1. ## somethings fishy...

I just plugged in some #s on a port calculator and...
box is 8 ft.^3
2 RE SE 15's
ported to 35Hz...
4x16.75 port
Now here comes the weird thing...
It tells me that I only need ~12" of port length. Is this correct? seems like everyone here is running some 20+ inch long ports while still being tuned in the mid 30's. Is this setup more along the lines of SPL than SQ? Im going for about a 50/50 mix of the two...

2. ## Re: somethings fishy...

Your calcs are correct. You only need a 12" long port because your box volume is so high. As box volume increases, port length decreases, and as port cross sectional area decreases, port length decreases. However, as you decrease your port cross sectional area, you run the risk of port noise.

3. ## Re: somethings fishy...

may i ask what calculator you used?

4. ## Re: somethings fishy...

The port calculator I used was one I put together in Excel. It will solve for tuning frequency, net box volume, or port length.

5. ## Re: somethings fishy...

Hey Simos, you think you could PLEASE tell us how to input the port calc formula into Excel? I'd be very greatful! Thanks a bunch!

6. ## Re: somethings fishy...

I attached the excel file I put together as a zip file. Not sure if it will work to attach it as a zip file or not. It should be fairly self explanatory as to what you need to do. The cells that are highlighted red contain formulas, so dont type any values in. The cells highlighted green require a value.

7. ## Re: somethings fishy...

Originally Posted by Simos
I attached the excel file I put together as a zip file. Not sure if it will work to attach it as a zip file or not. It should be fairly self explanatory as to what you need to do. The cells that are highlighted red contain formulas, so dont type any values in. The cells highlighted green require a value.
It is not 100% accurate but fairly close. I recommend doing it by hand or on the computers sientific calculator.

8. ## Re: somethings fishy...

Why is it not 100% accurate?

9. ## Re: somethings fishy...

Seems to be accurate to me, unless you feel its important to have better than 1/100th accuracy.

10. ## Re: somethings fishy...

Thanks Simos for the formula!

11. ## Re: somethings fishy...

Originally Posted by vincemarq
Thanks Simos for the formula!
No problem man, glad I could help.

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