General Box Building Rules?

[BooLeaN 10+ year member]

I was just wondering if anyone wanted to share some box building rules. What I mean are things such as if you make the box bigger you get more/less output, more/less SQ. If you make a port longer in the same box you get it tuned higher/lower etc. Tuning higher makes the box?? Tuning lower makes the box?? Anything at all about sealed ported bandpass etc. I'm sure lots of people know this stuff so if you have the time to share I am sure it will help me as well as lots of other people //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Thanks guys.

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[KARLEON 10+ year member]

Come on guys, lets all pitch in on our knowledge and create a nice lil thread. If alot of you help out with all sorts of tips, maybe this can become a sticky. I know lots of people have general questions concerning box building, and i really think this could be the thread where they can find that information instead of typing in the same ol thing. So i'll contribute....

Box Building materials

I would recommend 3/4 MDF to build your box out of

Liquid nails (to have a tight bond)

I used Silicon caulk to make sure the inside of the box is air tight.

Jig saw to cut nice holes.

oh and also, you might want to ask Lowes or Home depot (where ever you purchase the wood from) to cut the wood for you. So all you have to do is put it together. That helped me out alot. But i recommend you having your box layout already planed so you know the exact dimensions of the wood that needs to be cut.

Calculating airspace

Length x Width x Height divided by 1728

after that, you will have to count for the sub displacement and port displacement (if you are designing a ported box)

Box Bracing

Basically, you CANNOT brace a sub enclosure enough. And for the the people who might not know exactly what bracing is referring too, im simply just saying reinforcing the box. The idea box should be able to survive what ever is thrown to it. A box that flexing and is not properly braced can loose some of the box. You want everything to be sealed tight and braced well. This is a very important part of your install.

Some ways to brace a box would be using L shaped brackets in the inside. Maybe left over pieces of MDF wood. Lots of liquid nails to make sure the wood is tightly bonded. Extra nails. Basically, this is a chance to show off your skills and come up with any way you can think of to brace the heck out of your enclosure. Oh and JL audio's website has some nice information on box building.

Box Tuning

From by understanding, 28-33hz gives you great SQ in tuning. 34-38 is basically SQ with the ability to get loud. And 39 on up, is generally SPL. If i am wrong on this, someone please correct me. But thats just some of the knowledge i have learned.

 

Oh and dont forget when using 3/4 mdf wood as bracing, dont forget to calculate that displacement also.

You can apply fiberglass resin to the inside of the box.

You can double baffle the front of your box. What is meant by double baffle is, placing another 3/4 sheet of wood over the front of your box. to make it extra thick.

 

Well these are my tips. Im sure there are lots more tips out there, but I just wanted to show my support and get some more informative threads started on these boards so people can actually learn.

 

[KARLEON 10+ year member]

Oh and ANY BOX, built properly can sound good. But in general, Sealed boxes are smaller and can get the job done when there isn't enough space to work with. And it gives you good SQ (sound quality) not to mention its easier to build.

Ported/vented boxes are great also. (my personal favorite) Tuned properly and with the right amount of airspace, this box can deliever some awesome SQ and get hella loud while doing it. (Its all about your install)

Bandpass. I cant even go about saying how these are built. But if you have a bandpass box designed specifically for YOUR subs, then it should sound ok. But if not, this should be avoided. (in my opinion)

 

[DirtySchemer 10+ year member]

To find displacement for your sub...

1) Fill up a tub with water, and mark off the water level.

2) Submerge the bottom of your sub into the water and mark off the new level.

3) Calculated the difference in volume between the two lines and convert to your unit of measure.

 

[KARLEON 10+ year member]

TTT. come on people, i know you all have some tips and tricks to throw in this thread also.

Oh, and lets not forget stuffing polyfill into a smaller sealed enclosure to make the sub "think" its in a bigger box by slowing down the sound waves

 

[LoneRanger 10+ year member]

To find displacement for your sub... 1) Fill up a tub with water, and mark off the water level.

2) Submerge the bottom of your sub into the water and mark off the new level.

3) Calculated the difference in volume between the two lines and convert to your unit of measure.

please, for the love of god, don't stick your sub in water.

thank you, come again.

 

[Bill T. 10+ year member]

Warning: When getting wood cut at home depot, make sure they operator measures with a tape measure, not that POS that is attached to the saw. I got 2 bad cuts (1/4" off) because the guy working there was a moron. So I had to measure each piece, mark it... and line the blade up so he could cut it.

Bill T.

 

[KARLEON 10+ year member]

Thanks for the replies guys. Now i know I didnt cover everything. Any more? Oh and thanks for clearing that up Loneranger. And if anyone notice me posting something that isn't good, please feel free to correct me.

 

[BooLeaN 10+ year member]

LOL don't put the sub in water. I like that one //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

I have one that I used. When I cut the holes for my woofers, I measured the radius onto a board. I drilled a hole in the board at both ends so the hole to hole measurement equals the radius.

Then I drilled a hole in the center where I wanted my woofer, put a nail through the board's one hole and that one, a pencil on the other side, then wham, you have a perfect circle //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

I hope that makes sense.

 

[helotaxi 5,000+ posts]

To find displacement for your sub... 1) Fill up a tub with water, and mark off the water level.

2) Submerge the bottom of your sub into the water and mark off the new level.

3) Calculated the difference in volume between the two lines and convert to your unit of measure.

Make sure you wrap the sub in plastic before you do this. Most manufacturers specify the displacement in the sub's specs which makes this unneccessary.

 

[InhumanAcura 5,000+ posts]

I can suggest an easy tool to build if you want to come up with the volume of a fiberglass enclosure, spare tire tub, ect.

1. Build a cube w/o a top of 3/4 MDF (13.5x13.5x12.75)

2. Foil the inside

3. Lay a few layers of glass

4. Take the Mdf cube apart leaving a perfect cubic ft.

5. Mark the 1/4, 3/8, 1/2, ect.

6. Fill the object you wish to measure with water and empty ft by ft until you come up with your measurment.

Fiberglass is clear enough to see the water through. I couldnt figure a way to measure my spare tire well, and this is what i came up with.

 

[helotaxi 5,000+ posts]

You can do the same thing using 1 liter water bottles, takes longer but can give more accurate results if you are going to port it.

 

[vinnie_febs 10+ year member]

here is good website:

http://www.the12volt.com/caraudio/boxcalcs.asp

 

[simon21 10+ year member]

What I mean are things such as if you make the box bigger you get more/less output, more/less SQ. .

So what is the answer? Are bigger boxes better? If a manufacturer recommends a range, what will be the sound diffference from the top of the range to the bottom?

 

[BulldogSr04 10+ year member]

Heres one, port area is one of the key points to getting loud. I just rebuilt my box for more port area (16 sq inches vs 42.5 sq inches) and all i can say is holy shit

waaaaaaaaaaaay louder, and the bass is fuller with less cancellation.