T/S Parameters (particularly Bl)

[knockin'hoe97]

So to start off I don't know very much about this subject but the way I took it is BL is more or less the motor force/strength or something along those lines. If that is the case how can their be such a huge difference between say a d1 and a d2?

[SnowDrifter]

Without going into a long explanation: Think of it like this

Motor force is Bl^2/Re

As Re increases, Bl will also have to increase as the motor force is held constant.

[kalilac619]

^^^^^^What he said....BL will change with different coils used but motor force factor will always stay the same...

[knockin'hoe97]

Without going into a long explanation: Think of it like this

Motor force is Bl^2/Re

As Re increases, Bl will also have to increase as the motor force is held constant.

Ohhhhhh now that makes sense....i feel like people would only emphasize just "bl" when talking about motor force so when i was looking a different coil configurations and saw the the big difference in only bl it threw a big question mark in my head haha. Thank you very much for the clarification....side note ohm is resistance correct? if that's so are the coils longer on a 2ohm coil vs a 1 ohm?

[SnowDrifter]

I believe the windings are of greater length, but the coil height itself remains the same. They just use a bit thinner wire and more wraps

You might, in theory, get a bit more motor force out of a lower resistance coil since thicker wire, same number of layers, will make a slightly thicker coil, but I'm not sure the difference is anything that will be noticeable or have any real outcome on your build. That is, depending on how it's wound and how they change wire size. If they use a wider/thinner ribbon when doing flatwind coils, thickness should remain the same. However if the ribbon is thicker, then you'd see a small difference in coil thickness.

My old 12s had dual .5 ohm coils. Those were THICK. Needed to be really careful when reconing since there wasn't much clearance in the gap hehe

[bbeljefe]

Because current increases when you lower the impedance of a driver.

I should clarify that I don't completely understand BL but from what I do understand about it, manufacturers typically report Bl as the "force factor", which is calculated as BL = motor force (coil length * I), with I being the back emf induced by the coil and against the force of the motor.

[TheMonolith2001]

Here

http://www.speakerplans.com/page89.html

and again here

http://www.eminence.com/support/understanding-loudspeaker-data/

Are some decent explanations of what they all mean.