Bl?

[hondarider 10+ year member]

What is Bl? Do you want a higher number or a lower number?

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[CBFryman2 5,000+ posts]

BL is the linear force the motor can exert. for SQ BL/X is what matters in SPL the more the better.

 

[squeak9798 5,000+ posts]

Bl = B * L

B = amount of magnetic flux density per square centimeter in the gap

L = turns of wire in the gap

The measurement of Bl is not the linear amount of motor force. It is just the motor strength of that particular speaker...amount of magnetic flux density in the gap times the amount of wire in the gap.

Bl alone is meaningless. Higher or lower, neither is inherently better. It's all about what fits the overall design of the subwoofer the best. Whether that's 5Tm or 25Tm is rather irrelevant to the end consumer, as long as it suites the design of the subwoofer.

 

[squeak9798 5,000+ posts]

The measurement of Bl is not the linear amount of motor force.

Just to further clarify...while a plot of Bl over the entire excursion range of the driver can be used to determine the linearity of the motor (since Bl is not constant), the Bl measurement itself is not a linear measurement.

 

[CBFryman2 5,000+ posts]

Sorry, yeah, not a measuremnt of linear force, just motor force. The more motor force you have in a good design the more linear force you have which is what SPL drivers need. The more motor force you have over X (flatness of the BL/X curve) the better a driver will sound generally beasue it will have more cone controll, though that alone is not the determineing factor. (that is what technologiesl ike DM, XBL^2, LMT, Split Gap are designed to do)

 

[squeak9798 5,000+ posts]

Sorry, yeah, not a measuremnt of linear force, just motor force. The more motor force you have in a good design the more linear force you have which is what SPL drivers need. The more motor force you have over X (flatness of the BL/X curve) the better a driver will sound generally beasue it will have more cone controll, though that alone is not the determineing factor. (that is what technologiesl ike DM, XBL^2, LMT, Split Gap are designed to do)

More isn't necessarily better, especially when comparing two totally different drivers. Plus having more strength doesn't necessarily mean it's more linear.

And maintaining a constant (flat) BL over X (excursion) is what matters. Not that it's "more", just that it's constant. Even then there are those who don't necessarily like the sound of flat Bl drivers (many people don't like XBL^2 drivers, for example)

And it's motor strength, not force. Motor force is actually Bl^2/Re

But...moral of the story; Bl alone tells you nothing. And having higher Bl doesn't make the subwoofer inherently better than one with less Bl. All that matters is that the driver has the necessary Bl that the design requires. As long as it does...that's all that is important to the end user.

 

[VereChronicus 10+ year member]

Plenty of companies have figured out how to capitalize on the letters XMAX, regardless of it's actual importance to the end user. What's MTX trying to do on their site and in magazines vs the Kicker driver? As soon as a company figures out the perfect wording for a BL based sales pitch, it'll be a determining factor for customers too. Right now we are kind of stranded on this "power handling" specs war on the subwoofer packaging. That is if you use packaging in your sales technique. I believe it'll be a stat that'll become more commonly referred to in sales and purchasing conversations, regardless of how understood it is by either party. My $0.02.

 

[fosgate140 10+ year member]

sorry for the thread jack guys but squeak your knowledge of car audio is amazing i just thought id let you know

 

[Randy Savage 5,000+ posts]

But...moral of the story; Bl alone tells you nothing. And having higher Bl doesn't make the subwoofer inherently better than one with less Bl.

Series the coils and booyah!//content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[fosgate140 10+ year member]

i know a bit i just dont type that much i just read and i know a lot of poeple on here know many tricks to the trade and id like to let you guys know that a lot of you guys help a lot of poeple on here like myself and its much appreciated. sorry for the thread jack

 

[squeak9798 5,000+ posts]

sorry for the thread jack guys but squeak your knowledge of car audio is amazing i just thought id let you know

Well thank you for the compliment....but it's pretty much as Jmac said //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif I know enough to cause some trouble, and am quicker on the trigger than most.

But really, I just search the forum for Jmac's old posts and copy 'n paste //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[CBFryman2 5,000+ posts]

More isn't necessarily better, especially when comparing two totally different drivers. Plus having more strength doesn't necessarily mean it's more linear.
And maintaining a constant (flat) BL over X (excursion) is what matters. Not that it's "more", just that it's constant. Even then there are those who don't necessarily like the sound of flat Bl drivers (many people don't like XBL^2 drivers, for example)

And it's motor strength, not force. Motor force is actually Bl^2/Re

But...moral of the story; Bl alone tells you nothing. And having higher Bl doesn't make the subwoofer inherently better than one with less Bl. All that matters is that the driver has the necessary Bl that the design requires. As long as it does...that's all that is important to the end user.

i mentioned BL/X about 20 times //content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gif