Need to make a custom box for a 12 inch sub, how big should it be? Ported or not? Thanks

see response in general section

Thanks

12" x 12" x 12", basicly 1cu foot

varies on the sub. get the sub make and model number and get ahold of the builder.

Exactly.

Look up the sub online and find out the specs. It should give the proper cubic feet needed.

You are looking for the Thiele-Small (TS) parameters, and then match a box accordingly. A few tips: A ported box will give slightly higher output than a sealed box, a ported box is harder to tune correctly, a sealed box can be smaller and be EQ'ed to give better frequency response, the smaller the box-the higher the tuning frequency. Most driver websites will give suggest box size depending on your requirements. What driver do you have in mind?

The sub is a Hifonics and the amp is a JL audio 500. Don't really need it to thump but want a nice clean and deep bass.

Depending on which Hifonics driver it is:
Sealed design, go with no les than 1 cubic ft and no greater than 1.5 cf. Smaller box is tuned higher (around 45hz) more boom but less deep bass extension. Larger box is tuned around 38hz, little less output but deeper extension. You get the tradoffs. Either box should be stuffed.
Ported design, a little tougher to spec out but would be safe with 1.75cf to 2.25cf box. Port size should be tuned aound 33hz to 38hz. Hope this was helpful.
JL 500 amp is a good amp. I believe it also has an adjustable eg with frequency and slope adjustments.

Thanks for the info, know the direction to go now, Thanks