Hi,
Please can you help explain to a beginner how this design makes sense?
So up front is a 5" coaxial with a 1" dome, so basically a Q150 driver?
Four 9" woofers, so the guts of two KC92's?
It's high-density polyurethane, so thick plastic, there doesn't look like much air volume in that cabinet?
So these things are wired like normal speakers, they're not active, how does those subs work properly without a DSP?
Could I essentially get the same sound by buying four KC92's and a pair of Q150's, so a total of AUD$15K RRP and hooking them up to a DSP, with room correction, in a standard living room, it could possibly sound better than these AUD$60K speakers?
Is a coaxial with a curved baffle and loads of subs the Nirvana then?
I might head to the workshop at have a go at replicating this speaker shape in plywood with the CNC.
Thanks.
Please can you help explain to a beginner how this design makes sense?
So up front is a 5" coaxial with a 1" dome, so basically a Q150 driver?
Four 9" woofers, so the guts of two KC92's?
It's high-density polyurethane, so thick plastic, there doesn't look like much air volume in that cabinet?
So these things are wired like normal speakers, they're not active, how does those subs work properly without a DSP?
Could I essentially get the same sound by buying four KC92's and a pair of Q150's, so a total of AUD$15K RRP and hooking them up to a DSP, with room correction, in a standard living room, it could possibly sound better than these AUD$60K speakers?
Is a coaxial with a curved baffle and loads of subs the Nirvana then?
I might head to the workshop at have a go at replicating this speaker shape in plywood with the CNC.
Thanks.
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It's certainly a good configuration but it has cons as well pros. Perhaps the biggest con is the radiation pattern at low frequencies which is wider than ideal and with an off-axis hole around the mid/woofer crossover frequency. A coaxial driver is fairly tricky to get working well and the one in the blade is a well developed prestige midrange driver whereas the one in the Q150 is built down to a budget (e.g. no shorting rings I think but needs checking) and is also midwoofer rather than a midrange. Expect to hear small differences but likely not large one.
I've always been fascinated with KEF blade but I don't have a room or a budget for it.
The KEF blade is a full range point source, which is a highly prized characteristic that pays dividends in how the speaker interacts with the room. KEF has gone to a great extent to reduce/eliminate diffraction from the response. With 4 9" woofers, it has more bass than any other KEF. Its clearly a cost no object type of design. OTOH, it has been criticized for the side woofers playing as high as they do. Because of this response pattern widening, you would need a large room for them to really shine.
There is a thread here by @fluid where he did abec simulations of a blade-like configuration. This is where the pattern widening due to the side woofers is criticized.
Its an interesting idea to cannibalize parts from Q150 and KC92. If you are willing to spend that much, you would do almost as well with KEF Rseries with much less work and little risk.
The KEF blade is a full range point source, which is a highly prized characteristic that pays dividends in how the speaker interacts with the room. KEF has gone to a great extent to reduce/eliminate diffraction from the response. With 4 9" woofers, it has more bass than any other KEF. Its clearly a cost no object type of design. OTOH, it has been criticized for the side woofers playing as high as they do. Because of this response pattern widening, you would need a large room for them to really shine.
There is a thread here by @fluid where he did abec simulations of a blade-like configuration. This is where the pattern widening due to the side woofers is criticized.
Its an interesting idea to cannibalize parts from Q150 and KC92. If you are willing to spend that much, you would do almost as well with KEF Rseries with much less work and little risk.
It makes sense to a manufacturer offering an overpriced dream, that isn't one.
There is plenty of bits and parts for less money to build a great sounding system.
The problem is knowing how to.
Thanks, I did mention beginner and DSP, I'll be one of those guys that builds for the woodworking fun, knows it sounds good enough and will happily allow auto room correction to clean up my sound.
The Blade is a pretty speaker, salvage Q150 drivers and add suitable bass drivers, maybe just two instead of 4, active, separate amp for every driver, 8ch DSP, just thinking out loud...set the bass crossover to fix the pattern widening...take my time and use the CNC to cutout all the slices for a translam (stacked laminated plywood) cabinet...spitballing lol
The Blade is a pretty speaker, salvage Q150 drivers and add suitable bass drivers, maybe just two instead of 4, active, separate amp for every driver, 8ch DSP, just thinking out loud...set the bass crossover to fix the pattern widening...take my time and use the CNC to cutout all the slices for a translam (stacked laminated plywood) cabinet...spitballing lol
It doesn't have the radiation pattern of a point source though it is closer than most. A point source is generally not a particularly desirable radiation pattern for a pair of stereo speakers in a room.
Thanks for the pointer which I had not seen but the link seems to be missing. My criticism was based on measurements such as those shown here. Note the midrange driver is too small which is why the woofers are crossed high and why the distortion is high around the crossover. The design has some cons but overall it is a good one.
No, you just want to show off to your friends by copying a well known commercial product. 🙂
With this in mind, it seems like a reasonable approach. You won't achieve the level of performance of the Blades (due to inherent driver differences), but if your sound quality expectations aren't extreme you'll probably enjoy the project and the resulting sound. If you like the Q150's sound overall, that's another indicator that you're probably OK doing what you propose.
You could also start off a little easier and use the passive crossover from the Q150 and just bi-amp for the woofer to co-ax transition.
This is mostly to do with the crossover frequency, the physical separation between the drivers, and the crossover design. Just eyeballing things, it looks like the acoustic origin difference (Z offset) between the co-ax and the woofers is about 6 inches. This isn't an extreme amount given the wavelengths involved at the crossover frequency. Since the design isn't trying for time/phase coherence (multiple terms are used for this, so sorry if it lacks clarity) what you want in the end is a smooth hand-off from one drive unit's step response to the next, as shown in the Stereophile data.
https://www.stereophile.com/content/kef-blade-two-meta-loudspeaker-measurements
"Turning to the time domain, the Blade Two Meta's step response (fig.7) indicates that the tweeter and midrange sections of the Uni-Q drive unit are connected in negative acoustic polarity, the woofers in positive polarity. The decay of the tweeter's step, which arrives first at the microphone, blends smoothly with the start of the midrange step; its decay in turn smoothly blends with the start of the woofers' step. This, together with the different distances of each unit's acoustic center from the microphone, implies optimal crossover implementation."
No, the driver differs in a lot of details. It's optimized for midrange and a completely different driver.
Well, no. The KC92 are active and electronically compensate for the lack of port, enclosure volume and uses tons of power to compensate for that. The KEF Blade doesn't do any of that, even if the drivers may seem identical but they have different parts numbers, likely not identical but different in motor (magnet).
Polyurethane is a plastic with high internal damping, strong, freely formable material that can be produced without any seams, glue points or material change. From fabrication perspective, that's way above wood panel boxes and without any diffraction. The stiffening matrix is quite complex and requires a lot more work hours than wood bracing because it needs castings. The internal volume of the cabinet is more than 5x of the KC92, got an absorber chamber and two air flow optimized ports. That's not the plastics of your PC speakers. Or your Cherry/Razer Keyboard.
What do you mean with 'wired'? It's a passive speaker. The 'subs' work with passive crossover parts which are actually a lot more expensive than a DSP. And they can be tri-amped, which is not exactly as what I'd call 'like normal speakers'.
No. A lot of its sound is founded on the enclosure shape and material and the drivers aren't the same. 60k is for the pair. Yes, you could potentially build them cheaper with either hundreds of man hours if you do it yourself or with a few cast molds of about 20-30k each. If you'd built the speakers with wood or MDF, you can get away with material costs of ~2-3k each and a low number of hundred working hours. That means, you can get a pair of them at about 20-30k, so roughly half of the originals. If you choose more simplified shapes of the speaker, you can probably shave off 5-10k in costs.
You mean diffraction less speakers that are impulse compensated and practically point source at high end qualities? Yes, that's pretty close to the optimal speaker if you want the properties of that special speaker. You can of course separate the subs from the speaker but the homogenity will suffer because you need to XO the subs a lot deeper than on the blade. If you are willing to compromise on that and use much cheaper (but still excellent sub drivers), you may get away for 6-8k.
All in all it is a 3 way with side mounted woofers.
Tall deep towers can offer a lot of volume.
Crossover design is actually easier with 90 degree woofers.
" Soundstage" or any other magical wild guessing people make
with side mounted woofers is nonsense.
Being bass is non directional.
Far as marketing overpriced speakers you need
a skinny baffle and some sorta smooth fancy shape.
And boom there it is.
The front baffle stays slim, so another way to use 90 degree
woofers.
Tall deep towers can offer a lot of volume.
Crossover design is actually easier with 90 degree woofers.
" Soundstage" or any other magical wild guessing people make
with side mounted woofers is nonsense.
Being bass is non directional.
Far as marketing overpriced speakers you need
a skinny baffle and some sorta smooth fancy shape.
And boom there it is.
The front baffle stays slim, so another way to use 90 degree
woofers.
The sound stage comes mainly from the coax driver and the diffraction less baffle. The side mounted woofers actually DO contribute to the sound stage - they are crossed over at 450 Hz (Blade 2 Meta, Blade 1: 350 Hz) because the coax is a midrange and tweeter.
To help those that may be new to this.. curved surfaces diffract, unlike straight surfaces when they are used this way. What's of interest here is that they do so in a smooth way.