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Michael Hancock

Can some double check my calculations?

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Here is the quick rundown:

4 Soundqubed HDS300

FS 33.65 hz

QMS 6.912

QES .769

QTS .692

VAS .782 Ft3

 

Outside dimmensions of box:

16.3"x41"x27" = 10.44

all setup in  a common chamber

 

Port size:

8"x40"x65.88" @ 30 hz

 

I believe this is all correct but what a double check before I build this box.

Thanks

 

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You're assuming the thickness of the wood is zero, if using 3/4": 15.55x40.25x26.25 = 16429in^3/(1728in^3/ft^3) = 9.5 ft^3

 

You didn't list the model of your speaker (size wise), so I had to look it up... SQ sucks and doesn't list speaker displacement so we'll go with 0.14ft^3 each.

 

So your enclosure volume before the port is 9.5 - 4(0.14) = 8.94ft^3.

 

For your port: 8"x40"x65.88" = 12.2ft^3, Is your port going to be external?  If so, it needs to be 92" long. If it's internal, then it's not going to fit...

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Need different subs or more box space

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Box size isn't an issue for me.  I can go bigger, but wouldn't that also take it out of the recommended specs for the subs?

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No.  You are reading the specs not as they are.

For instance when a manufacturer recommends a 2cuft box tuned to 30Hz.  This means that your box is 2 cuft + the volume of the sub + the volume of the port.  If your sub and port has a volume of 1cuft then you'd need 3cuft to NET 2cuft.  This is done for a reason since when you change port area the length changes which causes a drastic change in overall enclosure volume.

 

Add to that you need to calculate the space INSIDE the box, not outside.  If you use 3" thick wood for a 2cuft enclosure it will be a bigger enclosure than if you use 3/4" thick wood.

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So in essense when figuring the port size, that space should be added to the box dimmensions.  Meaning that if my box is 5 ft3 and I know that I need 2 ft3 for port, then I need to buid a 7 ft3 box.  I am just throwing hypothetical numbers out there, just to make sure that I fully understand. 

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Yes fundamentally...but you also have to account for the wood and the subwoofers too as they take space

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What box calculator are you using?

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Bracing if using any is going to take away some internal space also

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