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KEF LS60 Wireless Just Announced

voodooless

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How comes they (the blades at least, because I have listened to them) do not sound even remotely like a dipole? Does it have to do with the frequencies played by the woofers being low enough to not be positional?
In a dipole, one side move forward, the other backward (well, usually it’s the same woofer on the flip side). This creates a null to the sides. In the the KEF system, all woofers go either outward or inward at the same time. Below the baffle step they basically work as one omni woofer.
 
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voodooless

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Haven't really looked into this sub. What kind of feedback system do they use..? Accelerometers..?!?
Nope, voice coil current measurements. Some (limited) information here. Usually this type of feedback is very bandwidth limited.
 

Vacceo

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In a dipole, one side move forward, the other backward. This creates a null to the sides. In the the KEF system, all woofers go either outward or inward. Below the baffle step they basically work as one omni woofer.
I wonder how that effect would sound on the side speakers of a multichannel. Since effects tend to go on the lower portion of frequencies, they´d probably sound more "enveloping" on a side position...
 

sweetmusic

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Any chance KEF will add Dirac? Build in room correction and I have no need for any other audio components.
 

HammerSandwich

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Exactly, with similar engineering usually smaller and/or curved structures have from vibration point of view advantages, here for example the LS50 Meta... (source: https://www.stereophile.com/content/kef-ls50-meta-loudspeaker-measurements )

vs the even more expensive series Reference 5... (source: https://www.stereophile.com/content/kef-reference-5-loudspeaker-measurements)
One problem with this comparison: Stereophile's accelerometer plots are all run at 7.55V. The Ref5's cabinet resonance appears 1.2dB worse than the LS50's, but the Ref is playing 4.6dB louder during the test.

But wait - there's more! This does not imply that the Ref5's cabinet is >3dB quieter. We're looking at panel vibrations in specific locations, not SPL measurements of each box's integrated acoustic output. A larger panel definitely can have more acoustic output with lower excursion, just like a larger woofer, so... It's complicated. KEF has good reasons for analyzing this stuff in computer models.

@John Atkinson, anything you'd like to share on this?
 

CrisOfTheFields

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Wow only thing I wish it had was an Asynchronous USB dac built in :( that would have made completed it. The Swan Hivi M5a may be a better value to dollar than the LS60 at 1700 with similar inputs for a 3-way, feel grateful though that we have these choices we didnt have in the past
 

voodooless

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How? Your still limited to xmax. The KC62 might have more xmax than the R11 drivers (it’s still 2 vs 4), yet the LS60 will not have as much Xmax, simply because there is no room. Best guess is that total displacement is about the same as R11, possibly a tiny bit better. But by all accounts it’s a closed design, so the R11 reflex will have a considerable advantage around the tuning frequency.
Case and point, an example, let's compare 4 woofers closed, vs 4 woofers reflex. Power handling is about 200W per woofer, which is a shitload for a 6.5" woofer. Hell, I'll give you 2.3x more Xmax for the closed box just for fun! Case and point, Peerless HDS180 Excl, with power handling doubled to 150W, vs TB W6-1139SI, also with 150W power handling. Xmax is 5.6 vs 13 mm! So what do we get in terms of MaxSPL:
1652333739984.png

Green is the HDS, blue is the TB Xmax monster. So What happened here? How can the HDS be so close and even do better? Well, obviously, below 30 Hz, the closed box wins. But otherwise, the reflex box does very well with a lot less Xmax. Well, most of the advantage stems from the much higher efficiency of the HDS, there is a 5 dB difference. Response of the two boxes is coindicentally very close BTW, so DSP need will be similar:
1652334015489.png


Obviously this is just one example, and other driver combinations can be found that give a different picture. This is just to illustrate that things are not as simple as they might seem.

Something else though. Here is a sim of what the directivity of a setup as the LS60 would look like:
1652334682221.png

Interesting to note is the dip at around 200 Hz going left and richt.

Another thing that could be done is beam stear the low fequencies by changing the phase of left and right woofers. This way one could lessen sidewall bounce for instance. It will limit bandwidth severely though. For instance with 1.5 ms difference:
1652335212266.png
 

jhaider

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Way back in the 90´s, Kef had a line of car speakers. I have no idea how good they are, I have never listened to them. I´m sure that some of us would love to have a renewed line available for integrating them on our vehicles.

I still have some of the Andrew Jones-designed "KEF KAR" speakers. I liked them enough that I still have them. :)
I think the first audio-related email I ever sent was to KEF about enclosures size for these in my doors. Andrew answered it.

That lineup included a 6.5" Uni-Q and a 6x9" Uni-Q. The tweeters were, I believe, shared with the then-current Reference line. There was a later effort to license the KEF brand and technology by a company called Coustic. These had blue impregnated poly cones, and I believe their designer came over from Infinity. They also had a 5.1-channel upmixer under the KEF brand. I'm not sure how long they lasted.
 
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sifi36

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4” Uni-Q and 5.25” woofers
F3 is 31 Hz at 85dB at 1m
F6 is 26Hz at 85dB at 1m

Seriously impressive for such a small enclosure
 

voodooless

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4” Uni-Q and 5.25” woofers
F3 is 31 Hz at 85dB at 1m
F6 is 26Hz at 85dB at 1m

Seriously impressive for such a small enclosure
Ah, I was right about the woofers after all :cool:

So the reason the blade comparison didn’t work was because the Uni-Q is smaller :facepalm:
 

sifi36

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That extension is lower than the Blade Two and comparable to Blade One, despite the much smaller drivers. It’s probably not quite so good when played louder, still crazy though!
 

voodooless

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That extension is lower than the Blade Two and comparable to Blade One, despite the much smaller drivers. It’s probably not quite so good when played louder, still crazy though!
It would need 22 mm of Xmax to get to the claimed 111 dB at 40 Hz. Highly unlikely it will reach that low at that level. Possibly > 60 Hz it will do that. Still quite respectable If used with a nice sub.
 

thewas

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But wait - there's more! This does not imply that the Ref5's cabinet is >3dB quieter. We're looking at panel vibrations in specific locations, not SPL measurements of each box's integrated acoustic output. A larger panel definitely can have more acoustic output with lower excursion, just like a larger woofer, so... It's complicated. KEF has good reasons for analyzing this stuff in computer models.
I fully agree, just doing a vibroacoustic measurement at a single point has quite limited informative value and can only be a first step to show some broadband (non local) problems.
 

Jukebox

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lots of excursion and lots of power (handling), combined with a thin enclosure and feedback system makes that work.

Now imagine chopping another 10cm away from the width. I wonder what those drivers look like? Loose 10 cm from this structure:

It's a complete new motor structure made from some kind of treated PVC (not audiophile material I know, luckily it's not about this on this forum :p ) to compensate for the narrow design of the speaker.
 

Audiotone

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sifi36

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It would need 22 mm of Xmax to get to the claimed 111 dB at 40 Hz. Highly unlikely it will reach that low at that level. Possibly > 60 Hz it will do that. Still quite respectable If used with a nice sub.

It should be able to get to 100-102dB at 30Hz, that would be an xmax of 10-13mm. Plenty loud enough for most.
 
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