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Brane X Portable Speaker uses new "Repel-Attract Driver"

cavedriver

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Was just looking over some "best of CES" reviews and this speaker came up for being able to produce massive bass very efficiently due to its novel "Repel-Attact Driver". If the design can do this with accuracy I expect it could replace most tradtional methods of bass driver design. Of course "accuracy" is a big question and a lot could go wrong so it will be interesting to see how it really performs in testing. Unsurprisingly the portable uses class D amps and plenty of DSP to manage it's sound. Here's an article with some more detail about the design:
 
This completely new driver technology breaks Hoffman’s Iron Law, which has dictated speaker sound for decades.


Uh huh. To h*ll with your physical laws!

Gotta think this is a dot.com sort of thing. Guys want to sit in big offices and drag down big bucks while the ride lasts. investors that get in early and sell before the crash make out big.
 
As I understand the article the claim is that this new speaker is 10 times more power efficient, not that it plays louder (massive bass).
 
As I understand the article the claim is that this new speaker is 10 times more power efficient, not that it plays louder (massive bass).
How do they do that? They only talk about a good magnet. You still have a big problem coupling the tiny cone to the air at bass.

In any event, we just need to plug the T/S parameters into WinISD etc., and see.
 
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As I understand the article the claim is that this new speaker is 10 times more power efficient, not that it plays louder (massive bass).
of course, but one tends to lead to the other... ;)

I am very intrigued by this magnet system. The energy needed to displace air in a woofer is apparently large (makes sense), and combined with the centering force of the fixed parts of the driver that just adds to the power requirement. My first thought was that the secondary magnets created an "anti-centering" field that tends to drive the voice coil to the two extremes of the travel range so that once the VC left a certain neutral center distance the magnetic field would actually be driving the coil away from center. The problem then of course is that increasing voltage would then drive it even further and there would be nothing to return it to center. Could reversing the VC polarity past a certain travel distance make this idea work? I don't know. Any speaker driver designers want to chime in?

Re-edit: should have just quoted the wiki page for the Lorentz Force, not a Lorentz transformation:
 
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To my knowledge, the major inefficiency of a cone driver is just that: the cone. It does not couple to the air efficiently. So no matter how good the motor, you don't get something for nothing.
 
of course, but one tends to lead to the other...
Not necessarily. It could be more efficient but have limited excursion or some other limitation.

My immediate thought is that the driver here has been specifically designed for the box it’s in, and the aim is to extend battery life. I wouldn’t expect low distortion to be a priority here either. This isn’t a high fidelity application. I may be wrong.

The question would then be how far the design can be improved. That’s assuming they want to: there is probably a lot more money in improving battery life of portable devices anyway.
 
Not necessarily. It could be more efficient but have limited excursion or some other limitation.

My immediate thought is that the driver here has been specifically designed for the box it’s in, and the aim is to extend battery life. I wouldn’t expect low distortion to be a priority here either. This isn’t a high fidelity application. I may be wrong.

The question would then be how far the design can be improved. That’s assuming they want to: there is probably a lot more money in improving battery life of portable devices anyway.
yeah, the wink was because I was joking...

...but seriously I originally based that comment on where reviewers were commenting on the very loud bass output of the system.

I agree the distortion is one area that may be the downfall for serious applications (although the reviews from the trade show failed to mention any inferior sound quality, you just can't trust those people)

They suggest the technology can be scaled but for what other applications is power draw an issue these days? Audio in electric cars (barely a concern), sail boaters?
 
A year later and these are finally shipping and there is a photo of the coil removed from the housing. It would appear that they are doing what I thought- when the cone is at rest it is weakly centered, and as soon as it is displaced by a small distance the magnets on the coil have their poles oriented such that they are driving the coil away from center and towards the poles (towards the ends of the coil's available travel). The circuitry must use awareness of the coil's position (based on coil load or some other position sensing method - can't tell?) to modulate the drive voltage (in other words, as the sum of the music output minus the strength of the magnets drive for the current position). I assume the magnets are not strong enough to actually drive the coil to it's travel limit - in other words, I assume the input voltage never has to go negative, but maybe it does? I really wonder what the distortion values look like. Also, the picture only shows the cone and coil, not the interior of the main magnet so we can't see if there are more parts in there:
 
Also, their "SEMA" and "GDA" technologies sound potentially very important, but as with all vaporware it will be interesting to see how they work if they come to fruition. The SEMA sounds a little like how Mr. Nestorovic described his "Leaf" tweeters but only in words since I've never seen a drawing of how the Leaf tweeters actually worked.
 
Why am I reading of this "breakthrough" and thinking of a push-pull electrostatic panel?
 
Why am I reading of this "breakthrough" and thinking of a push-pull electrostatic panel?
Dunno - but that was my first thought also.
 
Why am I reading of this "breakthrough" and thinking of a push-pull electrostatic panel?
I think the key difference is that an electrostatic has no fixed magnet opposing the air resistance, here they've added that to the driver. Electrostatics are of course also limited by the limits on the air gap, and hence the membrane excursion, and hence the bass output.
 
Negative spring technology coupled with permanent and electro-magnets if I understand correctly.
 
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