Determining port area

[bkolfo4]

I think it is a decimal place/units problem.

You have Sd in cm, XMax in mm, and I think Vd may need to be meters^3. I don't have the book in front of me to check it.

There are online calculators everywhere if you run a google search.

[walled01alero]

I think it is a decimal place/units problem.

You have Sd in cm, XMax in mm, and I think Vd may need to be meters^3. I don't have the book in front of me to check it.

There are online calculators everywhere if you run a google search.

Yeah that's the problem.

The inputs need to be converted to meters and square meters.

And the forumla given is quite a bit less conservative than Richard Small's formula

I did it for one sub at 35hz and got a 6in diameter port as the output, which is 28.27 in^2 of port area.

Mulitplying by four gives you 113.1 in^2

Which is way too much.

Using the better formula for one sub at 35hz:

A 4.25" in diameter port was the output. Which is 14.18 in^2 of port area. Multiplying by 4 gives, 56.74 in^2 of total port area.

Which is much better.

[walled01alero]

I think a single 8" aero would be perfect.

[walled01alero]

Quoting your first post:

I'm building a box ... 35 hertz. That ports the port area at 17531 cubic inches. Is this too much?

I just want to point out that you can't measure area in cubic units.

[herbykw]

I think it is a decimal place/units problem.

You have Sd in cm, XMax in mm, and I think Vd may need to be meters^3. I don't have the book in front of me to check it.

There are online calculators everywhere if you run a google search.

Yeah that's the problem.

The inputs need to be converted to meters and square meters.

And the forumla given is quite a bit less conservative than Richard Small's formula

I did it for one sub at 35hz and got a 6in diameter port as the output, which is 28.27 in^2 of port area.

Mulitplying by four gives you 113.1 in^2

Which is way too much.

Using the better formula for one sub at 35hz:

A 4.25" in diameter port was the output. Which is 14.18 in^2 of port area. Multiplying by 4 gives, 56.74 in^2 of total port area.

Which is much better.

Thank you, this sounds much more realistic. My previous set ups have been with 18" subs and 15" subs, so I always went for the large ports. I have never run more then 2 subs, and never subs this small. I would think that too much port area would be like playing free air, and too little would be choking the subs down.

[herbykw]

Quoting your first post:

I'm building a box ... 35 hertz. That ports the port area at 17531 cubic inches. Is this too much?

I just want to point out that you can't measure area in cubic units.

Thanks.

[walled01alero]

No prob.

[herbykw]

A 4.25" in diameter port was the output. Which is 14.18 in^2 of port area. Multiplying by 4 gives, 56.74 in^2 of total port area.

Which is much better.

So two 6" ports would be just about right. 56.52. Seemed like a lot. the box seems awkward. But as long as it works.

[shogen]

that looks crazy... lol