You will need
- - program for calculating box subwoofer.
To begin calculate the parameters of the dynamics. While it is useful to read additional information on specialized forums in that case, if you first build yourself a subwoofer.
Measure and use in the calculations the frequency, power, resistance, depth, coil size, sensitivity, and so forth, before using the formula. Do not forget about the material from which was made the membrane, and other similar aspects that can affect the calculations.
Choose which you will have the type of acoustic design. To do this, use the result of the ratio of resonant frequency to the speaker. If you are planning an outdoor enclosure or screen, use the ratio FS/Ots. If it is equal to 30 (the value can vary up to 50), this type of design available in this case.
If the value was greater than 50 and up to 80, it's better to make a sealed enclosure. If the value will be in the range from 80 to 110 here applies bass reflex type. In other cases (more than 105-110) used bandpass. Required to comply with these conditions, otherwise you'll just have to do all the work again.
Download the program for calculating the value box of the subwoofer. Such programs enough online better just download them from official sources. Also whenever possible, choose Russian-language software with intuitive interface.
Then enter the calculated settings you dynamics for the case of your subwoofer based on the selected type of acoustic design. In the future do not delete the program in case if you have still to redo the creative type of your subwoofer. Apply the calculations in practice.
Do not use formulas and programs without pre-measurement dynamics.