Assistance needed - porting pair of 12" Alpine Type R's
Hi, I am helping a friend design his first subwoofer system and am in need of some advice. I have built several sealed boxes in the past but this will be my first attempt at a ported enclosure. We have a total of about 4.4 cubic ft. of space to work with in the back of his Mitsubishi Lancer (44" by 16" by 14" to be exact) and will be using 2 12" Alpine Type R-1242D 4 ohm vc subs in this box. Could go up to 18" instead of 16" if needed. Wanted to do subs and ports firing back torwards the trunk lid. They will be getting about 400 watts RMS a piece. I know this is low wattage for these subs, but we dont want to go above this because his car has a rather small alternator and we want to keep dimming to an absolute minimum. We will be doing the Big 3 so that will help.
I would like some advice from anyone with experience with porting these Type-R subs, namely how much cubic ft. of space would be good for these subs ported, and the size the ports should be. Also, curious on whether it would be better to have one big enclosure for both subs and one port, or have each sub have its own enclosure space and port. I am looking for a box and port tuning that will be efficient, with a frequency curve that wont be too peaky. Looking for a good balance of Smoothness/SQ/SPL. My friend mostly listens to Rap, so a system that performs well in that proper frequency range would be great.
If I do go with a slot port ill probably run the port along the box wall. Ive heard this affects proper port length when tuning, exactly how it affects it would be appreciated. Ive heard the length along the box wall causes friction from the reverberations, lowering the tuning frequency, and that you can use the wall area as if it was double the length, true or false? The box will be 14" tall, so slot ports would be about 12 1/2" tall, and would need to know how wide to make them without having bad port noise. I will round off the ends of the wood around the ports to help with this.
I just need a place to start and specs to go on. If someone could give me what they think is a good ported size for these subs so I can make sure my box specs even fit the application, and the specs for the port id need for my box(port length, area, and tuning frequency).
P.S. - Ive read Alpine's suggested specs of 1.7 cubes, but I also know that their recommendations are VERY conservative, and that these subs like big enclosures. Im hoping to get some exact specs from someone who has had actual experience porting these same subs. Thanks in advance.
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