• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

KEF LS50 Meta Review (Speaker)

ernestcarl

Major Contributor
Joined
Sep 4, 2019
Messages
3,106
Likes
2,313
Location
Canada
Why even call it a "reference" monitor? I dunno. It really depends in what you want/need, I guess... Going beyond ASR's fixation with frequency response, I encourage people to listen to tracks that are very heavy into percussive instruments and compare between different speaker types. IMO, despite the numerous FIR and IIR equalization attempts I've done to my KH120 and S8 monitors (yet again, latter is cheaper) to make them sound as similar as possible, the S8 sounds more realistic to my ears. Where it comes to more natural sounding vocals, the KH120 is far better in that regard. I consider both as reference grade, but that's me. Your mileage may vary.
 

thewas

Master Contributor
Forum Donor
Joined
Jan 15, 2020
Messages
6,742
Likes
16,175
Yeah, the best (smoothest response) coaxials currently use smaller drivers. But why do you think the Sceptres are "pseudocoax" in their design? Because it uses a horn-loaded compression tweeter?
Some people call as "pseudocoax" loudspeakers where the individual drivers are placed one in front of the other creating usually unwanted edge diffraction and secondary sound sources, in the Sceptres the acoustic centre of the tweeter is actually behind like on a "real coax", but on the other hand its horn is in front of the mid bass driver.
 

q3cpma

Major Contributor
Joined
May 22, 2019
Messages
3,060
Likes
4,416
Location
France
Some people call as "pseudocoax" loudspeakers where the individual drivers are placed one in front of the other creating usually unwanted edge diffraction and secondary sound sources, in the Sceptres the acoustic centre is actually behind like on a "real coax", but on the other hand its horn is in front of the mid bass driver.
How about MEG's RL901K, where the woofer crosses low enough that diffraction is probably inexistent? Genelec seems to call this approximately coaxial.
 

thewas

Master Contributor
Forum Donor
Joined
Jan 15, 2020
Messages
6,742
Likes
16,175
How about MEG's RL901K, where the woofer crosses low enough that diffraction is probably inexistent? Genelec seems to call this approximately coaxial.
Yes and as said all these kind of namings and definitions are just names and not necessarily qualitative descriptor.
 

richard12511

Major Contributor
Forum Donor
Joined
Jan 23, 2020
Messages
4,335
Likes
6,700
Some people call as "pseudocoax" loudspeakers where the individual drivers are placed one in front of the other creating usually unwanted edge diffraction and secondary sound sources.


Like Me Geithain? I've always wondered if there is a disadvantage to doing the coaxial like that with smaller drivers simply placed in front of bigger ones.
 

thewas

Master Contributor
Forum Donor
Joined
Jan 15, 2020
Messages
6,742
Likes
16,175
Like Me Geithain? I've always wondered if there is a disadvantage to doing the coaxial like that with smaller drivers simply placed in front of bigger ones.
From measurement point of view there is the one I write above, although on the bigger 3-way models like 901/921 only the woofer is partially covered which isn't as big problem due to the only large wavelengths transmitted from it compared to a mid(-woofer) and an the other hand the audibility of those problems is important and to be determined which is almost impossible though as you would be comparing 2 different designs which have also other system differences.
 

Sancus

Major Contributor
Forum Donor
Joined
Nov 30, 2018
Messages
2,923
Likes
7,616
Location
Canada
Like Me Geithain? I've always wondered if there is a disadvantage to doing the coaxial like that with smaller drivers simply placed in front of bigger ones.

Well for one thing you can't build a large waveguide into the front like Genelec did.
 

Slash86

Member
Joined
Sep 13, 2021
Messages
7
Likes
6
Having gone through this thread, I have learnt a great deal of stuff.. but I am still very confused around the subwoofer setup with these Metas!

I have a very simplistic setup (pair of passive metas, Cambridge EVO 150 and SVS 3000 Micro) which is as close to sonic bliss as ive ever experienced before. But it is simple, so no high pass filter ,a simple non configurable LP filter for the sub out, no real EQ, no room calibration.

The sub was a bit of a crazy purchase. I was so blown away by the Meta +EVO that i felt i had to accept the fallout with my wallet and get it that extra sub , like the final touch to a perfect painting....

After playing around with the sub's crossover, I ended up with a crossover at 50Hz / 24db/oct slope. It feels very low, but any higher just resulted in some doubling up of bass (talking from ears, not measurements) which was really not pleasant.

I believe i can explain this because i did the LS50 setup before receiving the woofer, so I installed them 50cm from the back wall , without angling them.. because that sounded to me like the most even bass response i could get out of them (likely matching the spec sheet with 47Hz @-6db). But now, with the sub crossing over at 80, i get too much response around 60/80Hz

So my question is: Am I better sticking with this setup, accepting that i will not realistically be able to play more of the 50/80hz range from the Sub, or should I try to use the foam port bungs provided to block the rear ports and play with wall distance to reduce the bass response from the Metas and increase the crossover frequency?
(Kef support has confirmed to me that the rear port creates a boost in response in the 60/70hz range and that using the foam should get the curve back to a more linear response...)

If anyone as any idea to share... that would be helpful :)
 

thewas

Master Contributor
Forum Donor
Joined
Jan 15, 2020
Messages
6,742
Likes
16,175
I have temporarily a similar setup and also cross the sub on its lowest setting which is also confirmed by my measurements. The problen is that when you close the port of the Meta also their cone displacement and thus also distortion and intermodulation increases around the port tuning frequency. Also the response will roll off with closer to 12 dB per octave instead of 24 and will make the integration more difficult. I am afraid you will have to live with that compromise until you use a way to use a high-pass for your Metas. On the other hand for not too loud volumes even this setup can sound very good and is a significant subjective improvement compared to the Metas without subwoofer.
 

KMO

Addicted to Fun and Learning
Joined
Aug 9, 2021
Messages
629
Likes
901
Yes, if you're not crossing over the Metas, and they're unbunged, then the sub's LPF will likely need to be somewhere in the 45Hz-55Hz range.

Plugging the ports is certainly worth trying, if you're always going to be using the sub.

My measurements (above) show the full plugs give something like 12dB/octave drop-off from 100Hz (in-room). Whereas unbunged it's more like 24dB/octave from 50Hz.

That 12dB/octave drop off might suit a typical 24dB/12dB asymmetric (THX-style) receiver crossover.

And in your case it might suit a 12dB LPF? Might have your sub going higher than you like though.
 

nothingman

Senior Member
Joined
Sep 15, 2020
Messages
319
Likes
498
Location
USA
@Slash86 Your setup is not wrong on paper at all. Think of it this way: for the LS50WII and KC62 combination, KEF recommends a 45hz LPF for the KC62, 5hz lower than yours, and they expect that to be in tandem with a HPF to the LS50s set at 70hz. In that setup the mains are producing less bass than your Metas, and even then KEF suggests setting the KC62 to 45hz. The difference there is small, so it says something positive about your instincts that 50hz sounds about right.

Since you don’t have measurements and you don’t have control over both a HPF and LPF, then trusting your ears is the way to go. If yours tell you to stick to 50hz then don’t change it because it seems like a low number.

As for the plugs, I say give them a try. I would keep it symmetrical so that the phase behavior of the two speakers stays as similar as possible. I’ve tried them asymmetrically in my setup and it didn’t work well for channel balance and optimizing phase with the sub. Others smarter than me will know if they introduce other unwanted problems (distortions, port resonances, etc.).

I’m a little surprised that for the price the Evo 150 doesn’t have even rudimentary crossover settings. As long as they have that advanced display and a sub out, they should be offering the ability to control a HPF and LPF.
 

Slash86

Member
Joined
Sep 13, 2021
Messages
7
Likes
6
Thank you both! One answer tells me that my ears are not stupid and the other gives me a great baseline to try further configs with the plugs (I missed your post on page 22 @KMO which is exactly what I was looking for.. I guess I Was scrolling a bit too fast at this stage :))

Don’t get me wrong, I’m extremely pleased already …. Think I just caught some kind of Codio-19 bug wanting to get things just a tad better.

Will definitely try playing with the plugs until I maybe try to see if a high pass brings something more (once the wallet stops being sulky)
 

Slash86

Member
Joined
Sep 13, 2021
Messages
7
Likes
6
@Slash86 Your setup is not wrong on paper at all. Think of it this way: for the LS50WII and KC62 combination, KEF recommends a 45hz LPF for the KC62, 5hz lower than yours, and they expect that to be in tandem with a HPF to the LS50s set at 70hz. In that setup the mains are producing less bass than your Metas, and even then KEF suggests setting the KC62 to 45hz. The difference there is small, so it says something positive about your instincts that 50hz sounds about right.

Since you don’t have measurements and you don’t have control over both a HPF and LPF, then trusting your ears is the way to go. If yours tell you to stick to 50hz then don’t change it because it seems like a low number.

As for the plugs, I say give them a try. I would keep it symmetrical so that the phase behavior of the two speakers stays as similar as possible. I’ve tried them asymmetrically in my setup and it didn’t work well for channel balance and optimizing phase with the sub. Others smarter than me will know if they introduce other unwanted problems (distortions, port resonances, etc.).

I’m a little surprised that for the price the Evo 150 doesn’t have even rudimentary crossover settings. As long as they have that advanced display and a sub out, they should be offering the ability to control a HPF and LPF.
Thank you! Yes I was surprised with the EVO not having anything on that front … I guess the design brief was more around simplicity … matches the target market requirements I would imagine.

I just missed that when I decided to go for passive + evo rather than active Kef only, which is definitely a point in favour of the active when comparing these 2 setups… but I still prefer the overall flexibility I get.

I was initially reluctant to put the plugs in and have set the speakers further from the back wall (even if it looks shit in the living room) just to not use them … that intuition that it may cause other problems like hinted by @thewas

The other thing I was thinking was to invert the cables on one speaker to get some low level frequency cancellation.. but without the ability to make measurement, I thing I’m just opening the door to messing around with everything !
 

testp

Senior Member
Joined
Jul 22, 2020
Messages
390
Likes
229
The other thing I was thinking was to invert the cables on one speaker to get some low level frequency cancellation.. but without the ability to make measurement, I thing I’m just opening the door to messing around with everything !
you should try to invert sub, not main speakers( mains are in stereo and bass goes over 100Hz).
sub inverted and played together with non-inverted mains up to 80hz could also sound good and remove some dips, but also maybe create some peaks, so some measurements would help on that front.

best toy is minidsp(with mic) in this, play with high pass / low pass and sub inverted etc. and get brilliant bass response i think
 
Last edited:

abdo123

Master Contributor
Forum Donor
Joined
Nov 15, 2020
Messages
7,423
Likes
7,940
Location
Brussels, Belgium
@Slash86

If you want you can seal the port of the LS50 Meta and measure the anechoic bass response (guide here) and determine the natural acoustic roll-off of the driver.

For example, my mains (not LS50 Meta) have a natural LF roll-off at 100Hz Butterworth 12db/oct. Thus a low pass at 100Hz would give us a perfect 'anechoic' response and integration.

index.php


With this method all you have to do is set the complementary low-pass filter / crossover filter in the sub and no need for a high-pass.
 

Ron Texas

Master Contributor
Joined
Jun 10, 2018
Messages
6,076
Likes
8,911
Adding a high pass filter ( around 120 hz) to small speakers with a sub increases the dynamic range of the system dramatically. It also requires 2 subs located next to the mains. That's how my original LS50's are set up.
 

abdo123

Master Contributor
Forum Donor
Joined
Nov 15, 2020
Messages
7,423
Likes
7,940
Location
Brussels, Belgium
Adding a high pass filter ( around 120 hz) to small speakers with a sub increases the dynamic range of the system dramatically. It also requires 2 subs located next to the mains. That's how my original LS50's are set up.

Yes but he doesn't have that option, and even then people sitting in the near-field might not need the headroom and would rather not have the phase distortion caused by the electrical crossover.
 

killdozzer

Major Contributor
Joined
Aug 2, 2020
Messages
1,615
Likes
1,628
Location
Zagreb
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.
 
Top Bottom