KEF LS50 Meta Review (Speaker)

[tw 2022]

Thanks for the feedback everyone. Just ordered a pair of LS50 Meta to pair with my NAD D3045. I have a Rythmik L12 under my desk for bass duties. The NAD will let me set a crossover for the subwoofer at 80 or 120Hz. Which is the better option? Would 120Hz be too localizable?

I think 120 might work fine near field...Edit , but try both..

 

[this is me]

I have mine set at 100Hz with KC62. A little too much for me at 80Hz.

 

[goldark]

LS50 Metas got delivered today and spent some time listening. I have them set up nearfield in the office, running off a NAD D 3045. I have a Rythmik L12 I connected and disconnected to hear what they sounded like both with and without the aid of a subwoofer. I used the NAD's 80 Hz high pass option when using the L12. I've had many speakers set up in this office set up, with the latest being the Focal Aria 906 and the original LS50's.

Auditory memory can be notoriously unreliable, but in short, my impressions are that the LS50 Metas are the best near-field speaker that I've had in my office setup. Detailed, neutral, with great, focused, imaging. For my tastes, however, they require a subwoofer. When used with the L12, I get beautiful, full-range sound. Very impressed.

I also have the Ascend Sierra 2-EX V2, which also has excellent measurements: https://ascendacoustics.com/collect...cts/sierra-2ex-v2-pair?variant=40390917750838

For fun, I decided to try them out in the main system where the Ascends are and compared them. The Ascends have noticeably better and deeper bass, which I expected. The wider dispersion also gives a subjective impression of more "airiness" and "space." Both are very neutral, so I didn't notice a huge change in tonality. It was mostly spacial qualities and bass response that differed between the two speakers. For a nearfield setup at my desk, I prefer the LS50 Metas. In a far-field system in a medium room, the wider dispersion of the Ascends won out for me. You can't go wrong with either speaker IMO. I have Revel F206 in the bedroom. One day, I will set them up in the same room to compare, but I'd have to drag some subwoofers in there to normalize bass response, and I'm feeling too lazy to do that at the moment.

 

[yllanos]

Was contemplating LS50 Metas when i purchased new speakers a few weeks ago.. interestingly they perform similar to the Revel M16s that i ended up with.

I'm happy i didn't spend twice as much to get these! They do look good, but the Revels are no slouches in that regard either.

Interesting. I am currently debating between these two. Still not sure which way to go.

 

[jpqpi]

Can someone help me out here: @amirm measurements show 100% distortion at 50hz when SPL = 96dB @ 1 meter.

I ran those numbers using a peak spl caluculator online (http://www.hometheaterengineering.com/splcalculator.html) and this looks like at this short 1m distance this would have only needed about 19 watts of amplifier power.

So, if unacceptable distortion kicks in at 19watts, why would we need a much higher powered AMP to push it further into distortion? Obviously there is something I'm not getting here as this value seems to be way too low.

My plan is to use these as L and R in A Home Theatre setup with something like a SVS 3000 Micro sub (or 2) in a room that is 3.5 m x 7.5 m so ~27m2 but I want clean output at decent volumes. FYI, I also plan to get a Denon avc-x4800h which can put out 174wats @4ohm according to Amirs tests.

So, if I run this with a sub and that Denon AVR will the setup reach the required level for home theater without large distortion? I'm thinking 70 - 80 dB at seated position which would be about 3m from these speakers. Thoughts anyone?

Also, anyone see a reason that I couldn't use one of these on it's side as a center channel for a perfectly matching LCR across the front?

Thanks in Advance!

 

[pjn]

Can someone help me out here: @amirm measurements show 100% distortion at 50hz when SPL = 96dB @ 1 meter.

I ran those numbers using a peak spl caluculator online (http://www.hometheaterengineering.com/splcalculator.html) and this looks like at this short 1m distance this would have only needed about 19 watts of amplifier power. I would plan to use these as L and R in A HT with something like a SVS 3000 Micro sub (or 2) in a room that is 3.5 m x 7.5 m so ~27m2. FYI, I also plan to get a Denon avc-x4800h which can put out 174wats @4ohm according to Amirs tests.

If I run this with a sub and that Denon AVR will the setup reach the required level for home theater without large distortion? I'm thinking 70 - 80 dB at seated position which would be about 3m from these speakers. Thoughts?

Also, anyone see a reason that I couldn't use one of these on it's side as a center channel?

Thanks in Advance!

For a while I used one on its side as a center with 2 as L and R - it works pretty well. But doing it all over again, I would likely use R3s for L and R and an R2c for the center. I found (in my room- 15.5 x 15.5 x 8) that one of the LS50s had a nasty mode at 90Hz which could be partly controlled by crossing over at about 120Hz. The extra drivers on the R3 and R2 would likely take care of this. The rear facing port on the LS50 limits its usefulness as a center, but it depends whether you have space behind it (I did).
They are good speakers for their size and price.

 

[jpqpi]

For a while I used one on its side as a center with 2 as L and R - it works pretty well. But doing it all over again, I would likely use R3s for L and R and an R2c for the center. I found (in my room- 15.5 x 15.5 x 8) that one of the LS50s had a nasty mode at 90Hz which could be partly controlled by crossing over at about 120Hz. The extra drivers on the R3 and R2 would likely take care of this. The rear facing port on the LS50 limits its usefulness as a center, but it depends whether you have space behind it (I did).
They are good speakers for their size and price.

Thanks for you're input @pjn. That mode you were experiencing sounds like it's very room specific tbh. I believe speaker/sub placement becomes very important the lower you go below the schreoder frequency FYI. In any case, I would plan to cross these over at about 110-120hz and try to avoid the worst of the distortion that way and I would hope this would give me much more headroom to crank it up should the mood strike me. I just know if that's valid or not TBH

I take your point about the rear port with this as a center channel. I may use the supplied port plugs to plug it fully and do without the added low end that the port provides, especially given my crossover frequency choice.

 

[pablolie]

Thanks for you're input @pjn. That mode you were experiencing sounds like it's very room specific tbh. I believe speaker/sub placement becomes very important the lower you go below the schreoder frequency FYI. In any case, I would plan to cross these over at about 110-120hz and try to avoid the worst of the distortion that way and I would hope this would give me much more headroom to crank it up should the mood strike me. I just know if that's valid or not TBH
...

While I agree with what you say, the distortion characteristics you mention show themselves at what I'd regard as volume levels I personally don't use, and which these speakers probably weren't designed to reach to begin with. Below those, I think the usual xover at around 70-80Hz is perfectly fine and nicely supports the character of the LS50. Matching a single sub is hard enough, and while I am aware of the potential advantage of 2 subs, it is a harder task. Then again, I am a simplistic 2.1 guy that's perfectly happy with what that gets me.

 

[ehabheikal]

Thanks for you're input @pjn. That mode you were experiencing sounds like it's very room specific tbh. I believe speaker/sub placement becomes very important the lower you go below the schreoder frequency FYI. In any case, I would plan to cross these over at about 110-120hz and try to avoid the worst of the distortion that way and I would hope this would give me much more headroom to crank it up should the mood strike me. I just know if that's valid or not TBH

I take your point about the rear port with this as a center channel. I may use the supplied port plugs to plug it fully and do without the added low end that the port provides, especially given my crossover frequency choice.

I cross mine as you said at 120hz which is the high limit of my sub and happy about sq but would have liked to have 2 subs crossed at 200hz

 

[withoutsuit]

I think your plans will work well. I'm using two LS50 metas, port pluged with crossover 100hz (four subs). I'm planning a third LS50 meta for center duties as well - single speaker hard to get, mostly sells as pair.:/

 

[jpqpi]

@amirm Sorry to be a pain but any chance you might have some info on what SPL (@1m listening distance) you pushed this speaker to when you got to the level of subjectively unacceptable distortion/tonality changing? Failing that info being available maybe a rough guess as to how many watts you pushed to it with your beefy amp before it broke down this way.

It seems to me that the average power required to reach 96dB@1m is about 19W (@ 83dB SPL/1W/m sensitivity and using this calculator: http://www.hometheaterengineering.com/splcalculator.html). I'm guessing you pushed it much harder than that though when you cranked it up with your 1000W amp.

I was planning to eventually have about 250W/ch of Nilai500 class D to power these (and incidentally use a decent sub as well for the low end) but I cant get my head around the maths to figure out if this is total overkill or not and what level of distortion I can expect to encounter during the peaks when average listening levels are at about 65-75dB from 10ft away.

A few possibilities come to mind here:
Maybe our ears cant detect the distortion in the peaks present in music/HT content and therefore it is only the average levels that matter?
Or maybe distortion only kicks in in the speaker when it is being continuously pushed at a certain average level?
I also read here (https://www.axiomaudio.com/blog/distortion) that distortion at lower frequencies isn't as detectable to us as the same percentage of distortion is at higher frequencies.

Any comments you (or anyone else) could make to clear this up for me would be greatly appreciated if you have the time as I am fairly lost atm and could use a steer in the right direction

Cheers all, and I love the friendly but science based ethos of this forum,
Paul

 

[Descartes]

I think your plans will work well. I'm using two LS50 metas, port pluged with crossover 100hz (four subs). I'm planning a third LS50 meta for center duties as well - single speaker hard to get, mostly sells as pair.:/

KEF sells single LS50 Meta!

 

[Eetu]

@amirm Sorry to be a pain but any chance you might have some info on what SPL (@1m listening distance) you pushed this speaker to when you got to the level of subjectively unacceptable distortion/tonality changing? Failing that info being available maybe a rough guess as to how many watts you pushed to it with your beefy amp before it broke down this way.

It seems to me that the average power required to reach 96dB@1m is about 19W (@ 83dB SPL/1W/m sensitivity and using this calculator: http://www.hometheaterengineering.com/splcalculator.html). I'm guessing you pushed it much harder than that though when you cranked it up with your 1000W amp.

I was planning to eventually have about 250W/ch of Nilai500 class D to power these (and incidentally use a decent sub as well for the low end) but I cant get my head around the maths to figure out if this is total overkill or not and what level of distortion I can expect to encounter during the peaks when average listening levels are at about 65-75dB from 10ft away.

A few possibilities come to mind here:
Maybe our ears cant detect the distortion in the peaks present in music/HT content and therefore it is only the average levels that matter?
Or maybe distortion only kicks in in the speaker when it is being continuously pushed at a certain average level?
I also read here (https://www.axiomaudio.com/blog/distortion) that distortion at lower frequencies isn't as detectable to us as the same percentage of distortion is at higher frequencies.

Any comments you (or anyone else) could make to clear this up for me would be greatly appreciated if you have the time as I am fairly lost atm and could use a steer in the right direction

Cheers all, and I love the friendly but science based ethos of this forum,
Paul

I don't have the LS50 Metas but looking at the data:
- the THD is at 100% below 40Hz even at 86dB
- 96dB continuous at 1m is too much for the single speaker, transients/peaks should fare a bit better
- with 2 speakers you should be able to reach 3-6dB higher SPL when playing music than with a single speaker

The LS50 Meta is limited by the small 5" woofer and for best performance should be high-passed and used with a sub/subs. Once the bass below ~80Hz is filtered out I would also expect the woofer's IMD get reduced roughly by half so you would also get cleaner upper bass & mids.

 

[jpqpi]

KEF sells single LS50 Meta!

In the states, yes...Havent seen it sold singly in Europe though

 

[withoutsuit]

In the states, yes...Havent seen it sold singly in Europe though

And when it's available, its pretty expensive - so its better to buy a pair and try to sell one.

 

[phoenixdogfan]

And when it's available, its pretty expensive - so its better to buy a pair and try to sell one.

Buy a pair with a friend. Maybe even start a thread on this site for that purpose.

 

[abdo123]

Can someone help me out here: @amirm measurements show 100% distortion at 50hz when SPL = 96dB @ 1 meter.

I ran those numbers using a peak spl caluculator online (http://www.hometheaterengineering.com/splcalculator.html) and this looks like at this short 1m distance this would have only needed about 19 watts of amplifier power.

So, if unacceptable distortion kicks in at 19watts, why would we need a much higher powered AMP to push it further into distortion? Obviously there is something I'm not getting here as this value seems to be way too low.

My plan is to use these as L and R in A Home Theatre setup with something like a SVS 3000 Micro sub (or 2) in a room that is 3.5 m x 7.5 m so ~27m2 but I want clean output at decent volumes. FYI, I also plan to get a Denon avc-x4800h which can put out 174wats @4ohm according to Amirs tests.

So, if I run this with a sub and that Denon AVR will the setup reach the required level for home theater without large distortion? I'm thinking 70 - 80 dB at seated position which would be about 3m from these speakers. Thoughts anyone?

Also, anyone see a reason that I couldn't use one of these on it's side as a center channel for a perfectly matching LCR across the front?

Thanks in Advance!

Hey, I'm also planning to get these speakers for my living room so here is what my investigation yielded, you need to cross them at 120 Hz (Butterworth, 12db/oct, what almost all AVRs use for bass management) to make sure that you get to the advertised output of 106dB per speaker without much distortion at high volumes.

 

[abdo123]

In the states, yes...Havent seen it sold singly in Europe though

Let me know if you would like to share a pair for a center speaker.

 

[jpqpi]

Let me know if you would like to share a pair for a center speaker.

Would love to get one in white, sadly not right now though as I am still in negotiations with the Mrs on where all these speakers will go in our small Irish apartment May involve getting some new furniture that makes the whole setup work better (read hides at least the center speaker behind a speaker fabric style door - PS. I know this is far from ideal but it's that or no center speaker).

 

[Leif]

Going from experience I noticed the difference when going from ~50W/ch to ~80W/ch. It's better, can feel more power and goes a bit louder.

In my experience the LS50 Meta + AudioLab 6000A can go very loud, much louder than I would ever need, or endure. At normal volumes the combination sounds excellent. I cannot comment on any other combination.