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
