Adding a bucking magnet, what effects does it have

[pjpoes]

Ok so I've read some articles on the subject, and see that adding a bucking magnet seems to have the effect of increasing the motor force, and thus increasing efficiency a bit. I'm wondering, first, why does the magnet need to be positioned so its apposing the force the magnet on the driver? I understand this cancels the stray magnetic field, but if your interest isn't this, but rather, the increased motor force, would placing it with attractive poles change the effect? Doesn't it create an unequal magnetic gap?

I've been playing with this to see the effect myself (Best I can), and find that the bigger the magnet, the greater the changes (not suprsing), so I'm wondering, is their a point where its just too much? I mean, what about an equal sized magnet to the one on the woofer itself to maximize the motor strength and increase the efficiency? I'm finding it raises fs the larger the magnet, why would this be? What negatives does doing this create?

[stinems]

I'll bump this. Parts Express says the optimum size of the bucking magnet (for shielding purposes as opposed to augmenting efficiency) is about 1/2 to 2/3 the diamete of the speaker magnet. They are silent on the effects of the thickness, inner diameter of the bucking ring, nor the measured strength of the magnet.

Sam

[crazyhub]

If you compare with or without comp magnet (for ex the CA12RCY), you'll know the changes in parameters. BTW this particular complementary magnet is exactly the same than the one used in the driver (I added one to my CA12)
http://www.seas.no/index.php?option=...128&Itemid=150