Fi Q 12" or Adire Brahma 12" HELP!!!

[audioholic 5,000+ posts]

And oh yeah, the technical definition of BL (thanks wiki) is:

Bl - The product of magnet field strength in the voice coil gap and the length of wire in the magnetic field, in tesla-metres (T·m).

In laymans terms, this means the strength of the magnetic field displayed in the gap, as dictated by the motor's magnet (size, shape, and material type), and the amount of wire within this field. Bl optimization is created in various ways by various design types these days, but all work to maintain the same relationship between these two factors no matter where the coil lies in relation to the gap.

Hope I helped.

 

[Jaredturp 10+ year member]

Lots of good info... thanks all... sooo i may be dumbing the hell out of this, but like audioholic said with more motor force and over a ?longer area? there is less distortion.... is that why the old XXX has such a large and tall motor? Just a stupid observation.

 

[PV Audio 5,000+ posts]

B*L, it is the magnetic gap strength * stroke or heighth of gap, I can't remeber ATM. Basically, the Q will have a Parabola for the BL curve whereas the Brahma will have a fairly straight line for the BL curve that then drops off quickly. What this means is that the Brahma will have significantly less distortion than the Q. I also believe the Brahma used shorting rings which will also help minimize Le and linearize the Le vs. stroke curve, also vastly reducing distortion. Overall Brahma >> Q.
Read the papers on this site about XBL:

http://www.acousticdev.com/cms/index.php?option=com_content&view=section&layout=blog&id=12&Itemid=64

L stands for the length of the voice coil

Additionally, what if we make the field of the permanent magnet stronger? Well, that's call the B field inthe gap. Increase B, we increase the force as well. Or, what if we could somehow make the magnetic field

from the voice coil stronger? We can - increase the number of turns of the voice coil (increase the Length

of the wire in the gap). Guess what - in both cases, we increased the BL of the speaker (yes, this is the BL

of the T/S parameters - now you know where it comes from!).

http://www.stereointegrity.com/docs/WooferSpeed.pdf

 

[captaincheesey 10+ year member]

I think Audioholic beat you to it David, lol.

 

[PV Audio 5,000+ posts]

I think Audioholic beat you to it David, lol.

//content.invisioncic.com/y282845/emoticons/mad.gif.c18f003ab0ef8a0d9c27ca78d77a6392.gif Twice in one thread.

 

[audioholic 5,000+ posts]

Lots of good info... thanks all... sooo i may be dumbing the hell out of this, but like audioholic said with more motor force and over a ?longer area? there is less distortion.... is that why the old XXX has such a large and tall motor? Just a stupid observation.

The large top plate on the old XXX was used to help 'channel' the magnetic force of the motor the way the designers wanted. Old XXX's use xbl^2, yet plenty of other xbl^2 enabled drivers to not use such an over sized top plate design. It is not a characteristic of xbl^2 or BL optimization.

 

[Toxic Tuan 10+ year member]

For sealed SQ applications, I'd go with the Brahma. For a ported SQ, I'd probably have to say the FI Q purely because of the motor strength.

Tuan