John Sayers' Recording Studio Design Forum Archive

Hi,
This is my first post on this speaker forum. Today I noticed a buzzing sound coming from my monitor during certain parts of the music. On further investigation, the buzzing occurred for all the standard test frequencies between 80 Hz and 400 Hz, and only at SPLs greater than 75 dB @ 1 meter. As I removed the 7" driver to find out the part number, I noticed the rubber surround had separated from the cone partway around the speaker. Assuming that this is the cause of the buzzing, what kind of glue is best for gluing the rubber surround to the molded polypropylene speaker cone, that will stick well but will not cause degradation of the rubber surround over time?

Jorge, I recently refoamed some JBL speakers and have some glue left over. If you e-mail me your address, I will send it to you and you can send me back what I spend on postage.

Bill@doghousedaddies.com

Hi Grits,
Thank you for your kind offer. From what I have read, many refoaming glues may not necessarily stick well to polypropylene. I called Madisound Speaker Components in Middleton, Wisconsin, who do reconing of Dynaudio speakers, and the speaker repair technician was extraordinarily helpful. He told me Dynaudio supplies a special glue with reconing kits. It is Loctite #30540, a neoprene based black adhesive, that is used on all Dynaudio reconing jobs. He confirmed that most other glues won't stick well to polypropylene. Rather than send the speaker back for repair, I ordered the Loctite adhesive and plan to do it myself, understanding the importance of careful workmanship.

Excellent info Jorge!
I'll remember that.

Hi,
Here is an update.
I did the surround repair using the Loctite contact adhesive. The driver sounds identical to the other side, and has held up fine for the past week of moderate use. It is not the most professional looking repair from the back (the front looks fine), the contact adhesive is quite thick and not easy to spread neatly over a precisely limited area. You have to put on one coat on each surface, let it dry, then put on another coat and bond the 2 surfaces. Seems to be working fine, other than the aesthetics of the backside of the speaker cone/surround seam.

If I had it to do over again, I would first mix some solvent into the contact adhesive to make it easier to spread a thin coat more precisely.