KEF LS60 unboxing!

[Tangband]

Thanks for pointing that out. I'm pretty sure I was mistaken.
The idea of side-mounting woofers is not new but it was always hamstrung by three things.

One, good woofers are pretty deep, and you don't stagger them (and even if you do) the cabinet can end up being pretty wide. KEF appears to have made some custom 5.25" shallow woofers and/or staggered them to create a very shallow cabinet. Good job.

Second, the slim cabinet means your midrange can't be that big, and therefore can't have much output. I assume the unit here has decent xmax, but who knows. I would bet this is the weak point of this system (every system has one.) The most typical solution is an MTM of course.

Third, if the midrange is small, that means it wants to cross over fairly high in frequency, which means the woofers have to play higher, which is a problem because they are oriented towards the side. So they need to be relatively small so that they're effectively omni at their operating frequencies. KEF has addressed this by using an array of speakers which, in the horizontal plane, is only 5.25" wide, meaning it will radiate relatively widely at relatively high frequencies. I never considered that before; you get the output of a bigger woofer but the wide directivity of a smaller one.

Putting aside the engineering marketing and meta-materials and so forth, this speaker is a very clever conventional design which pulls off a driver arrangement that few speaker companies have done successfully.

The major drawback of this design - and I see no way around it - is it will be a very wide radiating design. This is not a big drawback, many people prefer designs like this, but I wouldn't expect any sidewall rejection from a speaker which literally has drivers pointing at your side walls. In this way it is decidedly not a competitor to next gen cardioid designs like Kii/Purefi, but is an outstanding hifi product nonetheless.

Interesting .
My take on this : this Kef ls60 speaker sound really wonderful with music .
In my three listening sessions, I could not hear the crossover frequency , and the sound was very 3 D in the illusion of the soundstage .

The technical side : using a very narrow ( 13 cm ) cabinet , youre loosing the baffle step for the 4 inch uniQ driver way above the crossover frequency at 350 Hz.

11600/13 = 892 Hz

What Kef has done to solve this is the same solution that linkwitz lxmini uses - dsp eq .

In this way the frequency response will be flat , but you will loose some headroom (up to 6 dB ) between 350 - 900 Hz because of this .

The Blades are constructed so that the baffle step width of the baffle matches the crossover frequency - the baffle is much wider, and this is a must with a passive speaker .

Ofcourse this could be done also with an active speaker without the need of dsp eq, but the look would be less good with a speaker thats 32 cm wide.
—————-
Edit : a good 4 incher can play rather loud if its crossed step ( like in this speaker ) at 350 Hz . One could argue though, that this 4 inch uniQ driver is in reality a 3 incher, because the tweeter takes up some space of the cone.

In my listening tests, most people seems to prefer a wide beaming loudspeaker - for 2 channel listening and in a big room . And the opposite for 5.1 listening .

 

[617]

Interesting .
My take on this : this Kef ls60 speaker sound really wonderful with music .
In my three listening sessions, I could not hear the crossover frequency , and the sound was very 3 D in the illusion of the soundstage .

The technical side : using a very narrow ( 13 cm ) cabinet , youre loosing the baffle step for the 4 inch uniQ driver way above the crossover frequency at 350 Hz.

11600/13 = 892 Hz

What Kef has done to solve this is the same solution that linkwitz lxmini uses - dsp eq .

In this way the frequency response will be flat , but you will loose some headroom (up to 6 dB ) between 350 - 900 Hz because of this .

The Blades are constructed so that the baffle step width of the baffle matches the crossover frequency - the baffle is much wider, and this is a must with a passive speaker .

Ofcourse this could be done also with an active speaker without the need of dsp eq, but the look would be less good with a speaker thats 32 cm wide.
—————-
Edit : a good 4 incher can play rather loud if its crossed step ( like in this speaker ) at 350 Hz . One could argue though, that this 4 inch uniQ driver is in reality a 3 incher, because the tweeter takes up some space of the cone.

In my listening tests, most people seems to prefer a wide beaming loudspeaker - for 2 channel listening and in a big room . And the opposite for 5.1 listening .

Interesting observations. I didn't think of the baffle step frequency. The mid is definitely the weak link in this system, and you are correct that the tweeter assembly eats a lot of radiating area. There's nothing stopping people from making high output small midranges, but you don't see a ton of them, especially in the diy space. Given that they call the LS50 a 'full range' speaker I guess KEF has gone to some effort to put some xmax into the uni-q.

I hadn't considered that the shape of the speaker dictates DSP but you are spot on. The lack of baffle reinforcement would make a passive speaker with this size and shape really impractical, but this is a great example of the design freedom you get with DSP and lots of cheap power.

Amazing how tricky it is to design a skinny loudspeaker! Believe me, I've tried. This might be the best one I've seen.

 

[Tangband]

Interesting observations. I didn't think of the baffle step frequency. The mid is definitely the weak link in this system, and you are correct that the tweeter assembly eats a lot of radiating area. There's nothing stopping people from making high output small midranges, but you don't see a ton of them, especially in the diy space. Given that they call the LS50 a 'full range' speaker I guess KEF has gone to some effort to put some xmax into the uni-q.

I hadn't considered that the shape of the speaker dictates DSP but you are spot on. The lack of baffle reinforcement would make a passive speaker with this size and shape really impractical, but this is a great example of the design freedom you get with DSP and lots of cheap power.

Amazing how tricky it is to design a skinny loudspeaker! Believe me, I've tried. This might be the best one I've seen.

Yes, Kef ls60 and I believe also the Lxmini are very innovating constructions.

 

[Purité Audio]

Still waiting for the LS50’s to arrive for a full-on KEF shoot out, anyone local to North London is welcome to come and listen another opinion is always welcome.


KEF LS60 in Graphite.
Keith

 

[samysound]

Still waiting for the LS50’s to arrive for a full-on KEF shoot out, anyone local to North London is welcome to come and listen another opinion is always welcome.


KEF LS60 in Graphite.
Keith

Hi Keith
How do these compare to the ggntkt? Can they produce similar output levels playing full range?

 

[Ron Texas]

@Purité Audio thank you for your informative post. The images are greatly appreciated.

 

[Purité Audio]

Hi Keith
How do these compare to the ggntkt? Can they produce similar output levels playing full range?

Samy how near do you sit and are you prepared to damage your hearing , I can sit 5 metres away in our largest room and both can play deafening loudly, perhaps if I sat 7-10 metres away … or needed to fill a much larger room with sound.
Keith