Formula for finding Fb (Enclosure Tuning Frequency)

[Chase R 10+ year member]

I'm currently using JL Audio's formula for finding the tuning frequency of my enclosure: JL Audio » header » Support » Tutorials » Tutorial: Enclosure Ports

There's also this formula I found online, which gives me a slightly higher Fb: Ported Vented Box Equations Formulas Design Calculator fb Tuning Frequency Length

Is there a de-facto tuning frequency formula used here? I'd rather not install software for a simple calculation.

My specs are:

- Av (port area): 15 in^2

- Vb (enclosure volume, net of port and woofer): 1 ft^3

- Effective Lv (port length): 35.63 inches (.625" correction factor)

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[trumpet 5,000+ posts]

It's as explained by the JL Audio article.

 

[Boomin_tahoe 5,000+ posts]

Which subs do you have? In reality, it comes down to tuning choice by the person.

 

[hispls 5,000+ posts]

Which subs do you have? In reality, it comes down to tuning choice by the person.

I think he is just asking how to calculate tuning once you know box and port sizes.

OP, you will never hear the difference if you're off 2-3 cycles from your target. By my testing you need to move increments of 5 before it's really audible, particularly if you're trying to tune for music.... if you're building it to be super peaky you may notice a little bit, but 2-3 hz is not dramatic.

 

[Chase R 10+ year member]

Thanks guys. I set up a spreadsheet in Google that does the Fb calculation for me using the JL Audio formula, so just wanted to make sure it is correct. Now on to the construction phase. Will be constructed from 3/4" birch.

And for the person that asked, the subwoofer I'm using is the Sundown E-10 v3. Sundown's recommendation is a 1 cu. ft. (net) enclosure @ 32 Hz with 16 in^2 of port area.