Building a Box

[AznVirus]

im going to attempt to make a custom box for my friend. im thinking of laying wood down for the inner layer, and fiberglass on the outer, and wrap it in some soft material like every box has. any tips on making it? does it matter where the port air holes are? shape? size?

[P11GT]

When building a box, theres lots to consder, the overall size for a start, the design (shape) you want it, the material, and the most important, the internal volume. Do you have the spec of the sub in question? Post up the make and model number, so i can have a look for you. Maybe i could design one for you, but i'll need info such as recommended internal volume(s), sub displacement, available height, width, depth oh and port length and diameter.

Heres a picture of mine that i built over 3 years ago and its still going strong. It houses a JL Audio 12W6 and is 2.0 CuFt and has a port length of 9 inches dia of 3 inches. The design of it is based on the MTX V80, a 8 inch sub which packs a hell of a punch and rated at 400 watts, particially to do with the design of the box. It has no side which have the same length, therefore the sound does not bounce and cancel itself out.

[AznVirus]

what did you make the box out of? im thinking of building it with wood and fiberglass/bondo to fill in the edges so no air will escape. im going to make one for my friend that will get 2 12"s. ill tell you what kind and what kind of frequency to do when he gets them. doesnt the frequency decide what kind of box is better: ported, bandpass, sealed?

[frogg]

Most people build boxes out of MDF, including mine which I think is 3/4" thick .. Then possibly pad the inside of it and carpet the outside.. Mine turned out pretty nice I'll take pics when I get my camera.

[AznVirus]

MDF? that would be wood am i right?

[frogg]

Yep, wood.. Medium Density Fiberboard I think..

[ty423]

Make sure you get the specs for the subs and build the box around those specs. I must agree totally with P11GT....he really knows his stuff...I am new to this but its exactly what I learned when I built my box....

[P11GT]

MDF = medium density fibreboard, like frogg said, 3/4 inch or 18mm is best, then you need some self taping screws, 1.5 inch does fine, wood glue, silicone sealer, port, if required, and temrinal. You can fill the inside with what i call, wadding, especially in sealed boxes, this fools the sub making it think that the internal volume is larger than it is. And to finish the outside, you need some strong spray glue, contact adhesive and some backless accoustic carpet of your choice.

Get the spec, i'll have a go. Did i say i needed the sub displacement aswell???

[greekman]

i built a box back in my day for 2 rf 15s. i made the box using fiberboard, then used some kind of bondo to seal it. i thought fiberglass was cool so i put that over the subs. then i covered it all w/ some heavy duty carpet. the only things i would repeat from this experience was the board and carpet. i disregarded specs for the subs and the subs sounded shitty (maybe it was also because i had a pyramid amp ). i've since learned from my mistakes.
take p11gt's advice. from what i know, i know that he knows a lot more than me, and it seems most of us when it comes to this subject.

[AznVirus]

http://www.mtx.com/caraudio/education/

good site to learn how big box needs to be and all that. self-taping screws, are those the ones that are just jagged on the sides so it sticks really well? what did you use for "wadding" the sealed box. where can i get the terminal and port?

oh ya i forgot, how did you cut out the hole where the subs are seated? i dont have one of those machines to cut perfect holes for the subs. also, do you seal the sub to the box so they cant be taken out, but no air can go inside?

[Kickercarg20]

To cut the whole I use a jigsaw and take my time. If you take your time you'll do fine just make sure your circle is right, look how deep the inside subs walls are and thats how big the circle is. Don't make the mistake I did the first time I made a box and think "hey, twelve inch sub twelve inch hole." forgot i had to screw it in, but i've gotten a lot better since then. You can get all the stuff you need from either Crutchfield or your local car audio shop. Make sure the subs sound good ported, i prefer sealed boxes but thats just my taste (it has a tighter/ higher bass compared to ported). If you're not sure about the screws just got to the hardware shop and look for self-taping screws, it's written on the box

[P11GT]

Yep, all that Kickercarg20 said.

Wheres the model and spec for this sub anyway?????

Self taping screws are those which have a pointed end and dont necessaraly need a pilot hole, but my advice, when screwing into MDF, its always best to drill a pilot hole as MDF can split and often does, especially if you over-tighten the screw, be warned!!!
The port and terminal can be bought from most car audio shop. If your having a real hard time grasping all this, you should be able to buy a nice pre-built box, ready carpeted and all you need do is to screw in the sub.
To find the right diameter hole required, just turn the sub over and look at the inner lip, judge what the diameter is and make sure you leave enough room for it to sit on the surface of the MDF. Use a piece of latt (strip of wood) halve the diameter to find the radius, and bang in a couple of nails in the latt for that radius. Then centre one nail and use the other to score a circle (like a geometry compass) on the MDF for the hole to be cut.
The wadding can be bought from most fabric shops. Its what they use in some cushions or like what they use in padded jacket. Its not too disimilar to cotton wool, but obviously made from a man made fabric and comes off the roll. There are many thicknesses but any will do as you need lots for a sealed enclosure. All you need to do is then pack it into the box really solidly, so you just leave enough room for the sub to fit into.
Sealed enclosure give tight accurate bass which requires a lot of power to drive it. Ported enclosure gives harder to control bass, but more rumble and SPL. When porting, its best to fit the port on the same side as the sub, dispite what diagrams may show, as the port is the main reason as to why theres more SPL.

[frogg]

P11GT,

Is there any specific type of carpet that you recommend? Also, if I went to a fabric shop, is there a specific name for the padding you mentioned?

Thanks alot !

[NismoPC]

Originally posted by frogg
? Also, if I went to a fabric shop, is there a specific name for the padding you mentioned?

It's called PolyFil. Spelling might be wrong, but they sell it in clear see-through bags and/or by bulk depending on which fabric store you go to.

[frogg]

About how much would be needed for a sealed box w/ 2 12's?