# I need math help!

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• posted on August 2, 2003, 7:57 pm
Dear All,
I am sure some of you can solve this in your head, but I don't know how to do this.
I have a box that I need to solve the interior volume for.
The side of the box has four sides. The base is 10-7/8", the one side that is at a 90 degree angle to the base in 4" high, the other two lengths are 10" and 10-1/2". The box is 8-7/8" wide and the material is 3/4" MDF.
What is my interior volume?
This box is for a subwoofer and I know the range that the box can fall within, 1/3 cubic foot to 3/4 cubic foot. I was aiming for the high side, and I hope I am close.
David.
Every neighbourhood has one, in mine, I'm him.
Remove the "splinter" from my email address to email me.
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<%-name%>
• posted on August 2, 2003, 6:33 pm
.255 cu ft.Check the forum post as to how I got the answer. I think I got it close enough

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<%-name%>
• posted on August 2, 2003, 8:02 pm
Volume = Length x Width x Height
Length multiplied by Width gives you the area of the bottom of the box in square units - as in square inches.
Multiply that number by the Height to find the Volume in cubic units - as in cubic inches.
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<%-name%>
• posted on August 2, 2003, 8:16 pm
Ah. OK. Sorry. The picture helps a lot.
Visually, divide your speaker housing into TWO boxes.
The rectangular one on the bottom - compute volume as already described.
The triangular box - for lack of a better term - on the top - compute the area using the same formula - then divide the result by 2.
Add the two volumes together to get the total volume.
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in
as
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<%-name%>
• posted on August 2, 2003, 8:05 pm
Here is a link to a pic of the box,
http://members.rogers.com/dfeisan/images/subbox1.jpg
Thanks,
David.
Every neighbourhood has one, in mine, I'm him.
Remove the "splinter" from my email address to email me.
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<%-name%>
• posted on August 2, 2003, 8:23 pm

Volume of bottom, rectangular solid part is length x width x height = volume 1 volume of prism-shaped top = length x width x height/2 = volume 2 total volume = volume 1 + volume 2
1 cubic foot = 12x12x12 cubic inches
Larry
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<%-name%>
• posted on August 2, 2003, 8:24 pm

In the picture, you can see the base of the side facing the camera, (the face bottom edge on my bench), that edge is 10-7/8". The only right angle on the side of the box is on the left, coming up from the base, that left edge in 4". The edge that the speaker in sitting on is 10-1/2". The right edge coming up from the base, the one with my speed square beside it is 10".
The depth, or width of the box, along the dimension where the clamps are is 8-7/8".
I am sure there are math terms for these measurements defining sides of an irregular polygon [I think that is what I am making :).], but I don't think I ever knew them...
Is this enough info to understand the shape of the box?
Thanks,
David.
Every neighbourhood has one, in mine, I'm him.
Remove the "splinter" from my email address to email me.
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<%-name%>
• posted on August 2, 2003, 10:39 pm
373.2527 cubic inches inside volume.

on
edge
is
think
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<%-name%>
• posted on August 2, 2003, 10:28 pm
http://pages.cthome.net/edhome
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<%-name%>
• posted on August 2, 2003, 10:45 pm

Damn, a fully on topic post using sawdust. U da man!!!!!
Wes
--
Whiskey Echo Sierra Sierra AT Gee Tee EYE EYE dot COM
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<%-name%>
• posted on August 3, 2003, 2:50 am
In article

That helps a lot.
Measure the inside of the bottom part where you can picture a regular box.
Volume 1.
pretend the angled part at the top iis another box on top of that, then divide volume by 2 to get volume 2
You'll be close.
djb
--
"If you wind up with a boring, miserable life because you listened to your mom,
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<%-name%>
• posted on August 2, 2003, 8:09 pm
I can't picture the box you're describing. Can you have mercy on this poor stubble-jumper and start again?
Then how do the other dimensions come into play?
djb
--
"I'll do the stupid thing first and then you shy people follow..." - Frank Zappa

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<%-name%>
• posted on August 2, 2003, 10:12 pm

Your dimensions are for the outside of the box, yes? And you need the interior airspace volume, not including the MDF walls, right?
I get .199 cubic feet... 343.27 cubic inches... Drew it in Autocad to get the area of the side...
If the dimensions you gave were for the inside of the box and not the outside... .363 ft cubed, or 627.4 inches cubed...
Jonathan
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<%-name%>
• posted on August 3, 2003, 12:03 am
He's not. It's likely a 6 inch.

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<%-name%>
• posted on August 3, 2003, 3:31 pm
LOL.... 6" That ain't a Sub Woofer... That's more of a mid range speaker...;~)

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<%-name%>
• posted on August 3, 2003, 3:08 pm
Dear Leon,

Umm, it will not be a 15" sub, I do not have the space.
This is for my 2003 Ford Ranger extended cab pickup. I didn't want to use up the entire back of the cab, I wanted to extend the centre console and put a sub in there that wouldn't interfere with the jump seats or front seat movement, reclining.
The sub I am using is a Kicker Solo Baric 8" sub, it is square, so in effect it sounds and acts larger than it's 8" size would suggest. The sub will be driven by a 350 watt RMS Alpine mono amp. This was the best set-up I could come up with, given my limited space
I have to finish it this weekend, the sub, speakers and amps are being installed on Tuesday. I will post pics if you really wanna know.
Thanks,
David.
Every neighbourhood has one, in mine, I'm him.
Remove the "splinter" from my email address to email me.
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<%-name%>
• posted on August 3, 2003, 3:44 pm
Ohhhh.. ;~) So are you gonna be one those people that ride around with the sub turned up so much that all the sheet metal and door trim panels rattle?
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<%-name%>
• posted on August 3, 2003, 4:53 pm
I havn't seen a car audio amp yet that would really put out what they say but assuming that yours does, I hope you have a large aftermarket alternator or you won't be able to listen to it and use your headlights at the same time.

up
a
effect
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<%-name%>
• posted on August 3, 2003, 10:37 pm
I can hear the subs in the kids cars pounding a half block away from my closed up house.

alternator
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<%-name%>
• posted on August 4, 2003, 1:01 am
Sure can but they are not putting out near as much power as they (or the manufacturer) claim. I spent a fair amount of time going over the numbers some time back from several different manufacturers. Their claimed output power just could not have been true. In a lot of cases, the claimed output power exceeded the input.

say