KEF Reference and Blade Meta announced, but where is the R Meta?????

[killdozzer]

In an active, each amp has to be able to deliver full power at a given frequency, I suppose. Also, the amps are likely specified much more narrowly to function (Current, etc.).

Thank you for your contribution. I still hope we might hear from the guy himself.

 

[thewas]

The German magazine "Stereo" has reviewed and measured in this month issue both the Blade Two Meta (26000€) and the Reference 5 Meta (20000€) and features also an interview with Dr. Jack Oclee-Brown about their differences and previous technologies like ACE.

They both measure quite flat from 200-2000 Hz and smoothly dropping aside to both frequency extremes (keep in mind though that the Stereo measurements are not really matching other ones), distortion values are very similar, a tad lower on the bass for the Reference and for the rest for the Blade. (cannot post them here due to copyright reasons)

According to the reviewer the Reference 5 (97% score) is tuned a bit more for detail and impact, while the Blade Two (99% score) for extremely coherent unity and long-term listening and would be his choice as the loudspeaker for a "lonely island".

 

[Vacceo]

I am in the process of upgrading my very old system living room system and the potential update of Kef R series sounds quite interesting.

I'm coming from an old set of IQ series speakers from 2006, so I guess anything will make quite a difference.

Renewing the speakers for a more modern Kef set sounds quite logical as the general dispersion and reflectivity pattern will be quite consistent to my current sound.

I also considered going for Arendal 1723 S, but those are completely different animals.

The listening distance is relatively short (2 meters to center speaker), hence, the coaxial nature of the center should work in KED's favor over the MTM design of the Arendals. The room is not huge (30 square meters), hence I should not need very loud speakers (minus for Arendal), however, the Arendal heights seem to be better performing. Room correction will be there, but I know it is not magic.

With all this data, would you expect a noticeable improvement on the R8a? Same goes for the R2c (an already very capable speaker). The R3 and R7 are quite nice speakers as they are, so any extra improvement should be welcome.

All in all, would you say waiting is a good idea and start upgrading the electronics first as the impact is not as huge and after some time, go for the speakers once the upgraded versions are out and reviewed?

 

[abdo123]

I am in the process of upgrading my very old system living room system and the potential update of Kef R series sounds quite interesting.

I'm coming from an old set of IQ series speakers from 2006, so I guess anything will make quite a difference.

Renewing the speakers for a more modern Kef set sounds quite logical as the general dispersion and reflectivity pattern will be quite consistent to my current sound.

I also considered going for Arendal 1723 S, but those are completely different animals.

The listening distance is relatively short (2 meters to center speaker), hence, the coaxial nature of the center should work in KED's favor over the MTM design of the Arendals. The room is not huge (30 square meters), hence I should not need very loud speakers (minus for Arendal), however, the Arendal heights seem to be better performing. Room correction will be there, but I know it is not magic.

With all this data, would you expect a noticeable improvement on the R8a? Same goes for the R2c (an already very capable speaker). The R3 and R7 are quite nice speakers as they are, so any extra improvement should be welcome.

All in all, would you say waiting is a good idea and start upgrading the electronics first as the impact is not as huge and after some time, go for the speakers once the upgraded versions are out and reviewed?

the R8a and the R2c should be WAY superior to any typical 2-way design from Arendal.

 

[Vacceo]

the R8a and the R2c should be WAY superior to any typical 2-way design from Arendal.

Prices are not that different, same for the Sonus Faber Sonetto II line, hence my doubts.

 

[tecnogadget]

the R8a and the R2c should be WAY superior to any typical 2-way design from Arendal.

Even though I my personal choice is KEF and Uni-Q design, I wouldn’t call the difference with a similar priced Arendal that high. It will only be WAY superior on the vertical dispersion metric, that’s where the supremacy starts and ends.

 

[abdo123]

Even though I my personal choice is KEF and Uni-Q design, I wouldn’t call the difference with a similar priced Arendal that high. It will only be WAY superior on the vertical dispersion metric, that’s where the supremacy starts and ends.

He’s talking about a center speaker so it’s a whole world of difference. Even with Atmos speakers you rarely sit on vertical axis if you have multiple seats.

 

[Vacceo]

He’s talking about a center speaker so it’s a whole world of difference. Even with Atmos speakers you rarely sit on vertical axis if you have multiple seats.

Right. Looking at graphs; spl aside, there seems to be not a huge difference between the R7 and the 1723 S. For the 1723 S center and the R2c, that is a different story looking at off axis consistency.

I have found no tests for the 1723 S Height, but the R8a seems a bit luckluster on both range and spl.

Hence my question about potential improvements on those cases with a future R revision with the new meta and reworked driver.

 

[Mnyb]

@jackocleebrown

Your previous answer was so nice and informative so that I missed that one question remains unanswered.

Bluntly, do you voice the different series differently Q , R , Reference ?

 

[jackocleebrown]

@jackocleebrown If you allow for one easier question, I wondered why is there such a huge difference from what is recommended amp power for passive LS50 to what KEF builds in the active version? I realise a certain amount of energy gets lost in the DSP, so to speak, I just didn't expect it to be such a huge difference. Upper limit is 100w recommendation for a passive one, but there's 230w in the active speakers; 200 for the mid/woofer and 30 for the tweeter, so 230 per channel. How significant is the role security plays in all this and what would be your recommendation if you were dealing with someone who is not likely to fry the speakers?

One other thing, in real numbers, how hungry is the dip of 3.9 ohm? If you want to set up the SPL to an average of 96dB and you want to make sure there's enough headroom on the side of the amp, what would be the required amp strength?

Hi Killdozzer,

The LS50W2 DSP includes protection systems for the drivers that prevent overload and allows the speaker to be pushed harder than in a passive system. This security is absolutely critical. Hence the higher power spec than you'd typically use with the LS50 META.

Amplifier power recommendations for passive speakers are quite tricky for us to set. The lower limit for LS50 META is 40W. For some customers who like to listen loud this won't be enough, but others would be perfectly satisfied. There's also a great deal of difference in how different amplifier manufacturers specify their products. The 100W max is also a rough guide, it's safe to use a higher power than this provided the speakers are not driven to the point of significant distortion.

I'd always recommend to make sure your amp can drive a 4 Ohm load (most can, except for some of the budget home cinema amps). And it's also a very good sign when the power spec for the amp is almost doubled comparing the 8 Ohms power spec to the 4 Ohm power spec.

I presume you're talking about the LS50 META? The speaker sensitivity is about 85dB SPL/2.83V/1m. To achieve 96dB SPL/1m average you need 10Vrms, which is 25.6W average into 3.9Ohms. I must say though that 96dB average SPL is rather a high replay level. The peaks in music will be at least 9dB higher than the average level, so you'd be hitting peak SPLs of ~105dB/1m and you would be at the clipping point of a 100W/4Ohm amp.

I'm in danger of making this a long post... but although you flagged the 3.9 Ohms dip, it's often not the minimum impedance that causes the greatest stress in amplifiers. AB amps struggle to deliver power into inductive and capacitive loads and typically the most difficult frequencies are either side of the impedance dip where the magnitude is still fairly low and the phase angle deviates from zero. Such impedances make the amplifier output stage work much harder and can cause protection systems in the amp to trigger. There's a metric called EPDR that attempts to capture this.

 

[jackocleebrown]

@jackocleebrown

Your previous answer was so nice and informative so that I missed that one question remains unanswered.

Bluntly, do you voice the different series differently Q , R , Reference ?

Hi Mnyb,

Sorry for missing this question. The voicing approach is the same for Q, R and Reference. We aim for neutral speakers, with well-controlled directivity and smooth off-axis responses. The extent to which we are able to achieve this varies depending on how successful we've been during the design and development of the loudspeakers. And we slowly try and refine our understanding of "neutral" based on feedback and our experience with our previous products, as I outlined in more detail in the other post.

 

[Mnyb]

Hi Mnyb,

Sorry for missing this question. The voicing approach is the same for Q, R and Reference. We aim for neutral speakers, with well-controlled directivity and smooth off-axis responses. The extent to which we are able to achieve this varies depending on how successful we've been during the design and development of the loudspeakers. And we slowly try and refine our understanding of "neutral" based on feedback and our experience with our previous products, as I outlined in more detail in the other post.

Thankyou, there are simply so(to) many opinions on this , so I had to ask I’ve also confused myself by watching YouTube reviews on these speakers.

 

[Virgulino]

Hi Dr @jackocleebrown !

I'm a huge fan of Kef and your work there!

Unfortunately I couldn't care less about the new Blade and Reference.

What I really want to see is what revolutionary product you guys will release next month!

I loved your Hydro Blaster Spray® - which reminds me that I need to buy more.

Best regards from Brazil.

 

[killdozzer]

Hi Killdozzer,

The LS50W2 DSP includes protection systems for the drivers that prevent overload and allows the speaker to be pushed harder than in a passive system. This security is absolutely critical. Hence the higher power spec than you'd typically use with the LS50 META.

Amplifier power recommendations for passive speakers are quite tricky for us to set. The lower limit for LS50 META is 40W. For some customers who like to listen loud this won't be enough, but others would be perfectly satisfied. There's also a great deal of difference in how different amplifier manufacturers specify their products. The 100W max is also a rough guide, it's safe to use a higher power than this provided the speakers are not driven to the point of significant distortion.

I'd always recommend to make sure your amp can drive a 4 Ohm load (most can, except for some of the budget home cinema amps). And it's also a very good sign when the power spec for the amp is almost doubled comparing the 8 Ohms power spec to the 4 Ohm power spec.

I presume you're talking about the LS50 META? The speaker sensitivity is about 85dB SPL/2.83V/1m. To achieve 96dB SPL/1m average you need 10Vrms, which is 25.6W average into 3.9Ohms. I must say though that 96dB average SPL is rather a high replay level. The peaks in music will be at least 9dB higher than the average level, so you'd be hitting peak SPLs of ~105dB/1m and you would be at the clipping point of a 100W/4Ohm amp.

I'm in danger of making this a long post... but although you flagged the 3.9 Ohms dip, it's often not the minimum impedance that causes the greatest stress in amplifiers. AB amps struggle to deliver power into inductive and capacitive loads and typically the most difficult frequencies are either side of the impedance dip where the magnitude is still fairly low and the phase angle deviates from zero. Such impedances make the amplifier output stage work much harder and can cause protection systems in the amp to trigger. There's a metric called EPDR that attempts to capture this.

Thank you very much @jackocleebrown !
Let me start by saying you could hardly make a post too long. I don't want to be "all compliments", but I really find it a fascinating read. I have no expertise in this nor similar fields. I'm just an amateur aficionado, but I do obsess over details.

My question was aiming at speaker's demand for power when played moderately loud. In your answer you also mention this "rule of thumb" - weaker amp is enough for low level listening. I was wondering if power plays a more significant role even when not pushed to its limits. This is also why I asked about the lowest impedance dip as stated in the white paper.

There's a reputation attached to LS50 as being power-hungry. There are numerous reviews stating this. I wanted to understand it better since I do realize that if you need 1w for 85dB, you'd need 8w for 94dB. Further few watts to account for the distance to your listening position, but that's still far from what is being mentioned. I simply thought that perhaps it's because of these impedance dips. I have the first model LS50 (my next step is Meta + Sub, but I'm still waiting for some detailed read on KC62). I power them with 110wpch into 8, but with an amp measured all the way down to 2 ohms and still stable and with arguably low increase in THD. I was quite satisfied when I moved from some weaker amps (although I didn't do a proper comparison and all this could be expectations).

When you say: "AB amps struggle to deliver power into inductive and capacitive loads and typically the most difficult frequencies are either side of the impedance dip where the magnitude is still fairly low and the phase angle deviates from zero. Such impedances make the amplifier output stage work much harder and can cause protection systems in the amp to trigger." do you, by any chance, have easily accessible numbers on how big would be this increase in power consumption for the most difficult frequencies?

Is there any real-world use of all that excess power or do we really have 40% of our power amps just idling by?

 

[stren]

Thank you very much @jackocleebrown !
Let me start by saying you could hardly make a post too long. I don't want to be "all compliments", but I really find it a fascinating read. I have no expertise in this nor similar fields. I'm just an amateur aficionado, but I do obsess over details.

My question was aiming at speaker's demand for power when played moderately loud. In your answer you also mention this "rule of thumb" - weaker amp is enough for low level listening. I was wondering if power plays a more significant role even when not pushed to its limits. This is also why I asked about the lowest impedance dip as stated in the white paper.

There's a reputation attached to LS50 as being power-hungry. There are numerous reviews stating this. I wanted to understand it better since I do realize that if you need 1w for 85dB, you'd need 8w for 94dB. Further few watts to account for the distance to your listening position, but that's still far from what is being mentioned. I simply thought that perhaps it's because of these impedance dips. I have the first model LS50 (my next step is Meta + Sub, but I'm still waiting for some detailed read on KC62). I power them with 110wpch into 8, but with an amp measured all the way down to 2 ohms and still stable and with arguably low increase in THD. I was quite satisfied when I moved from some weaker amps (although I didn't do a proper comparison and all this could be expectations).

When you say: "AB amps struggle to deliver power into inductive and capacitive loads and typically the most difficult frequencies are either side of the impedance dip where the magnitude is still fairly low and the phase angle deviates from zero. Such impedances make the amplifier output stage work much harder and can cause protection systems in the amp to trigger." do you, by any chance, have easily accessible numbers on how big would be this increase in power consumption for the most difficult frequencies?

Is there any real-world use of all that excess power or do we really have 40% of our power amps just idling by?

This made me wonder - does an active system like the LS50WII with seperate amps and digital crossovers have an advantage on amplifier loading by being an easier load to drive as there are less components that contribute awkward phase?

 

[ahofer]

There's a metric called EPDR that attempts to capture this.

We had quite a thread on this, with some debate about the effects of “apparent load”

Post in thread 'How important is doubling down power to 2 ohm or 1ohm on Hi Fi Speakers on high dynamic range music?'
https://audiosciencereview.com/foru...on-high-dynamic-range-music.23100/post-774127

I did come away thinking it was mostly a heat dissipation problem. I haven’t seen anyone publish ”EPDR?

 

[abdo123]

This made me wonder - does an active system like the LS50WII with seperate amps and digital crossovers have an advantage on amplifier loading by being an easier load to drive as there are less components that contribute awkward phase?

Definitely. Even the best designed analog crossovers influence the speaker's electrical impedance by a significant amount.

 

[Soniclife]

Definitely. Even the best designed analog crossovers influence the speaker's electrical impedance by a significant amount.

And waste efficiency on any driver that needs lowering in output to blend correctly.

 

[stren]

Not to get too side tracked here - but kinda surprised Kef didn't launch a version of the KC62 that acted as a matching stand/base for the LS50W. I know, subs should be where subs should be, but they are already lifestyle products, so why not go the whole hog. I guess the dev cost isn't worth it. But still.

 

[killdozzer]

Not to get too side tracked here - but kinda surprised Kef didn't launch a version of the KC62 that acted as a matching stand/base for the LS50W. I know, subs should be where subs should be, but they are already lifestyle products, so why not go the whole hog. I guess the dev cost isn't worth it. But still.

My guess is that KEF tries to go the other way when possible. Just like you have a single pair of binding posts on LS50, they don't want to inspire people in poor placement.

I also noticed that KEF is not really treating the KC62 as a lifestyle component. Their position on this is that KC62 is the MOST serious sub in its category. And the category is simply a "small room sub". I see them saying; nothing can play like this, be this small and have this build-quality.

I'm sorry if this came out preachy, that wasn't my intention. I just wanted to share an opinion and see what others think. I have a feeling that people labeling this little sub as lifestyle are often high-brow motivated. I'm saying this because for KC62 to be lifestyle, you'd have to have a vast array of subs just as small with equal or matching performance, but with plain looks and cheap, but so far, there are none (SVS Micro being a bit bigger and by everything I saw so far, not as enthralling).