KEF LS50 Meta Review (Speaker)

[killdozzer]

This doesnt need to be scientific, its just an opinion of a LS50 owner. The LS50 are hard to drive speakers for its size and category, and will bloom with more powerful and pricier amps. Some speakers dont change much with an increase of power, the LS50s do. It will work with lesser amps, but it definitely start singing with pricier amps. What makes you think only totl speakers possess this trait?

Pricey has nothing to do with it. A bit stronger, yes, but getting a 2x90 Yammy that measures well with low resistance and has been tested down to 2 ohm will do everything you need for LS50.

See this is my rather cheap 2x110 into 8 Yamaha:

I got it for 150€ second hand. My LS50's wish for nothing. Going for some boutique 2x110 and paying 8x the price might give me nothing but sound signature.

 

[MarkWinston]

Pricey has nothing to do with it. A bit stronger, yes, but getting a 2x90 Yammy that measures well with low resistance and has been tested down to 2 ohm will do everything you need for LS50.

See this is my rather cheap 2x110 into 8 Yamaha:
View attachment 156606

I got it for 150€ second hand. My LS50's wish for nothing. Going for some boutique 2x110 and paying 8x the price might give me nothing but sound signature.

To me, TO ME, more power equals pricier, which is generally a true statement. Im in no way saying you have a to buy a fancy pancy amp for the ls50 but it excels with way more powerful amps. Your ls50s wish for nothing more, until you feed it a beefier amp. I thought my Rotel RC-1572 MKII pre and RA-1552 MKII power amp do an excellent job, until I recently fed it with an Anthem MCA 225 Gen 2 I borrowed from the dealer here. At volume, no comparison. Makes me want to sell my Rotels. What Yamaha is that? I will most probably pick one up if I can find a used one in my area.

 

[killdozzer]

To me, TO ME, more power equals pricier, which is generally a true statement. Im in no way saying you have a to buy a fancy pancy amp for the ls50 but it excels with way more powerful amps. Your ls50s wish for nothing more, until you feed it a beefier amp. I thought my Rotel RC-1572 MKII pre and RA-1552 MKII power amp do an excellent job, until I recently fed it with an Anthem MCA 225 Gen 2 I borrowed from the dealer here. At volume, no comparison. Makes me want to sell my Rotels. What Yamaha is that? I will most probably pick one up if I can find a used one in my area.

Ah, OK. So more watts more bucks, relatively speaking in any amp class? Yes that's fine. But a clean watt being clean watt and being readily available these days, it's not a big task to get a strong amp for your speakers. What Denon 110 teaches us with it anniversary model; 80w into 8 ohms is quite enough if you can have it deliver 160 clean into 4 ohms and at least 200 into 2. Keeping THD low while under stress is more important than having the initial numbers big.

Just one other thing, there is an upper limit to this statement. When you give enough power to your LS50 for the resistance dips, after that more power will stop making a difference. Your task is only to cover the needs. Having loads of unused power doesn't affect anything.

BTW it's an old stereo amp I bought second hand. It's clean, reliable and non-coloring so I just stopped caring.

 

[q3cpma]

Here's a not so easy question @amirm would you advise someone to sell the original ones (after the turn in period) for cca 60% of the price and buy Meta instead?

Thank you very much for the review. I really enjoyed it and I think that Meta did very well.

Wouldn't it make more sense to go bigger for something like the R3, in that situation?

 

[MarkWinston]

Ah, OK. So more watts more bucks, relatively speaking in any amp class? Yes that's fine. But a clean watt being clean watt and being readily available these days, it's not a big task to get a strong amp for your speakers. What Denon 110 teaches us with it anniversary model; 80w into 8 ohms is quite enough if you can have it deliver 160 clean into 4 ohms and at least 200 into 2. Keeping THD low while under stress is more important than having the initial numbers big.

Just one other thing, there is an upper limit to this statement. When you give enough power to your LS50 for the resistance dips, after that more power will stop making a difference. Your task is only to cover the needs. Having loads of unused power doesn't affect anything.

BTW it's an old stereo amp I bought second hand. It's clean, reliable and non-coloring so I just stopped caring.
View attachment 156609

What model is the Yam?

 

[killdozzer]

Wouldn't it make more sense to go bigger for something like the R3, in that situation?

That's exactly why I ask and why I think it's not an easy question. I just think that if the answer is yes, go for the Meta and just sell your originals, this would mean that they ARE indeed sufficiently better.

 

[killdozzer]

What model is the Yam?

AX-890

 

[phoenixdogfan]

If you are willing to spend slightly over $1k on an amp, the Purifi Eval 1 will do the job as well as anything. I have one driving my Metas and I'm extremely happy with it.

 

[aarons915]

Here's a not so easy question @amirm would you advise someone to sell the original ones (after the turn in period) for cca 60% of the price and buy Meta instead?

Thank you very much for the review. I really enjoyed it and I think that Meta did very well.

@thewas has both and has claimed that even with EQ the meta sound better to his ears. I'm sure it's a subtle difference though and I would say if you're not using any EQ above the transition frequency, you'll make a much bigger difference (for free) by applying some filters to smooth out the original LS50 in the highs, but if you don't have any way of applying PEQ filters then I would say the meta would be a great upgrade. I actually plan on buying a set at some point to compare to the original LS50 with and without EQ so I'll be able to give a better answer in a few months.

 

[phoenixdogfan]

@thewas has both and has claimed that even with EQ the meta sound better to his ears. I'm sure it's a subtle difference though and I would say if you're not using any EQ above the transition frequency, you'll make a much bigger difference (for free) by applying some filters to smooth out the original LS50 in the highs, but if you don't have any way of applying PEQ filters then I would say the meta would be a great upgrade. I actually plan on buying a set at some point to compare to the original LS50 with and without EQ so I'll be able to give a better answer in a few months.

I have both, have used EQ (Maiky76's) on both as well a Dirac Live on both, and in my opinion the Metas a clearly better,

 

[aarons915]

I have both, have used EQ (Maiky76's) on both as well a Dirac Live on both, and in my opinion the Metas a clearly better,

Yes I believe I've heard you say that before but the reason why I want to compare them myself is because Maiky's EQ is based on the ASR measurements which don't match other's including soundstage and the countless in-room measurements that show a clear peak around 2k, what this means is that you'll still have a peak around 2k which will sound bright and cause fatigue in most people over time. Dirac is one of the best room EQ programs but they still try to force an in-room curve that may or may not be ideal for a given room size and/or dimensions. I've heard the meta and agree they sound great so I have no doubt they would beat the originals if you're using a room EQ or PEQ based on the ASR measurements. I have used PEQ based on the Soundstage measurements for years and they sound very neutral, if you're interested in comparing to the metas here is what I've been using, of course under 200Hz you'll have to use different filters to tame room modes. Note that I actually use a 100Hz 2nd order high pass as part of the EQ as it tames the slight rise below 300Hz. I also use the 15 deg measurement as my starting point which assumes you aren't listening directly on-axis as it's not nearly as smooth.

 

[phoenixdogfan]

Yes I believe I've heard you say that before but the reason why I want to compare them myself is because Maiky's EQ is based on the ASR measurements which don't match other's including soundstage and the countless in-room measurements that show a clear peak around 2k, what this means is that you'll still have a peak around 2k which will sound bright and cause fatigue in most people over time. Dirac is one of the best room EQ programs but they still try to force an in-room curve that may or may not be ideal for a given room size and/or dimensions. I've heard the meta and agree they sound great so I have no doubt they would beat the originals if you're using a room EQ or PEQ based on the ASR measurements. I have used PEQ based on the Soundstage measurements for years and they sound very neutral, if you're interested in comparing to the metas here is what I've been using, of course under 200Hz you'll have to use different filters to tame room modes. Note that I actually use a 100Hz 2nd order high pass as part of the EQ as it tames the slight rise below 300Hz. I also use the 15 deg measurement as my starting point which assumes you aren't listening directly on-axis as it's not nearly as smooth.

View attachment 156659

I also used a 15 degrees off axis for my listening, and for my Dirac Measurements as well. I will look into your eq when I have some time. Thank you for the input.

 

[killdozzer]

Thank you all for the input. REQ does indeed affect a lot of choices made. I'm starting to wonder why KEF waits with the Reference line? If the meta materials are so successful, one would think it would reach Reference.

 

[thewas]

I also use the 15 deg measurement as my starting point which assumes you aren't listening directly on-axis as it's not nearly as smooth.

So do I (based measurements of my own samples) for correction above transition region of my original ones:

My Metas measure so flat at 15° that I don't bother correcting them above transition region:

 

[Eruditarian]

I've been spending 10's of hours looking into amps, subs, various features like high pass filter for sub out, and room correction. After all this, I begin to wonder... should I just go for the LS50 Wireless II instead of the Metas? I was trying to avoid the former due to concerns with electronics failing, but it seems like it might save me some sanity in the long run, as well as having to figure out room correction + the other features.

I do realize some of the fun here is lost in that, but it also seems like it might actually end up being cheaper than finding a good amp + room correction software to drive the LS50 metas . Am I overthinking this? Am I too scared of failure for the Wireless IIs?

 

[Streamc]

I've been spending 10's of hours looking into amps, subs, various features like high pass filter for sub out, and room correction. After all this, I begin to wonder... should I just go for the LS50 Wireless II instead of the Metas? I was trying to avoid the former due to concerns with electronics failing, but it seems like it might save me some sanity in the long run, as well as having to figure out room correction + the other features.

I do realize some of the fun here is lost in that, but it also seems like it might actually end up being cheaper than finding a good amp + room correction software to drive the LS50 metas . Am I overthinking this? Am I too scared of failure for the Wireless IIs?

I think you would meet same difficulties with wireless too.

 

[KMO]

I do realize some of the fun here is lost in that, but it also seems like it might actually end up being cheaper than finding a good amp + room correction software to drive the LS50 metas . Am I overthinking this? Am I too scared of failure for the Wireless IIs?

The LS50 Wireless II do not incorporate room correction. They do offer some ability to do broad EQ adjustments, to address desk/wall placement, but nothing resembling even basic Audyssey, or the ability to program custom filters.

But certainly they might make your life easier for subwoofer crossover.

 

[Eruditarian]

The LS50 Wireless II do not incorporate room correction. They do offer some ability to do broad EQ adjustments, to address desk/wall placement, but nothing resembling even basic Audyssey, or the ability to program custom filters.

But certainly they might make your life easier for subwoofer crossover.

Ahh thanks for the distinction on the EQ the Wireless II offers versus "full-fledged" room correction!

I guess it's back to the drawing board a bit for me in terms of figuring out what a reasonable amp would be for PC/desktop use that doesn't end up running me a lot more than it would if I just sprung for the Wireless II...

I was initially thinking of doing something like the powernode + upstream correction on my PC (or via a miniDSP attachment), but I don't think the powernode is necessarily optimal for my use-case (and the node variant didnt seem to measure great in @amirm's test) given I don't care as much about streaming from non-PC sources, but do care about using the KEFs as my primary speakers for games/music, etc.

 

[Descartes]

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.

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Which one do you prefer KEF LS50 Meta or the KEF R3?

 

[Descartes]

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