Hi everyone,

After recently buying a set of RedLine 60's (the original version) on eBay and finding the ABR (Auxiliary Bass Radiators) completely missing due to rotted foam surrounds, I thought I would share the solution I found and prompt others to do the same (can we get a full list of affected speakers in one posting to help others in the future?)

Basically, the two 6.25 inch woofers in the original RL60 have rubber surrounds, not foam, so they are not affected by foam rot.  However, the large oblong ABR panels are very prone to this problem.  If the foam surround feels sticky to the touch, it is about to fail, but most of the original RedLine 60 speakers have probably had the foam disintegrate completely over the past 25 years or so.....

B&O still sell (correct as of May 2007) a replacement steel panel complete with bass reflex port for about £60 UK per pair, which completely replaces the ABR (it fits inside the wooden front panel of the speakers using the existing ABR screws).  This effectively upgrades the speakers to work in the same way as the newer RL60.2 version, which had the bass port as standard.  Due to the size and unusual shape of the ABR panels, I have not been able to find a way of re-foaming them, so I bought the upgrade from B&O.  I have been EXTREMELY impressed with the depth and quality of the bass since fitting these and I would thoroughly recommend this upgrade, even if you don't have problems with foam rot on your speakers!

A full, detailed picture-by-picture description of how to dismantle and re-assemble a pair of Red Line speakers can be found via the link below:-

http://hometown.aol.com/beophile/rl60demo1.html

As an aside, while you have the speakers in bits, it is worth considering replacing the electrolytic capacitors in the crossover circuits, as the originals will probably have dried out by now, reducing the treble response.  Wilmslow Audio (https://secure.wilmslow-audio.co.uk/catalog/) can supply replacements at around £20 per pair of speakers.

If any of you are able to share your knowledge on other affected speakers, I would greatly appreciate this for future purchases!

Cheers,

Steve (in Leicestershire, UK)

CX-100 series is notorious for this.  I luckily came across a pair practically free since they came with the 4500 system I bought, and the price for the whole system with speakers was less then I was ready to pay for the system alone without them.  The foam, was so bad on all 4 that the cones were barely supported by anything.  I bought 4 surrounds off ebay though.  I cleaned off the old foam with a razor blade, and glued the new ones on the elmers white glue.  You have to press the cone in a little several times as they dry to keep checking that you don't here any rubbing of the coil.  They sound incredible now though!

Austin 

The midrange speakers on the Pentas are another known problem.  I don't have Pentas though so I can't give any details about replacement, but I'm sure some others will chime in.

 (I'm posting as a seperate reply so it's easier to pick out individual speaker models)
 

I think you could safely include the large woofers on many of the older beovox speakers.  The foam on the woofers of my 3702 beovox's are rotted, but I haven't had time to replace them yet.

 

 So as of now I guess we have.....

Red Line 60

CX-100 series

Penta midranges

older Beovox woofers
 

edit: I had accidentally said my 3800 woofers were rotted too, but they aren't, and don't even have foam surrounds.

It's a question of age AND where the speakers are located. They dont like SUNLIGHT.

I have 3 pairs of pentas and several pairs of redlines, they are all intact, no damage at all. Only one redline 60 was exposed to direct sunlight for several years, this one is damaged by foam rot. Even after repair six or seven years ago, this one has some damage on the foam again. So i think, the main reason for this foam rot is 99% sunlight.

I also found some defect speakers on the MX3500 and MX5500 series, sunlight too.

Martin 

Beolab 6000 drivers have been known to fail. The suspension splits, although they seem to be rubber surrounds.

I recall reading somewhere that humidity plays a part in the deterioration of foam products, as well as UV.

Dillen also supplies Capacitor kits for the RL60 crossovers and offered to refoam the ABR's if you still have the surround and the metal plate.

I have repaired two pairs of RL60's with the replacement "ported plate" from B&O and they do sound fine. (I also have a spare pair of plates for RL60 brand new from B&O unused and still in the box they arrived in)

You can also add that the older Beovox range seem to be fine, the Beovox 5000, 4000, 3000, 2400 etc.

The S45 range, including the S30,60,75 all seem ok, but the slightly later uniphase that culminate in the M150's are also pretty bad for foam rot.

The Beovox 5700 are ok, but the others in that range, such as 4702, 3702 etc have some kind of rubber that just rots.

The ones using foam surrounds are vulnerable, as mentioned the CX100s, 50 etc, but the Pentas can suffer, along with the Redlines.

One thing that does hasten the decline of the foam surrounds is if the owner is a smoker, the tar causes them to decay, add in a warm environment, such as mounted high up as the redlines often were, and those surrounds rot away.

Damp environments are also hard on the earlier 1960's range of speakers, especially the cone tweeters.The only problem I've had with Beovox 3800s is that the tweeters can be damaged and make the sound very harsh.

 I can't comment on the later Beovox panel speakers.

The foam on my 3702's rotted, with absolutely no exposure to sunlight ever, so I don't think the sunlight is the main cause.

 edit: I had accidentally said my 3800 woofers were rotted too, but they aren't, and don't even have foam surrounds.
 

It's time and sunlight. With sunlight... and mayby some nicotin... it takes only some years until the foam is destroyed. Otherwise it can take mayby 20 years or longer...

The phase link units on M100s rots - I suppose any drive unit can deteriorate with age though. So far I am lucky - all my CXs are fine and the Pentas seem unaffected.

I don't think there is any definate reason for this. I've come across speakers of the same age & type with varying degrees of foam rot from nil to complete disintigration. 

I suspect it is a manufacturing anomily with some foam surrounds simply being better produced than others.

 

Chris.

The woofers on my Beovox S55's suffered badly from foam rot. This model is well known for foam rot. Almost all of them have suffered from it

S 80, S 80.2, M 150 all suffer serious rot in my experience.

C40, C75, Cx50 & Cx100 do also, but more variably. The sunlight thesis may be true as one of a pair may be affected but not the other, but that could also be heat, if one of the pair is closer to a radiator/fire/window.

I can't make any further helpful comment as all mine have been second-hand, so their previous history is uncertain (usually tragic, from their appearance, despite vendors' claims) but it would be interesting to hear from owners who have had 'speakers from new & kept them in one place - unlikely for a twenty-year-old loudspeaker, though!

Adam K.

The Red line 35 model 6515

I have experience with S45, X35 and M150 Beovoxes.

My parents oak S45 from '79 still no rot so far.

My former X35 speakers were nearly mint. No rot.

My M150 speakers I have been using for a year or something no rot as the bass units were changed to new B&O originals because of it by the first owner.

Thinking of it the vintage '67 type I have seen never had rot of any kinds.

Almost every pair of X35s I've had have had bad foam rot, but they weren't sorely missed (not after I'd heard a 'fully functioning' pair!).

In case anybody was reading this thread and wondering, S25s are not affected by foam rot at all.

The Beovox 5700's don't suffer from foam rot at all! Rubber surrounds

I have a similar problem with a pair of RL60s I've had for 22 years. Can anyone recommend a source for the ABR replacements? 

Both pairs of speakers Beovox C30 and S55 suffered from the dreaded foam rot. I have replaced the foam with a product from a company called good_hifi ( Netherlands) on Ebay and all seems to work OK.

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