If a system is driven beyond spec it doesn’t matter which part breaks.
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Do KEF Aluminum cone speakers have a serious design flaw?
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Roland68
Major Contributor
For over 20 years I have observed an increase in various types of damage to bass and midrange/bass drivers.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.
This is damage to surrounds, breaks/cracks in the area where the surrounds and cones transition, or breaks/cracks in the cone close to the surrounds.
This damage is caused by permanent overloading of the chassis.
Incidentally, I have often come across coil wires that have broken off in this context, causing the chassis to fail.
This can of course happen when listening to music, but in my experience it mostly happens when the speakers are used for films on a powerful AV or stereo amplifier without a subwoofer.
Out of ignorance, the main speakers are then operated without a subsonic filter and without any other limitation, often set to BIG in the AV amplifier, even though the speakers are more SMALL.
Due to the often very deep and heavy bass and low-frequency effects, most users do not even notice that they are using their speakers far beyond the permissible range.
And just because the manufacturer specifies a maximum continuous load capacity, that does not mean that it is a good idea to operate the speaker with it permanently; 50% of that is more of a value to aim for, otherwise the speakers are simply undersized for the application.
The breaks in the KEF drivers show quite clearly that KEF uses a really extremely hard alloy, which is already very perfect. The measurements also show that they have the resonances very well under control.
I would be really interested to know how much the users had to overload the chassis of the KEF speakers for something like that to happen.
I don't think it was only 10-20%.
uwotm8
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These reddit posts are made 2 or more years ago. No reputation killed so far.
But saying NO IT CAN'T BE TRUE is utter BS for sure.
Dynaudio and Morel tweeters are prone to physical damage due to both construction (dome stands out of baffle) and its structure - fabric is coated with something sticky, and if pushed a bit further it breaks and you can't totally revert it to normal shape (typical soft dome would just bounce back). A lot of used Dynaudio on sell have tweeters damaged like that. They do not apply tweeter shiled to home models as they do with pro. No reputation killed so far. Not by this, at least.
Older KEF, btw, check what happens with Q1 cones/surrounds with time. This is very common:
Looks like they're trying to become Purifi drivers, that fractal shape...
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uwotm8
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It does actually. Rewinding woofer voice coil is pretty obtainable thing even for a 3rd party service. Making new cone is not.
And now KEF are responsible for what ever genius couldn’t resist to turn the volume knob to ‘full speed ahead’ to make sure the more affordable part breaks? Come on …
terryforsythe
Major Contributor
Every one I have seen so far are two-way KEFs, such as the LS50, Q150 or Q350, without a high pass filter on the concentric mid-woofer. They are not designed to play low bass at high volume. Anyone who wants loud bass using speakers that only have a small concentric driver needs a crossover for the speakers and a subwoofer handling the bass below 80Hz-100Hz or so.These drivers do that
terryforsythe
Major Contributor
KEF needs a disclaimer that their speakers are not made for BDCs (brain-dead customers).
Yes I had vinyl player possibly a Thorens where the manual stated that should use the player outside in the rain….
I agree with previous posters that it’s probably by use of some AVR where some fool set all speakers to large even if they have subwoofers to get a more of everything
I have some R3s that I use for home theater (but they are high pass filtered at 75hz), honestly I don't worry, before I used Q350s at full bandwidth, even at high volume but without ever destroying them. I don't know what to think, if on a site like this, with a fairly large user base, many of which use kef speakers, there is no statistic of even a few of these cases, then I feel comfortable relegating the issue to a few sporadic cases of speaker abuse.
terryforsythe
Major Contributor
The majority of users in this forum have at least some fundamental understanding of speakers and, if not when they first join, obtain that knowledge fairly quickly if they are paying attention.
My guess is that the people blowing their drivers know little about speakers. They probably walked into a place like Best Buy, or went to Amazon, and purchased KEF speakers because they heard they were good, but nobody explained to them the pracitcal limits of using small drivers for low frequency bass reproduction. They ended up buying the wrong speakers for their application.
So what, a destroyed driver is a destroyed driver.
Had people come to me with this problem several times, usually its blown tweeters.
They are civilians, they assume if they pay £300 for speakers that they bought something that they can use like a P.A because £300 seems a lot for 'just speakers.' They don't understand why they have blown them 'It wasn't that loud' - but they are used to dance club sound levels.
It’s like challenging laws of physics and then complain at the Porsche dealership that I would have preferred the rims to break rather than totalling the car …
Maybe I give this a try sometime.
Maybe I give this a try sometime.
Yes there probably no elasticity to play with in the cones very rigid , the burnt coil drivers from other brands are probably equally destroyed even if the final resting position looks more ”normal” to a casual observer ? .
I provided warranty service for KEF and other speaker manufacturers for some years and sold them for 9. I saw many fried, baked and burned drivers and I saw some serious excursion abuse too. KEF is such a good company that they maybe covered these extremely abused speakers under warranty but let's get this straight, this is abuse and nothing less. Whether it be from ignorance or roudyness it is plain abuse and the owners obviously need bigger speakers.View attachment 432704
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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.
Rewinding the voice coil is now a usual thing. You apparently have no idea what you are gabbing about.
It's like reading how engines are failing while street racing. LOL The part in the article that refers to "gives no warning" is the funniest part
of all. In other words they didn't hear the driver bottoming out from overdriving it and when the cone explodes or frags they say it gives
no warning. They weren't LOOKING.
I'll bet 10 to1 there are hairline fractures in that cone before failure. Look at any off-sets on/in the cone surface; there will likely be evidence
of fractures forming. There has always been a reason to de-burr, smooth, and dampen, vibration-prone areas on surfaces subject to vibration.
The proper term in engine building is "to relieve" the parts from sharp right angles, shot peen, and then stress relieve further with heat for a
given time and THEN COOL very slowly. It's usually in an inert environment with a cooling medium like sand. Some welds can take days to
cool depending on what and where they are located.
Drill bits that need repairs or when manufactured for oil, water, or foundational work can take days to cool down if they were welded and then
stress relieved.
Everything I saw in those pictures was from abuse, whether intended or not. Transcendent POPS when shutting down, starting up, switching sources,
or using them for HT and sound effects. I suggest to anyone; to turn down the volume shutting down, switching sources, changing records, or
starting any listening session. It's just a good practice, just in case.
Regards
of all. In other words they didn't hear the driver bottoming out from overdriving it and when the cone explodes or frags they say it gives
no warning. They weren't LOOKING.
I'll bet 10 to1 there are hairline fractures in that cone before failure. Look at any off-sets on/in the cone surface; there will likely be evidence
of fractures forming. There has always been a reason to de-burr, smooth, and dampen, vibration-prone areas on surfaces subject to vibration.
The proper term in engine building is "to relieve" the parts from sharp right angles, shot peen, and then stress relieve further with heat for a
given time and THEN COOL very slowly. It's usually in an inert environment with a cooling medium like sand. Some welds can take days to
cool depending on what and where they are located.
Drill bits that need repairs or when manufactured for oil, water, or foundational work can take days to cool down if they were welded and then
stress relieved.
Everything I saw in those pictures was from abuse, whether intended or not. Transcendent POPS when shutting down, starting up, switching sources,
or using them for HT and sound effects. I suggest to anyone; to turn down the volume shutting down, switching sources, changing records, or
starting any listening session. It's just a good practice, just in case.
Regards
Yes. One time I was carrying some reasonably large standmount apeakers from car to house. A guy in the street saw them and said "wow, I bet they go loud!".
Audiophiles are just as bad though. Took the same speakers to someone's house who I was visiting for another reason, but I knew we shared an interest in audio. He wicked the volume up to a crazy high level. I asked him "Do you actually listen this loud?" He said "No..."
diddley
Addicted to Fun and Learning
The original post on reddit is from two 2 ! years ago so we can safely put no energy into this thread.
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