Kurt

iTrader: (1)

I have been designing a subwoofer box now for about a week and I need some input. My sub requires 2.064 cu/ft for a ported box.

1st design - which is a rectangle in shape and the inner dimensions are
15.5"h X 21.5"w X 10.5"d which equals 2.024 cu/ft

2nd design - which is a cube shape andthe inner dimensions are
15"h X 15"w X 15.5"d which equals 2.018 cu/ft

Should I go with the first design which is a rectangle shape and is not to deep or should I go with a more cube shape like the second design which has more depth. Since this the first box I have built, I really have no clue how the box shape will effect the sound.

trubidou

Generally, the rectangular shape is better. There is a rule based on the golden ratio that gives the ideal shape. It is ~ .618 x 1 x 1.618. Pick a value to represent the "1" and then multiply by .618 and 1.618 to get the other dimesions.

Kurt

iTrader: (1)

How do I know what value to pick to represent "1"?

Higgity Hank

Golden ratio has very little effect when designing a subwoofer, and almost nil effect when designing an In Car unit.

For mid's and highs, in the home, the golden ratio applies, and works out quite well, but with the lengths of the waves produced by sub bass, you can make the box a cube and it won't generate standing waves (in the box). The lower the note, the less concern the shape of the box is (unless you're building a wave cannon, TL or some other such device that relies on the waves)

In your plan, you mention the call for a ported box, what are you tuning the box to? Port size? Length? Remember, you've got to subtract the volume taken up by the port from the net volume of the box. Also subtract woofer volume, and the volume of the bracing. So you're going to need to build a larger box than either of those to begin with.

So HKL, pick the box that fits into your car best. But be sure to design the box properly. If designed properly, you'll hear wonderful things coming from the trunk... if not... could be smoke and a busted sub. (no ****... don't play below your tuning frequency, you could potentially unload the driver, especially at high volumes)

Kurt

iTrader: (1)

Thanks Hank, I forgot to subtract the volume of the port, woofer volume, and the amount of space for bracing. Thank god I haven't made any cuts yet. I will just have to make a small adjustment in my dimensions when I get home tonight. I plan on tuning the box to the port length and diameter. According to Audiobahn specs, I need a port that is 7.5" long and 4" in diameter.

Kurt

iTrader: (1)

At last the box is built. All the seems are sealed, every screw is tight, and the sub is mounted. I still need to carpet the box. I put everything in the trunk to see how it sounded. First off, it just fits through the trunk opening. I hooked everything up and help my breath. It sounds great. With the amp turned half way up, it is produces a nice sound. Tuning will come later after I reinstall the finished box. I took everything out so I could put the finishing touches on it. I will post pictures of every as soon as I get a hold of a digital camera.

Here is a detail cost list:
$19.95 for 3 pieces of 3/4" mdf (each piece was 2'X4')
$3.51 for #8 screws (box of 100)
$2.31 for silicon (extreme temp. good for -40 to 180 degrees)
I already had glue at the house
The port and terminal cup came from the old bandpass box.

Higgity Hank

Glad it's coming out well for you. You might want to consider something other than carpet though... it's a ***** to work with if you haven't done it a lot. I really like using bedliner (the roll on kind, usually around $20 at the auto parts place) It looks good and it's indestructable (at least in the trunk environment)

Kurt

iTrader: (1)

Good idea on the bedliner, but how thick is it? The reason I ask is because I have about a 1/2" gap to work with when putting the box in the trunk.

Higgity Hank

It's as thick as you make it... certainly wouldn't fill up a 1/2" if you only did one coat. You're putting it on with a roller, so you be the judge