How to restore dried out paper cones?

[-Matt-]

Just wondering what product (and method) you guys would recommend to restore dried out cones like this one? (Has sat in the sun for too long).

Bonus points if you can guess the make and model from that photo!

Also for discussion... Do you think condition like this compromises performance at all?

 

[sergeauckland]

My preferred method is to keep the grilles on. If that's not possible, then go over the cone with a spirit-based black marker, one that doesn't have the iridescence that some markers have. I test it on my thumbnail first.

I don't see it as having any audible issue, but I agree that they don't look as nice if you have to have the grilles off.

S.

 

[-Matt-]

I'm a grilles off kind of guy!

Thanks for the suggestion.

I've previously attacked that cone with a black marker and it did improve things for a while but it soon dried out again. I'm hoping for a better, more permanent fix if possible.

 

[MakeMineVinyl]

Order replacement drivers from the manufacturer if that is possible. Beyond that, I'd keep speakers out of the sun.

 

[DVDdoug]

Do you think condition like this compromises performance at all?

Probably not. Generally, speakers don't gradually deteriorate. Usually it's foam surround or paper disintegrating or the voice coil starts rattling, and it becomes very obvious that something is seriously wrong.

You can spray it with clear spray paint (or black or other color). That might increase the stiffness and "toughness" to extend its life. Don't spray the surround, which looks like rubber. You might be able to "treat" the rubber with "something" if you feel it will help.

Painting the cone will increase the mass which should lower the resonance, and I don't know what other effects... Assuming this is a car speaker, it's probably not in a perfectly-tuned cabinet so I wouldn't be too paranoid about slightly-changing the driver characteristics.

Everything in speaker design is a trade-off so adding-mass and lowering the resonance most-likely has a negative side... Maybe it lowers efficiency/sensitivity but I don't know...

Human nature being what it is, you'll probably perceive an improvement!

 

[Don Hills]

Water based ebony wood stain. Apply in several light coats, be careful not to saturate the cone. Airbrush works well. Solvent based stain reduces the risk of warping the cone but risks dissolving the glue holding the cone to the surround.

 

[-Matt-]

I'm wondering what these are impregnated with when they are made? Some sort of resin?

Edit: We posted at the same time. The above looks like a good suggestion.

 

[DMill]

I’ve done 3 repairs on rubber surrounds using kits you can buy online. They range from a complete pain in the ass to absolutely miserable. you need to have the right tools, workspace and patience. My guess is if the cone is not punctured it’s probably mostly ok. Repairs can be done if you enjoy that sort of thing. If you decide to repair it, do it before cocktail hour.

 

[Doodski]

Bonus points if you can guess the make and model from that photo!

Is that a flat cone or is the pic making it appear as flat? I'm trying to guess the make.

 

[-Matt-]

It is slightly convex. No more clues for now!

 

[thend]

Simply black ink.

 

[thewas]

Just please use as few paint or other substances as possible as you want to keep the mass, stiffness and break-up behaviour of the membrane as original as possible.

 

[OWC]

Don't think this is dried out, but just discolored.
Just some black dye will do just fine, but keep in mind that you will never get the original color back.
I do recognize the fat dust-cap, but drawing blanks when it comes to names atm
Looking at the edge around the frame it reminds me of some kind of B&W

 

[MCH]

This?

LTS 50 | Visaton

Coating liquid for loudspeaker cones (black). For better internal damping, reduction of partial oscillation and linearization of the frequency response. Prevents bleaching of the cone. Especially suited for cone speakers with paper cones. Water-soluble until hardened completely. Contents: 50 ml

www.visaton.de

However googling around came across this:

Phillips 9710 BB Fullrange mit Visaton LTS 50 versiegeln?, Hifi-Klassiker - HIFI-FORUM

Ich bin gerade dabei, meine Sonab OA-4 general zu überholen. Die Lautsprecher an sich sind in einem sehr guten Zustand. Sie werden von mir general üb

www.hifi-forum.de

Where someone explains that recoating the paper will change the response (true or bs?)

Here a patent on the subject (production, not restoration). Don't know if what they describe is close to how the cones are actually made nowadays, but in terms of paper coatings, what the patent says makes sense:

CN110636418A - Loudspeaker cone and preparation method and application thereof - Google Patents

The invention provides a loudspeaker cone and a preparation method and application thereof, wherein the loudspeaker cone is prepared from the raw materials of paper pulp, cationic styrene-acrylic emulsion and emulsified paraffin; the cationic styrene-acrylic emulsion and the emulsified paraffin...

patents.google.com

 

[-Matt-]

Don't think this is dried out, but just discolored.
Just some black dye will do just fine, but keep in mind that you will never get the original color back.

I think you are correct - it is more a case of discoloration. Certainly it is mainly the cosmetic appearance that I hope to address.

Just please use as few paint or other substances as possible as you want to keep the mass, stiffness and break-up behaviour of the membrane as original as possible.

Absolutely

This?

LTS 50 | Visaton

Coating liquid for loudspeaker cones (black). For better internal damping, reduction of partial oscillation and linearization of the frequency response. Prevents bleaching of the cone. Especially suited for cone speakers with paper cones. Water-soluble until hardened completely. Contents: 50 ml

www.visaton.de

...

That product makes specific claims that it will change the frequency response.

"For better internal damping, reduction of partial oscillation and linearization of the frequency response."

I don't really want to do that - just restore the colour, so I think I will avoid this one.

Subject to initial tests on plain paper, I will probably follow Don Hills' advice...

Water based ebony wood stain. Apply in several light coats, be careful not to saturate the cone.

Using this water based Littlefairs stuff:

https://www.amazon.co.uk/Littlefairs-Environmentally-Friendly-Water-Based/dp/B010EF2XLE?ref_=ast_sto_dp

I may be tempted to do before and after nearfield REW sweeps to see if anything changes.

 

[OWC]

I have used stain/dye in the past, but just make sure it's not alcohol based.
Also, some will have like a bit more of a red/green or blue color hint to it, so keep that in mind as well.

 

[beefkabob]

Madonna might know. She's got old cones.

 

[-Matt-]

I carefully painted the wood dye onto the woofers (used less than a thimble full for both). The dye took quite a bit of brushing to get it to penetrate in (there was sort of a waxy coating). Here are the before and after REW sweeps (mic about 2mm from the woofer, no smoothing, vector average of three measurements):

I probably didn't wait quite long enough for it to dry before measuring. I think the signal below 55 Hz is largely from the subwoofer and changes slightly due to different mic position. Above 55Hz the response is basically the same within experimental errors.

Here is a close up of the woofer appearance (it looks better in person):

From the main listening position I'm very happy with the visual improvement (Jubilee flyover by Red Arrows captured):

...some kind of B&W

Indeed - they are B&W CDM7 NT.

 

[Doodski]

I carefully painted the wood dye onto the woofers (used less than a thimble full for both). The dye took quite a bit of brushing to get it to penetrate in (there was sort of a waxy coating). Here are the before and after REW sweeps (mic about 2mm from the woofer, no smoothing, vector average of three measurements):

View attachment 210354

I probably didn't wait quite long enough for it to dry before measuring. I think the signal below 55 Hz is largely from the subwoofer and changes slightly due to different mic position. Above 55Hz the response is basically the same within experimental errors.

Here is a close up of the woofer appearance (it looks better in person):

View attachment 210355

From the main listening position I'm very happy with the visual improvement (Jubilee flyover by Red Arrows captured):
View attachment 210356


Indeed - they are B&W CDM7 NT.

That dye job looks fantastic.

 

[RickS]

Sorry, got to this a bit late...

Did you ask B&W? There are some coating products out there. At least one is by a speaker manufacturer (Visaton).

Hope the dye works out but would consider something more depending on manufacturer response. The appearance may be better but would consider something that might improve longevity too.