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Discussion Starter · #1 ·
I'd just like to have someone double check my cf before I get to finalizing this new design.


Enclosure will be made out of 3/4" MDF and driver displacement is .25cf x 2. Length is 65.5. I've calculated a couple different ways and the internal volume differs so I want to make sure I'm using the right method.


Thank you.

 

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Quote:
Originally Posted by bass addict  /t/1521016/quick-calculation-needed-for-verification#post_24439893


I'd just like to have someone double check my cf before I get to finalizing this new design.


Enclosure will be made out of 3/4" MDF and driver displacement is .25cf x 2. Length is 65.5. I've calculated a couple different ways and the internal volume differs so I want to make sure I'm using the right method.


Thank you.

 

I'm getting 18.6 cubic feet external volume

 

16.05 cubic feet internal
 

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Discussion Starter · #4 ·

Quote:
Originally Posted by steve nn  /t/1521016/quick-calculation-needed-for-verification/0_80#post_24439957


Just do a square box for the bottom potion and then second one down for the top two thirds of your pic. You very well might have already? http://www.hometheatershack.com/forums/enclosure-volume-calculator/ I'm sure someone can do it by the numbers though.

I did that but the only thing I'm racking my brain on is the extra dimension based on the inside 2 edges not having a side. I added .75 to one side on each but am not sure if that's right lol.

Quote:
Originally Posted by doublewing11  /t/1521016/quick-calculation-needed-for-verification/0_80#post_24439977


I'm getting 18.6 cubic feet

I sure as hell hope not.



I get anywhere between 8.05 and 8.3 depending on the aforementioned mystery side.
 

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Quote:
Originally Posted by bass addict  /t/1521016/quick-calculation-needed-for-verification#post_24439985



I did that but the only thing I'm racking my brain on is the extra dimension based on the inside 2 edges not having a side. I added .75 to one side on each but am not sure if that's right lol.

I sure as hell hope not.



I get anywhere between 8.05 and 8.3 depending on the aforementioned mystery side.
 

 

I just did a quick calc on iphone................external volume

 

Trapezoid area (b1 +b2)/2*H + rectangle area ( B*H) gives base area.............multiply by 65.5 for length and you have volume in cubic inches......multiply by 1 cf/ 1728 cubic inches and now you have cubic feet.   I don't have my TI-92 on hand.  I do a lot of stumpage with logs so I'm not too far off.

 

 

Edit: 


 

Freaking iphone........................the trapezoidal base was not divided by two.............now getting 11.2 minus approximately 2.5 cf for 3/4 inch MDF and driver

 

How's 8.7 cf?  I'll go find my calculator.....................phone calculations suck!!!
 

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Discussion Starter · #6 ·
Here's my calc


I added .75" to the height on both boxes as there won't be anything dividing them as one obviously. I'm hoping this is accurate. I get 8.24 total cubes after bracing. That's 4.1 per driver.

That's a little less then my front ones got (4.25 each).


 

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No, just do .10 on your thickness and you'll come out very close doing it as I said.. It's a option anyway.
 

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Discussion Starter · #8 ·

Quote:
Originally Posted by steve nn  /t/1521016/quick-calculation-needed-for-verification/0_80#post_24440128


No, just do .10 on your thickness and you'll come out very close. You can add that to your number if you like.

You lost me there Steve. Why .1? It's asking for thickness in relation to inches, which would be .75. Am I misunderstanding this?
 

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Just do your calc with your original drawing split in two. Ok I see what your saying. You are doing it as two units.. yeah you're good. What little we can't calc isn't going to matter.
 

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Discussion Starter · #10 ·

Quote:
Originally Posted by steve nn  /t/1521016/quick-calculation-needed-for-verification/0_80#post_24440167

Just do your calc with your original drawing split in two. Ok I see what your saying. You are doing it as two units.. yeah you're good. What little we can't calc isn't going to matter.

Cool. Always nice to have a second pair of eyes check it out.



The only thing I'm debating now is reducing the size a bit to put it under 4cf as I'll be running a bit more power than the fronts are getting.
 

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Discussion Starter · #11 ·

Quote:
Originally Posted by aaronlinkous  /t/1521016/quick-calculation-needed-for-verification/0_80#post_24440191





5.94 cf without the hole or port internally.

That's not quite accurate as I have an extra "leg" on my design.
 

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Quote:
Cool. Always nice to have a second pair of eyes check it out.

I didn't check it out. I know your all to capable. thumbs up
 

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Discussion Starter · #13 ·

Quote:
Originally Posted by steve nn  /t/1521016/quick-calculation-needed-for-verification/0_80#post_24440202


I didn't check it out. I know your all to capable. thumbs up

LOL. I do have my blonde moments though.
 

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Discussion Starter · #15 ·

Quote:
Originally Posted by aaronlinkous  /t/1521016/quick-calculation-needed-for-verification/0_80#post_24440214


I saw in your original post it did, but then in the screen crab of your calculator you didnt have it. So I thought you were updating the design. But thats how I usually figure out volum is to create the shape, then you group them and it'll show you volume.

The screen grab has it. I built each box separately and combined cf to get a total.


The only thing that's throwing me is the fact when you add .75" to the angled box, it might be inaccurately calculating overall volume due to it's angled design. It's probably not enough to worry about but my ocd...........................
 

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Quote:
Originally Posted by bass addict  /t/1521016/quick-calculation-needed-for-verification#post_24440110


Here's my calc


I added .75" to the height on both boxes as there won't be anything dividing them as one obviously. I'm hoping this is accurate. I get 8.24 total cubes after bracing. That's 4.1 per driver.

That's a little less then my front ones got (4.25 each).


 

 

Wait a second!  You said height was 23 inches in original post............................................you suckered me!  I'm a human calculator!!!  lol
 

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Discussion Starter · #17 ·

Quote:
Originally Posted by doublewing11  /t/1521016/quick-calculation-needed-for-verification/0_80#post_24440250



Wait a second!  You said height was 23 inches in original post............................................you suckered me!  I'm a human calculator!!!  lol

Height is 23". Seeing as I was building 2 separate boxes in the calc, I was taking into consideration the two sides that won't be there when combined into one box. So hence adding 1.5" to the total height. That should make my internal volume pretty close to accurate.
 

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Discussion Starter · #19 ·

Quote:
Originally Posted by dmadesign  /t/1521016/quick-calculation-needed-for-verification/0_80#post_24440661


I'm getting 9.04 cubic feet before I subtract the .5 cubic feet for the drivers with no internal braces. One problem I was having is with the dimensions you listed. I'm showing that the 20.5 inch face should actually be 19.98 inches long.


http://s218.photobucket.com/user/Fish_Time/media/subbox.png.html

I think you're right there. I don't have a cad program so I was doing the calc in my head.


After gluing all my sides together I realize I made another calculation error. When factoring in for my double baffle, I didn't take into consideration based on an angled design, I'm going to lose another 1.5" of surface area.
The width and height should have been lengthened accordingly.


At this point I'm just going to forge forward. This is my third box design trying to make this hide behind my second row and I'm not building another at this point. I'll have to run with a single 3/4" baffle and hopefully some extra bracing will be sufficient. I was hoping to flush the drivers more so they wouldn't be as obtrusive, but it is what it is. It's also going to be an extremely tight squeeze between the magnet and the back of the cab. I'm hoping this doesn't present any performance issues.
 

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Quote:
Originally Posted by dmadesign  /t/1521016/quick-calculation-needed-for-verification#post_24440661


I'm getting 9.04 cubic feet before I subtract the .5 cubic feet for the drivers with no internal braces. One problem I was having is with the dimensions you listed. I'm showing that the 20.5 inch face should actually be 19.98 inches long.


 

 

If I add the volume of the driver................I get what you calculated.

 

I used my brain................you guys use calculators.................hmmmmmmm.  lol
 
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