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KEF LS50 Meta Spinorama and Measurements

napilopez

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I've had KEF's new darling, the LS50 Meta, for a couple of months now, but have only just been able to complete measurements of them. I expected this one to be a fairly straightforward measurement, as luckily KEF provides its own spinorama for the LS50 Meta, complete with early reflections curves and all. It is available in the company's whitepaper(p10), but for ease of comparison and scale-matching, I've imported that spin to REW:

LS50 Meta Spin.png


We see a pretty darn good speaker, whose deviations from neutral are just a dip in the upper mids, some on-axis diffraction, and a slightly warm tilt; we can see the on-axis and listening window curves have a slightly negative slope rather than being completely neutral.

Though my results are largely similar, there are some small but notable differences. These may be due to differences in measurement technique or my own error, but if anything, the speaker comes out looking better in my spin. Here's mine:

LS50 Meta Spinorama.png

(Please note that some of the bumps from 400-800Hz are likely due to my new outdoor measurement rig, which I am still trying to refine.)

The differences are subtle, but worth noting:

Though the dip in the upper mids remains, my measurements show much better behavior on-axis. The most likely explanation for this is simply that I was not perfectly aligned with the center of the tweeter for the diffraction to take hold.

If so, it just shows how meaningless on-axis diffraction is so long as it gets smoothed out in the listening window. I repositioned my microphone about five times and was not able to match the on-axis diffraction shown by KEF. In any case, this is all but irrelevant considering KEF explicitly tells you to listen off-axis in the manual:

PXL_20201016_015835027 (1).jpg

The more important difference is the tilt or slope of the curves. Both KEF and my measurements show smooth, mostly flat lines, however, KEFs are more tilted/darker/warmer than mine. For example, here are my Listening Window and Early Reflections curves vs KEF's (dotted):

LS50 Meta mine vs KEF.png


If we line up the measurements in the low mids, KEF's measurements show roughly 2 dB less energy after 2kHz. This would definitely be an audible difference; while both sets of measurements indicate a good sounding speaker, KEF's suggest a slightly warm titlt, while mine suggest something more neutral.

I spent a while thinking about this difference in tilt. I thought it might be temperature, as it's getting colder here, and we've seen how temperature can affect woofer output in Amir's measurements. But the speakers were indoors right before I brought them out to measure, and 56 degrees isn't that cold.

So I decided to check out Soundstage Network's measurement of the LS50 Meta, as my measurements have always agreed closely with theirs. Indeed, digitizing their on-axis measurement, they seem to have the same achieved the same tilt as me:

LS50 Meta On-Axis me vs soundstage.png


The results are, for all intents and purposes, almost identical.

Moreover, if we compare my DI curves with KEFs, they are pracitcally identical too, which leads me to believe there's just a difference in our mic calibrations for some reason.

LS50 Meta DI.png


Either way, you're getting a very good speaker, but my results show a more neutral tonality than KEFs. Until someone else with reliable measurements gets their hand on the LS50 Meta, this might remain a bit of a mystery.

Still, I'm not complaining. I'll update with more detailed directivity stuffs and quick impressions a bit later. Directivity measurements and quick sound impressions in post #6.
 
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ernestcarl

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Looks very similar indeed... but, for me, I believe that upper mid dip should make it sound better — or more neutral as you say so yourself.
 

Dennis Murphy

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[QUOTE="napilopez, post: 598793, member: 3902"[/QUOTE]
I just had time to do one on-axis plot of the Meta before the visiting owner had to leave, but here's what I got. Pretty darn good, although I could hear the mid treble brightness even though it went away off axis.
LS50 On Axis.png
 
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napilopez

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I just had time to do one on-axis plot of the Meta before the visiting owner had to leave, but here's what I got. Pretty darn good, although I could hear the mid treble brightness even though it went away off axis.
View attachment 98877

Thanks for sharing! Another good sanity check. Your measurement shows little spectral tilt too.

Looks very similar indeed... but, for me, I believe that upper mid dip should make it sound better — or more neutral as you say so yourself.

I actually tend to prefer a little extra upper mid energy! Not much, but I'd rather have more than less here. The Meta isn't any worse though than non-coaxial speakers with crossovers in this region.
 
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napilopez

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Okay, directivity stuff. Horizontal 0-90:

LS50 Horizontal.png


Quite well controlled. A little messy around 1.2kHz but no worse than we usually see. You can also see that roughly 20 degrees off-axis seems to be best and roughly tames the on-axis peak at 4kHz. The curved baffle+ waveguide reduces edge diffraction so we don't see the off-axis curves get louder than the on-axis curves, and the changes are mostly quite smooth. The speaker also seems to be missing any notable resonances (there are some very small recurring bumps that may be from my measurement setup, nothing to really fret about).

Though also waveguided design, the LS50 Meta seems to have slightly wider directivity than KEF's R3, likely due to the curved baffle:
LS50M vs R3.png

I believe this is a big enough difference to be audible, but YMMV. For those planning on using subs to make up for the bass, this may be a good reason to opt for the smaller sibling if you know you prefer wider directivity.

Taking some averages, we see the estimated front, side, and rear reflections, as well as, the estimated total horizontal reflections and horizontal ERDI.

LS50 Horizontal Reflections.png


These are, as expected, very smooth, so imaging is naturally quite impeccable.

Also as expected, the vertical listening window is very wide.

LS50 Meta vertical LW.png


In fact, if you want to have the speakers on-axis, you could balance the slight brightness around 4kHz sound by being slightly above or below the tweeter. if you have a big desk, these would make good desktop speakers.

The floor and ceiling reflections are also very well controlled:

LS50 Meta Floor Ceiling.png


Polars.

Horizontal, normalized to on-axis:

LS50M Polar H Norm.png


Vertical, normalized:

LS50M Directivity (ver).png


Lastly, the woofer and port measurements:

LS50 Meta Woofer and Port.png


The midrange port noise is low enough to not cause substantial issues, but you can see the blip at 1.2kHz it rear its head a little in the off-axis horizontal measurements. Still, it seems to balance out overall.


Oh yeah, I should probably talk about how they actually sound :)

Honestly, there isn't much to say. They sound truly excellent. Not perfect, but truly very good.

These sound very neutral when listened to about 20 degrees off axis, but a bit laid back 'warm' for my tastes, probably because of the dip in the upper mids and slight tilt when listened to off-axis. It might not be as engaging with some music as some speakers with more energy in the upper mids and presence regions. As noted in another post, I'd rather have a db or two more energy in the upper mids than a dB or two less.

Don't get me wrong though, these are still very close to neutral. To my recollection, I like them significantly more than the original LS50s which I was never crazy about (I loved the wireless though) as I thought they were a bit bright and 'cold.'

Soundstage is a good balance of width and imaging prowess and the sweet spot is large. Dynamics are better than I expected from a speaker this size, and they have pretty decent bass extension, but they obviously sound better with a sub.

Maybe I'm being conditioned by the metamaterial marketing, but these seem to do really well at resolving detail at very low volumes, in quiet passages despite a slightly laid back sound. That was perhaps the most pleasant surprise.

I kind of struggle coming up with things to say about the LS50 Meta, but that's a good thing in my book. for the most part, they just sound 'right,' and that's all I really want from a speaker.
 
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andreasmaaan

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Thanks @napilopez, very interesting measurements. Great directivity control, nice measurements overall, and very nice to see a small ported two-way in which adequate care has been taken to neutralise port noise. Interesting that it seems to be the first modern KEF speaker I know of with a BBC dip! (Which is ofc easily EQ'd out if desired).
 
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napilopez

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The vertical polar stomps the competitive products from Revel, Focal, etc., showing the value of the coaxing point source design. Bet that helps with imaging as well.

In my old place, in which speakers were positioned so they could fire down the entire length of the apartment, I remember how good the R3s sounded basically anywhere I stood in the apartment. In my new place the speakers are on the long wall, so I can't get quite the same effect but yeah, imaging is a strength.

The Metas sound more neutral than the Chora 806 which are my reference and by comparison sound a bit thinner in the mids I think due to the verticals, even though the Choras have a more linear listening window. The Metas have the Choras beat on sweet spot width/stability too. But the Choras have a bit better dynamics and a wider soundstage, so it's basically a pick your poison affair. Initially I thought I preferred the Metas, and I probably do slightly with a sub, but I'm a real sucker for that wide treble directivity in the Focals.
 

ernestcarl

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I actually tend to prefer a little extra upper mid energy! Not much, but I'd rather have more than less here. The Meta isn't any worse though than non-coaxial speakers with crossovers in this region.

Interesting. One of the excesses of the another coaxial (Sceptre S8) which I have is there’s too much upper mid — or at least a section of it has a peak. Obviously a completely different design! But one of the things reviews have complained about. So my expectations and point of comparison is quite biased against any rise there.
 
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napilopez

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Thanks @napilopez, very interesting measurements. Great directivity control, nice measurements overall, and very nice to see a small ported two-way in which adequate care has been taken to neutralise port noise. Interesting that it seems to be the first modern KEF speaker I know of with a BBC dip! (Which is ofc easily EQ'd out if desired).

Yeah, as this upper mid dip does not appear to be present in the Wireless II, which for all intents and purposes appears to be an LS50W Meta + EQ and amps, I can only assume that it wasn't so much a tuning choice as the sacrifice they chose to make in lieu of EQ. But it's one some people don't seem to mind!

Here are KEF's measurements of the LS50W II

LS50 Wireless II Spin.png


If the differences with KEF's measurements of the LS50WII end up being the same as the differences with the Meta (assuming I get to measure the WII at some point), then it seems the Wireless II could be a very good alternative to a Genelec for someone looking for a super neutral coaxial speaker with some more flexibility.
 
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andreasmaaan

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I actually tend to prefer a little extra upper mid energy! Not much, but I'd rather have more than less here. The Meta isn't any worse though than non-coaxial speakers with crossovers in this region.

I agree with @ernestcarl, that is an unusual preference! The upper mids are generally a band in which I try to avoid excess energy at all costs :p

EDIT: on re-reading, I hope that didn't come across as rude @napilopez! Definitely didn't intend it that way. Was just interested to hear that your preferences in this respect are different from mine.
 
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andreasmaaan

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Yeah, as this upper mid dip does not appear to be present in the Wireless II, which for all intents and purposes appears to be an LS50W Meta + EQ and amps, I can only assume that it wasn't so much a tuning choice as the sacrifice they chose to make in lieu of EQ. But it's one some people don't seem to mind!

Skimping it on passive XO components, then, I guess. Or perceiving that the passive version should have a slightly different "voicing" for a different market, perhaps?
 

thewas

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Thank you for your great review and measurements which makes my waiting even harder, since I have ordered them at my dealer 3 weeks ago but there seems to be a shortage currently in my country. :(
The vertical polar stomps the competitive products from Revel, Focal, etc., showing the value of the coaxing point source design. Bet that helps with imaging as well.
In my experience it does, especially in my new house/room where my room acoustics are poorer and was the reason I recently sold my Neumann KH120 from my desktop system and replaced them with my old LS50 (with EQ of course as otherwise I don't like their tonality) and will use the Metas at my classic stereo listening system. If listened correctly placed (as high distance from side walls as possible and only 15° toed in) they create a soundstage like no other of my dozens of loudspeakers.
 

ernestcarl

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Thank you for your great review and measurements which makes my waiting even harder, since I have ordered them at my dealer 3 weeks ago but there seems to be a shortage currently in my country. :(

In my experience it does, especially in my new house/room where my room acoustics are poorer and was the reason I recently sold my Neumann KH120 from my desktop system and replaced them with my old LS50 (with EQ of course as otherwise I don't like their tonality) and will use the Metas at my classic stereo listening system. If listened correctly placed (as high distance from side walls as possible and only 15° toed in) they create a soundstage like no other of my dozens of loudspeakers.

I love coaxials and kind of wish they were more common. They really shine off-axis... I actually even listen to mine at the extreme edge of the horn’s beamwidth control and they still sound great to my ears. They do lot not lose their brightness — which is good — even if there is some amount of lobing. They are hard to get right though.
 
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napilopez

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Thank you for your great review and measurements which makes my waiting even harder, since I have ordered them at my dealer 3 weeks ago but there seems to be a shortage currently in my country. :(

In my experience it does, especially in my new house/room where my room acoustics are poorer and was the reason I recently sold my Neumann KH120 from my desktop system and replaced them with my old LS50 (with EQ of course as otherwise I don't like their tonality) and will use the Metas at my classic stereo listening system. If listened correctly placed (as high distance from side walls as possible and only 15° toed in) they create a soundstage like no other of my dozens of loudspeakers.

I really do feel there's an extra degree of 'coherence' to the soundstage. I wish someone could blind test this, because I'm very curious. As we've discussed many times on ASR, I'd love to see further research into the impact of vertical reflections on sound.

Anyway, I'm still a bit puzzled by the extra tilt in KEFs measurements. Just saw the new Stereophile has the Meta measured(the magazine, not up on the site yet), and it too shows no significant tilt. I thought KEF might've been starting from an off-axis angle, but then there shouldn't be on-axis diffraction. *Shrugs*

I think between me, soundstage network/the NRC, dennis murphy, and Stereophile, that's enough measurements to suggest these probably do not have a tilt, so that's something to keep in mind if you want to EQ them; you might end up making them bright if you go off of KEF's measurements.
 
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thewas

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I really do feel there's an extra degree of 'coherence' to the soundstage. I wish someone could blind test this, because I'm very curious. As we've discussed many times on ASR, I'd love to see further research into the impact of vertical reflections on sound.
So do I.

Anyway, I'm still a bit puzzled by the extra tilt in KEFs measurements. Just saw the new Stereophile has the Meta measured(the magazine, not up on the site yet), and it too shows no significant tilt. I thought KEF might've been starting from an off-axis angle, but then there shouldn't be on-axis diffraction. *Shrugs*

I think between me, soundstage network/the NRC, dennis murphy, and Stereophile, that's enough measurements to suggest these do not have a tilt, so that's something to keep in mind. If you want to EQ them; you might end up making them bright.
Interestingly the German magazine Stereoplay published measurements 2 days ago in their newest issue which on the other hand also show a slight tilt, due to copyrights I don't upload them here but sent them to you via PM, really strange.... :D
 
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