Do KEF Aluminum cone speakers have a serious design flaw?

[PHD]

It seems that when driven too hard, even for a short burst under normal use, they can blow out and even inflict an injury.

KEF Speakers Are Blowing Out at an Alarming Rate, and Nobody Sees It Coming Until Its Too Late

What’s causing these sudden blowouts, and how can you avoid them?

www.headphonesty.com

Has anyone seen this happening? Perhaps, Amir should try to replicate it and provide the conditions leading to this.

I just got a used pair of R3, and I'm starting to worry that it could happen to me.

 

[kharan]

Your crossover is at 400 Hz, it should be quite safe.

Though owners of two ways should be careful.

 

[RickS]

This article sniffs too much like clickbait. What is the alarming rate and many admit they were pushing the speaker hard?

No actual testing, conjecture with regard to the design AND a rush to judgement before getting a KEF response. Author has no technical background and does not consult any more credible technical source(s).

Given how many own KEF speakers here, does ASR have any reported instances? I would not be worried.

 

[Doodski]

This does not appear to be normal operation.

 

[PGansz]

So an idiot played bass heavy music as loud as possible, clipped his amp and blew out his driver after what...20, 30, 50 times doing this on a $350/pair of speakers?

Then a clickbait article gets written.

Nice.

 

[ssashton]

I'd guess all the photos at the top of the article are not caused by voice coil overload. Those cones have been physically hit or pulled apart by fingers.

 

[sq225917]

There's a reddit thread that collects all the examples on the web, 15 since they first introduced them, its a nothing burger and $hit journalism and that's why I've blocked the source from my media feeds.

 

[sq225917]

I'd guess all the photos at the top of the article are not caused by voice coil overload. Those cones have been physically hit or pulled apart by fingers.

No they've been torn apart by smashing them into the end stops. The surround is quite restrictive and that contributes to the damage when hideously overdrive.

 

[Old_School_Brad]

No they've been torn apart by smashing them into the end stops. The surround is quite restrictive and that contributes to the damage when hideously overdrive.

Yeah, overdriven drivers -no doubt about it. There might be something to the rigidity and restrictive surround combined with a metal cone, but in the end, overdriven speakers will always self-destruct.

This isn't the manufacturer's fault; it's user error.

 

[Mart68]

Probably the only thing the article gets right is the driver not giving any hint it's being pushed too hard before it blows.

People have been blowing drivers since the dawn of time thinking they can take a dinky little speaker and a 30 watt amp and crank it up without end. Nothing new here.

 

[ssashton]

No they've been torn apart by smashing them into the end stops. The surround is quite restrictive and that contributes to the damage when hideously overdrive.

It surprises me the VC can apply such a force, even if only once!

 

[terryforsythe]

I just got a used pair of R3, and I'm starting to worry that it could happen to me.

Don't act like Marty. Use common sense and you will be fine. If you hear audible distortion, turn down the volume.

 

[terryforsythe]

Perhaps, Amir should try to replicate it and provide the conditions leading to this.

No need to. The conditions are blatantly obvious.

 

[Old_School_Brad]

Don't act like Marty. Use common sense and you will be fine. If you hear audible distortion, turn down the volume.

That video’s audio is quite different from the movie. Just saying.. (Watch till the end).

 

[BeeKay]

The problem in a nutshell

 

[thegeton]

I have 3 different pair of KEF speakers some over 5 years old; play them robustly; often; and have had zero issues.

YMMV

 

[uwotm8]

This sniffs too much like clickbait. What is an alarming rate

This does not appear to be normal operation

So an idiot played bass heavy music as loud as possible, clipped his amp and blew out his driver after what...20, 30, 50 times doing this on a $350/pair of speakers?

You can just check google or reddit or whatever.
Yes, this does not happen on "normal" volumes.
Typical case is "I forgot that my amp was set to high volume and pressed play button".
But sometimes it's described as not max volume and not "very high" (all credits to authors).

This problem exist from from the moment LS50 and Qx50 hit the market and this is not a clickbait.

So yep... basically be careful with 2-way KEF, at least LS50/Q150/Q350, they can go reversed cone mode.

AFAIK ceramic Accutone drivers tend to shatter if overpowered and again it's not a clickbait.

 

[007Shorty]

I doubt that these reports are accurate. It seems like someone blew compressed air into the port.

If there is any truth to this, this type of damage requires enormous mechanical stress. This could then lead to work hardening, embrittlement and eventual breakage of the aluminum alloy.

With a thermal imaging camera you should be able to see the work hardening process of the membrane. I would expect a thermal pattern on the membrane due to the stiffening ribs. Since the membranes appear to be anodized, the infrared emission coefficient should be around 0.8 and the waste heat should be easily visible. I think @amirm has such a camera, right?

 

[uwotm8]

https://www.reddit.com/r/audiophile/comments/1371xf9/blown_drivers_on_a_pair_of_kef_ls50s_posted_on

https://www.reddit.com/r/hometheater/comments/zw1rlw/blown_kef_speakers

https://www.reddit.com/r/audiophile/comments/18fjp3m/blown_kef_ls50_meta

https://www.reddit.com/r/KEF/comments/yv98te/so_this_happened_last_night

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The defence of "KEF believers" is kinda funny tho; iconic Steve Jobs' "you're holding it wrong" is the first thing what comes to mind.
These drivers do that
And any driver can be destroyed by overpowering, but it's rarely looks like that. There's enough "overpowering driver crash tests" on YouTube and what happens mostly is just a burned coil, not a cone damage.

 

[BeeKay]

Is this some new TikTok style suicide hype? How to kill a brand’s reputation with a smile? Utter BS to me.