What size enclosure (sealed)for Alpine 12"1242D(METAL Music)

Box should be 1.2 cubic feet. port should be 13 square inches depth 16 inches and Fb/F3 will be 42/35 (Fb=port freq F3=cut-off freq

This really depends on the subwoofer. All subs are NOT alike. I would recommend visiting the manufacturers website for more information. Typically 1-1.5 cubic feet works with most 10 in subs. But again, please check the manufacturer for more specific instructions.

You have a lot of choices for this. First, unless you are tuning the sub to a specific frequency you have options. You didn't specify the size of sub so it's difficult to say specifically, but if it's a 12 inch sub, you need about 1.5 to 2 cubic feet. Of course the performance of the sub depends on the music you listen to. If you listen to rock, pop, classical, or country, I recommend a sealed box. A sealed box gives you better control over your sub. The air acts as a cusion and decreases the return time of the cone to rest position. This gives you tighter bass. If you listen to rap or hip hop, I recommend a ported enclosure. This type of enclosure allows for more cone excursion, thus allowing the sub to recreate lower frequencies. Hope this helps.

1.1 cubic ft. sealed, 1.5 ported

about 1.5 cubic feet for a sealed box and it does matter if its ported.. if you port it you need to find the right size port hole and length to suit the box and suit it to the most common music type you listen to..

almost any 10 will use .75 cubic feet up to 1.25 cu ft. thats about the size of a milk crate give or take. a sealed box will give you the cleanest tightest bass. A ported box will be louder but also larger at the cost of decreased power handling ability and sound quality. If your subs are designed for small enclosures use a sealed box around .75 to 1.00 cu ft.

For this sub the enclosure is pretty basic.

Sealed box- 2 ft cubed with a shared chamber would be fine. Can go smaller is you need the extra space. THe minimum requirment is .7 per sub.

Ported box- 3 ft cubed, with the port tuned to about 45 hz will work.. 45 hz isn't very low bass, but is at the very bottomn end of the frequency response for this driver.Also, if you are gonna run a ported enclosure, be ware of power handeling issus, and be careful not to over drive the woofer..800 watts rms for the pair on the high side.

It depends on the size of the subs- 8z 10z 12z 15z? whether or not you port the box is up to you- a ported box is generally louder than a sealed box -as you are coupling and tuning the sound from the rear of the driver with the sound generated from the front of the sub- but the box is also generally larger as well.Then aside from your preference of ported/sealed you have to account for the recommendations of the manufacturer as to whether the sub/speakers are meant to be placed in a ported or sealed enclosure. Most 10 inch subs do well in a box that yields .75 cubic feet to1.0 cubic feet.most 12z do well in 1.0 cu feet to 1.5 subic feet and 15z do well in 1.5 to 2.5 cubic feet. I have a set of 15z that require 4.25 cubic feet per sub-so its important to look into the manufacturers recommendations. The easiest box to make would be a sealed enclosure-and the sound quality generally yields a tighter more accurate bass sound along with increased power handling capability- try going to rockford fosgate .com and look into the woofer box wizard its a program that calculates air space for whatever size box you have room for-hope that helps you-good luck

Wow you are in luck, I used to be an Audiobahn dealer. Designing sub enclosures is my fulltime job. So here you go.-
If you are looking for sound that is very smooth, and has a very low end shaking everything setting off car alarms. You will need a PORTED BOX that is 3 CUBIC FEET FOR EACH SUB WOOFER. It actually calls for 2.7cu.ft but after you add speaker displacement and bracing it should be at least 3 cu.ft. The port can be either round or square made of plastic or 3/4" wood respectively. My port suggestions are dependent on how much space you have. The shortest round port might make some noise (too much pressure!). So think about that first. Anyway the short port is 3" diameter and 15.5" long. The longer port is 4" in diameter and 28.25" long. The rectangular wood port can also be either (port measurements are inside diamensions) 3" w x 3" w x 18.5" long (short port) or 2 w x 10.5 h x 48' long. The second longer wood port is recommended most but will take up a lot of space. The fact that you have to subtract the port volume from the box makes for space issues in cars. Also the second wood port sounds better and won't make much wind noise, but takes up .75 cu.ft worth of space. So in plain english your box will have to have an internal volume of 3.75cu.ft. An example of this could be made of 3/4" thick MDF, have 1" x 1" internal bracing and measure (box dimensions are external and assumes the use of 3/4" MDF) 12" h x 18" w x 30" deep. The port is an integral part of the box fitting inside. I'm sorry I can't provide any drawings to make things easier. Now this box size is one that I ran through a computer program I use. So it is not the same as the manufactures recommendations. I will list those as well.
The second box is an example using a round short port and also uses 3/4" MDF, 1 x 1" bracing, the 3" dia x 15.5" long port, and measures 12" x 18" x 24" externally.
If space is an issue try checking out the information below. -I got it from Audiobahn-
If for some reason it doesn't show up or you need assistance let me know. Good luck and enjoy your new setup-I'm sure you'll be happily disturbing the peace soon!
-Dynami
Model # AW1006T
Ported
Air Space (Cu. Ft.) 0.65
Port Size (Inches) 2 x 6.5
Port Vel. (%) 48.31
-3dB (Hz) 31.5
Tune Freq. (Hz) 40
Sub Disp. (Cu. Ft.) 0.21
Port Disp.(Cu. Ft.) 0.01
Total Vol. (Cu. Ft.) 0.75
Ported
Air Space (Cu. Ft.) 1.4
Port Size (Inches) 3 x 6.75
Port Vel. (%) 24.19
-3dB (Hz) 30
Tune Freq. (Hz) 39
Sub Disp. (Cu. Ft.) 0.21
Port Disp.(Cu. Ft.) 0.024
Total Vol. (Cu. Ft.) 1.5
Ported
Air Space (Cu. Ft.) 2.4
Port Size (Inches) 4 x 6.25
Port Vel. (%) 14.39
-3dB (Hz) 29
Tune Freq. (Hz) 39
Sub Disp. (Cu. Ft.) 0.21
Port Disp.(Cu. Ft.) 0.04
Total Vol. (Cu. Ft.) 2.5
EBP 74 80 80

Sealed NR NR NR
Minimum (Cu. Ft.) 0.5
Maximum (Cu. Ft.) 1
SPL (dB) 80
All sealed boxes already include the displacment for the subwoofer. NR = (Not Recommended)

According to MTX they need 1.25 cubic ft per sub sealed and 2 cubic feet vented. Most pre-fab boxes will work for those subs.