ok. i entered the Mms, the BL and the Re and left the Sd open. it is saying that the sd should be 0.0222 m^2 instead of 0.289. i think that this could very well be a measurement error because a slight error in diameter/radius can lead to quite an big error in surface area since to calculate surface area it is r^2π. is this a possibility? btw thank you all for responding!

Generally, 1/3 to 1/2 of the surround diameter is included when determining Sd.

The Sd of the TremorX-10-4 is specified as 0.289 m^2, making the effective cone area diameter only 192mm (7.56 inches), while the the driver frame diameter is 263.5mm (10.37 inches).

With that small of an Sd, appears almost none of the surround was considered part of the Sd.

Anyway you look at it the specs seem suspect..