Hardware reliability issues with the KEF LS-50W

This morning I came to play my music via. Roon as normal and I noticed a lot of distortion on mid-highs in the right speaker. At first I thought it was just me (I’d not yet had my morning coffee) but it became increasingly obvious something was wrong. So, to cut a long story short, the KEF’s appear to have developed a fault in the right speaker. There isn’t any noticeable noise from the speakers when music isn’t playing. It is only when the drivers are having to produce sound that the distortion is audible. This suggest to me that’s something has happened to the tweeter driver? I’ve no idea what as nothing has changed overnight.

To be absolutely certain it wasn’t something else I’ve spent the best part of today troubleshooting (trying Roon and Audirvana, ethernet/optical/USB inputs) and the issue is there in all cases.

@DarwinOS I think this was slightly different to your issue?

Anyway, I am now waiting to hear back from my dealer. But, for now, it looks like these will be going back. I’ve only had them 6 weeks.

Quick update: spoke with the dealer who are going to take this up with KEF. The speakers will be getting boxed up and sent back to the KEF in the coming days (hopefully by end of this week). Fortunately my dealer is going to arrange pick-up and delivery costs.

My dealer did confirm that they’ve had one other pair of KEF’s back as faulty. But he did qualify this by pointing out that they have sold a lot of them.

I have been using these speakers daily for 5 weeks. I’d estimate they’ve got about > 200 hrs on them.

Sounds like what was going on with mine and others.
Good on your dealer for paying shipping.
It would be nice to know what is going wrong inside that speaker and if Kef has fixed it in manufacturing.

Well, it’s definitely an issue with the KEF’s as the rest of the AV chain feeding them is now feeding my Naim/Tannoys as a stand-in and it all sounds fine to me (just as an aside, this set-up sounds pretty damn good if a little more laid back than the KEFs).

I didn’t notice any issues with bass, etc. it was mainly distortion of vocals and anything higher frequency than that.

Yes, I’ve got a good dealer so I will be discussing ‘options’ with them; I’m not just going to accept a repair on them.

Yes I’m assuming it’s the Kef’s. Everyone I have seen with this issue, including me, has gotten brand new speakers. I don’t think they even try to repair them. It’s pretty bad to think they might go out again though and the warranty isn’t very good at all. Good thing I got them with a credit card that doubles the warranty.
Kef must know at this point what is causing the problem. Too many people reporting the same thing.

Has anyone contacted KEF for comment on this reliability issue? I was considering these recently but have gone right off the idea now to the extent that I am not even looking at the passive versions. Dynaudio are favourites to get my money as a result.
Posting these back to the supplier would be expensive (no dealers near me).

1 Like

Hmm major bummer must be v frustrating. Is it just Sod’s law applying here that two of the more active members of this kef space have seen these similar issues? Hope so.

Separately I was going to ask when the kef LS50 wireless icon appeared in the signal path. Has it been there a while… ? I didn’t notice it previously sitting in last place straight after my SMS-200.

I will be asking my dealer this exact question. If I am not satisfied that KEF have a credible answer that sufficiently re-assures me I will be seeking to replace them. It’s a real shame as I am sitting here listening to Daft Punk on my Naim/Tannoy set up and whilst the sound is fine it is lacking the presence and transparency of the KEFs.

We were just talking about this. Synchronicity strikes. Sorry for the jinx.

Aye… I am a bit surprised to be honest. I wonder if its the 25W Class A/B amp driving the tweeter. Even at such a low wattage it will still be putting out the heat and if its not cooling sufficiently well then that’ll bugger up the voltage regulators in no time. Still, I’d expect an amp to last a bit longer than 5 weeks (if indeed it is that amp).

I have emailed Kef UK for a comment on the issue. If these can fail at the 200h mark then there is a serious design or poor quality component issue.

1 Like

I’ve a set in a box I’ve bought s/h waiting to be set up once we get back into our house post renovations.

I do hope this is a 0.002% problem and the 2 sets mentioned here are those!


I just received a pair of new LS50W from Crutchfield. I intentionally bought from them because they have a clear 60 day return policy for $10 return shipping. I previously demoed them at home overnight. Have been burning them in for the past few days but they do sound fantastic - holographic 3d soundstage is the primary improvement for me, along with a lot more presence and energy throughout the frequency range. But the reliability issues are a real concern and have me thinking I should buy from a local dealer in case I need to return them for service/replacement …

Another update: my dealer has been in discussion with their KEF representative. Plan is as follows:

  • KEF are currently testing out a brand new pair and as long as they are satisfied they will then be sent out to me. Not sure what they can test here that is going to help as the speakers have been fine up until the ~200hr mark.
  • The faulty pair will be collected at the same time that the new pair are delivered.
  • Once KEF have received my faulty pair back they are going to investigate. My dealer has asked for an official statement from them on the reason for the failure.

I sent a few weblinks to my dealer to forward to KEF about failures and concerns about their reliability (incl. threads from this site).

Will update further as and when things progress.


I got thus problem (right speaker…distortion on vocals) straight after updating the firmware (to latest from factory original). The problem is intermittent (goes away for a while if the right speaker is disconnected from the mains power for a while). I have contacted Kef and think the problem is firmware…not hardware related. I told them that I will return the speakers after the next firmware update (If that occurs before the warranty runs out!). Looks like the problem is systemic and luckily not just my pair.
Thanks guys.

1 Like

Interesting. Mine had distortion constantly even after being switched off for a while. So firmware suggests the DSP screwing up somewhere? Or in the DAC stage? I’d be cautious here and ask for a replacement pair. As much as a systemic firmware problem is a better outlook than hardware until Kef can categorically and definitively say as such then I’d get the hardware replaced.

Incidentally I’ve been on the latest firmware since new and my problems only occurred 5-6 weeks later.

Yes you are right…I spent ages trying to pin down the fault, once it was spotted (and tried everything I could possibly think to try…resets, renewing app settings, using all input types etc.!). The firmware update may have just been a coincidence. Now all I do is listen for the fault…so I don’t use the speakers for pleasure any more and mostly leave them off!

I’ve just sent a link to this forum thread as a PS addition to my email correspondence with Kef support.

I live in London (UK) and may take the speakers back to the factory soon (I purchased them from the factory in April) + I’m a retired electronic engineer and after the warranty runs out (April 2018), and if new problems occur, will rip then apart! Meanwhile I will wait a little longer to see if they come up with anything.


1 Like

Ahhh… how much I’d love for you to have a peek inside your faulty set before they go back… :slight_smile: guess I’ll have to wait until you warranty expires!!! Very interested to know what components they’ve used for the Class A/B and D amps… (sad I know).

That’s a real shame. The only reason I’m not listening to mine right now is because they are boxed up ready for collection at the end of the week.

I threw the boxes away…my last KEF speakers lasted for 20 years (passive…so no flaky software/firmware/apps used!) Being rare and expensive these speakers will never get an ‘IFIXIT’ teardown so DIY surgery to them could be great ‘fun’. Anyway let’s hope that it’s not the tweeters (the non-wireless LS-50’s cones seem to be robust?)

1 Like

I updated the firmware today (9-Oct-17) MCU v2.3.0, WiFi v1.1.4, DSP v0.54 and the my fault was worse straight afterwards.
Could be that some right speaker circuitry gets hot during firmware updates (just my latest theory!)
Anyway time for them to go back…they are OK still from a cold start (from mains disconnected) but the distortion comes back after a while (and a few standbys to on switches using the remote)