Kef ls50 meta cone cracking

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Well gentlemen, just had another email from Kef,offering to send me 2 replacement speakers, so long as I pay transport. What can I say ,except very happy, just waiting for instructions. They wanted to send them from uk but I explained to them that since brexit, we are getting screwed with ridiculous import charges so have asked if they could possibly get them sent from there Spanish Office. Am a waiting for a response. Must say still a bit concerned as to what I do to ensure that the problem doesn't happen again, how can I ensure that there is not too much power going to them,if that is what they say has caused the problem.
The issue maybe, as I have stated before, there is not enough power getting to them......
Hopefully they will send a pair through the Spanish office and then you can immediately sell them... :)
 
If David, you accept that his AE speakers have received the same treatment - and it may be that you don't believe they have??
But if you do....the obvious question is:
Why have the AE cones not suffered any visible damage....
(Possibly because, as you rightly say, 'quality drivers are good for many decades'?).
I'm not saying that Kef are not quality drivers, but you must agree that this would mean that they're (undeniably) less durable. Unacceptably fragile might be a more appropriate description.
I would say the AE cone is stronger in some ways compared to the KEF as the AE cone is a “straight” cone, whereas the KEF cone is more fluted, curved to act as a waveguide for the HF unit it surrounds. So naturally, the KEF cone is going to be more susceptible to excessive excursion than a straight cone - although you don’t see too many straight cones around any more. If the cone curved the other way, so forwards rather than backwards as you go towards the edges, it would be immensely strong, and it’ll be the roll surrounds that will first show signs of excess. Straight will also be strong, and in these designs it’s also the roll surround that would likely suffer first.

That said, used within their limitations, it still wouldn’t be an issue, as it will have been something KEF will have tested. All manufacturers will test speakers to destruction x otherwise, how will they know their limits? This kind of testing will also highlight shortfalls In the design.

And while most people will see a 5.25” cone mentioned in the specs, it has less driver area than a normal 5.25” cone as you have to minus the area the treble unit takes up in the middle.
 

bigfish786

Moderator
Jan 29, 2013
556
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19,270
All they have to do is mark the value as “warranty replacement, value £10 for customs purposes only”
And that should mean 0 charges.

you could always offer to send the damaged drivers back to them to inspect. At their cost obviously.
 
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nopiano

Well-known member
Well gentlemen, just had another email from Kef,offering to send me 2 replacement speakers, so long as I pay transport. What can I say ,except very happy, just waiting for instructions. They wanted to send them from uk but I explained to them that since brexit, we are getting screwed with ridiculous import charges so have asked if they could possibly get them sent from there Spanish Office. Am a waiting for a response. Must say still a bit concerned as to what I do to ensure that the problem doesn't happen again, how can I ensure that there is not too much power going to them,if that is what they say has caused the problem.
Great. Perhaps their ears were burning? Delighted for you, and that you’re comfortable replacing them yourself.
 

Gray

Well-known member
Must say still a bit concerned as to what I do to ensure that the problem doesn't happen again, how can I ensure that there is not too much power going to them,if that is what they say has caused the problem.
Your best bet would be to do what you said you were going to do - fit them, carefully (putting a screwdriver through them would be a bit ironic), test them, then get rid of them.
Wonder what changed Kef's mind....reading this thread maybe?
 
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I would say the AE cone is stronger in some ways compared to the KEF as the AE cone is a “straight” cone, whereas the KEF cone is more fluted, curved to act as a waveguide for the HF unit it surrounds. So naturally, the KEF cone is going to be more susceptible to excessive excursion than a straight cone - although you don’t see too many straight cones around any more. If the cone curved the other way, so forwards rather than backwards as you go towards the edges, it would be immensely strong, and it’ll be the roll surrounds that will first show signs of excess. Straight will also be strong, and in these designs it’s also the roll surround that would likely suffer first.

That said, used within their limitations, it still wouldn’t be an issue, as it will have been something KEF will have tested. All manufacturers will test speakers to destruction x otherwise, how will they know their limits? This kind of testing will also highlight shortfalls In the design.

And while most people will see a 5.25” cone mentioned in the specs, it has less driver area than a normal 5.25” cone as you have to minus the area the treble unit takes up in the middle.
I think you're trying to protect a list cause here.
Are you perchance a KEF dealer?
 

rayolight

Well-known member
Jul 21, 2021
82
42
570
All they have to do is mark the value as “warranty replacement, value £10 for customs purposes only”
And that should mean 0 charges.

you could always offer to send the damaged drivers back to them to inspect. At their cost obviously.
Believe it or not but we're being charged 3 euros duty for delivery of a birthday card at moment, they are really taking the p***
 

Edbostan

Well-known member
Aug 5, 2021
213
104
970
I would say the AE cone is stronger in some ways compared to the KEF as the AE cone is a “straight” cone, whereas the KEF cone is more fluted, curved to act as a waveguide for the HF unit it surrounds. So naturally, the KEF cone is going to be more susceptible to excessive excursion than a straight cone - although you don’t see too many straight cones around any more. If the cone curved the other way, so forwards rather than backwards as you go towards the edges, it would be immensely strong, and it’ll be the roll surrounds that will first show signs of excess. Straight will also be strong, and in these designs it’s also the roll surround that would likely suffer first.

That said, used within their limitations, it still wouldn’t be an issue, as it will have been something KEF will have tested. All manufacturers will test speakers to destruction x otherwise, how will they know their limits? This kind of testing will also highlight shortfalls In the design.

And while most people will see a 5.25” cone mentioned in the specs, it has less driver area than a normal 5.25” cone as you have to minus the area the treble unit takes up in the middle.
Is the newest cone over engineered? Those ribs would prevent the cone flexing in an east to west direction but allowing the cone to flex more north to south. That would create a stress in the cone and possibly the damage shown
 
Is the newest cone over engineered? Those ribs would prevent the cone flexing in an east to west direction but allowing the cone to flex more north to south. That would create a stress in the cone and possibly the damage shown
The ribs are there to help strengthen the cone due to its shape, but those will be for the cone in general - obviously they’ll have little effect on the outer edges of the cone. Again, a straight cone will be stronger (although all cones will flex, to an extent), but would completely throw the intended dispersion characteristics of the HF unit.

But as I’ve mentioned, use any cone within its limits and you’ll not see any signs of stress for many decades, if at all. Cones made of softer material will flex when they’re pushed too far, and usually return to their original shape afterwards - a stiff cone will deform if stressed over a long period of time, or even if used once, if pushed too far. Again, manufacturers put their drivers through numerous different stress tests to cover normal and abnormal use, as they have to know what they can handle, and what they can’t.
 

rayolight

Well-known member
Jul 21, 2021
82
42
570
I would say the AE cone is stronger in some ways compared to the KEF as the AE cone is a “straight” cone, whereas the KEF cone is more fluted, curved to act as a waveguide for the HF unit it surrounds. So naturally, the KEF cone is going to be more susceptible to excessive excursion than a straight cone - although you don’t see too many straight cones around any more. If the cone curved the other way, so forwards rather than backwards as you go towards the edges, it would be immensely strong, and it’ll be the roll surrounds that will first show signs of excess. Straight will also be strong, and in these designs it’s also the roll surround that would likely suffer first.

That said, used within their limitations, it still wouldn’t be an issue, as it will have been something KEF will have tested. All manufacturers will test speakers to destruction x otherwise, how will they know their limits? This kind of testing will also highlight shortfalls In the design.

And while most people will see a 5.25” cone mentioned in the specs, it has less driver area than a normal 5.25” cone as you have to minus the area the treble unit takes up in the middle.
There is one thing that is very obvious, and that is the lack of absorption and flexibility on the Kef rubber surround . I'm no expert on speaker design but the rubber surround on the AE1's just handles the movement effortlessly, whereas the kef surround hardly moves. Surely this will limit the speakers ability to withstand the impact of certain frequencies hence the problem
 
This explains a little more about the roll surround, which actually allows a fair amount of movement.

 

12th Monkey

Moderator
Well gentlemen, just had another email from Kef,offering to send me 2 replacement speakers, so long as I pay transport. What can I say ,except very happy, just waiting for instructions. They wanted to send them from uk but I explained to them that since brexit, we are getting screwed with ridiculous import charges so have asked if they could possibly get them sent from there Spanish Office. Am a waiting for a response. Must say still a bit concerned as to what I do to ensure that the problem doesn't happen again, how can I ensure that there is not too much power going to them,if that is what they say has caused the problem.
Good to hear.
 

Shildondurham

Well-known member
Feb 7, 2016
71
7
10,545
Wonder if they read this thread and changed their minds? Power to the people.
my opinion is if it was genuinely caused by normal use it must have been a defective unit as surely more people would have posted similar experiences here?? It’s certainly caught the attention of plenty of users.
 
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Stuart.W.D

Well-known member
Sep 29, 2013
151
88
18,670
I own the original KEF LS50's and a pair of KEF Q150's both speakers work excellent with no issues at all. Speakers are run through 70 watts.
 

rayolight

Well-known member
Jul 21, 2021
82
42
570
I've been driving a pair of Acoustic Energy AE1's for 35 years with a 130 watt amp and no issues, which is why I am concerned about the kefs
 

rayolight

Well-known member
Jul 21, 2021
82
42
570
I just thought I'd give you an update on the current situation with my kef ls50 meta speakers. As you will be aware contacted kef May 30th and since then have sent a couple of emails and had several phone calls.Well as of today still waiting for them to send me a quote for DHL to deliver new speakers to Spain . It appears that they are very short staffed suffering with covid ,incredibly busy and very sorry for the delay,but as they are very kindly offering me a new pair of drivers and I am only paying for delivery I'm not really in a position to complain . On a positive note,I found that SuperGlue 3 contains rubber and have made an excellent repair on the damaged cone which will do until the new drivers eventually get here. Patience is a virtue I'm told😇
.
 

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Edbostan

Well-known member
Aug 5, 2021
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I just thought I'd give you an update on the current situation with my kef ls50 meta speakers. As you will be aware contacted kef May 30th and since then have sent a couple of emails and had several phone calls.Well as of today still waiting for them to send me a quote for DHL to deliver new speakers to Spain . It appears that they are very short staffed suffering with covid ,incredibly busy and very sorry for the delay,but as they are very kindly offering me a new pair of drivers and I am only paying for delivery I'm not really in a position to complain . On a positive note,I found that SuperGlue 3 contains rubber and have made an excellent repair on the damaged cone which will do until the new drivers eventually get here. Patience is a virtue I'm told😇
.
I hope they sent instructions on how to remove the damaged drivers. Seems you got a great deal. Will be interesting to see the damage on the other side of the cone.
 
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rayolight

Well-known member
Jul 21, 2021
82
42
570
I hope they sent instructions on how to remove the damaged drivers. Seems you got a great deal. Will be interesting to see the damage on the other side of the cone.
Replacement is relatively easy apparently, 6 screws behind the logo ring on the outer surface of the face and then spade connects. Regarding the damaged drivers I am not expecting to see any visible damage as the speakers have played perfectly during the whole episode and without pointing out the damage you really wouldn't know there had been any . They sound as good as new or my ears have deteriorated to a point where I can't here anything different 😄🦻
 

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