Quick port math question

[mat3833 10+ year member]

OK, I'm trying to help a friend out. He needs a box for a 15" driver. Here are the box dimensions:
24d
24w
15t

Internal volume equals 3.955. Minus roughly .15 for sub displacement and you get 3.805 cubes. Using a single 6" aero to get tuning in the 32hz range I'm getting multiple different answers using quick calculators.

If my volume before the port displacement is 3.805 to get 32hz tuning I need a port 15.17 inches long. Port displacement would be just about .25 cubes so I need to add just a hair to an outside dimension to compensate.

Is my math right? It's been awhile since I faffed around with port tuning.

Matt

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[winkychevelle 10+ year member]

A 6inch port 18inches long would give you 3.5ft³ internally and 32hz final turning

That's putting the port in the box. 18inchs of 6inch port takes up .3ft³ so 3.8-.3=3.5

Plenty for most 15s ported.

Depending on the 15 idk if you have enough port area.

 

[mat3833 10+ year member]

A 6inch port 18inches long would give you 3.5ft³ internally and 32hz final turning

That's putting the port in the box. 18inchs of 6inch port takes up .3ft³ so 3.8-.3=3.5

Plenty for most 15s ported.

Depending on the 15 idk if you have enough port area.

I'm using the known 3.805 cubes as my starting point. Then I'll add volume to the enclosure to compensate for the port displacement. I don't get 18 inches of port on any calculator. With 3.805 as my box volume I need 15.7ish inches of port length to equal 32ish Hz right?

I know I'm doing this a little backwards, but space limitations are pretty strict.

Matt

 

[djdilliodon!]

OK, I'm trying to help a friend out. He needs a box for a 15" driver. Here are the box dimensions:
24d
24w
15t

Internal volume equals 3.955. Minus roughly .15 for sub displacement and you get 3.805 cubes. Using a single 6" aero to get tuning in the 32hz range I'm getting multiple different answers using quick calculators.

If my volume before the port displacement is 3.805 to get 32hz tuning I need a port 15.17 inches long. Port displacement would be just about .25 cubes so I need to add just a hair to an outside dimension to compensate.

Is my math right? It's been awhile since I faffed around with port tuning.

Matt

If this is for the Dayton, a 6” aero port will be perfect. The enclosure height of 15” may not work as the OD I believe is 15.6”. It would be better if you can push it to at least 16” or 17” if possible.

 

[mat3833 10+ year member]

If this is for the Dayton, a 6” aero port will be perfect. The enclosure height of 15” may not work as the OD I believe is 15.6”. It would be better if you can push it to at least 16” or 17” if possible.

Sub up port back sub will be on a 24x24 face and port will be on a 15x24 face

Matt

 

[djdilliodon!]

Sub up port back sub will be on a 24x24 face and port will be on a 15x24 face

Matt

And I’m an idiot thinking you guys would put it on the 15” side .

 

[mat3833 10+ year member]

And I’m an idiot thinking you guys would put it on the 15” side .

LOL, I've been there man.

Matt

 

[winkychevelle 10+ year member]

http://www.psp-inc.com/tools2.html

 

[mat3833 10+ year member]

http://www.psp-inc.com/tools2.html

Yep, that calculator gives me 16.3 inches or so, winisd gives me 15 and change, etc. If I'm keeping a known internal volume after displacements. What is my port length required for 32hz tuning for a 3.805 cubic foot enclosure.

The inch difference is a bit concerning.

Etc.

 

[winkychevelle 10+ year member]

Yep, that calculator gives me 16.3 inches or so, winisd gives me 15 and change, etc. If I'm keeping a known internal volume after displacements. What is my port length required for 32hz tuning for a 3.805 cubic foot enclosure.

The inch difference is a bit concerning.

Etc.

9 chances out of 10 you are looking at flared port vs none flared.

Since flared Ports only use half of the flares length for calculation. So a 3inch flared would only add 1.5inch of tuning length.

You aren't going to notice the difference in 32-33hz. That said I use the psp tool for all my aeroport boxes