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.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?
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...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.
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.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)
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: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.
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.
Ah, I was right about the woofers after allTo celebrate 60 years of innovation and technology, KEF have developed the LS60 Wireless: the world’s first Single Apparent Source wireless system. This very technology has been adapted from KEF's flagship Blade speaker. The first noticeable feature of the LS60 is it's slimline design which has...petertyson.co.uk
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
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.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!
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.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.
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 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.