weight of the magnet means one thing: inefficient motor design.

what size spiders? 8 inch? If so, kinda last decade **** there buddy.

30 MM is pretty damn good, but nothing to write home about. Can be had for only a couple hundred bucks.

If you could claim 30 MM with 1% variation in BL then we'd be talking some big numbers.

3 inch voice coil means if its copper, you're ****ed from square one, and even if its aluminum, it'd better have shorting rings else you'll have ZERO output above 60 Hz.