how far

[yamaha326]

how much space does the magnet need to be away from the back of the box?

[Moe Lester]

IMO it really doesnt matter too much. I like to keep it at least a few inches away personally.

[80_Cutlass_mn]

I would say a good rule of thumb for ported boxes and sub vents alike...keep them from any obstructions at least the same length as the vent is wide. So if you have a sub with a vent of say an inch or so, keep the back of the vent at least 1 inch from any obstructions so and so forth. Same with ported boxes depending on the way you port it.

[yamaha326]

it is a sealed