What is XBL^2?

[alxmlr789 10+ year member]

its teh secks. thats all..

I wouldnt mind knowing either, as i have one sitting in my living room. lol

Click to read more...

 

[xtremebassjunky 10+ year member]

i am curious as well.

and honestly i don't know much about xbl^2 technology.

besides the fact that it is employed with RE XXX's

 

[mlstrass 5,000+ posts]

Adire had a white paper on it I believe. Not sure if you can still access the site though. Dan Wiggins also did a comparison of XBL^2, split coil, and one other design. Try a search on yahoo/google...

 

[CrazedCat 10+ year member]

www.adireaudio.com/Files/XBL2TechPaper.pdf

 

[Brian Owens 10+ year member]

Multiple gaps in the motor. From the patent:

"An electro-mechanical transducer, including a magnetic assembly producing a magnetic field having two or more displaced regions of greater intensity, having magnetic flux in substantially similar directions, separated by and surrounded by regions of lower intensity magnetic field, and an electrically conductive and mobile member disposed in and capable of moving through a magnetic field."

Another description:

XBL™ - XBL is our patented motor linearity solution (US Patent 7,039,213). XBL combines multiple magnetic gaps with one or more voice coils to yield the flattest, most extended BL curve of any motor design. This proven technology is usable in any size transducer, and will provide measurable increases in output with a simultaneous reduction in distortion.

 

[Brian Owens 10+ year member]

http://www.patentmonkey.com/PM/patentid/7039213.aspx

 

[audioholic 5,000+ posts]

Its an ancient Chinese secret.

 

[bose301s 5,000+ posts]

Multiple gaps in the motor. From the patent:
"An electro-mechanical transducer, including a magnetic assembly producing a magnetic field having two or more displaced regions of greater intensity, having magnetic flux in substantially similar directions, separated by and surrounded by regions of lower intensity magnetic field, and an electrically conductive and mobile member disposed in and capable of moving through a magnetic field."

Another description:

XBL™ - XBL is our patented motor linearity solution (US Patent 7,039,213). XBL combines multiple magnetic gaps with one or more voice coils to yield the flattest, most extended BL curve of any motor design. This proven technology is usable in any size transducer, and will provide measurable increases in output with a simultaneous reduction in distortion.

Ok, I always wondered this as well. I had heard it referred to as split gap but I was never 100% sure what that meant.

 

[sundownz Pro Seller]

You cut the top plate into a [ shape and the pole into a ] shape. The cut-out area is referred to as the "rebate" -- this rebate steers the flux towards the two separate gaps on either side of itself to extend the BL field out farther to either side than a motor without the rebate. This creates a flat BL curve and thus less BL distortion and more linear x-max.

Some people get the idea that XBL^2 actually loses BL, but it really does not, it steers it around... in some motors I've drawn up in FEA I was able to get a higher BL with XBL^2 than with other "standard" topologies. Even in motors where the "at rest" BL is a bit lower, the average BL over the useful range of the speaker will be higher.

 

[newusername 10+ year member]

You cut the top plate into a [ shape and the pole into a ] shape. The cut-out area is referred to as the "rebate" -- this rebate steers the flux towards the two separate gaps on either side of itself to extend the BL field out farther to either side than a motor without the rebate. This creates a flat BL curve and thus less BL distortion and more linear x-max.
Some people get the idea that XBL^2 actually loses BL, but it really does not, it steers it around... in some motors I've drawn up in FEA I was able to get a higher BL with XBL^2 than with other "standard" topologies. Even in motors where the "at rest" BL is a bit lower, the average BL over the useful range of the speaker will be higher.

BL linearity is there but BL is still lost. Not only are you taking steel out of the motor, but you are intentionally taking B out of the area that the coil is located the most....right where it straddles.

But the only linear BL approach that I know of that does not have some efficiency trade-offs is MMAG.

 

[bose301s 5,000+ posts]

You cut the top plate into a [ shape and the pole into a ] shape. The cut-out area is referred to as the "rebate" -- this rebate steers the flux towards the two separate gaps on either side of itself to extend the BL field out farther to either side than a motor without the rebate. This creates a flat BL curve and thus less BL distortion and more linear x-max.
Some people get the idea that XBL^2 actually loses BL, but it really does not, it steers it around... in some motors I've drawn up in FEA I was able to get a higher BL with XBL^2 than with other "standard" topologies. Even in motors where the "at rest" BL is a bit lower, the average BL over the useful range of the speaker will be higher.

How does the LMS tech from TC work then?

 

[newusername 10+ year member]

How does the LMS tech from TC work then?

LMS uses a variable density coil.

Not to be a spammer or to toot my own horn (of course, I'll do it anyway):

http://www.soundsolutionsaudio.com/forum/index.php?showtopic=9421

I haven't updated it in a bit as I have discovered more about the effects of inductance...and more specifically, inductance variation, but it is for the most part very accurate (in my opinion).

 

[audioholic 5,000+ posts]

LMS uses a variable density coil.
Not to be a spammer or to toot my own horn (of course, I'll do it anyway):

http://www.soundsolutionsaudio.com/forum/index.php?showtopic=9421

I haven't updated it in a bit as I have discovered more about the effects of inductance...and more specifically, inductance variation, but it is for the most part very accurate (in my opinion).

Kudo's to you Neil, you are not only gaining TONS of knowledge in the field, you are awesome about sharing it with others. Respect.

 

[sundownz Pro Seller]

BL linearity is there but BL is still lost. Not only are you taking steel out of the motor, but you are intentionally taking B out of the area that the coil is located the most....right where it straddles.
But the only linear BL approach that I know of that does not have some efficiency trade-offs is MMAG.

I've done some designs and gained at-rest BL over an underhung topology with the same magnet structure in my FEA simulation. IIRC I had to change the top plate height a bit, but it was very close to the same -- and the magnet structure and other details were un-changed.

It does lose at-rest BL vs other non-underhung topologies, but also steer it to the outside edges -- I'd imagine the average BL over the total travel would probably be about the same, if not greater. I'd like to sit down and crunch numbers at some point to see if that is an accurate statement.

It's hard to do a straight A-B comparison, though, as you end up with significantly different top plates with the same height coil to achieve similar goals -- and with the same height top plate for the same x-max you end up with significantly different coils. So I'm not sure how the best way to go about the "average BL" calculation would be as a "fair" comparison to all topologies.

 

[newusername 10+ year member]

I've done some designs and gained at-rest BL over an underhung topology with the same magnet structure in my FEA simulation. IIRC I had to change the top plate height a bit, but it was very close to the same -- and the magnet structure and other details were un-changed.
It does lose at-rest BL vs other non-underhung topologies, but also steer it to the outside edges -- I'd imagine the average BL over the total travel would probably be about the same, if not greater. I'd like to sit down and crunch numbers at some point to see if that is an accurate statement.

It's hard to do a straight A-B comparison, though, as you end up with significantly different top plates with the same height coil to achieve similar goals -- and with the same height top plate for the same x-max you end up with significantly different coils. So I'm not sure how the best way to go about the "average BL" calculation would be as a "fair" comparison to all topologies.

Yes, if you change the height of the top plate, it's naturally a bit different story. Naturally, the average BL is quite good because it's more linear and it compares very similar to how other topologies do. For example, split coil avoids flux in the heart of the gap and LMS requires large gap spacing where parts of the coil are intentionally integrating less flux.

My point is that those three approaches (XBL^2, Split Coil, and LMS) all sacrifice some efficiency (or perhaps sensitivity would be a more appropriate term) for BL linearity. The only approach I know of that does not is MMAG, but it's trade off is primarily price and mounting depth.