Finding surrounds that actually fits, both the sizes, lip angle(s) and cone height
can be difficult.
Many of the sets offered are generic surrounds, guaranteed to fit everywhere
and they are rarely as good as advertized.

2mm is not the whole world and your speakers will be fine and will provide for many years of
listening pleasure, I'm sure.
However, it is a fact that the foam should be at rest when the cone is the same.
Any pre-tension in either direction is bound to cause distortion since the cone
will be easier to move in one direction than the other or it will have a dead spot somewhere near the center.
Very easy to see if you have a good signal source, a microphone
and a scope or, even better, a distortion meter.
No moot and no mysteries. Pure physics.

Martin

Hi  is there any diffrence in sound when refoaming the cx with rubber instead of a foam one?

thanks, great strategy, i will try to do so ;)

I am going to repair my old defect b&o beovox cx100:

just got hands on new surroundings for my b&o cx100, i found 8 pcs, incl. glue, i gave $42 incl shipping ;) 

Hi All,

I hope it's OK to revive this thread with some additional perspective.  I just completed a re-do on one of my C75's woofers.  It was rubbing after a refoaming job. (confirmed with the low Hz test tone),  so I "faced my fear" and cut the center cap off that bad boy.  Fortunately, I was able to cut away the tacky glued outside edge fairly easily with a razorblade. (No new surround needed!)

 The shims held things in place nicely, and I have to say that it wasn't tough.  The non-shimming methods usually/often work, I know, but I'm firmly in the shimming camp, now.  I really like not wondering how well centered it is, and not having to be so fussy with the clothes pins, etc.   Worth the trouble, IMO, to cut the cap and re-glue it. ( But I have really good "up close" vision)

I'm liking the the cut and fold back the cap method. Less stuff to buy.   

Steve

My kind of man, shimming is it, then you know where you are, without shimming it will allways be guess work, and you get a chance to clean and check  under the dustcap. Good pics

You only need to remove the dustcaps & shim to glue down the outer edges of the new foam rings, the rest of the work can & should be done prior to this. Leave them in place until you do this to save them being exposed for any length of time.

Chris.

What happens to the surround using a battery you can see on this drawing, a 5 Mm pull will allso pull the outer edge of the surround away from its natural rest position by +-5 Mm