KEF Reference 1 META Bookshelf Speaker Review by Erin's Audio Corner

[HarmonicTHD]

Another interesting thing with this loudspeaker - Kef uses an laminate aluminium baffle , probably to make it stiffer , and shifting resonances to a higher frequency and with a lower amplitude for an overall better sound. This costs money and also makes a real difference.
View attachment 204740

… and just looks gorgeous (at least to me ) I love it when form follows function.

 

[thewas]

Another interesting thing with this loudspeaker - Kef uses an laminate aluminium baffle , probably to make it stiffer , and shifting resonances to a higher frequency and with a lower amplitude for an overall better sound. This costs money and also makes a real difference.

There is a white paper about those loudspeakers where every innovation is discussed, like for example the decoupling chassis but not a single mention about that front baffle which is for aesthetic reasons from metal on the Ref with the even superior Blade not having it, repeating your wrong assumptions in every thread doesn't make them less wrong.

Using different port lenghts, in my opinion, is not entirely beneficial because:

1. There are really only one optimal length for the tube with an optimal box volume thats dependent entirely on the drivers TS parameters.

That is also not correct, the TS parameters do not dictate/generate a single "optimal" tuning frequency and bandwidth but this is a choice of the loudspeaker designer depending on the desired FR response curve and the correlating compromises on placement, bass bandwidth, max SPL etc.

 

[AwesomeSauce2015]

Another interesting thing with this loudspeaker - Kef uses an laminate aluminium baffle , probably to make it stiffer , and shifting resonances to a higher frequency and with a lower amplitude for an overall better sound. This costs money and also makes a real difference.

Although I cannot state whether or not the fancy baffle actually makes a difference in the performance, as I am not KEF's engineering team, I will definitely say that MDF (or most wood in general) is already good enough, or else why would literally everyone else use wood in their enclosures and baffles? (See: Revel Salon 2, JBL M2, etc). Genelec uses fancy metal enclosures but I think the reason they do that is to reduce material / labor costs. Despite all this, we have normal-enclosure-d speakers with as good as or better performance than the Reference series. So while the metal may look nice, and may subjectively work as a placebo to "improve" sound, it really isn't showing up on measurements when you consider measurement error.

Also, consider that while yes, the metal may be stiffer, it may also be heavier / denser. This will in turn push the resonances down in frequency. Additionally, just because a resonance is higher in frequency doesn't necessarily mean that it is lower in amplitude. If the driver is imparting more force on the baffle at that frequency, then the resonance could be worse.

So basically, I would have to agree that the fancy baffle is probably just for looks and to differentiate the Reference line from the R-line. It may make a very small difference to the sound, but looking at the R3, we can see that the Reference 1 really doesn't need anything that it would get from a metal baffle.

And lastly, keep in mind that KEF is moving more towards "lifestyle" designs. Basically, they want to increase the WAF of their speakers so that more people are able to buy them. I mean, look at the LS50 Wireless, it's one of their flagship speakers, that they then made a wireless version of. You don't see Klipsch making a wireless version of their top line. So KEF is definitely trying to break into a larger market, one which is interested in looks, and the fancy metal baffle makes it look nicer, and that's about it from an engineering standpoint.

 

[Dbassist]

There is a white paper about those loudspeakers where every innovation is discussed, like for example the decoupling chassis but not a single mention about that front baffle which is for aesthetic reasons from metal on the Ref with the even superior Blade not having it, repeating your wrong assumptions in every thread doesn't make them less wrong.

There is also another white paper for KEF Reference, from the previous version.

https://us.kef.com/pub/media/wysiwyg/documents/thereference/REF_White_Paper_preview_path_200514.pdf

It is mentioned that the baffle provides strength and mass to the cabinet. Not much beyond that is said, but it is there.

 

[jhaider]

What a fine speaker (and review)!

One thing I think is interesting is the evolution of thinking on cabinet diffraction by the more technically competent speaker companies over the last ~15 years or so. If you look at the speakers that represented top-tier engineering back then - e.g. KEF 20x/2, Revel Ultima, Vivid, TAD and Pioneer EX, NHT xD, GedLee, Grimm, JBL LSR 6-series studio monitors - they were all quite curvy or often had big roundovers or highly sculpted baffles.

Compare:

I'm not sure there's a 90 degree angle or for that matter even a flat plane on our Revel Gem2's! But today everyone except Genelec and Vivid seem to have gone boxy: 201/2 to Ref1/Ref1M, Revel Studio2 to F328Be, JBL 6328 to 708, and so on. While fashion, production costs, and bass efficiency (cabinet volume) play into that, what's notable to me here is this boring box shape with nothing but a slight waveguide around the concentric driver does not seem to suffer notable from diffraction effects.

201/2 is still IMO the prettiest speaker KEF has made to date though. My wife would probably prefer this one, albeit with a full-face grille.

 

[RustyGates]

Niceeee.

Will be picking these up in Copper/Black with a Bryston 4B Cubed in a few months.

 

[Beave]

In comparing the measurements of this one vs. the R3, the biggest difference (to me at least) is the tradeoff of bass vs. sensitivity. The R3 has about 4dB higher sensitivity, while the Ref 1 has relatively more midbass output (in the 50-150Hz range). The R3 tweeter also seems a little hotter on axis, relative to the Ref 1.

Otherwise, dispersion and even distortion are pretty similar.

 

[Tangband]

There is also another white paper for KEF Reference, from the previous version.

https://us.kef.com/pub/media/wysiwyg/documents/thereference/REF_White_Paper_preview_path_200514.pdf

It is mentioned that the baffle provides strength and mass to the cabinet. Not much beyond that is said, but it is there.

Yes - this is interesting reading . In point 37 its written :

”These braces are connected to the cabinet walls using a layer of damping material. The drivers are also braced by the internal structure and connected using a layer of damping material to further control the cabinet vibration. The front baffle of the cabinet is constructed in an exceptionally strong laminated aluminium and resin composite, this adds a great deal of strength and mass to the cabinets. ”

 

[Tangband]

That is also not correct, the TS parameters do not dictate/generate a single "optimal" tuning frequency and bandwidth but this is a choice of the loudspeaker designer depending on the desired FR response curve and the correlating compromises on placement, bass bandwidth, max SPL etc.

You are writing the same as I do..
Ofcourse theres tradeoffs, but….
You can optimise the loudspeakers for highest possible SPL with the tuning in bass region ( there is one optimal tubelenght for a given driver /box ) and then eq with a dsp .

 

[thewas]

There is also another white paper for KEF Reference, from the previous version.

https://us.kef.com/pub/media/wysiwyg/documents/thereference/REF_White_Paper_preview_path_200514.pdf

It is mentioned that the baffle provides strength and mass to the cabinet. Not much beyond that is said, but it is there.

Yes, in contrary to other improvements no comparison measurements or simulated data, in opposition for example to the LS50 enclosure https://us.kef.com/pub/media/wysiwyg/documents/ls50/ls50_white_paper.pdf

 

[Rja4000]

Measurements look fine.
But at this price level (for passive), you have very serious competitors.
Including active coaxial designs.

 

[thewas]

You are writing the same as I do..
Ofcourse theres tradeoffs, but….
You can optimise the loudspeakers for highest possible SPL with the tuning in bass region ( there is one optimal tubelenght for a given driver /box ) and then eq with a dsp .

What you suggest would not be what you wrote the "optimal tuning" but rather a poor narrow "one bass note" one, for example seen in old Bose Acoustimass subwoofers. An optimal tuning is the one that comes as close as possible to the desired bass response which for loudspeakers with no room correction usually is one smoothly decreasing to match the inverse the room gain function from the room dimensions and nearby boundaries and is what is usually tried to be achieved from KEF loudspeakers. By the way even my the B&W DM 640 I had bought in 1992 came with 3 different ports to be mounted (long, short and closed), so its not a new innovation.

 

[Absolute]

What a fine speaker (and review)!

One thing I think is interesting is the evolution of thinking on cabinet diffraction by the more technically competent speaker companies over the last ~15 years or so. If you look at the speakers that represented top-tier engineering back then - e.g. KEF 20x/2, Revel Ultima, Vivid, TAD and Pioneer EX, NHT xD, GedLee, Grimm, JBL LSR 6-series studio monitors - they were all quite curvy or often had big roundovers or highly sculpted baffles.

I'm not sure there's a 90 degree angle or for that matter even a flat plane on our Revel Gem2's! But today everyone except Genelec and Vivid seem to have gone boxy: 201/2 to Ref1/Ref1M, Revel Studio2 to F328Be, JBL 6328 to 708, and so on. While fashion, production costs, and bass efficiency (cabinet volume) play into that, what's notable to me here is this boring box shape with nothing but a slight waveguide around the concentric driver does not seem to suffer notable from diffraction effects.



201/2 is still IMO the prettiest speaker KEF has made to date though. My wife would probably prefer this one, albeit with a full-face grille.

Is this diffraction?

The most interesting question with the Ref 1 Meta is how good it is compared to the R3. How close can you get with a simple EQ with the R3?
Here's a comparison from @pierre 's excellent site after EQ to make it easier to compare;

Tonality wise it looks like you'll get much of the same. Distortion wise? Looks smoother on the Ref 1, but the difference may not be all that much.

 

[abdo123]

In comparing the measurements of this one vs. the R3, the biggest difference (to me at least) is the tradeoff of bass vs. sensitivity. The R3 has about 4dB higher sensitivity, while the Ref 1 has relatively more midbass output (in the 50-150Hz range). The R3 tweeter also seems a little hotter on axis, relative to the Ref 1.

Otherwise, dispersion and even distortion are pretty similar.

It’s interesting how the directivity is pretty much the same.

Would be interesting for A/B blind tests.

 

[KMO]

You are writing the same as I do..
Ofcourse theres tradeoffs, but….
You can optimise the loudspeakers for highest possible SPL with the tuning in bass region ( there is one optimal tubelenght for a given driver /box ) and then eq with a dsp .

There's no one correct answer for highest SPL throughout the bass region.

There may be one correct answer for highest peak, which will be at a frequency determined by box size, but there are other answers that will trade that off for higher output at lower frequencies, which you may need more. In the original Reference paper, there are simulations showing what they're aiming for:

So you can "optimise" to get the flat region to extend to 60Hz (but fall off rapidly afterwards), or stretch down to 25Hz, at the cost of being a few 3dB down at 60Hz.

For many listeners the ported version will be much more favourable than the closed due to the additional bass extension, however, the additional bass extension
is not without compromise. [...]

This creates something of a dilemma as, depending on their personal preference and room characteristics and loudspeaker position, some listeners will prefer the
ported response while others will prefer the closed box response.

For The Reference, as a solution to this issue, the main loudspeakers are supplied with two different length port liners. The shorter of the two liners results in a loudspeaker response similar to that shown in the ported system above. Fitting the longer liner results in a frequency response similar to that shown in Figure 19, the same closed box response is shown for easy comparison with Figure 16. This low frequency alignment is specifically designed to roll off very slowly and gently in the upper bass octaves. In many listening rooms this will compensate for the natural bass augmentation due to the closest room boundaries.

 

[Tangband]

What you suggest would not be what you wrote the "optimal tuning" but rather a poor narrow "one bass note" one, for example seen in old Bose Acoustimass subwoofers. An optimal tuning is the one that comes as close as possible to the desired bass response which for loudspeakers with no room correction usually is one smoothly decreasing to match the inverse the room gain function from the room dimensions and nearby boundaries and is what is usually tried to be achieved from KEF loudspeakers. By the way even my the B&W DM 640 I had bought in 1992 came with 3 different ports to be mounted (long, short and closed), so its not a new innovation.

Agree - I dont like ”one bass note ” , but there are tradeoffs laborating with the bass port lenghts. Wrongly tuned, it gonna sound bad and the max spl with lowest distortion gonna be compromised.

The correct place to do this bass tuning is, for me, in a dsp such as GLM or minidsp and to laborate with the placement of the speaker in the room. Doing this only with different bass ports are gonna be rather crude and unprecise.
For me, the bass reflex solution is not mainly about extension but more about getting lower distortion at the tuning freq, where the bass unit is almost standing still and the bassport does almost all the work .
One also has to remember that those whitepapers from Kef is interesting reading - but ultimately also salespoints .

 

[jonfitch]

It’s interesting how the directivity is pretty much the same.

Would be interesting for A/B blind tests.

The original reference series had narrower dispersion than the R series. So this update seems primarily to increase the high frequency dispersion of the Reference series by maybe around 5 degrees or so, bringing it at least on par with the improvements from the R series. I would expect relative to the old Reference series the Ref Meta will sound a bit brighter.

 

[thewas]

Agree - I dont like ”one bass note ” , but there are tradeoffs laborating with the bass port lenghts. Wrongly tuned, it gonna sound bad and the max spl with lowest distortion gonna be compromised.

Yes, but for example the two different bass ports of the KEF which you criticised don't belong to such.

The correct place to do this bass tuning is, for me, in a dsp such as GLM or minidsp and to laborate with the placement of the speaker in the room. Doing this only with different bass ports are gonna be rather crude and unprecise.

I don't agree and prefer reaching acoustically (for example using different ports and placement) as close as possible to the desired optimal bass response in room and EQ only for the fine tuning and mainly correctiong some modal peaks.

For me, the bass reflex solution is not mainly about extension but more about getting lower distortion at the tuning freq, where the bass unit is almost standing still and the bassport does almost all the work .

Not only for you, otherwise people would just use EQ to reach to desired response.

So you can "optimise" to get the flat region to extend to 60Hz (but fall off rapidly afterwards), or stretch down to 25Hz, at the cost of being a few 3dB down at 60Hz.

Exactly, this way you can get the loudspeaker closer to having the inverse of the room gain function for different rooms and placements.

 

[TheBatsEar]

There is a white paper about those loudspeakers where every innovation is discussed, like for example the decoupling chassis

Is there a list without marketing stuff? For example, "reduction of distortion through the use of meta materials" isn't something that makes sense to me. They put a dampened labyrinth behind the tweeter so the sound emitted to that side doesn't get reflected back to the membrane, that makes sense to me.

Would like to avoid that wall of text if they had just a list of items in technical terms.

 

[KMO]

The correct place to do this bass tuning is, for me, in a dsp such as GLM or minidsp and to laborate with the placement of the speaker in the room.

Those have their place, sure, but you can't reasonably expect to boost the lowest 30Hz and below frequencies by >6dB with DSP, like the long port does. How much amplifier power are you planning to spend on overdriving low frequencies to achieve that effect?