bl of a sub

i was checking out the massive audio dmx 12 specs and i noticed that there are 4 different wiring configurations because its a quad 1ohm. they are quad 1, serie/parallel 1, dual 2, and series 4. my question is this, all but the quad 1 have a bl of around 12.00. but when you wire it in the quad 1 configuration the bl jumps up to 24.00 why is that?35 Hertz custom car audio and automotive fabrication

That could occur if the voice coils are designed such that different wiring makes it electrically longer.  A longer voice coil in the same magnetic field with create higher BL.Support the12volt.com