Stiffening Speaker Cones with Glue

[nashvillebill]

I've seen many posts about stiffening old speaker cones (like the ones in the 4024a Mach Ones) but superglue (cyanoacrylate, or CA) seems to be the usual implement of destruction.

I've got an old Peavey Black Widow 15" woofer that could stand to be a little tighter in the old paper cone. It's either glue it, or buy a new basket assembly, so I figure I've got nothing to lose by trying the glue approach.

However, superglue at the local Wally World only comes in tiny little tubes. It'd take $50 worth of those itty bitty tubes to do the speaker

How about Aileen's Tacky Glue? Got a whole bottle of it, seems like I could paint it on gently with a paintbrush and not have too much buildup. Anybody used that?

 

[bobaloniny]

Ive seen recently in here somewhere, where it was used watered down to seal very porous cloth surround, and he seemed to have good results with that. I also saw a vid on youtube where the guy used Aileens and coffee filters to basically build about 1/2 of the speaker cone for an 1930s or 40s floorstanding radio with good results as far as he was concerned.
I think the more you stiffen the less low end you end up with, but if its that floppy anyway..and youre willing to gamble..Id go with watered down..try it after a coat, and if you think it needs it..give er another.

 

[speedle]

Add it to the cone, not the surround, and you'll add mass, which will change the fs of the driver if you add too much. Add it to the surround and not the cone, and you'll likely stiffen up the surround, raising the fs.

 

[cubby01]

I'm kinda confused as to what the OP is trying to stiffen? Are you wanting a more rigid cone to better handle breakup? Or is it that the pleated accordion surround has gotten so flexible that you want to raise the fs back closer to original spec. I can't really imagine using super glue for the latter.

 

[TerryO]

I've been modifying drivers for a couple of decades and I've learned that when it comes to cone treatments, some drivers don't need it, other drivers respond to different treatments depending on what you're trying to do and if you overdo it, you can take the life right out of the driver.

Here's some of the better one's that work:
Modge Podge
Golden Harvest (GH-50) Latex wallpaper border adhesive
Damar (Oil painting preservative varnish)

You may want to check out my buddy, Bud Purvin's patented EnAble cone treatment, as it seems to be quite effective. Giant thread about it on diyAudio.

Best Regards,
TerryO

 

[bobaloniny]

I'm kinda confused as to what the OP is trying to stiffen? Are you wanting a more rigid cone to better handle breakup? Or is it that the pleated accordion surround has gotten so flexible that you want to raise the fs back closer to original spec. I can't really imagine using super glue for the latter.

I believe he said cones

 

[amason3]

I've seen many posts about stiffening old speaker cones (like the ones in the 4024a Mach Ones) but superglue (cyanoacrylate, or CA) seems to be the usual implement of destruction.

I've got an old Peavey Black Widow 15" woofer that could stand to be a little tighter in the old paper cone. It's either glue it, or buy a new basket assembly, so I figure I've got nothing to lose by trying the glue approach.

Why do you need to stiffen the cone? If it's bottoming out then you're running more wattage than the speaker can handle anyway, and if the surround is weak you need to replace that, b/c you're not going to get a uniform thickness of glue to stiffen it no matter what you do.

 

[cubby01]

I believe he said cones

That's what I read too. Got confused when surrounds got thrown into the mix. I'll go back to my rock now.

 

[Copa1934]

I've seen many posts about stiffening old speaker cones (like the ones in the 4024a Mach Ones) but superglue (cyanoacrylate, or CA) seems to be the usual implement of destruction.

I've got an old Peavey Black Widow 15" woofer that could stand to be a little tighter in the old paper cone. It's either glue it, or buy a new basket assembly, so I figure I've got nothing to lose by trying the glue approach.

However, superglue at the local Wally World only comes in tiny little tubes. It'd take $50 worth of those itty bitty tubes to do the speaker

How about Aileen's Tacky Glue? Got a whole bottle of it, seems like I could paint it on gently with a paintbrush and not have too much buildup. Anybody used that?

I think the assumption, not of the OP, is that cones don't deteriorate. Anything that is made up of some kind of emulsion, such as paper, will break down to some degree. Whether or not it loses mass is a subject that could be debated unless someone actually weighed a cone new and after 20 years or more of service.

In the Mach One thread it was found the bottom end was improved. I'm no expert so I can't explain this, but common sense would tell you that if a speaker has a given spec new, and changes as it loses stiffness, certainly restoring that stiffness to some degree will restore performance. No need to get over scientific about it, really.

Cones are vibrating all the time, otherwise why make them out of metal, carbon fiber, Kevlar, etc?

As for weight, sure there may be some added weight, but again some common sense here. A half ounce (wet) bottle of S.G. will do at least one 15" woofer (applied correctly). That's wet mind you. Probably half or more evaporates. I hardly think that is significant enough to worry someone, and the sonic difference, if at all negative, will likely only be audible to a meter and not the average persons ears.

I had a Mach One speaker that was breaking up only at higher volumes. I used the S.G. trick behind one of the circular ridges (which was collapsing on itself) and on the face and sure enough the speaker actually works again. Change in characteristics? I couldn't tell, which to me was all that matters.

Changing the characteristics just because? That I'm not sure I would do.

 

[Michael Powers]

I've read somewhere of a manufacturer that does this to the raw drivers they purchase. I thought that they painted a coat of watered down white Elmer's glue onto the backs of the cones to stiffen it & shift the cone's breakup frequency up above the crossover point they were using.

 

[87RangerXLT]

Ive seen recently in here somewhere, where it was used watered down to seal very porous cloth surround, and he seemed to have good results with that. I also saw a vid on youtube where the guy used Aileens and coffee filters to basically build about 1/2 of the speaker cone for an 1930s or 40s floorstanding radio with good results as far as he was concerned.
I think the more you stiffen the less low end you end up with, but if its that floppy anyway..and youre willing to gamble..Id go with watered down..try it after a coat, and if you think it needs it..give er another.

Do you mean this video?

http://www.youtube.com/watch?v=jW7xuJ2gHOY

I found it very helpful. He is actually a member over at Video Karma.

 

[spkrdtr]

A number of speaker companies used coated woofers and midranges over the years. The purpose is to tame cone breakup resonance modes - most of which raise their ugly heads at elevated frequencies. In doing the coating, they are able to extend the frequency range and avoid ugly response peaks.

It's been rumored that Spica's TC-50 Audax and polydax woofer/mids were coated with a diluted mixture of Elmer's glue. Even with that they had to develop a factory adjustable crossover to tame those peakes which led to their system of service codes.

Speaker legend Roy Allison coated his early Allison woofer with a sticky material.
The EnAble process of adding a dot pattern around the cone in selecsted areas is another approach to addressing the same issue.

 

[nashvillebill]

Yes, I mean the cones (not the surrounds).

This speaker was in a Peavey Databass (bass amp). They put a single 15 inch Black Widow rated around 300 or 350 watts into a combo amp...driving it with 450 watts. (yep!!) Compounding the issue is that this is a very shallow cone. After 20+ years of being pounded, the paper cone has gotten soft and a little flabby.

The glue is a poor man's attempt at restoring it to some semblence of rigidity.

 

[spkrdtr]

Yes, I mean the cones (not the surrounds).

This speaker was in a Peavey Databass (bass amp). They put a single 15 inch Black Widow rated around 300 or 350 watts into a combo amp...driving it with 450 watts. (yep!!) Compounding the issue is that this is a very shallow cone. After 20+ years of being pounded, the paper cone has gotten soft and a little flabby.

The glue is a poor man's attempt at restoring it to some semblence of rigidity.

sounds like you need a recone job and be done with it.

 

[nashvillebill]

Typically, you don't recone Peavey Scorpions or Black Widows, you remove the magnet from the basket assembly and buy a new basket assembly for about $85.

 

[Nat]

Painting on varnish until you can see it soaked through to the back would do it, I believe. You can get the effect you want without most of the effects you don't want by painting only the central part of the cone, which is where the softening has taken place usually. Since its a small part of the cone's area, you won't add that much mass.

 

[Nat]

Oh -- make sure you get the part under the dust cap, either by painting from the back or removing and replacing the dustcap.

 

[mfrench]

I used Franklin Titebond II wood glue on an old paper Rola speaker at the suggestions of a longtime audio tweaker. The speaker had a slight tear. I used the glue and a cigartette paper to repair the tear, and coated the rest of the cone (not the accordion paper surround). It seems to have worked.

 

[rifftrax]

I used Franklin Titebond II wood glue on an old paper Rola speaker at the suggestions of a longtime audio tweaker. The speaker had a slight tear. I used the glue and a cigartette paper to repair the tear, and coated the rest of the cone (not the accordion paper surround). It seems to have worked.

I've used wood glue with many speakers to stiffen the paper of the cones and the sound always seems to improve. The addition of mass is extremely minimal really but the diaphrams are always a significant degree more rigid afterwards. I can only surmise that it tones down breakup and gives the cone closer to pistonic movement.

 

[michiganpat]

tacky or elmers glue still is fairly flexible after drying, so I'd go with a wood glue, varnish, or CA glue which dries rigid...the CA won't add significant mass, the others might add enough to lower the Fs of the driver a bit...