Speakerlab cone treatment repair - HELP!

[tgmartin]

Got a pair of Speakerlab DAS2 with rotted foam surrounds and when cleaning up the woofs, the brushed on treatment started to come loose from the plastic cone and just peeled off. Looks and smells like PVA (Elmer's or ModPodge Titebond glue *) translucent, pretty fexible and seems to have added 4 or 5 grams of weight to the cone. It was added after the surround was installed as it was thickly painted over the surround up to where the roll starts. Anybody really know what this is? I'd like to restore it after refoaming.

In reading a little about differences in these PVA glues it looks like there are differences in the amount of glycerine in them making some more flexible than others. I'm curious about how this may affect their ability to adhere to the surface of Polyethylene cones. Any factoids?

I tried asking before but got no response. This is Take Two.

* Turns out Titebond is "Aliphatic Resin" not PVA and is apparently less flexible and more yellow colored when it dries.

 

[klipschorn]

Correct me if I'm wrong. I sounds like you are referring to the coating on the cone. If so, there is a product available at Parts Express, part number 340-513. There are many comments and questions and answers there which may be useful to you. https://www.parts-express.com/Wet-Look-4-oz.-Black-340-513?quantity=1

One thing for certain is that it will affect the high frequency response of the speaker, which may be the very reason it was used by the manufacturer. (see the first comment dated Jan. 27, 2018) It will also lower fs but this is dependant upon how much is used. My SWAG (Scientific Wild Ass Guess) is that the effect on fs would be minimal and very likely unnoticeable to the ear.

This was found on that system. https://www.hifi-classic.net/review/speakerlab-das-2-483.html

In reading your recent posts in your AK profile, you're more than casually familiar with various speaker cone coatings. However, this one of which I made mention wasn't listed, so I thought it might be of interest to you.

There's much info on this system available by using SPEAKERLAB DAS2 in a search engine.

Robert

 

[tgmartin]

Thanks for the reply and suggestions.

The cone on this driver is plastic (supposedly polyethylene) and the treatment is translucent to clear. I'm interested in reproducing this as closely as possible as I have a second unit that I haven't screwed up YET and I'd like to have them functionally match.

At this point I think I'll try either "Aleen's Tacky Glue" or "Mod Podge" PVA types as they appear to have higher glycerine content and flexibility than Elmer's. Like I said initially, the original stuff smells and feels like PVA of some sort.

The PE product is advertised as being for paper and is black tinted. It would appear that one of the challenges I face is that the treatment needs to adhere to this plastic, at least as well as the original (seemingly not perfect as it stripped off!). I'm not really concerned with the color.

Original driver condition:



You can see how the coating or treatment has been applied to about half of the foam's "roll" and the uncoated part has deteriorated.

Driver after cleanup:



Treatment or coating after releasing from cone:



Flexibility and thickness:





Anyhoo, that's the situation. THANKS again for your input!

 

[GordonW]

One thing that might help- I have found, that SOMETIMES, the "primer" that comes with plastic-bonding superglue kits, works with OTHER types of glues as well.

This is what I used:

Amazon.com: Loctite Super Glue Plastics Bonding System with Activator 2-Gram (681925) (2 Pack) … : Industrial & Scientific

Amazon.com: Loctite Super Glue Plastics Bonding System with Activator 2-Gram (681925) (2 Pack) … : Industrial & Scientific

www.amazon.com

I originally got one of these to use with some other superglue I had (the primer seemed to last far beyond after the original superglue in the kit was used up). However, out of desperation- I tried using it with other types of adhesives, and found that some PVA and other glues also seemed to have their bond to polypropylene, augmented by the same primer from this kit. It wasn't universal, but it worked a good portion of the time.

That, plus some of the PVA coating that's used to seal fabric surrounds (such as this: https://www.simplyspeakers.com/spea...b96YfSTkQLl-sRI1bh3x2FQtJIyXliRoksCrRQQ1U_Eth ), and you probably could readily be back in business. I think that's the same white PVA compound that we use at work, and it seemed to do OK with the Loctite plastic primer.

Regards,
Gordon.