I'm starting my first sub project and have a few questions. I used WinISD and another program from AJ Vented Designer to get dimensions for a box. What I come up with is somewhere around 3.5 cubic feet. The shape of the box is a long rectangle that simply will not fit in my space. Is it okay to change the dimensions of the box as long as the internal volume remains the same?

My other question is about porting. Both of these programs recommend 2X 4" tubes at a length of 25.5" to avoid port noise. Can the port be extended beyond the interior of the box? And can there be right angles in the tube itself? The ports simply will not fit internally. Also I think the tuning frequency is 25hz.

I'm using an Infinity Reference 1230 12" car sub I have laying around. I figured I might put it to good use since my original home thater sub's (JBL PB-12) amplifier just died. Would a different driver be better? And are there similar drivers that I could use this box? I don't want to make something I can't upgrade later on.

I'm going to use the Rythmik Audio A350 Basic. Or should I consider the special edition with the MOSFET transistors? Does this make a difference in the sound at all?

Thanks in advance for the time.

Link to the woofer specs
http://manuals.harman.com/INF/CAR/Boxes%20and%20Parameters/Ref1230w%20Tech%20Sheet.pdf

Changing the shape of the box will have little to no audible effect on the sub as long as the net volume stays the same.

They can extent outside the box. They can also be bent inside the box. Parts Express' Dayton line of ports has elbows.

I've seen some successful subs built from Infinity drivers but I'm not sure which line. The T/S parameters look average in my opinion. I know nothing about your JBL sub so I don't know if other drivers will fit. If your current driver fits, I'm sure that any sub with a stamped steel frame will fit. The Adire Shiva and Dayton DVC
come to mine. On the other hand, the cut out is 11.25" for your sub. There are some cast frame subs that will drop in there as well.

Not sure about the amps.

-Robert

Thanks for the quick reply. I haven't built the box yet, I was looking for some input. I figured the dimensions could be changed as long as the volume remained the same. I think I'll go with the Infinity driver now and drop something else in later. How similar would the T/S parameters be if I were to change the driver? And could I bend the the pipe right where it comes out of the box? Run it along the top. I wanted to have the woofer front firing and the ports on the same face of the box. I plan to have it facing a wall. Downfiring the sub would do little as I'm in a basement room with a big cement slab under the floor.