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 wrote:

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 wrote:

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,

stevepe wrote:

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

Søren Mexico wrote:

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......

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