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Dust cap repair, SWR Workingmans 15 cab

NighthawkGS

NighthawkGS

Jan 26, 2019
84
12
Bezerkeley, CA
#1
Hi folks... Think I read most of the threads regarding speaker dust caps, but no exact match, so here's my question, thanks!

Picked up a SWR workingman's 15 inch cab last week. Love it with my genzler mg800. (Never expected to love something from SWR! Just not my style.)

After one loud gig, with a Baer ml112 stacked on top of it, and one quiet rock band rehearsal, started making bad sounds with substantial volume and/or bass boost. (Cab only rated for 200 watts, but we play quietly, and I EQ the bass down pretty severely.)

Took a look, the dust cap was half unglued. Sound seem to be coming from there, sounded and felt like escaping air. No bad sounds coming from the cab port, like I get with my little 10in Basslite when it's farting.

Tried to glue it back, using rubber cement. Now, the problem is worse!

Does that make sense? That the sound would be worse, even though it looks like it's glued down now?

I'm ready to go buy some super glue gel, as recommended by BFM in numerous posts, and just lay a bead all the way around. Does that sound smart?

I have a few other 15 in drivers I could throw in, but I really like the stock sound, and the cab only weighs about 45 lb, would be 10+ pounds more with a stouter speaker (CB158) or a vintage speaker (EV15L; K130).

Thanks for any suggestions, and for reading this long post!
 
#3
Thanks for quick reply! Pic attached. Definitely does seem to be loose where I tried to glue, so that's a welcome development.

I'm okay with ordering some specialized glue. There seem to be a lot of opinions on the glue to use, but of course, speaker repair glue seems like an excellent choice. ;)

What it seems I really need is a glue that will soaked in beneath the detached pleat, but also sit on top of the still glued pleat and prevent that from coming loose.

Laying a big old bead around the perimeter of the dust cap sure would be a quick and easy solution... if that seems like a good idea?
 

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#5
Don't let that glue run down under the dust cap into the gap or you will have a paperweight.

A speaker repair guy will have the materials and experience to do this quickly and inexpensively.

Hopefully the glue you tried didn't leave a residue that prevents a future repair.
 
#8
Glue was from a tire to repair kit... In retrospect, a poor choice. ;(

Have a lot of glues around. Some folks have recommended E6000, kind of like Shoe Goo. BFM sure was keen on super glue gel, some others too, but at this point, will order some speaker repair glue... unless someone else pipes in.

Please holler if folks think I should pull the dust cap off entirely then reglue, thanks!
 
#9
Parts Express glue ordered... if anyone has any suggestions, would love to hear... Otherwise, guess I will study under the masters at YouTube. :-)

Since half the dust cap is still glued on, reckon I will start by dabbing a little glue on the still glued part, and presumably it will soak through the paper dust cap and cone to do its job of keeping the cap from coming off later... and I may also try tacking down the part that I tried to use rubber cement on, if that works, then seems pretty straightforward. Use enough glue to hold the cap on, without letting excess glue get under the cap to turn the speaker into a 15 in 10 lb paper weight. :-(
 
#10
A lot of times, in a recone, fitment of the dust cap consists of holding it in place and running a bead of glue around the perimeter where the cap meets the cone. While getting glue under the cap (if it has a flat mating surface) may well be better, it also lends itself to having glue run down into the coil, which can't happen if you apply the bead with the cap pressed in place.
 
#11
Thanks! Sounds like the glue will hopefully penetrate the pleated part of the cap, that constitutes the mating surface between cap and cone... and with luck, the part that I already applied rubber cement to will still adhere. Haven't come up with a safe sounding way to remove the rubber cement yet...
 
#12
With dust caps that have a flanged edge, the glue is (and must be) applied to the surface under the flange. For cut edge dust caps, the glue is applied in a controlled bead around the outer edge as it's held against (gently) the cone.

One performance aspect that the dust cap helps with (on some drivers) is keeping the cone neck more stable and concentric farther from the cone neck, which helps with keeping the neck and top of the bobbin concentric. This is more important with thinner, more compliant cones.
 
#14
I know folks are just dying to hear how this turned out, so, here's the latest. :)

I think the second glue job went fine. Too much glue? Anyway, it's a red herring I think. I do generally prefer to screw things up myself, but, turns out an old old-school speaker guy was less than a mile away!

He pressed the cone down probably half an inch, and quickly said the speaker was roached. He also called attention to a rubbing sound. Needs a recone... Talked him down to $79... Says parts findable. I am hoping it will sound as good as before, maybe with bit more power handling.

I think I blew the speaker by paralleling it with a Baer ML-112 at the outdoor gig. Baer has twice the power handling, and the original speaker with tiny magnet couldn't possibly have taken the 200 watts as claimed. Also seems like lightweight speakers suck the power more.

Not sure how useful a 15 cab that delivers warm fat lows but handles less than 150 watts, will be in the real world. But, maybe! Only 45 lbs, and not a sterile Neo. My bands are relatively quiet, and I've gone many years running less than 150 watts. Might work with my Berg cn112.

Did try all three of my 15s in that cab. Didn't like the CB158, which would have been good as extension cab. K130, too bright. EV 15L, actually pretty good, but at 4 Ohms and very high sensitivity, it would be on a suicide mission underneath a Genzler MG800. :)

Would modeling the cab help me reliably select a replacement driver?
 

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#17
If you gently move the cone and hear a scratching sound, it's toast. I re-glued a dust cap to a friends 4x10. It was making a horrible sound and he brought it in. I gently lifted the dust cap by running a toothpick around the edge, cleaned up the flange and ran a very thin bead of glue around it and placed it on the speaker.
Once the glue dried (I left the speaker on it's back) it sounded just fine.
 
#18
Samatza said:
If you gently move the cone and hear a scratching sound, it's toast.
Click to expand...

Thanks... No scratching sound, but a rubbing sound. And the cone really moved quite a ways, with no resistance, which is unlike any of my other drivers that I tried.

Really liked the sound of this cab, hope that continues with a working and reconed speaker. Possible that I'm just a 15-inch guy... Or a non Neo guy... The two boutique 12 inch cabs I have are not blowing me away yet, insufficient volume (loudness) perhaps. Maybe a Neo 15 in...
 

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