Did my first attempt refoaming larger drivers like the Beovox S80 I just got.

No batteries used to center the cone, just the touch of my hands! And it sounds fantastic!

Nice job and beautiful cabinet. I have done the woofers on my S55 and S120.2 speakers. I found them easy to center and refoam as well. I wish all woofers were like that.  The CX-50 and CX-100 series weren't bad either but I did use a frequency generator to test the centering on those.  I really depended on the generator for the RL-140 speakers. Those woofers are by far the most difficult. I know Søren Mexico will tell me to shim, shim, shim but if I can do it without cutting open the dust cover I would rather try it

Leslie I would trust the touch of your hand over my shims or battery trick anyday.

As usual - good job.

I think I did one set of CX-100 drivers that way.. I dont really think size makes it anymore difficult.

sonavor:

Nice job and beautiful cabinet. I have done the woofers on my S55 and S120.2 speakers. I found them easy to center and refoam as well. I wish all woofers were like that.  The CX-50 and CX-100 series weren't bad either but I did use a frequency generator to test the centering on those.  I really depended on the generator for the RL-140 speakers. Those woofers are by far the most difficult. I know Søren Mexico will tell me to shim, shim, shim but if I can do it without cutting open the dust cover I would rather try it

You guys get on my strong stretched nerves, yes shim,shim,shim, will be back shortly with a drawing and motivation for shimming for all of you

Eugene:

Leslie I would trust the touch of your hand over my shims or battery trick anyday.

As usual - good job.

I think I did one set of CX-100 drivers that way.. I dont really think size makes it anymore difficult.

Thanks Eugene! What's shimming? Have tried to translate that word, but nothing....

sonavor:

Nice job and beautiful cabinet.

Thank you Sonavor, the cabinets are indeed "awesome" and in new condition

Shim and the magnet methood aside. I said I trust Leslie's touch more than some people using shims and magnets for a good reason.

In the end no amount of "proper" preparation can account for the clumsiness of some DIY jobs. It would be fun to have a thread were we post up pics of botched refoam jobs we come across whether it be our own experience or something we spy on eBay. Most of us have seen them. In particular a lot of poor tortured CX100 drivers.

In my own experience last year I had to refoam a set of S80 drivers that had been previously "profeesionaly refoamed" a few years earlier. The surround was installed behind the driver not over the face. I also had to re-refoam a set of CX100 that done with cheap wafer thin surround and barely any glue. started to come apart very quickly.

In the end I trust Leslie eyes and his care for detail we have all seen it in his other work, but next time at least use a magnet. Your apt to give one of us purists a stroke if you dont.

sonavor:

Nice job and beautiful cabinet. I have done the woofers on my S55 and S120.2 speakers. I found them easy to center and refoam as well. I wish all woofers were like that.  The CX-50 and CX-100 series weren't bad either but I did use a frequency generator to test the centering on those.  I really depended on the generator for the RL-140 speakers. Those woofers are by far the most difficult. I know Søren Mexico will tell me to shim, shim, shim but if I can do it without cutting open the dust cover I would rather try it

First of all congrats Leslie as always a top job. But now to why shimming, (I dont understand why you always try to avoid that) its easy. First af all here a pic of what happens when you use the battery trick, with a 1.5 V cell, you pull the cone some 4-5 Mm and when gluing the outer surround edge, the edge is pulled to the inside,  about 3-4 Mm. So if the max pull of the driver is 10 Mm, you are of center (rest position) with some 30 %. Dont tell me that there wont be some distortion because of this.

And now to why shimming.

When the surround is of, the only thing that keep the cone and the cone tube in place is the spider, if the spider is only a little damaged or misaligned, the gap between tube and magnet will not be parallel, and if there is only a 0.1 Mm like in the RL140 drivers, you've got trouble.

By shimming, and pushing the shims all the way to the buttom of the voice coil, you get the tube parallel to the magnet and same distans all around, after gluing, the surround keep this adjustment. The dustcap is no problem, just cut it near to the cone, but leave about 5 Mm not cut, kip it to the side and when the surround glue is dry, kip it back and glue it. Dont cut the dustcap before you have cleaned everything and the inner edge of the surround is glued on.

I know I'm stressing this, but in my opinion its the only way you can be sure, not do it again.

I'm sure Leslie did the refoam, like he did, only to get me going

Hi Leslie,

Would you tell us how you liked the fit of the foam surrounds, and which supplier are they from?  I haven't found very many places to get surrounds for these odd sized woofers, and fit can be a problem.  

I'm a shimmer.  Listen to Soren.

Thanks,

Steve

Eugene:

In the end no amount of "proper" preparation can account for the clumsiness of some DIY jobs. It would be fun to have a thread were we post up pics of botched refoam jobs we come across whether it be our own experience or something we spy on eBay. Most of us have seen them. In particular a lot of poor tortured CX100 drivers.

On the new forum we will get Wikies and bloggs where we can set up things like that, and better, good how toos.

stevepe:

Would you tell us how you liked the fit of the foam surrounds, and which supplier are they from?  I haven't found very many places to get surrounds for these odd sized woofers, and fit can be a problem.  

I'm a shimmer.  Listen to Soren.

Thanks,

Steve

As you are over here, http://stores.ebay.com/surroundaround-speaker-repair-shop?_rdc=1, I bought from this shop 6,5" and 8" surronds, the ones Leslie made is 8", a normal speaker size 20.5 Cm. The quality of the surrounds is OK, in 2010 I made some RL 140, and to be sure to get it right I bought from Martin 4 drivers, one came damaged from the transport, Martin send a new one for free, I cut of the surround on the damaged one, I then ordered some 6.5" for the RL 140 and 8" for my S45s, they fit exactly and as far as I can tell, same quality as from Martin, they are a bit darker to the color, but thickness and "feel" the same, the S45s has been playing without problems ever since, the RL 140 I did for a friend and no claims.

and shim and dont tell your FS (Fabric Selector (wife)) she may think its a new seksgame

stevepe:

Hi Leslie,

Would you tell us how you liked the fit of the foam surrounds, and which supplier are they from?  I haven't found very many places to get surrounds for these odd sized woofers, and fit can be a problem.  

I'm a shimmer.  Listen to Soren.

Thanks,

Steve

 

Best place to buy these surrounds is Goodhifi.com from the Netherlands. I think he's advertising on Ebay.com as well.

Søren Mexico:

And now to why shimming.

When the surround is of, the only thing that keep the cone and the cone tube in place is the spider, if the spider is only a little damaged or misaligned, the gap between tube and magnet will not be parallel, and if there is only a 0.1 Mm like in the RL140 drivers, you've got trouble.

By shimming, and pushing the shims all the way to the buttom of the voice coil, you get the tube parallel to the magnet and same distans all around, after gluing, the surround keep this adjustment. The dustcap is no problem, just cut it near to the cone, but leave about 5 Mm not cut, kip it to the side and when the surround glue is dry, kip it back and glue it. Dont cut the dustcap before you have cleaned everything and the inner edge of the surround is glued on.

I know I'm stressing this, but in my opinion its the only way you can be sure, not do it again.

 

Great Soren, never knew that and your drawing is great!

But I wonder, isn't that something for people to do who don't have the skills placing surrounds in a precise way?

I mean, my work is pretty accurate and the results eventually sounds great. Did about 15 pair of CX's and not one of them failed.

I will ask Goodhifi what they think of this regarding this shimming thing, just to have a 2nd opinion.

So I've heard from the experts that shimming is the way to centre the cone acurately but there might be a chance that dirt wil come in between the coil and magnet. If that's the case then the driver can be thrown away as I've been told.

There are brands from where the dustcap (dustcap and cone is one piece) cannot be removed so only refoaming can be done. I think I'll stick to refoaming only! If the speaker sounds okay, I'm happy!

It greatly depends on the driver as to whether shimming is absolutely vital or not Leslie, but some are absolutely essential, such as RL140's! SO basically I agree with Sorens post that shimming is the most accurate way of repairing speakers, although one thing I would argue is that if your spider is slightly out then really this should also be repaired!

Shimming helps to enure the surround will find it's natural centre assuming all else is in good condition! It also helps to set the height of the cone which as Soren demonstrates is impossible with the battery method, which IMO is just not suitable!

I am sure Martin belives shimming should be used in all cases too and I think he has mentioned this before!

Makes sense Olly and I never thought that in some cases like the RL140's should be refoamed in a more precise way. I'm not discussing the fact that shimming is needless but in my case I think I can do it without shimming. But nevertheless I will give it a try (shimming) as soon as I get my first RL140. Does this only counts for the RL140 or are there other types that needs (more) accurate work to refoam?

@Martin, where are you......

This explains a lot!

Here is what Martin said in another thread

I've written a lot about this subject and with all that can go wrong I am
afraid to sound negative. My main concerns are all the woofers that gets
damaged in DIY-attempts. The CX woofers are still available but almost
all other 1980's B&O woofers aren't and modern replacements just aren't as good.
Everytime I think I've seen all that can go wrong, a woofer with a new issue comes in.
Last week I had a woofer that was dropped on the floor distorting the
metal basket beyond repair.
"It slipped out of my hands, can you fix it ?"

The pro refoam'ers are worth their cost. Refoam'ing is not as easy as most
surround suppliers try to convince you and some of the cheaper surrounds
just doesn't fit anywhere. You can do a search and read a lot more.
But there are success stories too.
Some people are better DIY'ers than others.
Some people just have more luck.
Fair enough, but hardly a week goes by without a failed DIY attempt arriving
here by post.
I like challenges but some of them are just a bit too far gone to rescue
and that's really a shame.

1. It's all a matter of centering the coil around the center piece and it's
almost always done by inserting shims.

Some refoam kits come with little cardboard pieces that are supposed
to fit between the coil former and the magnet center piece.
I never saw any that fitted particularly well and woofers don't all have
the same gap so don't expect to be able to use those. You can try but don't think
you are doing something wrong if they don't fit.
If you are determined to DIY, you can cut pieces from plastic sheets of
different thickness and see if you can come up with a suitable fit.
I suppose most refoam'ers have their own methods. I use some special
made tools, CNC machined rings and holders, specifically made for each
driver type.
Sometimes the spider also needs adjusting the same way as the outer surround.
Mainly on larger woofers that were played with bad surrounds for a long time
so the whole cone assy have sacked a bit. It's rare to see on the CX drivers.

2. If white glue is what we in Denmark call woodworkers glue, it will be
nothing but trouble and I simply cannot see how anyone can recommend it.
It hardens completely, becomes brittle and will not bind to the metal basket.
I have seen it used on some of the drivers that come here and the only
good thing I can say is that it is usually easily removed, often without
damaging the surround.
The cone is a different matter though; On polypropylene cones (plastic material)
the glue will easily come off, almost by itself but it is a lot of trouble
if it's a cardboard cone. Water will losen it but it will easily end up a mess.

Contact glue can also be a mess and most of them will pull lines that can easily
end up inside the coil where it will be very difficult to remove or across
the cone where it won't look good.
I would recommend when you buy new surrounds, order some proper speaker cement.
You will also need new dustcaps, get them a bit larger in diameter than the original
to make them cover any glue remains from the old dustcaps.
Speaker cement is very easy to work with, it settles reasonably well within
10 hours and completely within about 24 hours or so.
It has an incredibly strong bond to almost any material and remains just
slightly flexible and elastic (I use it for glass panel repairs too).
IPA will losen it if needed.

3. You could do that, or just fit a new electrolytic type.
I dare say, you won't hear much difference in the CX50 speakers, really.

Martin

Leslie:

This explains a lot!

Very good thread Leslie, I dont doubt that you are very handy with your fingers, we have seen what you can do several times, but for me, not shimming is like working in the dark, you just dont know if the cone is centered. Consider that 0.1 Mm is 2-3 human hairs ( one of mine is 0.04 Mm. ) I have very fine hair.

Hello all,

Leslie contacted us and we answered some of his questions, then we read the comments above, there's a few things we would like to add.

Fist of all, pls realise that refoaming is an exciting experience for most people. We are not used to repairing anything ourselves (anymore) and shimming makes it more exciting. Because many of the speakers mentioned above have pretty big tolerances we recommend the 'cloth peg' method for beginners because it works well enough, especially because only about 5% of the centering is done by the foam ring, the gasket does most of the job - this is a simple law of science because the gasket is so muct closer to the coil.

But, if you shim, pls use the right tools and do it in the right environment. The manual linked under 'This explains a lot!' talks about paper shims. According to my experience these are either to big (thick), to soft (thin) and might tear leaving debris between the coil and the magnet. Professional re-cone kits (that's when you replace everything, coil, cone, spider, wires, dust-cap) will be provided with shims made of foto film. This is what we recommend if you want to shim. It's thin, extremely strong, and can be used many times.

Then there's the problem of dust and debris if you shim. Speakers are equipped with a dust-cap to protect them from (the name says so....) dust. In the factory the department that puts all the parts together to become a speaker has to be a dust free (or low dust) environment. Imagine people shiiming their woofer on a dusty table in their garage...... If you shim, do so in a nice an clean environment.

The manual 'This explains a lot!' show you how to cut a dust-cap and re-use it. of course, in many cases (guess from experience: 50%) this is the case, but in the same amount of cases the cap will be damaged and has to be replaced. Because the cap effects the sound and finding an exact copy is very hard we recommend to be careful in removing the cap. Don't forget the cap is probably made of paper and 20-30 years old as well....

And finally, like Lesly mentioned, there's woofers out there that simply can not be shimmed because the cone and cap are made out of one piece. The most common kind our customers have are the Dynaudio 9" and 11" woofers. These are really nice woofers - worth a repair, but can not be shimmed. We wonder if the 'shimming refoamers' will throw these away .

This are just our 2 cents, based on our experience with our customers,

Kind regards,

Still my S80's sounds great without shimming!

And next time when I have my RL140's I 'll try to use the shimming method!

GoodHifi:

Hello all,

Leslie contacted us and we answered some of his questions, then we read the comments above, there's a few things we would like to add.

Fist of all, pls realise that refoaming is an exciting experience for most people. We are not used to repairing anything ourselves (anymore) and shimming makes it more exciting. Because many of the speakers mentioned above have pretty big tolerances we recommend the 'cloth peg' method for beginners because it works well enough, especially because only about 5% of the centering is done by the foam ring, the gasket does most of the job - this is a simple law of science because the gasket is so muct closer to the coil.

But, if you shim, pls use the right tools and do it in the right environment. The manual linked under 'This explains a lot!' talks about paper shims. According to my experience these are either to big (thick), to soft (thin) and might tear leaving debris between the coil and the magnet. Professional re-cone kits (that's when you replace everything, coil, cone, spider, wires, dust-cap) will be provided with shims made of foto film. This is what we recommend if you want to shim. It's thin, extremely strong, and can be used many times.

Then there's the problem of dust and debris if you shim. Speakers are equipped with a dust-cap to protect them from (the name says so....) dust. In the factory the department that puts all the parts together to become a speaker has to be a dust free (or low dust) environment. Imagine people shiiming their woofer on a dusty table in their garage...... If you shim, do so in a nice an clean environment.

The manual 'This explains a lot!' show you how to cut a dust-cap and re-use it. of course, in many cases (guess from experience: 50%) this is the case, but in the same amount of cases the cap will be damaged and has to be replaced. Because the cap effects the sound and finding an exact copy is very hard we recommend to be careful in removing the cap. Don't forget the cap is probably made of paper and 20-30 years old as well....

And finally, like Lesly mentioned, there's woofers out there that simply can not be shimmed because the cone and cap are made out of one piece. The most common kind our customers have are the Dynaudio 9" and 11" woofers. These are really nice woofers - worth a repair, but can not be shimmed. We wonder if the 'shimming refoamers' will throw these away .

This are just our 2 cents, based on our experience with our customers,

Kind regards,

 

What can I say more