Kef R3 META, digital crossover?

[LionIT]

I managed to remove the Shadow Flare of the woofer, but I have some difficulties with that of the Uni-Q. Even with smartphone tools it is difficult to find grip for traction.
From the online videos I saw that the flares are painted so I exclude the gel double-sided tape.
Advice is accepted!

 

[Rõlnnbacke]

I managed to remove the Shadow Flare of the woofer, but I have some difficulties with that of the Uni-Q. Even with smartphone tools it is difficult to find grip for traction.
From the online videos I saw that the flares are painted so I exclude the gel double-sided tape.
Advice is accepted!

I've managed it once with the black or. R3 with a 'precision screwdriver' as a lever, very carefull of course. It left a 'precision dent' on the baffle, a 'dentety dent', only visible with close inspection.
I guess your enterprise will be very difficult; good luck! I must say I think the R3 meta allready is very good, I have them too and I've not yet have had any wish for something even better.

 

[LionIT]

Thanks for the advice.
II found suction cup sets on a well-known Chinese store. They are of the right size and normally intended to pull hailstones damage on cars. As soon as I try them I will update you.

 

[Ivanovich]

Great thread!

I’m now thinking of picking up a pair of open box Q150s for ~$260/pr to source the Coaxial drivers. I’d pay that for one Scan-Speak Revelator! I’d add use them in a 3-way DIY design using a pair of Hypex Fusion Amp FA123, 3-channel plate amps with DSP for X-over and EQ, and 10” subwoofers that I already own. I currently have them in an unfinished (woodwork finish-wise) DIY MTMW design. I like it but I’m intrigued by the coaxial and need a new project! lol

The design goal would be to extend the low end FR and potentially improve the directivity mismatch with baffle/cabinet design. Would be looking at a tower with 11”-12” baffle.

 

[Digital_Thor]

Great thread!

I’m now thinking of picking up a pair of open box Q150s for ~$260/pr to source the Coaxial drivers. I’d pay that for one Scan-Speak Revelator! I’d add use them in a 3-way DIY design using a pair of Hypex Fusion Amp FA123, 3-channel plate amps with DSP for X-over and EQ, and 10” subwoofers that I already own. I currently have them in an unfinished (woodwork finish-wise) DIY MTMW design. I like it but I’m intrigued by the coaxial and need a new project! lol

The design goal would be to extend the low end FR and potentially improve the directivity mismatch with baffle/cabinet design. Would be looking at a tower with 11”-12” baffle.

And what woofers are you planning to use? What room size and expected SPL?
Even though the Q150 driver has a Z-fldx suspension, I wouldn't cross it much lower than 300Hz, if you want a bit of 'physics' to the sound. The midwoofer in the KEF coax - opposed to the dedicated R version - also has lower sensitivity... Just if you plan to pair it with 2 x 10" woofers in parallel+ two subwoofers... Or something like that.

 

[Ivanovich]

It’s a medium sized listening area of the basement, 15’x17’x7.5’ in an open larger space finished basement. About 87db, which matches the KEF and the Dayton RSS265HF-4 10” woofer. I’d start to look at crossing the woofer and mid at about 150-200Hz

The room also has 4 12” subwoofers strewn throughout the space to smooth resonant peaks and valleys.

Looking at the FR of the Q100 by Erin from 10 years ago does not inspire much confidence that I am advancing the quality of what already have! Anyone know if the Q150 drivers are better than the Q100s, or are they the same?

 

[Digital_Thor]

Here's a bit of inspiration:
https://www.diyaudio.com/community/threads/kef-q150-breeding.402547/
https://www.diyaudio.com/community/...-coax-upper-end-other-uniq-adventures.377221/

 

[capslock]

There are a lot of advantages to a digital crossover over passive for more precision. Powering the drivers directly will also decrease distortion. How much of a notable difference is the question.

How will powering the drivers directly lower the distortion? That may actually happen if the passive crossover contains nonlinear components such as electrolytic capacitors or steel / ferrite core inductors. If it doesn't, I'd argue that the series resistance of the crossover helps as it gets a little closer to current drive.

You could also argue that steep crossover slopes will decrease distortion, but you can't claim that benefit if you apply the same slopes as in the passive version.

 

[capslock]

I tried to listen to so many speaker systems, and found out - finally - that I prefer a smooth power response the best. This made me fall for the KEF coax, which I first only thought could be obtained, by buying the finished speaker, which would also relieve me from the burden of making a good-looking speaker cabinet
For me, the "standard" KEF sound and approach, was not fully to my liking. The modern trend with small drivers, do make sense in several aspects, but I do also like the more "full" and authoritarian sound that bigger woofers can bring to the sound, from below around 400Hz. Further, the slight rise at the top ( yes I know about the toe-in) was not my taste either.
Since I was never blessed with the patience to learn how to build a passive filter, I jumped straight to active filtering with DSP and an amplifier for each driver unit.
Above 400Hz I only use the DSP to make the speakers measured performance look like what you often see in NFS scans. Below, when you enter the long-wavelength territory, I start fiddling with the DSP to sum the mains with my subwoofers and the room.

Finding a set of "loose" KEF unit, was my happy trip down DIY-lane. And now, I think I would just buy a set of R3's and "steal" the Coax to build what I want.
And I want relative narrow towers, with larger woofers and closed boxes, point source sound, that still reach subwoofers with a smooth downwards roll-off.
And I think the result sounds awesome.... looks are getting there.. but I'm no champ in wood working - so I had to live with some compromises
You could just pull the passive filter and do the active swap directly in the original cabinet... if you wish. Cause if you are already going that far... what else could be fun to do too?View attachment 399914

So I had to decide to take that chance. Maybe I could live with a set of R7, with plugged ports and some EQ to "clean" up the linear problems in the upper frequencies.
But ask yourself - are your DIY-skills ready to rumble? Because it can be done... you just gotta be willing to fight a bit for it. Though.... I would also never shame anyone for not doing it. I'm just me, with my little personal HIFI adventure

Wow! Which Uni-Q is that?

 

[Digital_Thor]

SP1763AA. As I was told, it should be the 12 gen from a KEF R3 - last version before Meta. I owned the LS50 Meta and found this R version better in the midrange - also like the added sensitivity... so I guess I had to live with the supposedly "less" good tweeter of the none Meta. Couldn't really hear it. Maybe the Meta can be crossed lower... but I cross this none Meta at 2200Hz - seems fine.
Did my little amateur spinorama, and added subwoofers - then confirmed that it looked ok in the listening position. Sound great - but I'm of course super biased
Measurements are done with gating for speaker EQ and smoothing for room EQ. Around 3,5ms to reach around 600Hz for the speaker alone, on my little turn-table. Then I smooth 1/12'th in the listening position, since my room is not super damped. I just look if the overall downwards tilt is following the "guideline".

I'm still working on the smoothness in the sub-range... but I sense that most music from Trentemøller to Katie Melua, sounds smooth, deep, powerful, and yet very detailed, precisely centered between the speakers, no S and T sounds, and the two WO24P Satori woofers ads that richness and detailed fullness to male voices, cello's sax's and jazzy jives. The cab is just a simple 75 liters closed one, with quite simple and straight forward bracing. Not fancy edges or anything. And the coax sits in a small heavy stuffed chamber with pure wool inside - around 3,5 liters. I cross the coax at 2200Hz with LR24, and 500Hz to the Satori - also LR24. The I let the Satori play with a first order HP at 70Hz, just to relieve them from the very lowest bass... but still have that smooth overtake to subwoofers. The 4 subwoofers cross at both around 80 and 110Hz with LR96. It's a steep filter, and according to Geddes - I should not do that.... it just seems to work ok. Will keep testing though - that's the hobby

 

[Vergiliusma]

Kef explains that due to the vertically asymmetric design they have developed the passive crossover of the R3 with the aim of having a linear PR, rather than a linear FR on the axis

And that's the better trade-off in that case, imo.

In that range, the off-axis response is still greatly contributing to overall perception, which shifts towards axial dominance higher in frequency.