Vintage woofer re-foam - remove dust cap or not?

[ymarko]

I have several vintage speakers (Advent/1, Advent Heritage tower, Advent subwoofer, Mirage SM-1, AAL) all of them need new 8" or 10" foam surrounds.

I've never done anything like that, so I read few instructions online. They are confusing, because some instructions say that I have to remove a dust cap (to shim and center the cone), and some instructions say I don not have to remove the dust cap. Personally, I hate to destroy a perfect original cap on a vintage speaker.

I spoke with a local repair guy and he said I must remove a dust cap and shim, otherwise I will not be able to do job correctly.

I called to SimplySpeaker.com and they said no need to remove a dust cap because their "special" adhesive let me do the job correctly without removing a dust cap. But their kits are very expensive for me.

I got foam surrounds from eBay yesterday (didn't receive yet). Seller specialized on these surrounds and has extremely well eBay feedback rating with multiple return customers. He says no need to remove a dust cap. He recommends use either Contact Cement or Elmer's Wood Glue.

So my 2 questions are:
1. Do I have to remove a dust cap to re-foam a woofer or not? Why such a discrepancy here that some say "Yes" while some say "No"?
2. What would be the best adhesive (glue) to use (for a beginner, who does not need to rush things)?

Thank you.

 

[qboneus]

I have done many foams that did not involve pulling the dust cap.
In those circumstances I use a partially discharged AAA battery with leads tacked to the +/- of said AAA, the leads are terminated in alligator clips.
to keep the VC centered and assist with your refoam simply attach the leads from the AAA to the speakers +/- terminals.
One polarity will push the woofer out, the other draw it in; helping to press the foam to the cone or, alternatively foam to the basket meanwhile keeping the voice coil centered.
I have used aileens tacky craft glue with good results in the past, even some elmers that have never failed and give good pot times.
Tal

 

[terra1]

To shim or not to shim depends on how comfortable you feel and the condition of the driver.
Does it easily move smoothly and quietly as you test it for rub by moving the cone in and out?

It's obvious there have been success and failures using either method.

Shimming is thought of to be the most dependable.

I prefer not to shim for the reasons you stated.
http://www.audiokarma.org/forums/showpost.php?p=1735492&postcount=22

Aileene's or the white glue that often comes in kits dry slower than the clear glues. So it can afford you some leeway as far as making adjustments before it sets completely.

 

[krimney]

shimming..

shim only if you have to. I've done dozens without shimming.

first, clean all the old surround off the cone and basket.

then glue the new surround to the cone and let it dry, depending on the glue this may take several hours or overnight.

then use large paper clamps to secure the surround to the basket, once these are on you can move the cone ina and out and see if it rubs, you could even hook it up and play some low music through it. Adjsut the surround and clamps accordingly, then remove the clamps one at a time and glue the surround to the basket, replace clamp and repeat until all clamps have been done and entire surround has been glued.

enjoy the music...

 

[Blast]

I've refoamed 4.5" to 10" woofers. The larger the easier. None needed shims. You'll put the foam in the cone first- that's the easy part. Then, when gluing the foam to the frame, put pressure down equally and evenly around the frame. You shouldn't have any trouble.

My problem is getting glue all over the place- the smaller the speaker the harder it is to keep the glue off. 10" woofers clean as a whistle!
Brian

 

[BrocLuno]

Don't remove unless there is an overarching reason. As long as the spider is good and there are no VC rubs, just do it slowly and carefully Aileens Tacky Glue all the way - even for poly-cones. Tried the others, no dice - just Aileens for me now

 

[tarior]

Yes, shim them. Always. It is the only way to be certain that the voice coil is perfectly parallel to the pole piece and magnet gap. A test tone or battery will not do this. The better kits will include the proper dustcaps, and if you do a clean job, it will be hard to tell if it was ever off.
I've been doing speaker repair for a sideline biz for 11 years, and I've fixed alot of "shimless" foam jobs that sounded OK, until you turned up the volume a little and the skewed voice coil made mechanical contact with something it shouldn't have.

 

[lukiedog]

No shims. Don't use contact cement either. Use Aileen's Craft Glue available in many places (incl Walmart) for a few bucks.

 

[BmWr75]

I've refoamed a number of woofers and have always used a AA battery to center the voice coil. Get yourself two pieces of wire. Strip off 1/4" of wire from both ends. Rubber band the wires, one to each end of the battery. I use alligator clip jumpers to connect the the wires and then the + and - terminals of the speaker. Any other connection method should work fine too. This will pull the woofer in or push it out depending on how you connect the leads to the woofer. Regardless, I think it centers the voice coil perfectly. Use the woofer movement to help you glue the surround to the frame.

 

[Big Tuna]

1. NEVER use contact cement
2. NEVER use wood glue
Those dry too hard and are VERY messy. The adhesive must remain slightly pliable when fully dried to allow for flexing of the surrounds where they contact the frame and cone. I have been doing speaker repair for many years now and I have the ability to "feel" for the center of VC without the means of batteries or shims. I was taught by a gentleman who was in the electronics and audio speaker repair business for over 50 years. He worked with Ronald Reagan at WHO radio In Des Moines back in the days when Ronnie was there. Sadly he is no longer with us, but his skills live in me and I am very grateful to him. I have passed my skills on to a few lucky AKers who were patient enough to put up with me, heheh!

 

[Big Tuna]

My answers to your 2 questions are:
1. You don't HAVE to. Some dust caps cannot be removed without irrepairable damage to the cone or the cap itself. If you are a fan of originality, then don't remove them and start training your hands to "feel" for the VC center with a junker woofer that you don't care if it gets damaged or not.
and 2. aileens white glue or the white glue I get for my surround jobs from www.speakerrepair.com
you can PM me if you would like any help or advice. I will do my best to help you do the best that you can.

Charlie:nutz: