could someone calculate this tuning?

[Lil Poot 5,000+ posts]

need to know what this box is tuned to please. subs will displace .4 cubes each.

Click to read more...

 

[Mike465 10+ year member]

How long is the port?

 

[Lil Poot 5,000+ posts]

shows on the cut sheet, 10 inches x 40.

 

[Mike465 10+ year member]

Ok total volume before port displacement is --------13.828125 cubic feet.

Total volume port displacement is ----------------------1.215 cubic feet

Total volume displaced by subs is-------------------------.8 cubic feet

Total volume after displacement is --------------------11.812 cubic feet

Tuning Frequency is---------------------------------------44Hz

 

[Lil Poot 5,000+ posts]

hmm... the box designer says its 38 hz, and another designer says 44 hz. i'm confused //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[DBBOOM 10+ year member]

http://www.carstereo.com/help/Articles.cfm?id=31

 

[Mike465 10+ year member]

Sorry it has been updated. Entered in the wrong number for volume, and did not account for sub displacement.

Yes, 44Hz is correct.

 

[Mike465 10+ year member]

hmm... the box designer says its 38 hz, and another designer says 44 hz. i'm confused //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

Looks to me that he calculated it with gross volume and not net volume. If he used 13.828 cubic feet then thats why it is 38Hz. You would have to make the port 17.36 inches long for it to be tuned to 38Hz

 

[Lil Poot 5,000+ posts]

http://www.carstereo.com/help/Articles.cfm?id=31

that says i should use a width/height ratio of less than 1:8 and wont calculate it for me //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[Mike465 10+ year member]

that says i should use a width/height ratio of less than 1:8 and wont calculate it for me //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

That calculator is not as accurate. If you mist use an online calculator use this one. It's better.

http://www.the12volt.com/caraudio/boxcalcs.asp#porsq

 

[Lil Poot 5,000+ posts]

ok, how about making that port section 16 inches long to do 16.75 counting the thickness of the front piece its attaching to?

 

[DBBOOM 10+ year member]

that says i should use a width/height ratio of less than 1:8 and wont calculate it for me //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

Invert the numbers and override and you get 39hz, seems pretty dead on. It gives ratio suggestions to avoid port noise.

 

[Mike465 10+ year member]

Invert the numbers and override and you get 39hz, seems pretty dead on. It gives ratio suggestions to avoid port noise.

Using that same calculator you used and entering in 39Hz for tuning is not correct

Volume---------------- 11.812 cubic feet

Tuning------------------39HZ

Number of ports------1

Type of port-----------Square

Slot port----------------Yes

Port Height-------------4.5"

Port Width--------------40"

Port Length------------13.68"

 

[DBBOOM 10+ year member]

Using that same calculator you used and entering in 39Hz for tuning is not correct
Volume---------------- 11.812 cubic feet

Tuning------------------39HZ

Number of ports------1

Type of port-----------Square

Slot port----------------Yes

Port Height-------------4.5"

Port Width--------------40"

Port Length------------13.68"

By the pic the port height after wood thickness subtraction is 3.75'', correct?

 

[Mike465 10+ year member]

By the pic the port height after wood thickness subtraction is 3.75'', correct?

I know the picture looks confusing but if you look at it you will see a double dimention line on the bottom indacating that he is not measuring from the bottom of the box but the bottom of the port opening.