Before you can build any box you have to know what size the subs need. Ported boxes are bigger most of the times. I can tell you the size of the port for that box size if you tell me what you want it tuned. But if the cubit feet is too much for the sub it will have to much excursion and blow the sub. Also it might sound bad.
i ahve know i dea what the subs need. I went to the web site and everything. They say the recremened is sealed, ported, bandbass, etc. My subs are alpine type e's 1242. However, the site does have the type s's. It says for ported the sub need aprox. 1.25-2.0 cu.ft. for one. So for two i need around 2.50-4.0. So my box will work right??
If I had two sub in one box I would divide the box in the middle. Better on your subs and easer to get the right port length. I would port with round pcv pipes at 36hz. You can cut the pipes off shorter if it sounds to low. Try 2.0 cu. ft. then put the sub and port in and you will have a little under 2.0 cu. ft. but will still be in the range of 1.25-2.0 cu. ft. Port Diameter 3 inches x Port Length 8 ¾ inches. Put the ports anywhere, just keep in mind you need as much room on the inside and outside as the port diameter. Just stay away from anything 3 inches and you will be fine.
Wait...how much space does my sub take up?? Another is, how will i make my box 2.0 cu. for each sub? It is currently 1.6 without the sub. Would fiber fill make the box seem larger? I am really confused.
My subs are 10's with 1.1 cu ft each and tuned at 36 hzs . Each sub has a driver volume of 0.05 and the ports are 0.05. So not but .10 cu ft your 12's and ports should be 0.15. It's more trouble to make the box bigger than build a new one. If you have 1.6 cu ft enclosure volume on each side without the subs and ports. Your net volumes around 1.45 cu ft each sub. It's going to be hard to tune at a set hz's without more info on the sub. Like the driver volume and a technical data report, But this is not rocket science 0.2 hear or 1 inch one way or the other is close enough. Try 3 inch round and 7 or 8 inches long. This will put you around 36, 37 hz's each sub
Okay thanks. I read on this forum that it takes more watts to actually hear a box tuned to about 30 hz's aposed to 60 hz or higher. I believe they said that it will be louder if it were around 60hz's just not as deep sounding. And since my subs are only 250 rms each. I think i should try to get higher than in the 30's. What do you think?