Question on port size

[telewacker]

I'm hoping someone can help me figure this out!

A cab I like has a slot back port. It's internal volume is 4553 cu in and the port 51.5 sq in.

I have a cab with an internal volume of 5288 cu in. How many sq in should the slot back port be to achieve the same response?

 

[Ron]

https://www.soundqubed.com/Calculate-Port-Size_ep_54.html

From the above link it looks like the port area is simply proportional to the the volume of the box.

So the port area of the larger cab should be 5288/4553 x 51.5 = 59.8 sq inches.

 

[telewacker]

Excellent. Thanks Ron.

 

[Kelly]

https://www.soundqubed.com/Calculate-Port-Size_ep_54.html

From the above link it looks like the port area is simply proportional to the the volume of the box.

So the port area of the larger cab should be 5288/4553 x 51.5 = 59.8 sq inches.

The numbers at that site are for tuning the port to 40 hertz. Sounds low for a guitar cab.

 

[telewacker]

The numbers at that site are for tuning the port to 40 hertz. Sounds low for a guitar cab.

They're talking about a ducted port 16.5" deep. The cab I mentioned has no more of a duct than the thickness of the plywood of the back panel.