Have a torn speaker cone ? - UK Vintage Radio Repair and Restoration Discussion Forum

johnny · 6th Jul 2016, 3:44 pm

All is not lost no matter how bad the tear is. I carefully realigned the tear up and then applied a coat of black nail varnish to both sides of the tear and left to dry. Once it had dried, I applied another 2 coats and once dried, the speaker was as good as new

MurphyNut · 7th Jul 2016, 2:44 am

I would imagine we all have our own ways of repairing speaker cones, I soak small strips of paper in PVA wood glue (50/50 - water/glue) and lay these across the damaged areas.
Once dry this really makes a permanent repair, I like the way the glue from the strips soaks into cone and it all becomes one, rather than just sticking onto the surface. I finish off by painting the cone with a thin coat of black paint, I know this last part of the process isn't necessary but it finishes it off nicely.

Ti Pwun · 7th Jul 2016, 3:06 am

I would also go with something flexible like PVA wood glue. After a while, the nail varnish will crack and break free, especially if the volume is used at a high level.

threeseven · 7th Jul 2016, 10:20 am

I use black silicone gasket, applied generously to thoroughly coat the area then scrape off the excess and leave to set over a few days. I like the way it remains flexible.

Ian - G4JQT · 7th Jul 2016, 12:22 pm

Copydex rubber solution glue, watered down about 50:50. Use kitchen towel which stronger than other tissues and flexible.

Push the tear back into place as best you can. Dab area with glue from both sides if possible. Lay on paper slightly larger than damaged area and gently dab with more glue.

The glue solution is very flexible, actually soaks into the cone (so won't ever peel off) and is all held together by the paper which will cover any holes or missing scraps. The paper wrinkles up at first, but flattens and tightens when dry.

Ian

johnny · 7th Jul 2016, 2:29 pm

Well, there are many ways it seems to get that speaker working again. I bet there are a lot more ways to do it, so lets hear about them.

Silicon · 7th Jul 2016, 10:23 pm

Ideally the 'bandage' applied to the cone should be as light and strong as possible.

Anything that adds mass or changes the flexibility of the cone will affect the sound.

I have often wondered if the synthetic fibre sheets used for anti-weed mesh would be better than paper.

johnny · 8th Jul 2016, 4:27 pm

Most tears I have seen can easily be "threaded" or stitched. It takes a little patience as one has to do both side of the tear. A dentist's shap ended tooth pick is a good tool to have as one can lift the fibers and mesh them before applying the magic solution. Ofcourse, the bigger the speaker, the more vibration of the cone at higher levels.

emeritus · 8th Jul 2016, 5:48 pm

Last year I did a course on bookbinding (some of my electrical textbooks are more than 100 years old and very much in need of restoration). One thing I learned was that restorers use Japanese paper made from long fibres of the Mulberry tree for reinforcing in general, and mending tears in particular. A type I was recommended to use is Kizuku Tosa Kozo in 18gsm (the weight normally used by the British Library for their restorations). It is so thin and translucent that it can be applied over text, and certainly not cheap (£13.25 for an approx. 2' x 3' sheet), but as only a thin strip needs to be applied across a tear, it goes a long way.

When still wet, can be moulded in three dimensions to reinforce corners and embossing, so it would be suitable for mending the corrugations at a speaker's edge. I haven't needed to repair any speakers recently, but I would use this for any that might come my way in future. I have used it to restore missing corners of pages, applying one piece from each side, so it could be used to bridge holes. When the glue has dried it is certainly very strong and flexible. I use a fast-drying archival quality pH-neutral PVA-type glue (EVA) intended for book binding that will not attack paper and does stay flexible when dried: apparently PVA glue intended for woodworking is somewhat acidic and prone to damage the type of paper used for books.

Ti Pwun · 9th Jul 2016, 9:14 am

^
Very interesting post. I don't repair many speakers but that's definitely useful info.

emeritus · 9th Jul 2016, 10:26 am

I forgot to mention that, because the Japanese paper is hand made, the fibres lie at random orientations, so there is no direction of weakness. Machine made paper is made in long webs and its fibres are aligned along the axis of the web. Thus you can easily tear a sheet of toilet paper along its length, but it is difficult to tear across its width, other than at the perforations.

Ti Pwun · 10th Jul 2016, 10:19 am

Definitely sounds like it's the right material for the job. Thanks.

FrankB · 11th Jul 2016, 2:23 am

I have used both toilet paper and tissue paper to repair cones with.
General Cement made a flexible cement specifically for cone repair.
Lacking the cement, I have used a very thin coat of RTV silicone sealant.

6th Jul 2016, 3:44 pm	#1
johnny Retired Dormant Member Join Date: May 2006 Location: Basildon, Essex, UK. Posts: 45	Have a torn speaker cone ? All is not lost no matter how bad the tear is. I carefully realigned the tear up and then applied a coat of black nail varnish to both sides of the tear and left to dry. Once it had dried, I applied another 2 coats and once dried, the speaker was as good as new

7th Jul 2016, 2:44 am	#2
MurphyNut Heptode Join Date: Apr 2016 Location: Croxley Green, Hertfordshire, UK. Posts: 979	Re: Have a torn speaker cone ? I would imagine we all have our own ways of repairing speaker cones, I soak small strips of paper in PVA wood glue (50/50 - water/glue) and lay these across the damaged areas. Once dry this really makes a permanent repair, I like the way the glue from the strips soaks into cone and it all becomes one, rather than just sticking onto the surface. I finish off by painting the cone with a thin coat of black paint, I know this last part of the process isn't necessary but it finishes it off nicely. __________________ Clive

7th Jul 2016, 3:06 am	#3
Ti Pwun Heptode Join Date: Aug 2013 Location: Bradford, West Yorkshire, UK. Posts: 888	Re: Have a torn speaker cone ? I would also go with something flexible like PVA wood glue. After a while, the nail varnish will crack and break free, especially if the volume is used at a high level.

7th Jul 2016, 10:20 am	#4
threeseven Octode Join Date: May 2010 Location: Worcestershire, UK. Posts: 1,880	Re: Have a torn speaker cone ? I use black silicone gasket, applied generously to thoroughly coat the area then scrape off the excess and leave to set over a few days. I like the way it remains flexible. __________________ BVWS member

7th Jul 2016, 12:22 pm	#5
Ian - G4JQT Octode Join Date: Jun 2004 Location: Reading/Fakenham, UK. Posts: 1,323	Re: Have a torn speaker cone ? Copydex rubber solution glue, watered down about 50:50. Use kitchen towel which stronger than other tissues and flexible. Push the tear back into place as best you can. Dab area with glue from both sides if possible. Lay on paper slightly larger than damaged area and gently dab with more glue. The glue solution is very flexible, actually soaks into the cone (so won't ever peel off) and is all held together by the paper which will cover any holes or missing scraps. The paper wrinkles up at first, but flattens and tightens when dry. Ian

7th Jul 2016, 2:29 pm	#6
johnny Retired Dormant Member Join Date: May 2006 Location: Basildon, Essex, UK. Posts: 45	Re: Have a torn speaker cone ? Well, there are many ways it seems to get that speaker working again. I bet there are a lot more ways to do it, so lets hear about them.

7th Jul 2016, 10:23 pm	#7
Silicon Nonode Join Date: Jun 2007 Location: Coulsdon, London, UK. Posts: 2,163	Re: Have a torn speaker cone ? Ideally the 'bandage' applied to the cone should be as light and strong as possible. Anything that adds mass or changes the flexibility of the cone will affect the sound. I have often wondered if the synthetic fibre sheets used for anti-weed mesh would be better than paper.

8th Jul 2016, 4:27 pm	#8
johnny Retired Dormant Member Join Date: May 2006 Location: Basildon, Essex, UK. Posts: 45	Re: Have a torn speaker cone ? Most tears I have seen can easily be "threaded" or stitched. It takes a little patience as one has to do both side of the tear. A dentist's shap ended tooth pick is a good tool to have as one can lift the fibers and mesh them before applying the magic solution. Ofcourse, the bigger the speaker, the more vibration of the cone at higher levels.

8th Jul 2016, 5:48 pm	#9
emeritus Dekatron Join Date: Jan 2012 Location: Brentwood, Essex, UK. Posts: 5,339	Re: Have a torn speaker cone ? Last year I did a course on bookbinding (some of my electrical textbooks are more than 100 years old and very much in need of restoration). One thing I learned was that restorers use Japanese paper made from long fibres of the Mulberry tree for reinforcing in general, and mending tears in particular. A type I was recommended to use is Kizuku Tosa Kozo in 18gsm (the weight normally used by the British Library for their restorations). It is so thin and translucent that it can be applied over text, and certainly not cheap (£13.25 for an approx. 2' x 3' sheet), but as only a thin strip needs to be applied across a tear, it goes a long way. When still wet, can be moulded in three dimensions to reinforce corners and embossing, so it would be suitable for mending the corrugations at a speaker's edge. I haven't needed to repair any speakers recently, but I would use this for any that might come my way in future. I have used it to restore missing corners of pages, applying one piece from each side, so it could be used to bridge holes. When the glue has dried it is certainly very strong and flexible. I use a fast-drying archival quality pH-neutral PVA-type glue (EVA) intended for book binding that will not attack paper and does stay flexible when dried: apparently PVA glue intended for woodworking is somewhat acidic and prone to damage the type of paper used for books. Last edited by emeritus; 8th Jul 2016 at 6:03 pm.

9th Jul 2016, 9:14 am	#10
Ti Pwun Heptode Join Date: Aug 2013 Location: Bradford, West Yorkshire, UK. Posts: 888	Re: Have a torn speaker cone ? ^ Very interesting post. I don't repair many speakers but that's definitely useful info.

9th Jul 2016, 10:26 am	#11
emeritus Dekatron Join Date: Jan 2012 Location: Brentwood, Essex, UK. Posts: 5,339	Re: Have a torn speaker cone ? I forgot to mention that, because the Japanese paper is hand made, the fibres lie at random orientations, so there is no direction of weakness. Machine made paper is made in long webs and its fibres are aligned along the axis of the web. Thus you can easily tear a sheet of toilet paper along its length, but it is difficult to tear across its width, other than at the perforations.

10th Jul 2016, 10:19 am	#12
Ti Pwun Heptode Join Date: Aug 2013 Location: Bradford, West Yorkshire, UK. Posts: 888	Re: Have a torn speaker cone ? Definitely sounds like it's the right material for the job. Thanks.

11th Jul 2016, 2:23 am	#13
FrankB Heptode Join Date: Oct 2005 Location: Olympia, Washington, USA. Posts: 664	Re: Have a torn speaker cone ? I have used both toilet paper and tissue paper to repair cones with. General Cement made a flexible cement specifically for cone repair. Lacking the cement, I have used a very thin coat of RTV silicone sealant.