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KEF LS50 Meta Review (Speaker)

Descartes

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Here are the requested 7.1 pics (of 5 of them at least).

View attachment 148029 View attachment 148030

Amplification comes from Denon AVR-4308 (with Audyssey Pro kit). The AVR-4308 seems to be fully capable of driving 7 LS50s - I understand they don't make receivers like that any more. I had initially thought I might need to splash for a multichannel power amp, but the money went on the KEF KF92 subwoofer instead.

Because the stands are short for the surrounds, I have to remove the sofa headrests for optimum critical listening. But on the other hand the low height helps to make them unobtrusive enough to not get objections to having speakers standing everywhere. (Previous set up was 5.1 KHT2005 on their slim pole stands, with surrounds tucked in the corners, so the LS50 Metas are comparatively obtrusive).

Crossover is currently set to 80Hz for all speakers. Left side of TV has a 50Hz null (hitting L speaker and the potential left-of-TV sub position), and right side of TV has a 110Hz null (hitting R speaker and current sub position). With 80Hz crossover, 50Hz comes mainly from the sub on the right, and 110Hz can come from L and/or C, even if it's nulled for R.

LS50s get a mixture of port bung choices, based on REW checks, to try to equalise direct response (no Audyssey and/or bass management). R gets a half bung for being a bit too close to a corner; SL and SBR get full bung for wall/corner placement; SBL and SR are next to open doorways, which apparently means they need no bung.

Still plenty of scope for more experimentation on placement and room treatments - but at least the speakers are sorted!

Interestingly, out of a sample of 8 speakers, one turned out to be faulty - one of the first (and oldest) pair that came from the dealer's stock. Took a while to conclude it actually was faulty, not just a weird room artefact from that front right corner, but checking REW measurements confirmed it:

View attachment 148036

That measurement was at 80dB, 30cm. Turns out a 2%+ distortion peak was not super-obvious, at least to me, but it did eventually niggle me enough to make me investigate. (There was no corresponding significant frequency response flaw). No problem getting it replaced on warranty, and the original was sent back to KEF's Maidstone HQ for investigation. Apparently a failed crossover.
How does it sound with action movies
 

KMO

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How does it sound with action movies
It seems like more than enough for me. But I've never owned anything more powerful, so maybe I don't know what I'm missing. :) This was an upgrade from the KEF KHT2005.

Can certainly go up to levels where I'm quite uncomfortable about disturbing the neighbourhood. If I wanted to go louder, I'd go to an actual cinema. They seem to keep up with the subwoofer - I'd probably want to turn that down or pop it in "apartment" mode first before cranking the system up further.

(Okay, that's not very quantitative. Let's say up to -10dB on the master volume, which I believe should mean -10dB from reference after Audyssey Pro calibration. I believe it tries to get to reference. It certainly set all trims higher with the LS50 than the KHT2005, corresponding to their lower sensitivity).

That's with centre 2.0m from main listening position, and the L+R just a tad further away.
 

Descartes

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It seems like more than enough for me. But I've never owned anything more powerful, so maybe I don't know what I'm missing. :) This was an upgrade from the KEF KHT2005.

Can certainly go up to levels where I'm quite uncomfortable about disturbing the neighbourhood. If I wanted to go louder, I'd go to an actual cinema. They seem to keep up with the subwoofer - I'd probably want to turn that down or pop it in "apartment" mode first before cranking the system up further.

(Okay, that's not very quantitative. Let's say up to -10dB on the master volume, which I believe should mean -10dB from reference after Audyssey Pro calibration. I believe it tries to get to reference. It certainly set all trims higher with the LS50 than the KHT2005, corresponding to their lower sensitivity).

That's with centre 2.0m from main listening position, and the L+R just a tad further away.
How loud do you watch movies at SPL?
 

KMO

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I think dialogue was around 75dB when I checked, which is what I'd expect at -10dB from reference. Peaks should then be up to 95dB on mains.

I'd play music somewhere between 75dB and 85dB - I remember checking that more precisely. Top end of that is getting a bit loud for continuous playback.
 

tusing

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So my pair was the one that got sent into Amir for review. I finally had the chance to set them up this weekend. Running these with a KC62 sub in wireless mode. First impressions were... meh.

Then I moved the speaker forward two inches. Apparently the wall was far too close to the rear port, because the sound instantly transformed into some of the most beautiful sound I have ever heard. It's the first time music has brought me to tears in a long time. Certain items in music (papers shuffling, door knocks) felt so real that I would jump thinking someone is in my apartment at 4 AM.

These are incredible speakers. Proof that research and audio engineering works. And I honestly don't feel the need to use room correction. As Amir's measurements show, these play well with rooms.
 

Descartes

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So my pair was the one that got sent into Amir for review. I finally had the chance to set them up this weekend. Running these with a KC62 sub in wireless mode. First impressions were... meh.

Then I moved the speaker forward two inches. Apparently the wall was far too close to the rear port, because the sound instantly transformed into some of the most beautiful sound I have ever heard. It's the first time music has brought me to tears in a long time. Certain items in music (papers shuffling, door knocks) felt so real that I would jump thinking someone is in my apartment at 4 AM.

These are incredible speakers. Proof that research and audio engineering works. And I honestly don't feel the need to use room correction. As Amir's measurements show, these play well with rooms.
Great to hear did you have LS50 before or is this your first pair? I just wonder how much better the LS50meta are vs the original LS50! Are they worth the upgrade?
 

tusing

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Great to hear did you have LS50 before or is this your first pair? I just wonder how much better the LS50meta are vs the original LS50! Are they worth the upgrade?
I had the old pair and sold them. I find the Metas more clear with more body. But then again, I'm running the Metas without the Audessey EQ, which has a target curve that can make speakers sound thin. I'm also running them with sand filled speaker stands. So it's not directly comparable.
 

Descartes

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I had the old pair and sold them. I find the Metas more clear with more body. But then again, I'm running the Metas without the Audessey EQ, which has a target curve that can make speakers sound thin. I'm also running them with sand filled speaker stands. So it's not directly comparable.
Thank you for your answer and sending them to Amir!

I was wondering didd you listen to the speakers one after the other with the same:
- music recording
- volume level
- room
- environment
- equipment…
and in a blinded manner where someone else was changing the speakers for you?

If not then it is completely subjective!
 

tusing

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Thank you for your answer and sending them to Amir!

I was wondering didd you listen to the speakers one after the other with the same:
- music recording
- volume level
- room
- environment
- equipment…
and in a blinded manner where someone else was changing the speakers for you?

If not then it is completely subjective!
Agreed, that's why I don't really feel comfortable comparing them. The Metas were first and foremost an aesthetic upgrade for my new place, in which the black LS50s I previously had were not an option.
 

Descartes

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Agreed, that's why I don't really feel comfortable comparing them. The Metas were first and foremost an aesthetic upgrade for my new place, in which the black LS50s I previously had were not an option.
Yes the new ones look very cool!
 

Descartes

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This is a review and detailed measurements of the KEF LS50 Meta bookshelf coaxial speaker. It was kindly purchased new by a member and drop shipped to me and costs US $1,500 for a pair.

The LS50 Meta comes in different colors and I must say, it looks stunning in white:

View attachment 145854

You could sell it as a decoration piece and it would still sell strongly!

Even the back panel oozes beauty and custom design:

View attachment 145855

Love the wide apart binding posts that are easy to tighten and loosen.

Speaker also feels quite dense and solid which is good.

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

I performed over 1000 measurement which resulted in error rate of about 1%. Clear high frequency response is responsible for ease of measurement in this regard.

Reference axis is approximately the center of the tweeter.

KEF LS50 Meta Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:

View attachment 145856

Ah, close to perfection. The only issue is the roughness in the crossover region with some hills and valleys. Directivity which is a metric of how close off-axis sounds are to direct on-axis (what hits your ears first), is very good as well.

The above is substantially better than older LS50 which had an uneven frequency response.

Sensitivity is low at around 83 dB or so.

With both drivers co-located, I could not separate their response but could provide the port/cabinet contributions:

View attachment 145857

I can't figure out that bump around 1.5 to 2 kHz. Could be resonance from the woofer that we can't see.

Back to our spin measurements, here are the off-axis responses:

View attachment 145858

Put that together with on-axis and we get one well behaved speaker:

View attachment 145859

We can see the well managed directivity control better in beam width and horizontal directivity:
View attachment 145861

View attachment 145860

The price you pay for this is slightly narrow directivity of ± 50 degrees instead of the usual ±60 degrees. So I suggest pointing the speaker at you.

Vertically the coaxial driver cleans the clocks of any standard 2-way speaker:

View attachment 145862

So not very critical if you sit at the level of the tweeter or not.

Looking at the mid frequency 3-D directivity balloon, we see the best response since I started showing it (which hasn't been long as of this writing):
View attachment 145866

The globes are not very deformed and nicely project energy forward.

Company touts lower distortion for this speaker versus the old KEF LS50. Let's look at that:

View attachment 145863

View attachment 145864

Looks like distortion in from 200 Hz and up is excellent but down low, even at 86 dBSPL, we hit 100% THD. Unfortunately I don't have comparable measurements for LS50 as that was a long time ago before I standardized this way.

Impedance is quite low at 3.7 ohm and stays there for good bit of the spectrum:
View attachment 145865

Combined with low sensitivity, you need to have a beefy amplifier to drive them.

Finally, for the fans of timing graphs, here are the impulse and waterfall responses:

View attachment 145867

View attachment 145868

KEF LS50 Meta Speaker Listening Tests
I always test speakers with the same set of tracks and in the same order. Usually the first few seconds of the first track tells me most of what I need to know about the sound of the speaker and this situation was no different. The sound was "right" and very nice. For confirm I went through the rest of my test playlist and the answer stayed the same.

Wanting to see the effect of the dips in 1 to 3 kHz, I developed a single filter at 1189 Hz. Getting it to fill that gap requires a Q of something like 7. At that level, turning it on and off showed such basically non-existent difference as predicted by psychoacoustics. We just don't have that kind of disorientation in frequency in that range. I suppose if you wanted to be anal about it, you could fill the holes. It wouldn't make things worse and maybe the combination would make more of a difference. For me, it wasn't worth the time. :) I was happy with the speaker as is.

Was it all perfect? No. As I turned up bass heavy track, the low bass notes change their tonality and quickly become distorted. Notch the volume even higher and you are greeted with scary crackle. You can visually see this in the driver. It separates from the tweeter which is kind of disconcerting but that is how the coaxial driver works. By the time you see any significant separation/movement of the woofer, the bass starts to change. Push it to move more and you are in distortion territory. The driver is simply too small/lacks the excursion for high dynamic range.

That said, I had no trouble getting usable volume out of one speaker. With two speakers, it would be plenty for most people. Problem is, I am not most people. :) I don't want to know limits of equipment I use.

Conclusions
KEF moves the bar it set with the LS50 with the Meta revision. I was not a fan of the original but they have won me over with near perfect measurements and listening test results. Make this speaker handle more dynamics in bass and I would kiss the ground it walks on. But that is not there so a notch lower for me. But really, this is an excellent speaker. No doubt about that.

I am happy to recommend the KEF LS50 Meta. Suggest pairing it with a subwoofer if you want to play loud bass though.

Edit: video review posted as well:


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Thank you for such great reviews, i have learned so much since reading your reviews!

It makes me wonder if I should sell my old LS50 and then buy the new LS50 Meta or just get the Revel F35?

Since you reviewed both I suspect that you have a preference!
 

BrokenEnglishGuy

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Thank you for such great reviews, i have learned so much since reading your reviews!

It makes me wonder if I should sell my old LS50 and then buy the new LS50 Meta or just get the Revel F35?

Since you reviewed both I suspect that you have a preference!
It depend.. If you really like the small point source in the middle presentation from the ls50/mm the f35 gonna sound like a tower..., for some its a good thing and for other a bad thing.
 

Descartes

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How loud can one listen to the KEF LS50 meta crossed over at 100HZ with subs before it starts distorting!
 

Descartes

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Relative newbie to the audio world and truly amazed by the level of knowledge many of you exhibit.

I currently have the LS50 Meta paired with a single KC62 and am pleased with their performance in a relatively small listening room. My question is what would the ideal Low Pass as well as High Pass setting be. I’m running a Parasound New Classic 200 integrated that gives me the option to set both.
How loud do you listen to?
 

Ata

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How loud can one listen to the KEF LS50 meta crossed over at 100HZ with subs before it starts distorting!

In my 96 cubic meter room, sitting about 2.6m away from the Metas supported by a 12" sealed sub crossed at 100Hz, it gets very loud without distortion picking up noticeably. How loud, I'd need to measure.
 

MarkWinston

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In my 96 cubic meter room, sitting about 2.6m away from the Metas supported by a 12" sealed sub crossed at 100Hz, it gets very loud without distortion picking up noticeably. How loud, I'd need to measure.
Please do measure as Im seriously considering the Metas to replace my old LS50s and I would like to know if it would play louder than the OGs before audible distortion. TIA!
 

Descartes

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In my 96 cubic meter room, sitting about 2.6m away from the Metas supported by a 12" sealed sub crossed at 100Hz, it gets very loud without distortion picking up noticeably. How loud, I'd need to measure.
Please do!
 

phoenixdogfan

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I really don't think you'll be disappointed with the slam and dynamic range of the Metas + a 12 inch sub (either SVS or Rhythmic). Just be certain you have something that will do both high and low pass filters in order to take the burden off the Metas mid/woofer. I would see about giving both a listen. The Metas are much better than the OG LS 50s which I also own (and have since 2015) IMHO.

BTW, I'd be extremely careful about mating either speaker with the KC62. At best, it's a woofer, not a sub. Even if it can produce sub 40 hz frequencies, it will produce them at such a low level that it will be useless for movies, and also probably for a lot of music as well. Kef also has a dual 9 inch KC 92, and that would be the one to have if you're interested in a Kef sub.
 
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MarkWinston

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I really don't think you'll be disappointed with the slam and dynamic range of the Metas + a 12 inch sub (either SVS or Rhythmic). Just be certain you have something that will do both high and low pass filters in order to take the burden off the Metas mid/woofer. I would see about giving both a listen. The Metas are much better than the OG LS 50s which I also own (and have since 2015) IMHO.

BTW, I'd be extremely careful about mating either speaker with the KC62. At best, it's a woofer, not a sub. Even if it can produce sub 40 hz frequencies, it will produce them at such a low level that it will be useless for movies, and also probably for a lot of music as well. Kef also has a dual 9 inch KC 92, and that would be the one to have if you're interested in a Kef sub.

The KC62 isnt as bad as you put it, it does 20ish hz easy. Its struggles to do 11hz as claimed by KEF, 30s is a walk in the park for them. It isnt a woofer like some budget 200 bucks sub.
 

Ata

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I have measured my setup (LS50M + SVS SB-1000 Pro driven by Denon X2500H) using REW and UMIK-1. The AVR's Audyssey is ON FLAT and calibrated using the UMIK-1 and the iOS app with the mid-frequency hole removed. MLP is approximately 2.7m from the speakers.

My methodology is probably questionable, but for the record I simply measured, separately, both speakers from Audyssey Reference Level (REF) -10db to +2db in 2db increments. I am not sure what it is but suspect it is 90db SPL at MLP. I could not and did not eliminate the distortions caused by the room, merely observed the point where distortions rise objectively speaking.

It seems distortion kicks in around REF-2db (around 88db SPL) and becomes objectionable around REF level. REF+2db distortion is objectively and subjectively too much.

For stereo listening, this translates to:

- 94db (88+6) SPL at my MLP position at 2.7m;
- 102db (88+6+8) SPL roughly if MLP were 1m from both speakers.

Since I normally listen to music at no louder than 80db that gives me 10-15db spare before serious distortion kicks in.

EDIT: Note, my 88-90db SPL distortion breakup at MLP is comparable SPL to the 96db/1m that Amir used in his review. The distortions I see are higher, probably because of the different measurement method. :)
 

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