How to tune for specific frequency?

[MDH69]

Im wanting to use some Qpower shallow sealed sub boxes ....Manufacturer states they are .51cubic feet.

If i wanted to port them and tune to say 40hz ,what size port diameter and length would i need to get in that area?

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[Buck 5,000+ posts]

You need to know your net airspace and the surface area of the whole port. I would tune lower

 

[Buck 5,000+ posts]

I really like Q power deluxes, they are actually good subs for what they are, well designed. I would suggest those if you could fit them.

 

[MDH69]

You need to know your net airspace and the surface area of the whole port. I would tune lower

It has no ports at all...not sure where to begin with it all...3 inch tube 4 inches long?..2 inch port 3 inches long?..Aside from box dimensions and advertised cubic feet i have no other specs.

 

[Buck 5,000+ posts]

It has no ports at all...not sure where to begin with it all...3 inch tube 4 inches long?..2 inch port 3 inches long?..Aside from box dimensions and advertised cubic feet i have no other specs.

If you're going to port a box, you need to build your own from scratch or have someone build it for you. Don't modify a already made sealed box into a ported one, it probably won't be proper airspace at all.