Xbl2 technology: what is it? superior to other designs? why?

 

Silver Member
Username: Phuktupbasshead

Scottsdale, Arizona United State...

Post Number: 172
Registered: May-05
Explain why this technology is supposedly so good. I'm very curious and can't seem to find my own answers. Would love to understand what exactly this is and which subs carry it...
THANKS!!
 

Silver Member
Username: Addicted2bass

Miami, Florida USA

Post Number: 941
Registered: Nov-04
adire audio subs Reaudio XXX carry it now, AA atlas and avalanche use to carry it..and also there are some drawbacks to this design as are their some good things such as linearity, flatter BL curve which results in good sq,but the drawbacks are this motor isnt very efficent which is why they require so much power....and also its gives up some BL to make it more linear.
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 8787
Registered: Dec-03
XBL^2 is an underhung design if memory serves, and gives a very flat BL curve, which implies a strong motor strengh and very good motor control of cone movement throughout the operating range of the speaker. Basically it's extremely good for SQ, even at high excursion, which makes it a good SQL speaker motor design.

If you google on the tecnology you should be able to find the design white papers on-line somewhere. I don't have them handy myself.
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 4332
Registered: May-04
As far as the technical aspect, it breaks the magnetic gap into more than one region, meaning instead of a typical motor that has a single high flux gap in the center, there are two or more gaps in the motor that have narrower high flux regions. Then, the coil is sized to optimize BL over the curve, mainly so that the coil will extend from the center of the top gap to the center of the bottom gap, that way when it leaves one high flux region, it enters the other. Most subwoofers use the voice coil to achieve a higher excursion, the downside of that is that the higher the excursion, the less coil is in the gap, so you lose motor strength and control, so distortion is increased and overall BL is decreased. Adire's method uses the gap more effectively and distributes it over a shorter coil, while decreasing required top plate length, thus the production cost. Coil length is decreased compared to designs like overhung and evenhung, so inductance is less and transient performance and efficiency is better. It's one of the best, if not the best motor design out there.
 

Silver Member
Username: Addicted2bass

Miami, Florida USA

Post Number: 942
Registered: Nov-04
^^^i had to read 10 times to understand and stil dont fully understand lol.but ill keep reading it
 

Silver Member
Username: Mike_anthes

Canton, SD USA

Post Number: 208
Registered: Aug-04
yea ik...its tuff stuff to understand...what kinda stuff do ya have to take school wise to become one of the guys that works for adire and re and all those companies...jw...
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 4333
Registered: May-04
BTW, the main benefit of this topology isn't fully realized with subwoofers. This actually sees more benefit with midbasses, midranges, tweeters, and full range drivers. Typically, and XBL^2 driver will still only have 30% of the distortion other designs have at 70% of maximum linear excursion (x-max). In many cases, this translates to around a 1% distortion rating at 70% excursion, while others are between 3 and 5%. This allows a design that yields very clean sound at higher volumes and can fully realize the potential of enclosures such as sealed and infinite baffle, where excursion is naturally higher and SQ tends to suffer at high volumes due to that.

The biggest benefit of XBL^2 is that it allows a smaller driver to have higher output levels and a wider bandwidth, meaning a 6" midbass driver could potentially have the depth of a typical 8" driver and rival some 10" drivers for depth, and be very linear and accurate doing it. Their Extremis midbass driver is a good example of this, it is a 6.8" driver having a 13mm one way X-max, only a .13mH inductance, and is ideal for ported boxes tuned in the 30s, offering in-room extension down to the 20s. Inductive rolloff occurs around 8khz and there are no nasty breakup modes from the cone, crossover will typically be 2-3khz. To give you an idea, the Scan-Speak Revelator and SEAS Excel drivers, which are renowned high end home audio drivers, have a good bit more inductance, right at half or less than half the excursion level, less motor strength, and less bandwidth. As their designs progress even further, Adire is going to be a very difficult manufacturer to beat, or even level with for that matter.

Apocalypse, think about a magnet reacting to another magnet. The most strength will naturally occur when the magnets are closest together, and become weaker as they move further away. Similarly, in the case of a speaker, you have a fixed magnet and the voice coil, in which the coil is an electromagnet. They will either repel or attract each other with current applied. With a typical speaker, the center point of the motor (permanent magnet) is where the strength is focused, and at rest, the voice coil is centered in that. As current is applied, forces either repel or attract this, moving the coil up or down. As you can imagine, as it moves, less and less of the voice coil is retained within the gap, so magnetic control over the entire voice coil is reduced. The idea with these motor designs is that the longer the coil, the more there is to apply strength to, so you'll get more excursion with a longer coil. XBL^2, from a functional standpoint, has two or more points that focus strength over a narrower gap, just think of it as two magnets, and as the coil leaves one gap, it will enter another, which allows a higher level of control and motor strength than if it were one. As the coil moves further from one gap, it moves closer to the other, so you will have more control over the coil since you are always within a strong point of flux, and you will get more motor strength over the excursion limitations.

About efficiency, XBL^2 is actually more efficient than most motor designs out there overall, it is the soft parts that tend to bring down the efficiency of the subs they are used in. Adire uses epoxy treated paper cones in their subs, which are heavier than many other materials, but chosen for their damping ability, they also use a wider profile surround as opposed to a taller one, which controls the subwoofer very well, but cuts down surface area, and tighter suspension designs than many. XBL^2 isn't really the reason a Brahma isn't as efficient than other subs, but rather the reason it isn't less efficient than it already is. Adire is also more true with their sensitivity specs than many other manufacturers. Remember as well, that sensitivity specs are very misleading and give no clue to how loud a subwoofer will be at higher volumes. Excursion is low at 1 watt , a subwoofer with a parabolic BL curve will do well at 1 watt, but lose motor strength (thus efficiency) at higher volumes. XBL^2, on the other hand, offers flat BL and will give more BL at higher volumes than many other motor designs, making it more efficient with the power.
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 4334
Registered: May-04
"yea ik...its tuff stuff to understand...what kinda stuff do ya have to take school wise to become one of the guys that works for adire and re and all those companies...jw..."

Engineering and more engineering. It takes a lot to design a good speaker motor really, and requires good FEA modeling. Adire gives cutaway views of their motor designs to give an idea, but it still won't give you a nitty gritty view of what is going on. Remember in science class how you spread lead filings over a sheet of paper and put them on a magnet to see the flux? That is how a motor for a speaker works, and in the case of Adires design, the top plate and the polepiece are designed with machined grooves to sort of "direct" the magnetic flux lines into more defined flux lines along the path of excursion.
 

Gold Member
Username: Subfanatic

Ky

Post Number: 4637
Registered: Dec-04
how does it compare to TC motors?
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 4336
Registered: May-04
I'm guessing you're talking about LMT (Linear Motor Technology)

LMT basically it makes the coil fatter at the top and bottom of the voice coil so that you get more motor strength as more coil leaves the magnetic gap. It is basically a 2nd layer of coil at the top and bottom portions of the coil. The result is a very flat BL curve and capability of high excursion, but there are a lot of issues that plague the design. One is that you will lose overall BL due to having to space the coil further from the gap to have clearance for the added layer(s), and you have higher mass and higher inductance due to the added coil. You also have the cost of added coil. When you get lower BL, higher mass, and higher inductance, efficiency of the driver and transient performance suffers, which is the major complaint of the first LMT designs in the aspect that they are very, very power hungry. There are ways to aid the problems with the design, but most will add to other problems no matter how you slice it. Example, you could copper plate the polepiece to shunt out eddy current and lower inductance, but that is going to drop BL even further and increases cost. If you wanted to up the BL, that is going to require more motor, thus more cost. TCs motors are long coil, shorter gap designs, and that applies to the designs they're using now. These long coils (especially high excursion performers like Eclipse Tis and Ti Pros) require dual mirrored spiders to keep themselves more linear at higher excursions since longer coils are more prone to rocking and damage from rocking, and will require more clearance from the motor to assure that it doesn't mechanically bottom out. That again is going to increase cost. You could make the motor a very good performer, but no matter which way you slice it, it isn't a cost effective alternative and likely won't be great for the average buyer as the sheer cost to make the driver will hinder it from being the top dog in it's price range. Of course, all designs can and will be improved, it just takes time.
 

Silver Member
Username: Mike_anthes

Canton, SD USA

Post Number: 211
Registered: Aug-04
yea i get the just of how a speaker works...ive taken a few cheapos apart and it looks rather simple if you ask me like the magnet and in the magnet is a hollow ring and then their is a toilet paper type thing that fits in hollow part of the magnet...the voice coil is wrapped around that...now heres a question...how do they make other kinds of vc..like 1, 2, 4, 6, 8, ohms etc...like is the wiring thicker or longer...thanks...
 

Gold Member
Username: Invain

Michigan United States

Post Number: 3344
Registered: Aug-04
The "toilet paper type thing" is called the former, and the "hollow ring" is the pole piece.
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 8823
Registered: Dec-03
the impedance is based on the total resistance of the voie coil wire.. that'd determined by the gauge of wire, it's length, and the material from which it's made.
 

Silver Member
Username: Mike_anthes

Canton, SD USA

Post Number: 212
Registered: Aug-04
sweet thanks guys...glass or jon or anybody for that matter could you guys recomend me a book or just a few websites...that explains more about this stuff id love to learn how it all works...
 

Silver Member
Username: Phuktupbasshead

Scottsdale, Arizona United State...

Post Number: 173
Registered: May-05
Thanks for all your responses - especially you, Jonathan!

More input welcome... this is the greatest thread I've ever started!!!!!
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 8839
Registered: Dec-03
www.the12volt.com
left menu, toward the bottom, link called "BOOKS"
outstanding list of books on electronics, acoustics, and mobile installing.
 

Silver Member
Username: Phuktupbasshead

Scottsdale, Arizona United State...

Post Number: 175
Registered: May-05
thanks, GlassWolf.
I'll check it out!
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