please check these measurements...

[cappy72 10+ year member]

I am not going to get into a long story but I need to know 1 thing, what volume and tuning freq is this box. I bought one today and I want to make sure it is correct...

the width is 30"

the depth is 15"

the height is 15"

the port depth (from front to back) is 10.25"

the port length ( from the inside left to right) is 16.25"

the actual width of the port opening is about 2.75" (its closer to 2 7/8's)

the wood is 3/4"

Please let me know the volume and tuning freq... thanks

Click to read more...

 

[Moe Lester 10+ year member]

it seems like its somewhere around 2 cubes @ 38hz. That should be a pretty close guess without knowing exactly how you measured the port, or what the sub displacement is.

 

[cappy72 10+ year member]

hmmm... can you do me a solid and give me a more accurate number ...

or tell me if it could be 2.5 @30hz...

I have a 12 XXX in it

 

[Moe Lester 10+ year member]

the only way its 30hz is if the port and sub displacement are not included...

 

[cappy72 10+ year member]

ok so box alone. it is possible that it is 30hz...

with box its more like 40ish

sound about right?

 

[Moe Lester 10+ year member]

no, that box cannot be 30hz

id call it 2 @ 38 + or - .2 cubes and 1-2 hz. thats it.

 

[slicks5150 10+ year member]

with those measurments the interior volume of that box is 3.00586ft^3 before displacement. and the tune is around 33hz.

assuming that the height of the port is 14.5"s

 

[Moe Lester 10+ year member]

with those measurments the interior volume of that box is 3.00586ft^3 and the tune is around 33hz with out displacement.assuming that the height of the port is 14.5"s

well why would you calculate the tuning without displacements?

bottom line is, you did not get what was advertised to you.

 

[slicks5150 10+ year member]

it'sbefore displament because I know not what the displacement is and how did you figure it was 2 cubes at 38 hz??? displacemnent wount take that much away from the internal volume.

 

[cappy72 10+ year member]

ok I figured I didnt get exactly what they were telling me... and ideally I was looking for approx 2^3 @35ish ...

so I believe what i have now is a good substitute. any disagreements?

 

[slicks5150 10+ year member]

what kind of sub are you putting in it. . .and you are most deffinitly far away from 2ft^3 at 35hz.

 

[Moe Lester 10+ year member]

the XXX's displacement is .21 cubes, the port is a MINIMUM of 26.5" long. The real length depends on how he measured it. I doubt end correction was factored in, nor was it measured down the middle. So if the port is 13.5 high, and 2.75 wide, 3/4" MDF. we can get a rough estimate that the port is 13.5 x 3.5 x 26.5 = .724 cubic feet.

.724 + .21 = .934 cubes.

3 - .934 = 2.066

a port 2.75 x 13.5 needs to be ~26.25" long to achieve a tuning of 40hz for 2 cubes. However i believe that the port was measured on the inside walls, not down the center, nor was end correction added in. Its probably ~ 4" longer measured down the center and with end correction factored in. That will reduce the box volume slightly, but the tuning is still going to drop.

I cant give you an exact airspace/tuning because im not the one measuring it. Im sure he measured the box differently than I would have, so the best i can do is try to make a somewhat accurate guess.

 

[cappy72 10+ year member]

i measured the port from one end to the other, on the outside of the actual L

I didnt account for the thickness of the wood.

my box is 15" high that means the port is 13.5" high

2.74 wide is the actual distance of the opening

here using moe's pictures

the black line is 16.25

the red line is the 10.25

the blue x's mean that wall is not there