Kef ls50 meta cone cracking

[plastic penguin]

I can't believe listening to music at high levels, unless it's constantly played at distorted levels will cause such rips. These LS50s weren't made in huge numbers, so it's hard to swallow this pair got past quality control.

I would suggest the OP isn't giving the whole picture.

 

[Al ears]

It’d be nice to see a full photo of the drivers, but the first pic looks like external damage, the second pic looks like overdriving/fatigue. Fatigue doesn’t necessarily take place outside of the speaker’s and amplifier’s power limits - play bass heavy music, causing the drivers to move out further than theyre comfortable with, and you’ll end up with what looks like the right sided photo. A speaker like this should be used carefully in larger rooms or at higher volumes, and really, anyone wanting high output levels with heavy bass output should really be looking at another speaker. This is where a good dealer comes in, and shows the downside of buy-whatever-you-like mail order.

I will restate that if the speaker was used with an amp that is within the speakers stated specs it shouldn't end up with defects like this whatever type of music that was played through it.
You don't see manufacturers stating 'not for heavy metal' very often....

 

[Al ears]

Yes, my point was that the old paper cones don't suffer in the same way (the OP's old cones haven't - and presumably he gave the old speakers the same stick).

I would have thought paper comes or their drive units would have given up the ghost long before metal ones, perhaps they handle deformation better?

 

[GSV Ethics Gradient]

I would have thought paper comes or their drive units would have given up the ghost long before metal ones, perhaps they handle deformation better?

It may be that having greater flexibility saves them - they'll distort at lower volumes, but might bend rather than break?

 

[Tinman1952]

I can't believe listening to music at high levels, unless it's constantly played at distorted levels will cause such rips. These LS50s weren't made in huge numbers, so it's hard to swallow this pair got past quality control.

I would suggest the OP isn't giving the whole picture.

Agreed. I suspect a UFO........unidentified flying object! 🙄

 

[davidf]

I will restate that if the speaker was used with an amp that is within the speakers stated specs it shouldn't end up with defects like this whatever type of music that was played through it.
You don't see manufacturers stating 'not for heavy metal' very often....

I don’t mean heavy metal, and I agree with your statement, but play heavy, exaggerated bass lines through systems and you can’t play them as loud as more neutral sounding music because the bass is too much. Continuous heavy bass played loud enough will result in what is show in the second photo - too much cone excursion.

 

[plastic penguin]

Agreed. I suspect a UFO........unidentified flying object! 🙄

Witchcraft I reckon.

 

[Edbostan]

I have a pair of Kef ls50 meta speakers bought in October 2021,noticed this morning that the meta cone has cracked in one place and showing signs of cracking in other areas. I will contact my supplier to get it sorted under warranty, but am interested in what might have caused the problem. The other speaker is perfect . My amp is a Vincent sv-237mk. I would be interested to hear if any other member has had a similar problem

The cracking seems to be near those ribs. Perhaps the ribs have weakened the integrity of the cone.

 

[Gray]

I would suggest the OP isn't giving the whole picture.

Well if he is, there will be many more such cases.

 

[bigfish786]

Had a quick Google this morning and there are several other occasions of this happening to kef speakers. Hope the op can get these sorted,
makes you wonder if it’s too stiff to cope, or is there some obvious mismatch I am not aware of?

 

[Gray]

...there are several other occasions of this happening to kef speakers

Thought there might be.

 

[rayolight]

It does look like they’ve been overworked.

Definitely not overworked, room only 10x12ft,and I'm 73 so no heavy rock,normally volume set to 3,and never had a problem with other Acoustic Energy speakers, had AE1's for 40years

 

[rayolight]

Had a quick Google this morning and there are several other occasions of this happening to kef speakers. Hope the op can get these sorted,
makes you wonder if it’s too stiff to cope, or is there some obvious mismatch I am not aware of?

Really interested to hear this,have sent a message to kef no reply yet. NOBODY, goes in my music room,I do all cleaning, speakers see NO direct sunlight,my AE500's have similar metalic cones but no problems with them. I'm at a loss

 

[rayolight]

The cracking seems to be near those ribs. Perhaps the ribs have weakened the integrity of the cone.

I agree,there are 2 other places that look suspect,

 

[rayolight]

It’d be nice to see a full photo of the drivers, but the first pic looks like external damage, the second pic looks like overdriving/fatigue. Fatigue doesn’t necessarily take place outside of the speaker’s and amplifier’s power limits - play bass heavy music, causing the drivers to move out further than theyre comfortable with, and you’ll end up with what looks like the right sided photo. A speaker like this should be used carefully in larger rooms or at higher volumes, and really, anyone wanting high output levels with heavy bass output should really be looking at another speaker. This is where a good dealer comes in, and shows the downside of buy-whatever-you-like mail order.

The speakers have definitely not been overdriven, The strange thing is the sound from the speaker is not distorted,i only noticed the damage by accident
Pictures enclosed

 

[rayolight]

AE1's are rock solid

Btw, 40 years? I thought AE1's were released in 1987.

Ok 35years,its still a long time

 

[Gray]

Looks catastrophic in that first photo.
And yet there's no sign of trouble whatsoever on the other one?

 

[rayolight]

The speakers have been looked after like all my equipment and definitely not thwacked as has been mentioned, the kefs are only 8 months old,I cannot stress enough that they have not been overdriven ,the room is only 10 x12ft,i have no children here, I'm 73 ,and average volume on my amp is 3. It was only a shadow on the speaker that made me look at it. I have noticed no problem with the sound which i find amazing, no fluttering which you would expect from a paper cone,think i could probably join break with superglue at a push if the supplier decides to be awkward. Interesting that there have been other comments regarding this problem on the web.

 

[Al ears]

Perhaps a case of a did get batch of metal cones?
will be interesting to see what KEF come back.with although the dealer you bought them from should be first port of call if still within warranty

 

[rayolight]

I'm not very hopeful as I agree it does look as though the speaker has been damaged, which i can assure you it hasn't. Am sure the supplier will do everything he can to get out of replacement. According to kef the speakers are guaranteed for 5 years and I have only had them since last October, perhaps they should send a disclaimer if you play level 42 music. At a push I think I can join the tear with superglue. As I have mentioned before, there is actually no noticeable degradation in sound to my ears which I find amazing. It was only by chance I noticed the tear. Will have to wait and see 👀

 

[Al ears]

I'm not very hopeful as I agree it does look as though the speaker has been damaged, which i can assure you it hasn't. Am sure the supplier will do everything he can to get out of replacement. According to kef the speakers are guaranteed for 5 years and I have only had them since last October, perhaps they should send a disclaimer if you play level 42 music. At a push I think I can join the tear with superglue. As I have mentioned before, there is actually no noticeable degradation in sound to my ears which I find amazing. It was only by chance I noticed the tear. Will have to wait and see 👀

If said dealer wants to keep your custom it is in his best interest to replace them.

 

[rayolight]

I've spent about 4000 euros with them to date,but am not confident

 

[rayolight]

I've tried to send you a small video ,to show how little the sound is affected but apparently this is not possible

 

[AEJim]

I can't comment too specifically on the speaker (being from another manufacturer) but it's feasible for the cone to have been damaged that way in use - you have a powerful amp and vinyl in particular can put out some hefty low frequency information (not always audible) which can really push a smaller speaker driver even at modest volume. I experienced this happening first hand on very early AE1 mkIII's.

It's certainly the case you may not hear any obvious ill effect, there will be air leakage and the break-up/stiffness/dispersion will have altered but if the coil is undamaged it can be surprisingly subtle. If indeed the coil is undamaged it's another sign they may not have been overdriven for warranty.

The dealer should be your first port of call - they know you as a good customer and will be able to talk to their KEF rep. They may want to inspect the speakers and have them in for repair, at worst you may have to pay for a new driver if they determine it as "user error". Often it's at the dealer/manufacturer's discretion when the cause isn't obvious.

If you let me know your AE1 serial numbers I'll tell you the day they were made to clear up any confusion as to their age.

 

[davidf]

The speakers have definitely not been overdriven, The strange thing is the sound from the speaker is not distorted,i only noticed the damage by accident
Pictures enclosed

Sorry, but from those photos, there’s no way that can happen to those drivers. They’ve either been stressed, or physically damaged. If they’re never stressed, aluminium cones will last many, many decades.