Like everyone, I Googled “sub box calculator software” to work out how big my sub box needed to be.
Unfortunately the sub box calculators I found did not give me everything I needed.
Here are the three sub box calculator web pages you need to calculate and understand the dimensions you need for your sub box.
1. Glossary – This page explains all of the parameters, what they mean and you what numbers you need for the sound you want http://www.eminence.com/support/understanding-loudspeaker-data/
2. Get the Gtc – Sometimes you don’t get this and you need to know it so you can make your sub box sound the way you want it. This page calculates The Qtc for you http://www.ajdesigner.com/phpsubwooferclosed/resonance_frequency_equation_qtc.php#ajscroll
3. Get your sub box volume. Put all the figures from the two pages above to get the sub box volume you need http://www.ajdesigner.com/fl_subwoofer/subwoofer.php
4. Build your box. This page calculates the dimensions you need to get you volume. Sliding scales, easily experiment with different lengths, widths and heights to get the volume you need. It even takes into consideration the thickness of the wood you are using http://www.bcae1.com/spboxnew2.htm
5. General Tips. http://www.carstereo.com/help/Articles.cfm?id=29
Getting your sub specs
The manufacturer website should also be your first port of call when you need the specs of your sub. Some manufacturers make it easier to find than others.
If your sub came supplied with a box, it is always worth comparing the size of the box supplied with the results given by these sub box calculators.
If the sub box you have now is generic, the difference in sizes could be huge, if on the other hand the sub box you have now was supplied by the manufacturer of the speaker, it is worth double checking your measurements if there is a big difference in your figures and the size of the sub box that was supplied.
Try before you buy. Save money
If you are looking at buying a new sub woofer and building your own box because what you have now is not what you want, it is worth finding out why.
For example, if your off the shelf sub and box is too boomy, run your subs specs through these sub box calculators, you may find out why your sub is not performing as you want it. The box you may have may be completely unsuitable for the speaker you have in it.
In other words, before spending more money on a new sub, find out if the sub box you have now is causing you the problem. If you sub box is the problem, you can save money by just building a box of the correct size, no need to buy a new sub if the one you have now is fine and was just being held back by a bad sub box.