I am not convinced that it is sunlight or nicotine that rots the foam.  The left hand speaker in my Beovision LX2500 (made by ITT in W Germany, I note) had rotted - the right is still perfect!  Since the LX was assembed by B&O I know that these speakers have not been away from either side of the 25" screen screen since 1987!

I have replaced the foam and it sounds so much better now.  I have also replaced the foam in  a pair of CX100s and my Red Line 140s.  I must look at the drivers on my Pentas - but am worried about how to take off the covers!!!

Small foam strips in your Beo4, behind the screen, tend to rot, and they never see sunlight!

Andy T.

Do RL 6000 have rubber or foam surrounds?

Cheers

Nigel

Beovox S80.2 and Beovox S120 do rot as well.

Both pairs of mine had to be fixed.

Beovox S40 speakers can also be added to the list.

I've got one pair waiting for restoration over here 😎

Both the woofers & subwoofers on MS150's can be added.

Chris.

I came up with a radically new modification last year and now have a wonderful sounding pair of Redline 60s.  Many folks have used my suggestion and love the bass they are now getting and will never have the foam issue again.   I've already posted this in another thread here at the Workbench, but here again is the link:

You can also look at the older paper cone speakers, especially those with a latex/paper surround.

This gives way after many years of use, most folk are surprised to find they can be repaired, but you cannot replace the surround with rubber.

Reason for this is that these old paper cone speakers work in a slightly differant way, and they need surrounds that allow vibration but not any real degree of movement. The cones have very little travel in them.

So you are looking at Type K, Type S as these have the larger drivers in them. You may also have some issues with Beovox 4000, Beovox 3000, and also the MKIII Beovox 5000 - the earlier ones should be fine.

There may be others of the paper cone elements that are affected, but these are the ones I have come across or are the ones that I suspect are most likely to suffer. Part of it may come from folk thinking that such physically large speakers can be driven with a modern amp, but their power rating is very much smaller than modern units - some of them will not cope with 25 Watts - proper Watts and not Japanese ones.

Well, I once had a pair of S45's (1983 production) and it suffered greatly from foam rot 2-3 years after purchase (2005). Shortly after, I had aquired another pair because theese speakers are cheap in Denmark (I assume that a lot were produced).