Below is a little info on a possible driver that MIGHT be available late this fall. IT incorporates MMAG (multiple magnetic air gaps) and LRRP (low reluctance return path) technology.
LRRP has never been used before in a subwoofer and has never been used in a transducer as I'm using it in this driver. On a lot of pro drivers that use neo on their poles it can be difficult to get enough motor strength due to the small diameter of the coil so a bucking magnet is added to the top of the pole to increase BL. This however isn't very effective because the magnetic flux must flow through air in order to complete the magnetic circuit causing it to have high "reluctance". In LRRP a "top plate" is added on top of the bucking magnet to reduce reluctance. Doing this can increase BL up to 50 percent versus around 20 percent from just adding the bucking magnet alone.
Another huge advantage with the additional plate is it creates a B field at the top of the stroke opposite of that of the main gap so active breaking is added to the top of the motor. I went a step further and made the back plate aluminum so not only does this driver have breaking at the top of the stroke but it also has breaking equal to the motor strength in the rearward stroke as well. Why is this an advantage? Well as long as the cones inertia does not over come the breaking area's strength you can put an unlimited amount of power to the driver and not have it bottom out or over drive it. It also increases transient response as the breaking area "throws" the coil back to its center resting point.
By incorporating MMAG the driver retains 100% BL over its entire stroke. Theoretical numbers below.
The Magnetar will have:
motor force factor 594
xmax 45mm one way at 100% BL
If another driver with a normal overhung coil and an xmax per 70% BL at 45mm it would look like:
motor force factor 594
xmax 45mm one way at 70% BL
So at 70 % BL:
motor force factor 291.25 at xmax
THE MAGNETAR WILL HAVE TWICE THE MOTOR FORCE AS THE OVERHUNG SUB AT XMAX.
Now take some of the current SPL subs with motor force factors in the 325 range.
motor force factor 323
xmax 35mm at 70% BL
This means at xmax these drivers have a BL of around 16.8 and a motor force factor of around 168 at xmax giving them less than 30 percent motor strength of the Magnetar giving the Magnetar a HUGE advantage in SPL.
The Magnetar will use N52 neo 4 inches in diameter about 2.4 inches thick, a 4 inch 8 layer coil 50mm long. The red area in the pic is where the magnets are and the arrows show the flow of magnetic flux