Cone Repair on 602B & 604B

I have some very small repairs to make on the cones of these two Duplexes. The small holes in the 602 are in the surround and the small tear in the 604 is in the area of the surround, although the cone and surround are of the same material and piece and not separate.

I am wondering about the best way to go about repairing these. The issue of concern on the. 604B was repaired, likely long ago. The small tear has occurred outside the edge of the repair. I wonder and worry that the repair caused stress and ultimately the new damage. And considering this is a 604B, I do not want to do anything to compromise the integrity of the original cone. This cone is really thin, even compared to the 602.

I have reached out with a message to Great Plains Audio requesting advice and guidance on the best process to repairing these. Any advice here would be greatly appreciated as well. I'd also be happy to post photos if that would help matters any, at least in terms of assessing the extent of the issue.

Scott

You may want to post some pictures, so the pros here can evaluate the damage...

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Originally Posted by slial

I have reached out with a message to Great Plains Audio requesting advice and guidance on the best process to repairing these.

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Hi Scott, sounds like you are taking work away from them so don't be disappointed if they don't reply.

There are any number of ways to do the repairs and, as juniper has said, a picture or two would be very helpful in determining the course of action. It may be as simple as facial tissue and cut back PVA glue.

I will upload the photos this evening. As for GPA, they actually replied and indicated they only do full cone replacements and not repairs. At this point I would like to avoid that if possible. The only come they can supply would turn my B into an E.

Here are some photos. I have included photos of both obvious areas of some need and some that might be suspect.

604B:

Images reflect 2 older repairs (one of which is near the new tear), a small hole, an older repair, a small spot that seems creased and might be suspect.

Attachment 1904

Attachment 1905

Attachment 1906

Attachment 1907

602b:

Attachment 1912

Attachment 1913

Attachment 1914

Attachment 1915

Attachment 1916

When it's at the surround like that and the surround is paper I would consider using cut back rubber cement. The solvent is acetone and you'll have to be careful how much you thin it. Usually 10:1 is enough. Try even less to start and gradually add acetone until you think it's right. You want it easy to apply thinly but not so runny that it's hard to control. It's hit and miss and there's no way I can help more without being there. I would use facial tissue or TP as a scrim. Do the repair on the back on the cone if possible and just lightly dress the front (no tissue) after the patches on the back have set. Some have also tried a cut back silicone but I haven't found a good way to clean or prime the cone and the silicone tended to delaminate over time.

Does anybody have any photos or detailed description of this process? I am sure I can handle it in house but also want as much info ahead if time. One thing is sure...I'll practice on a less important cone to get the hang if it.

Get some of those little children's art class paint brushes from your local dollar store [make sure they won't melt with the acetone] and while you're there pick up some flat toothpicks [not the round kind]

Use one brush to gently clean the area with a small amount of acetone. Then apply a small amount of the rubber cement solution with a different brush and lay a small piece of tissue [pre-cut to the required size] over the cement. use the skinny handle part of the paint brush to form the tissue into place in and around the accordion part of the surround. Apply another small amount of cement over the tissue and smooth it out making sure that a little cement is taken beyond the edges of the tissue and feather it out as best you can. Use the blunt end of the toothpicks to remove any excess. More is not better here, just like too little is no good. Make sure you get it looking right before you walk away as once is begins to set, you'll only make a mess if you try and fix anything. When it's dry to the touch, turn the driver over and use a brush to apply a small amount of the solution [no tissue] to the affected area on the front of the cone. Let dry for 24 hours.

How much larger than the wound should the tissue be? Should the small year that is visible in the photos be glued down before being covered with the tissue/glue combo? The sides of the tear line up perfectly and I would think that securing that down first would simplify matters with the tissue.

Are there any other methods or materiala out there I should be aware of, or is this the tried and true approach?

Scott

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Originally Posted by Cal Weldon

Get some of those little children's art class paint brushes from your local dollar store [make sure they won't melt with the acetone] and while you're there pick up some flat toothpicks [not the round kind]

Use one brush to gently clean the area with a small amount of acetone. Then apply a small amount of the rubber cement solution with a different brush and lay a small piece of tissue [pre-cut to the required size] over the cement. use the skinny handle part of the paint brush to form the tissue into place in and around the accordion part of the surround. Apply another small amount of cement over the tissue and smooth it out making sure that a little cement is taken beyond the edges of the tissue and feather it out as best you can. Use the blunt end of the toothpicks to remove any excess. More is not better here, just like too little is no good. Make sure you get it looking right before you walk away as once is begins to set, you'll only make a mess if you try and fix anything. When it's dry to the touch, turn the driver over and use a brush to apply a small amount of the solution [no tissue] to the affected area on the front of the cone. Let dry for 24 hours.

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Quote:

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Originally Posted by Cal Weldon

Get some of those little children's art class paint brushes from your local dollar store [make sure they won't melt with the acetone] and while you're there pick up some flat toothpicks [not the round kind]

Use one brush to gently clean the area with a small amount of acetone. Then apply a small amount of the rubber cement solution with a different brush and lay a small piece of tissue [pre-cut to the required size] over the cement. use the skinny handle part of the paint brush to form the tissue into place in and around the accordion part of the surround. Apply another small amount of cement over the tissue and smooth it out making sure that a little cement is taken beyond the edges of the tissue and feather it out as best you can. Use the blunt end of the toothpicks to remove any excess. More is not better here, just like too little is no good. Make sure you get it looking right before you walk away as once is begins to set, you'll only make a mess if you try and fix anything. When it's dry to the touch, turn the driver over and use a brush to apply a small amount of the solution [no tissue] to the affected area on the front of the cone. Let dry for 24 hours.

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This is an excellent method that will last a considerable time. We use thinned rubber cement and talc to seal pneumatic valve pouches in pipe organs and player pianos. They have to remain flexible under stress for years.

If you have an art supply house our good paint center nearby, check for "Best-Test" products. They offer a premium rubber cement and their "Bestine" thinner which is 100% pure heptane.

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Originally Posted by bowtie427ss

This is an excellent method that will last a considerable time. We use thinned rubber cement and talc to seal pneumatic valve pouches in pipe organs and player pianos. They have to remain flexible under stress for years.

If you have an art supply house our good paint center nearby, check for "Best-Test" products. They offer a premium rubber cement and their "Bestine" thinner which is 100% pure heptane.

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That is great info. There are many art supply stores nearby with Rhode Island School of Design not far away. I will look for this stuff. When you say these repairs should last a "considerable" amount of time, what are talking about? Many years I assume?

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When you say these repairs should last a "considerable" amount of time, what are talking about? Many years I assume?

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In the closed pneumatic systems where i use it most often, we expect more or less 20 years of reliability minimum with newly installed leather, and a minimum of 5 years when used to rejuvinate pouches(when deemed acceptable condition) that are up to 100 years old.

I can't say with any certainty how long such a repair might last on a speaker cone, but i think similar results could be expected. However, i offer no guarantees.

It's probably reasonable that repairs done by Cal's method will last the remaining life of the cone.

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Originally Posted by bowtie427ss

In the closed pneumatic systems where i use it most often, we expect more or less 20 years of reliability minimum with newly installed leather, and a minimum of 5 years when used to rejuvinate pouches(when deemed acceptable condition) that are up to 100 years old.

I can't say with any certainty how long such a repair might last on a speaker cone, but i think similar results could be expected. However, i offer no guarantees.

It's probably reasonable that repairs done by Cal's method will last the remaining life of the cone.

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I figured as much. I will have to get my hands on a cone I don't need and practice this method. No way I starting cold on a Duplex.

Hi Scott,

Make the patch slightly larger than the 'wound.'
Yes, align all pieces best you can before starting.
If they lined up perfect and this wasn't in the surround area, I would recommend clear nail polish as you wouldn't even need a patch.
This repair will last indefinitely if:
1. you prep the area well
2. you do a good job with the patch

If you do a lousy job and it falls off, then so what, you start again and do it properly this time, no biggie.

Just go to any electronics repair shop, tell them what you are doing and they might just give you a speaker to try it out on. Try and get one with the same style cone/surround.

Nice to hear bowtie's story. :)

Quote:

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Originally Posted by Cal Weldon

Hi Scott,

Make the patch slightly larger than the 'wound.'
Yes, align all pieces best you can before starting.
If they lined up perfect and this wasn't in the surround area, I would recommend clear nail polish as you wouldn't even need a patch.
This repair will last indefinitely if:
1. you prep the area well
2. you do a good job with the patch

If you do a lousy job and it falls off, then so what, you start again and do it properly this time, no biggie.

Just go to any electronics repair shop, tell them what you are doing and they might just give you a speaker to try it out on. Try and get one with the same style cone/surround.

Nice to hear bowtie's story. :)

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Cal,

If you look at the photo you can see the tear is in the cone area but the original issue was in the surround. So would I use the nail polish as a glue to adhere the seam of the tear and then cover the whole spot with nail polish? This would likely require holding it in place until it sets too.

That's tough to see in the pics so here's what I suggest and you'll have to take it from there.

If you are doing repairs in the surround then use the rubber cement method. If you are clear of the surround and are working only on the cone and have good alignment of the damaged area, use the clear nail polish straight up, no thinner, no tissue. You still do the repairs on both sides of the cone.

Any specifics or preferences for nail polish?

Also, do you have any photos of repairs you have done? This might help me visualize the desired outcome.

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Originally Posted by slial

Any specifics or preferences for nail polish?

Also, do you have any photos of repairs you have done? This might help me visualize the desired outcome.

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Although I consider myself a modern day sensitive man I don't have a clue as to the nail polish. Here's how I acquire it: "Honey can I borrow some clear nail polish? I don't need much. Thanks Honey, I love you."

Photos? No. Just try it, you'll find you are an expert after just once, trust me, it's not hard. Just pretend they are you're children and you'll do fine. I like the idea of trying it on a spare driver first though.

Quote:

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Originally Posted by Cal Weldon

Some have also tried a cut back silicone but I haven't found a good way to clean or prime the cone and the silicone tended to delaminate over time.

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I have no idea what you could use to dilute pure Silicone caulking and I can understand why it wouldn't stick not used full strength. Also, caulking must never be feathered at its edges, the feathered edge will always delaminate and once started, will always fail and is why bathtub surround caulking always fails. You would have to mask off the area around the repair, apply the caulk, smooth with your finger to the thickness of the masking tape, and then remove the tape before the caulk sets up.

Probably the same applies to rubber cement.

Hi James,

We don't want him to use caulk so it's a bit of a non-issue but a bit about a feathered edge: It's all about the substrate preparation, the sealant being applied, the applicator's knowledge and the tooling of the product. You're right, the average Joe should avoid feathering but we have offered Scott a means of dealing with those potential concerns. A cutback will penetrate the paper pulp better than straight up and if it is cleaned properly first, a feathering won't be a problem here. Working in and around a surround can be awfully tricky to mask off and it's taking at chance at delaminating some of the cone if you use anything other than frog tape.

I think he'll be just fine. :)

Cheers.

I picked up the Best-Test rubber cement and Bestine thinner, and now just need to get some small brushes that will tolerate the acetone. Then on to some clear nail
polish and some practice comes and I should be good to go.

Scott

Quote:

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Originally Posted by Cal Weldon

Hi James,

Hi James,

We don't want him to use caulk so it's a bit of a non-issue but a bit about a feathered edge: It's all about the substrate preparation, the sealant being applied, the applicator's knowledge and the tooling of the product. You're right, the average Joe should avoid feathering but we have offered Scott a means of dealing with those potential concerns. A cutback will penetrate the paper pulp better than straight up and if it is cleaned properly first, a feathering won't be a problem here. Working in and around a surround can be awfully tricky to mask off and it's taking at chance at delaminating some of the cone if you use anything other than frog tape.

I think he'll be just fine. :)

Cheers.

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Quote:

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Originally Posted by slial

I picked up the Best-Test rubber cement and Bestine thinner, and now just need to get some small brushes that will tolerate the acetone. Then on to some clear nail
polish and some practice comes and I should be good to go.

Scott

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Take some pictures and post up your work so others can benefit!

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Originally Posted by Alien_Shore

Take some pictures and post up your work so others can benefit!

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I will definitely snap some shots of the work.

Is there any more input on the tissue paper itself? Cal recommended facial tissue, and I was just curious about the options here, especially since it would be nice to go gray/black to match it up as best as possible.

Scott

Quote:

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Originally Posted by slial

I will definitely snap some shots of the work.

Is there any more input on the tissue paper itself? Cal recommended facial tissue, and I was just curious about the options here, especially since it would be nice to go gray/black to match it up as best as possible.

Scott

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I've heard of cigarette paper being used for repairs .


:)

Toilet paper can be used as well as facial tissue in and around the surround. If you are on the cone, then writing paper, rolling paper or something equally stiff may be used. As far as colour matching, I wouldn't worry, the patches tend to become rather translucent when the rubber cement goes on. Try it on a scrap piece first.

Any update on the repair?

Instead of rubber cement Cal, what about product like "Super RC Z 56 Glue, made by J and Z Products, Harbor City , CA - and also other manufacturers, to attach canopies on Radio Controlled airplanes?? Designed to withstand shock and vibration !!

Ever try that ? I have, a lot.

It dries clear and glossy, is flexible, and it is "cut" with water so you can apply with an artist's brush - as much or as few THIN coats as you need.

I use paper from inside a cigarette box, or, model aircraft wing paper covering, as the patch. I think any of the Z-56 type glues are superb, easy to apply with minimal added mass, and it always remains flexible. Often, when applied from the rear of the cone, you don't see any ugly looking repair !!

Surely "I" can not be the ONLY person who uses this for cone repairs. If you haven't used it, get a bottle and TRY it out. I love the finished results.

Comments from fellow users are welcomed !! Cal, try it and let us know how you like it.

Does this post of mine help anyone ??

Jeff Medwin

Hi Jeff,

Sounds like a good one. Is it flexible enough to use on the surrounds as opposed to the cones? That's why I suggested the rubber cement. I have used it with good results. I hope someone else here has an opportunity to try the product you recommend. TBH, I have enough drivers to last a lifetime so if I have one with a tear, I'm just as likely to give it to someone else to fix. Not trying to be a snob or anything - just saying. That's what an addiction is all about.

- Buy
- Buy more
- Buy too much
- Admit you have a problem
- Buy more to help comfort yourself.

My name is Cal and I'm a Speakerholic. :-)

- - - Updated - - -

I just did a little research. It appears the RC56 is another name for Tacky Glue. It's a modified PVA. I am familiar with it and yes it would be great stuff for drivers. Now if it is better than rubber cement on a surrounds, who knows? Interesting to hear opinions.

Cal,

I think it is very flexible, and I have used it on surrounds. I am guessing I was told about this by Don Davis, the brilliant ex-Austin Texas Vintage speaker repair guy, sometimes known as Dr. Field Coil.

I do not know what "tacky glue" is, and so I am not particularly sure if you have it right. This is water soluble, dries see-through clear and with a sheen, and it is for RC airplane Canopies mostly. At least two hobby industry companies make it. I really like it...no problem on surrounds, the paper could crumble away and it will remain and be flexible I have been told. Surely others know about using this product.

Jeff Medwin

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Originally Posted by LowOhms

"tacky glue"

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Hi Jeff,

Tacky glue is a generic term like you would use 'wood glue'

RC56 is brand specific Tacky glue. When they use letters and numbers they can sell it for more.

Sorry for the long delay on this repair project. I have been completely sidetracked by kids and job. I intend to begin the repair in the coming days and will post images and results.

Scott