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KEF LS50 Meta Review (Speaker)

MarkWinston

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Do you have any in room measurement showing KC62 easily reaching 20Hz ?
Here is one I found on another forum, in room, no room correction, heavily treated with corner traps and wall panels. It is no slouch. The claimed 11hz@ -3db? Doubt it. 20hz in room? Perfectly possible. And more.
20211029_011620.jpg
 

phoenixdogfan

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Now every time I talk about "my Metas", people will think I'm referring to social media posts in Zuckerberg's utterly malignant platform. :(
 

Ata

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Yes, what was Zuck thinking, the name is the least of that company's problems...
 

MarkWinston

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Now every time I talk about "my Metas", people will think I'm referring to social media posts in Zuckerberg's utterly malignant platform. :(

Off topic for a sec...
FB_IMG_1635484130484.jpg
 

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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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Again an outstanding review thank you very much!
Would you cross them at 80Hz or 100Hz?
 

8bits

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Just registered to post that now that my setup is finalised (not really, are we ever "done" with our setup?), I am super glad to have found this forum and platform. In a sea of ignorance and myths, this is a beacon of light.

Just hooked up an SVS SB1000 Pro to my pair of Kef LS50 Metas and got goosebumps. The difference that a sub (no doubt 2 would be even better but I have limited space) made to my listening pleasure is kinda crazy and would never think it would be this dramatic.

I plugged the ports of the speakers and crossed over at 100Hz with a 18dB slope. I think this transition made more sense by looking at this audioexpress measurement:
20210630203429_Figure1-KEFLS50Meta-Measurements.png

What do you all think? The ports open option looks to be more inconsistent to crossover with a sub. Am I wrong? Be gentle with me btw, I am still learning.
 

Ata

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Just registered to post that now that my setup is finalised (not really, are we ever "done" with our setup?), I am super glad to have found this forum and platform. In a sea of ignorance and myths, this is a beacon of light.

Just hooked up an SVS SB1000 Pro to my pair of Kef LS50 Metas and got goosebumps. The difference that a sub (no doubt 2 would be even better but I have limited space) made to my listening pleasure is kinda crazy and would never think it would be this dramatic.

I plugged the ports of the speakers and crossed over at 100Hz with a 18dB slope. I think this transition made more sense by looking at this audioexpress measurement:
20210630203429_Figure1-KEFLS50Meta-Measurements.png

What do you all think? The ports open option looks to be more inconsistent to crossover with a sub. Am I wrong? Be gentle with me btw, I am still learning.

Welcome and congrats on your first post! I would say it is a well formulated question and a measurement to support it.

Your setup is very similar to mine. What Amp/AVR are you using for the bass management? How far from the back wall are the LS50Ms?
 

thewas

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What do you all think? The ports open option looks to be more inconsistent to crossover with a sub. Am I wrong? Be gentle with me btw, I am still learning.
If you used a highpass filter for your LS50M, your choice makes definitely sense, also welcome to the ASR, I also have a pair of LS50 Meta plus sub. How did you highpass the Metas at 100 Hz?
 

tvrgeek

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Just gave a pair of these a listen as they have been so well reviewed. Very strange. If in a perfect sweet spot, like a desk or control board, they are quite deserving of their reputation, but move your head a foot and imaging goes crazy. At least that is my perception. So when someone said "they built a new LS35a", that may be very accurate. Nearfield monitor. Unfortunately, not what I want in my living room and just a little big for my desk where I would very much like them.

Been listening to a LOT of speakers to see what a decade of advances has brought forth. What is out there mere mortals can afford that can beat my old DIY Seas based set? So far, not many, though the Revel M105 and Dynaudio Special 40 did impress me. Not enough to blow the dust off my coin purse yet. I may just have to give it another shot myself.

FWIW, I would never run a ported system without a HP filter to limit cone excursion below cutoff.
 

phoenixsong

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Just gave a pair of these a listen as they have been so well reviewed. Very strange. If in a perfect sweet spot, like a desk or control board, they are quite deserving of their reputation, but move your head a foot and imaging goes crazy. At least that is my perception. So when someone said "they built a new LS35a", that may be very accurate. Nearfield monitor. Unfortunately, not what I want in my living room and just a little big for my desk where I would very much like them.

Been listening to a LOT of speakers to see what a decade of advances has brought forth. What is out there mere mortals can afford that can beat my old DIY Seas based set? So far, not many, though the Revel M105 and Dynaudio Special 40 did impress me. Not enough to blow the dust off my coin purse yet. I may just have to give it another shot myself.

FWIW, I would never run a ported system without a HP filter to limit cone excursion below cutoff.
Yeah Amir did raise this point as seen from the following- "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." Also, from the diagram, directivity shrinks to about 20 degrees if you want deviation to remain within a few decibels
 

Tangband

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Just registered to post that now that my setup is finalised (not really, are we ever "done" with our setup?), I am super glad to have found this forum and platform. In a sea of ignorance and myths, this is a beacon of light.

Just hooked up an SVS SB1000 Pro to my pair of Kef LS50 Metas and got goosebumps. The difference that a sub (no doubt 2 would be even better but I have limited space) made to my listening pleasure is kinda crazy and would never think it would be this dramatic.

I plugged the ports of the speakers and crossed over at 100Hz with a 18dB slope. I think this transition made more sense by looking at this audioexpress measurement:
20210630203429_Figure1-KEFLS50Meta-Measurements.png

What do you all think? The ports open option looks to be more inconsistent to crossover with a sub. Am I wrong? Be gentle with me btw, I am still learning.
Its a good thing to plug the ports to get good integration , yes .
With only one subwoofer, I would use a steeper crossover than 18 dB/oct at 100 Hz if there is a possibility to do that .
24 or 36 dB / oct LP and HP maybe.

Two SVS in stereo with the subs near each ls50m crossed at 100 Hz could have only 12dB / oct crossover with better sound and integration than only one sub.
 

sychan

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Just gave a pair of these a listen as they have been so well reviewed. Very strange. If in a perfect sweet spot, like a desk or control board, they are quite deserving of their reputation, but move your head a foot and imaging goes crazy.

Might want to look at speakers with BMRs and/or ribbon(ish) tweeters, they tend to have nicely wide and controlled horizontal dispersion (though obviously not great vertical for the ribbon). The Philharmonic BMR is in the same price range:
 

Ata

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Just gave a pair of these a listen as they have been so well reviewed. Very strange. If in a perfect sweet spot, like a desk or control board, they are quite deserving of their reputation, but move your head a foot and imaging goes crazy. At least that is my perception. So when someone said "they built a new LS35a", that may be very accurate. Nearfield monitor. Unfortunately, not what I want in my living room and just a little big for my desk where I would very much like them.

Move your head a foot in nearfield situation and almost any speaker will sound worse or different -- not sure what is your point? At a distance of about 2.7m I get very a wide 1.6+m sweetspot, basically all of the sofa.

That is not to say the speakers don't benefit from room correction, so far my experiments with DIRAC and hand-made REW convolutions have been very beneficial to the sound.
 

BoredErica

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I think comparisons of this to 8030c or kh80 often fails to take into account the fact that being passive allows for a noise free amp. Even the kh80 is not silent. And as others have said, these look better. I think my habit of listening at an average of 65-70db makes life easier for speakers and amps. People say this speaker is very hard to drive, but if I sit 2feet from speakers at 85db, seems like I need very little power? Something like this (https://www.audiosciencereview.com/...ics-sylph-d200-amplifier-module-review.25295/) should be sufficient?
 

Tokyo_John

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I bought a KC62 to accompany my LS50 Metas a few months ago, and swapped in a MiniDSP SHD for my Topping D90. Speakers are driven by a March Audio P252 (Hypex) amp without pre-amp. Running Dirac Live with wide field correction and a calibrated mic (+boom stand) and flat target response made an enormous difference, like popping and draining my ears after being water-logged.

The SHD is crossed over at 60 Hz at the moment, mostly because I'm in a non-ideal space (moving in March to a new place) and the sub is stuck in a semi-enclosed corner cabinet...I had to cross-over at 60 Hz to get rid of localization issues. When I can place it better, I'll probably go up to 80 Hz, or higher if I can avoid localizing. Of course a stereo pair of subs allows 100 Hz + but that's not really an option for me at the moment.

My max volume level for listening is well under 90 dB-SPL, with kids around and living in Tokyo. We use it for music, TV, and movies. At these levels, the present system provides more than enough power for a medium size room. The sound field is marvelous and the bass is plenty deep and loud for my tastes/needs. I was skeptical before, but now I'm a believer. KEF knows what they are doing.

Total cost of this system is around 5 grand (USD). I don't think I can do much better at this total price point.
 

BoredErica

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Just registered to post that now that my setup is finalised (not really, are we ever "done" with our setup?), I am super glad to have found this forum and platform. In a sea of ignorance and myths, this is a beacon of light.

Just hooked up an SVS SB1000 Pro to my pair of Kef LS50 Metas and got goosebumps. The difference that a sub (no doubt 2 would be even better but I have limited space) made to my listening pleasure is kinda crazy and would never think it would be this dramatic.

I plugged the ports of the speakers and crossed over at 100Hz with a 18dB slope. I think this transition made more sense by looking at this audioexpress measurement:
20210630203429_Figure1-KEFLS50Meta-Measurements.png
What do you all think? The ports open option looks to be more inconsistent to crossover with a sub. Am I wrong? Be gentle with me btw, I am still learning.
Makes me wonder. The LS50 Meta manual suggests sealing port if speaker is too close to a wall (like with most desktop applications). Here it shows the bass response decreases with port sealed. It's possible to EQ it back but of course that puts more load on the speakers and increases changes of distortions being audible. Or maybe being near a wall/corner boosts the bass naturally and it makes up for it anyways?
 

KMO

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Yes, being near a wall boosts the bass, and the primary point of sealing the port is to reduce the mid-bass to counteract that, hopefully restoring smooth in-room response.

It's effectively a happy artefact of having the port that you can easily reduce bass by plugging it. It's not that the port is causing a particular bass problem itself - you'd always get extra bass by putting any speaker close to a wall, ported or not.

(However the port does end up unable to function if you get really close - less than port diameter clearance).

In-room, the LS50 response probably won't look much like those anechoic graphs in 8bits' posts - the "extension" area between 100Hz and 50Hz where the anechoic response drops off slowly is going to be boosted by room effects, and if you're lucky, the room response will be mostly flat there. That's what KEF is aiming at.

You can see that sort of effect in my in-room measurements I posted above. Far from ideal room, but still not far off being nearly flat to 50Hz.

index.php


So it's probably not the case that it's straightforwardly true that bunging the ports is better for sub integration. Sure, the anechoic response looks more linear, but that doesn't follow to the room.
 
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BoredErica

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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.
How far is the speaker to the wall now?
 
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