Anyone check out the new Kef Blade?

Randall Smith · May 21, 2011

http://soundstageglobal.com/index.p...blade&catid=69:best-of-munich-2011&Itemid=163

Here is a brief description of it from our show coverage. I love the way it looks and cannot wait to hear it. Hopefully, Jeff will get it in for review.

Thoughts?

Phelonious Ponk · May 21, 2011

Cool shape. No front-firing midrange driver seems a bit odd.

Tim

JackD201 · May 21, 2011

There are Tim. The tweets and mids are concentric units. The pics make the midrange look like wave guides for the tweeter, which, come to think of it, they probably are.

Randall Smith · May 21, 2011

The midrange does act like a wave guide. If you look at some measurements from some of there other speakers with the same concentric driver, you will see a suck out in the highs. I was told that the suck out was due to diffraction between the tweeter and the surround of the midrange driver. This suck out is only found when measuring the speaker on-axis and isn't present if you listen off-axis.

mep · May 21, 2011

Randall Smith said:
The midrange does act like a wave guide. If you look at some measurements from some of there other speakers with the same concentric driver, you will see a suck out in the highs. I was told that the suck out was due to diffraction between the tweeter and the surround of the midrange driver. This suck out is only found when measuring the speaker on-axis and isn't present if you listen off-axis.

Who listens off-axis??

Randall Smith · May 22, 2011

mep said:
Who listens off-axis??

slightly off-axis, as in with a bit of toe-in

Phelonious Ponk · May 22, 2011

mep said:
Who listens off-axis??

Everyone with room reflections. I see the point in accurate off-axis response, but frankly, not if it is at the expense of on-axis response.

Tim

JackD201 · May 22, 2011

I wonder what the XO frequency to the woofers are.

fishnchips · May 22, 2011

Concentric drivers make me fundamentally uneasy, be they by KEF, TAD or the latest by Genelec. I understand the advantages of the configuration, but a tweeter's vibration amplitude is very small, in the order of micrometers, nanometers even, at very low levels. How can the loading parameters be defined if the surrounding driver, acting as a waveguide in this case, moves millimeters either way, i.e. a thousand or a million times more than the amplitude of the wave they are supposed to be "guiding"? Isn't this bound to lead to a massive loss of definition, even in the face of benign-looking steady-state measurements?

Mark Seaton · May 24, 2011

fishnchips said:
Concentric drivers make me fundamentally uneasy, be they by KEF, TAD or the latest by Genelec. I understand the advantages of the configuration, but a tweeter's vibration amplitude is very small, in the order of micrometers, nanometers even, at very low levels. How can the loading parameters be defined if the surrounding driver, acting as a waveguide in this case, moves millimeters either way, i.e. a thousand or a million times more than the amplitude of the wave they are supposed to be "guiding"? Isn't this bound to lead to a massive loss of definition, even in the face of benign-looking steady-state measurements?

Considering that 1/4 wavelength of 20kHz is 4.3mm, it shouldn't be hard to understand why it does not lead to "massive loss of definition." Sure, extremely high excursion might start to cause some issues which could be measured similar to intermodulation, but the ratios of Xmax vs. wavelength have to start becoming significant.

Most over-analysis of hardware by audiophiles is done in extreme isolation rather than in a more holistic manner. A coaxial driver is a non-ideal driver to the idealist, yet quite elegant when well executed to the realist.

fishnchips · May 24, 2011

Mark Seaton said:
Considering that 1/4 wavelength of 20kHz is 4.3mm, it shouldn't be hard to understand why it does not lead to "massive loss of definition."

You are taking the wrong set of data. What you should be looking at is amplitude of vibration or "particle displacement", not wavelength in air. They are two completely different things.

JackD201 · May 24, 2011

Please explain how the particles displaced at the source do not affect the particles displaced and colliding at your eardrums if not through wave behavior and the subsequent wavelengths mentioned.

fishnchips · May 24, 2011

They do but that's beside the point. As far as I know, Webster's horn equation presupposes an immovable horn. I'll be happy to be shown a comparable analysis based on a moving horn.

JackD201 · May 25, 2011

Classic "pass the buck" Fish.

fishnchips · May 25, 2011

Webster, not Buck.

Vincent Kars · May 25, 2011

JackD201 said:
I wonder what the XO frequency to the woofers are.

Crossover frequencies 350Hz, 2.3kHz
http://www.kef.com/en/release/bladeloudspeaker/blade

Mark Seaton · May 25, 2011

fishnchips said:
They do but that's beside the point. As far as I know, Webster's horn equation presupposes an immovable horn. I'll be happy to be shown a comparable analysis based on a moving horn.

All measures in audio are relative to frequency, wavelength and period (nothing new). "Large" or "small" are entirely different things at 20kHz vs. 20Hz. "Moving" is subject to the same relative considerations vs. frequency, and this case is very similar to that of a wide band driver. Also remember that in the case of a separate horn, sound produced by a moving horn would not be wanted. In this case the moving "horn" is the cone, which is supposed to make the resulting sound.

Yes, there will be some modulation, but unless you have lots of excursion, the relative amount is very low, just as it is in a wide band driver. This is where 3-4 way implementations with a coax have notable advantages, as the excursion remains relatively low. It is then up to the speaker designer and enthusiast to decide if the very significant spacial advantages are more or less advantageous than a non moving waveguide.

JackD201 · May 25, 2011

Vincent Kars said:
Crossover frequencies 350Hz, 2.3kHz
http://www.kef.com/en/release/bladeloudspeaker/blade

Thanks Vincent

fishnchips · May 25, 2011

Mark Seaton said:
"Large" or "small" are entirely different things at 20kHz vs. 20Hz.

Yes, indeed, and sometimes "small" can actually mean extremely small:
http://www.physics.sc.edu/~kunchur/...isalignment-of-acoustic-signals---Kunchur.pdf
http://www.physics.sc.edu/~kunchur/papers/Temporal-resolution-by-bandwidth-restriction--Kunchur.pdf
The result of ~6 microseconds in the twin papers above is equivalent to a mere ~2 mm.

Mark Seaton said:
"Moving" is subject to the same relative considerations vs. frequency

This too is true. Consider for example an additional factor: A tweeter is typically vibrating at extremely tiny amplitudes. In order for it to work at all, it needs to be mounted on a Newtonian frame of reference that is fixed in relation to the vibrating element. Otherwise chaotic behavior will ensue. I do not know what degree of relative immobility in relation to the frame can be achieved in the context of a concentric driver, but I suspect it ain't much to write home about. This would gravely impair treble resolution as well, over and above the impairment I described in my initial post.

JackD201 · May 25, 2011

fishnchips said:
Webster, not Buck.

Hahahahaha! Good one!

Anyone check out the new Kef Blade?

New Member

New Member

WBF Founding Member

New Member

Member Sponsor & WBF Founding Member

New Member

New Member

WBF Founding Member

Banned

WBF Technical Expert (Speaker & Acoustics)

Banned

WBF Founding Member

Banned

WBF Founding Member

Banned

WBF Technical Expert: Computer Audio

WBF Technical Expert (Speaker & Acoustics)

WBF Founding Member

Banned

WBF Founding Member

Similar threads