the completely separated surround is a bit more of a challenge but you do have the centering help from the spider which, I understand in your case is well attached to the frame and cone. Some folks use a test tone as Dave described and some use a battery with the pos terminal connected to the pos terminal on the woofer. This will raise the cone up. 1.5 V battery will work fine. Don't go too high on voltage or you could damage the spider/cone glue joint. I use a variable voltage DC power supply so I can dial in the voltage needed to lift the cone enough to get the glue under the surround. Once all the glue is applied, I turn off the DC power supply and let the cone fall by gravity and the surround should land against the frame centered with the help from the spider. Do this on a level surface. As a repair professional, I have a set of thick plastic clamping rings sized for different size woofers. I place this on the surround and clamp it with 4-6 pinch clamps. Or, you could use a bunch of clothespins.

[wilson]

Thanks for all your help. Is there nothing I should do to reinforce the spider to aluminum bond while I have these out?

The spiders are firmly attached now, but it appears to be the same type of bond that has let go on the surrounds.

I'd hate to get these fully restored only to have the spiders separate from the baskets.

Thanks again.

[Carlspeak]

Thanks for all your help. Is there nothing I should do to reinforce the spider to aluminum bond while I have these out?

The spiders are firmly attached now, but it appears to be the same type of bond that has let go on the surrounds.

I'd hate to get these fully restored only to have the spiders separate from the baskets.

Thanks again.

The spider is made of a thermoset resin treated cloth and thus has different adhesion characteristics than foam. However, if you want an insurance policy on the spider to frame glue joint, you could drip some superglue around the outer portion of the spider that's now glued to the frame and then run your finger around it pressing the super glue into the spider. This gets a bit messy, but the glue goes away from your finger in a day or two.

[wilson]

Both the spider and the cloth surround are adhered to fiberboard rings and it's the rings that are adhered to the aluminum frame. It's the fiberboard to aluminum bond that I'm worried about (the cloth surround is still firmly adhered to the fiberboard). I will run a bead of glue around the spiders ring where it is bonded to the aluminum for insurance.

Thanks for all the help!

[Carlspeak]

I've had to re glue a few of those loose fiberboards myself. I use the same MEK brown glue.