KEF R Series with MAT white paper

[davidbosch]

I know this is r thread but seeing as the Kef guys are here... Any plans for a centre version of the ls60w and/or adding wysa support? The thinness of the ls60w is really useful for slotting under a TV horizontally. I'm guessing the market is too small to justify but I can dream right?

Also the old walnut r11's are on clearance at best buy for less than half the price of the r11 metas.

Clearance R11 non meta vs R7 meta vs Used Reference 1 Non meta vs Used LS60... all in that 3 to 6K range...

Hi @stren , The LS60W has opposing LF drivers on both sides, which would not make sense to put in a centre speaker on the top and bottom faces, so no plans for that I'm afraid!

 

[exm]

I think there might be a mistake here actually. Sorry, this is embarrassing. I'm checking with the colleague who published this data and will clarify the mystery shortly.

And on the website, you are completely right, and the UK website as well. I have forwarded this to our online media team to correct it. Thank you for letting me now, even after lots of people proofreading and double-checking these details, it seems mistakes sometimes make their way through.

I noticed that the Reference White Paper has the same frequency response for the Ref 2 Center. Please note that the non-Meta Ref 2 center was listed with the same frequency range, which has been questioned over various forums (asr, avs, av) also! Especially with the R6 released (which is basically the R Series version of the Reference 2), it doesn't makes sense that Kef lists the Reference 2 (Meta) as 80Hz – 35kHz [+/- 3db] whereas the R6 is 65 Hz - 28 kHz [+/- 3db]. If this is an ongoing document issue (hey, we understand - mistakes are human!), can you at least clarify the Reference 2 Meta FREQUENCY RESPONSE (±3dB)?

 

[Mario Sanchez]

Hi Mario, if you have a look at the white paper, there's a figure with the crossover topology. The HF high pass is second order electrical, the MF low pass is first order electrical. The acoustical transfer functions of the filtered drivers are of higher order though thanks to their natural roll off and sum correctly around crossover.

Thank you! I'm trying to reverse the allpass behaviour of my R6Meta (now with a "s" for plurality) around the crossover, so this information is of great assistance.

 

[stren]

Hi @stren , The LS60W has opposing LF drivers on both sides, which would not make sense to put in a centre speaker on the top and bottom faces, so no plans for that I'm afraid!

I was imagining it would have feet to lift it off a media center far enough to make it work. Not sure how far that would need to be.

 

[thewas]

The DIs do look almost the same. The 2018 speakers have a pretty decent MF-HF integration but there was room for improvement. The crossover is a bit different, the parallel capacitor in the HF circuit is deleted, so the filter is a second-order high pass whereas in the 2018 one the parallel circuit functioned as a notch. The crossover frequency is also lower (2.3 vs 2.9 kHz). This helped improve the off axis response clearly within +/-45 deg.

If you take the 2018 R3 and EQ it to have a similar measured response to the R3 Meta, I think you won't be awfully far, but I don't think they will really sound the same. The MF and HF drivers are quite different in distortion and other behaviour. The Meta also has much improved behaviour in at least 7 resonances, and in my experience, since these can sound quite annoying when you hit them while listening to music, one tends to balance the speaker slightly to attenuate the frequency regions where they happen. As you point out, distortion will also be different, generally higher in 2018 R3. Even at normal volume, harmonic distortion will play a part in how the speaker sounds to us, and thus have an effect on the balance we end up with. Then small things, like the capacitor in series with the tweeter, have (for some reasons we understand and some other we don't fully yet) a considerable effect on how the speaker sounds with music, which can't really be seen in the frequency response.

If you can get a really cheap 2018 R3, EQ or not, it's already a bargain of a speaker. EQ'ing it closer to the R3 Meta might make it better, might not be enough probably. I would just go further and EQ it like you would an active speaker to really try to smooth the response and then I think that would be more interesting.

Thank you very much for your very detailed and helpful response, I usually EQ loudspeakers above 500 Hz based on my own kind of gated listening window average (no need though for the LS50 Meta as they are already quite optimal there) so might give it a try. Anyway I have some time to decide whether I go for the old or R3 Meta till the indigo blue version is released. By the way since the weekend I am combining each of my LS50 Meta with a very low distortion active servo controlled subwoofer making them kind of poor mans LS60:

Figure caption: Distortion of a single LS50 Meta plus subwoofer at the LP at average 90 dB (so around 93-96 with both), less than 2% THD and 1% 3rd harmonic in the bass is quite good.

 

[davidbosch]

I was imagining it would have feet to lift it off a media center far enough to make it work. Not sure how far that would need to be.

It's not a crazy idea. For the common use case where the centre speaker is on a surface that would render the bottom drivers pointless, as they'd be radiating onto a nearby surface and you'd end up with a nasty vertical dispersion and a clear resonance even if you separate it a good amount. However, if the speaker were to be freestanding with no obstructions and close to ear level (with a high screen or behind it?)... you'd have a nice wide horizontal and vertical directivity with plenty of LF, plus the very slim profile. That does sound attractive.

 

[davidbosch]

I noticed that the Reference White Paper has the same frequency response for the Ref 2 Center. Please note that the non-Meta Ref 2 center was listed with the same frequency range, which has been questioned over various forums (asr, avs, av) also! Especially with the R6 released (which is basically the R Series version of the Reference 2), it doesn't makes sense that Kef lists the Reference 2 (Meta) as 80Hz – 35kHz [+/- 3db] whereas the R6 is 65 Hz - 28 kHz [+/- 3db]. If this is an ongoing document issue (hey, we understand - mistakes are human!), can you at least clarify the Reference 2 Meta FREQUENCY RESPONSE (±3dB)?

Hi Mark, I have not received a reply on this regarding the R6 Meta. I am following up. Regarding the Ref 2 Meta, I wasn't aware there was an ongoing online discussion about its frequency response. Would you mind pointing me to it?

 

[exm]

Hi Mark, I have not received a reply on this regarding the R6 Meta. I am following up. Regarding the Ref 2 Meta, I wasn't aware there was an ongoing online discussion about its frequency response. Would you mind pointing me to it?

For example, https://www.avsforum.com/threads/kef-owners-thread.724103/page-1110

I usually use a crossover setting +10Db for the specs listed at +-3Db, so that would mean I can't use 80Hz for the Reference 2 (Meta or non-Meta).

 

[Vacceo]

Hi @stren , The LS60W has opposing LF drivers on both sides, which would not make sense to put in a centre speaker on the top and bottom faces, so no plans for that I'm afraid!

If only I could add an extra LS50 WII as center speaker on my current pair...

Or another 5 as satellites with 4 LSXII as height.

 

[thegeton]

"...It took about 1 minute of gently massaging the ring all around to fully seat it."

Thanks for this. Just noticed that the R3 Meta on the right in my setup has a slightly protruding Shadow Flare.

20230504 Update: Done! Checked both speakers and both received some gentle massages. It will probably take some time to determine if I ever notice anything...

 

[stren]

It's not a crazy idea. For the common use case where the centre speaker is on a surface that would render the bottom drivers pointless, as they'd be radiating onto a nearby surface and you'd end up with a nasty vertical dispersion and a clear resonance even if you separate it a good amount. However, if the speaker were to be freestanding with no obstructions and close to ear level (with a high screen or behind it?)... you'd have a nice wide horizontal and vertical directivity with plenty of LF, plus the very slim profile. That does sound attractive.

So I guess the question would be - even for the LS60 - how much clearance to the side of it do you need before it messes with it? I was envisioning getting some next to my media stand - but the media stand would need to be close. How close is too close?

Edit - > Found it in the manual - 7.5cm

 

[fcracer]

Hi folks, I'd like to share with you the white paper for the new KEF R Series with MAT (the newly released Meta models).

Big apologies for the delay we've had in publishing it, as I know some of you have been awaiting it since the market launch of the series. We've been a bit busy in R&D but I've made sure to include lots of interesting data and figures.

We've tried to go into as much detail as possible on the new technology in this iteration as well as adding new explanations on existing technology, so that you can have a global view of what we've achieved.

I sincerely hope you'll find it an interesting read and enjoy flicking through the pages.

Hi David, just a small data point.

Based on your excellent sharing of information, and the fact your team has designed amazing speakers, I was able to convince a friend to purchase a pair of R3 Meta for his apartment.

Not sure when they’ll arrive but the decision to buy them was 100% driven from your open sharing of the engineering information and measurements. I steered him away from another brand that doesn’t share information in this way.

 

[peterjedi]

Hello David Bosch,

I have enjoyed reading all of your posts. I have a question, do Kef speakers require a good Class D Amp with good filters? From various internet reads that is the conclusion that I am getting. If this is not right place to post this I can move it to the Amps section.

Thanks in advance

 

[pierre]

@davidbosch sent me the data for all the KEF meta speakers.
For each speaker, we got precise data above 300Hz and full range precise On Axis. I interpolated the data between -3dB point and 300Hz.
Results are visible at www.spinorama.org. Please have a look and ping me if you find errors, it was a lot of graphs to incorporate at the same time and mistakes are possible. The speakers are all good or even best in class. Congrats to KEF.

 

[thewas]

@davidbosch sent me the data for all the KEF meta speakers.
For each speaker, we got precise data above 300Hz and full range precise On Axis. I interpolated the data between -3dB point and 300Hz.
Results is visible at www.spinorama.org. Please have a look and ping me if you find errors, it was a lot of graphs to incorporate at the same time and mistakes are possible. The speakers are all good or even best in class. Congrats to KEF.

Thank you for your great effort and database, really appreciated.
The new additions don't seem to appear though at the ranking list yet? https://www.spinorama.org/scores.html?quality=High

 

[pierre]

Thank you for your great effort and database, really appreciated.
The new additions don't seem to appear though at the ranking list yet? https://www.spinorama.org/scores.html?quality=High

That's because I qualified the data as Medium (High is mostly for Klippel generated data). If you want to see them all, remove the ?quality=High in the url. You then see all speakers but high variation in quality of measurements gives inconsistent results (from data is already eq-ed, highly smoothed, etc).

 

[thewas]

That's because I qualified the data as Medium (High is mostly for Klippel generated data). If you want to see them all, remove the ?quality=High in the url. You then see all speakers but high variation in quality of measurements gives inconsistent results (from data is already eq-ed, highly smoothed, etc).

That makes absolutely sense, thank you very much again.

 

[thewas]

New video about the Ci5160REFM-THX and Ci3160REFM-THX which are THX Certified Ultra.

 

[pjn]

New video about the Ci5160REFM-THX and Ci3160REFM-THX which are THX Certified Ultra.

A brief moment of lust, but notably content free! And those windows and floor are surely going to cause all sorts of acoustic problems!

 

[tmj]

I will be very honest with you, I could give you room sizes, but they will probably mean nothing once you account for all the variables such as proportions, building materials, treatment, speaker positions, listener positions, etc. As well as your listening habits (type of music and how loud you want to play it). As you know the larger the room, and the farther away the listener is to the speakers, the louder they will need to be played to sound as loud. The R3 Meta is surprisingly very capable of producing ample clean bass but it does have a ceiling that becomes obvious in large/lossy rooms at high volumes. R11 Meta goes extremely loud before it distorts but in a small room where the stereo triangle will be less than 3 metres per side, the LF array is relatively too big wrt the listener so the stereo image will suffer. If you're in the UK, a lot of people find R5 the right compromise between size, footprint, bass extension and distortion capabilities (and price) for the size and construction of living rooms we have.

Hi David. It was under the impression that the optimal size of a speaker would not only depend on the listening distance but also on the room size.
I have been on the lookout for upgrading my old KEF R3 in a 2.1 setup to a new 5.1 KEF R surround setup, where I will be using the R3 as surround speakers. The room is big, 6 x 8 x 2.7 meters, and openly connected to areas with about the same volume jointly. However, as I sit around 2.6 meters away from the speakers, I am in doubt if I should go for the R7 or R11 to go with the R6. Ideally, I would not like to compromise on the stereo image, but at the same time, I also want the speakers to sound full and project a big wall of sound. On the other hand, I would rarely go past 80 db in average listening level. Would I be shooting myself in the foot by going for the R11 as I sit less than 3 meters away?