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QC Spook regarding the new KEF R Meta

Mario Sanchez

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Jan 11, 2021
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Greetings, fellow members of ASR.

I recently laid my eyes on the new KEF R Meta series, purchasing one R6 Meta unit first and ordering two more for LCR duty a few days back, which arrived earlier today. It was a pleasant surprise as the projected arrival time is quite a bit later this week, but the surprise quickly turned into a scare. The protagonist unit in this incident is an R6 Meta with Serial Number R220601302AP48B1GN. I had only thought about reporting this after the matter, so please excuse the scarcity of photographic evidence.

After setting up the pair and playing some music, I immediately noticed one of the units sounded off in the midrange. I then ran a sweep, and there were audible distortion when the sweep hit the upper mids, I decided to give the unit a quick near-field measurement, driving only the uni-Q, which gave me the result below, note that this was freehanded at ~10cm so it isn't representative of SPL@1m:
1682991092594.png

Scary, isn't it? I thought so too, so I contacted my seller to query about the possibility for an exchange, while attempting to isolate the issue.

Eyeballing the above THD sweep, the distortion anomaly happens all across the treble and decays rapidly beneath the 1KHz mark, suggesting that the tweeter was the offending component. It was then that I noticed some particulates stuck on the tweeter assembly which appeared akin to sawdust. I pulled out a lense cleaner and gave the assembly a nice gush to rid the assembly of the particulates, for who can stand the idea of dusty particles defiling their speaker? I then decided to re-measure the unit to see if it changed anything. and surprise surprise, it went away:
1682992193373.png

Now, while unpacking the speaker, I actually noticed similar particulates stuck on the surface of the particular unit's cabinet, and closer examination revealed some more of it stuck near the trim ring of one of the woofers. I carefully removed the trim ring on the woofer, and there it was (excuse the blurry photo, I'm on my backup phone and the camera isn't great)

Problem Unit.jpg

For comparison, here is the other woofer unit with the trim ring also removed:
DSC_1466.JPG

You might have noticed the difference. There are particulates in the right woofer's cutout, there were also some of this particulate stuck on the trim ring itself. Here's a closer shot, this time I pulled out a better camera. This was done after I gave the dusty side a wipedown, though you can still see the particulates in areas I can't quite reach:

IMG_20230501_210436.jpg

And again a shot of the other woofer at the same location for comparison:
IMG_20230501_210446.jpg

I also carefully removed the trim rings of the other units, and all of them were like the second photo, which reinforces my belief that the right woofer on my offending unit was the culprit of this whole incident.

Personally, my partially educated guess is that something happened during the machining of the MDF part of this unit's cabinet, resulting in a higher-than-usual amount of dust particulates in the cutout housing the woofer's trim ring. This is initially fine, as the particulates are constrained to the woofer cutout by the presence of the trim ring, meaning the speaker passes the factory QC without a problem. During transportation, however, some of these particulates went loose from vibration and handling, which would explain the curious presence of particulates inside the foam sheet wrapping of the speaker, some of the particulates ended up on the surface of the speaker, and some into the tweeter assembly, resulting in a distortion anomaly.

As of now, the speaker has been restored to functionality, and once it was clear of the distortion issues, a captivating experience ensued. I'm not the best at putting my feeling to words, so I'll leave the subjective impression to someone more well-versed than I do. I don't plan to return or exchange them, but still, I feel the need to report this issue, and let it be seen, such that if others were unfortunate enough to encounter a similar incident, they might find this information helpful, and in hopes that some revisions can be made the QC process of this speaker, reducing the possibility for episodes like these to occur in the future.

May we all find performant audio gears which we can live out the rest of our lives with.
 

HarmonicTHD

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Greetings, fellow members of ASR.

I recently laid my eyes on the new KEF R Meta series, purchasing one R6 Meta unit first and ordering two more for LCR duty a few days back, which arrived earlier today. It was a pleasant surprise as the projected arrival time is quite a bit later this week, but the surprise quickly turned into a scare. The protagonist unit in this incident is an R6 Meta with Serial Number R220601302AP48B1GN. I had only thought about reporting this after the matter, so please excuse the scarcity of photographic evidence.

After setting up the pair and playing some music, I immediately noticed one of the units sounded off in the midrange. I then ran a sweep, and there were audible distortion when the sweep hit the upper mids, I decided to give the unit a quick near-field measurement, driving only the uni-Q, which gave me the result below, note that this was freehanded at ~10cm so it isn't representative of SPL@1m:
View attachment 282891
Scary, isn't it? I thought so too, so I contacted my seller to query about the possibility for an exchange, while attempting to isolate the issue.

Eyeballing the above THD sweep, the distortion anomaly happens all across the treble and decays rapidly beneath the 1KHz mark, suggesting that the tweeter was the offending component. It was then that I noticed some particulates stuck on the tweeter assembly which appeared akin to sawdust. I pulled out a lense cleaner and gave the assembly a nice gush to rid the assembly of the particulates, for who can stand the idea of dusty particles defiling their speaker? I then decided to re-measure the unit to see if it changed anything. and surprise surprise, it went away:
View attachment 282893
Now, while unpacking the speaker, I actually noticed similar particulates stuck on the surface of the particular unit's cabinet, and closer examination revealed some more of it stuck near the trim ring of one of the woofers. I carefully removed the trim ring on the woofer, and there it was (excuse the blurry photo, I'm on my backup phone and the camera isn't great)

View attachment 282895
For comparison, here is the other woofer unit with the trim ring also removed:
View attachment 282896
You might have noticed the difference. There are particulates in the right woofer's cutout, there were also some of this particulate stuck on the trim ring itself. Here's a closer shot, this time I pulled out a better camera. This was done after I gave the dusty side a wipedown, though you can still see the particulates in areas I can't quite reach:

View attachment 282897
And again a shot of the other woofer at the same location for comparison:
View attachment 282898
I also carefully removed the trim rings of the other units, and all of them were like the second photo, which reinforces my belief that the right woofer on my offending unit was the culprit of this whole incident.

Personally, my partially educated guess is that something happened during the machining of the MDF part of this unit's cabinet, resulting in a higher-than-usual amount of dust particulates in the cutout housing the woofer's trim ring. This is initially fine, as the particulates are constrained to the woofer cutout by the presence of the trim ring, meaning the speaker passes the factory QC without a problem. During transportation, however, some of these particulates went loose from vibration and handling, which would explain the curious presence of particulates inside the foam sheet wrapping of the speaker, some of the particulates ended up on the surface of the speaker, and some into the tweeter assembly, resulting in a distortion anomaly.

As of now, the speaker has been restored to functionality, and once it was clear of the distortion issues, a captivating experience ensued. I'm not the best at putting my feeling to words, so I'll leave the subjective impression to someone more well-versed than I do. I don't plan to return or exchange them, but still, I feel the need to report this issue, and let it be seen, such that if others were unfortunate enough to encounter a similar incident, they might find this information helpful, and in hopes that some revisions can be made the QC process of this speaker, reducing the possibility for episodes like these to occur in the future.

May we all find performant audio gears which we can live out the rest of our lives with.
Contact KEF directly so they can sort it.
 
OP
Mario Sanchez

Mario Sanchez

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Contact KEF directly so they can sort it.
The glitch has been resolved, so there needn't be a RMA case, but I am curious if there's a better way for end-users to report possible product concerns (I already included the SN, so if they wish to track it down it should be possible) to KEF. I am leaving country by the end of the week and won't be back for a few months, so if it needs to be sent somewhere for inspection I'll have to do it quick...
 

jackocleebrown

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The glitch has been resolved, so there needn't be a RMA case, but I am curious if there's a better way for end-users to report possible product concerns (I already included the SN, so if they wish to track it down it should be possible) to KEF. I am leaving country by the end of the week and won't be back for a few months, so if it needs to be sent somewhere for inspection I'll have to do it quick...
Hi Mario, thanks for reporting this issue. I've raised it internally and we'll figure out how it happened. Just to confirm, those particles look like sawdust?
 

SDC

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20230417_163950.jpg

20230417_163908.jpg

I had similar problem. But my case 3rd HD was the problem. I returned the unit so don't know what caused it.
 

fineMen

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Yes, the particles appears to be sawdust, they are also quite fine in size.
As a DIYer I used many times tweeters that were full of debris. A raise in distortion was never observed. It could be a decentered voice coil aka rub 'n buzz that just healed itself (for some time?) with changing temperature or any other unknown reason. I would return the item anyway.
 

jackocleebrown

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I had similar problem. But my case 3rd HD was the problem. I returned the unit so don't know what caused it.
Hi SDC, sorry that you also had problems. Was this also an audible buzzing in your case too?
 

SDC

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Hi SDC, sorry that you also had problems. Was this also an audible buzzing in your case too?

In my case sine sweep sounded weird. No other buzzing noise.

Didn't listen to music cause I tested the moment I got the center.
(TMI, but had same problem with Salon 2 so I always test before listening.)
 
OP
Mario Sanchez

Mario Sanchez

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As a DIYer I used many times tweeters that were full of debris. A raise in distortion was never observed. It could be a decentered voice coil aka rub 'n buzz that just healed itself (for some time?) with changing temperature or any other unknown reason. I would return the item anyway.
It might have to do with KEF's fairly intricate design around the tweeter part of its drivers, which would give a tendency for particles stuck inside it to throw a proverbial brick into the operation of the system. It's just that there also happens to be particulates on the driver and the cabinet, apparently of an internal origin, likely expelled after factory QC, and a dusty cabinet cutout which could have given rise to these particles. It's like a "smoking gun" situation.
 
OP
Mario Sanchez

Mario Sanchez

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Hi SDC, sorry that you also had problems. Was this also an audible buzzing in your case too?
I'll amend that my unit wasn't buzzing either, the sweep sounded conspicuously colored like my recently retired JBL 306P, which also had a THD rise in the upper mids section, and unlike the first R6M unit I received, which is what prompted the measurement.
 

fineMen

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It might have to do with KEF's fairly intricate design around the tweeter part of its drivers, which would give a tendency for particles stuck inside it to throw a proverbial brick into the operation of the system. It's just that there also happens to be particulates on the driver and the cabinet, apparently of an internal origin, likely expelled after factory QC, and a dusty cabinet cutout which could have given rise to these particles. It's like a "smoking gun" situation.

How would you know that the debirs didn't creep into the voice coil gap also? You do what you like. I'm a fanboy of K.E.F's, and so expect them to be very genererous when somebody calls out a fault that a regular customer wouldn't indentify objectively, but more 'feel' as a quality degradation.
 
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Mario Sanchez

Mario Sanchez

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How would you know that the debirs didn't creep into the voice coil gap also?
That would be a possibility, but if it did then I'll know what hit me, and the eventual RMA process would probably be faster with a known suspect.
 

Descartes

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QA&QC are absolutely critical, too bad not all speakers benefit from it!
 
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