How to Calculate Bass-Reflex Enclosure
By Ron Roberts
The size of a bass-reflex enclosure is mainly determined by the size of the loudspeaker/driver being put in the cabinet. The Thiele-Small parameters help with all the design issues of a bass-reflex enclosure, and are provided with any good-quality component speaker. If they're not provided, the Thiele-Small database provides all relevant data for more than 5,000 different loudspeakers.
Consult the data sheet for your speaker for the Thiele/Small (T/S) parameters. Copy the following data:
Electrical resistance of voice coil (Re )
Resonant frequency of loudspeaker (Fs)
Electrical Q of loudspeaker (Qes)
Mechanical Q of loudspeaker (Qms)
Total Q of loudspeaker (Qts)
Equivalent air volume (Vas)
Download free software for building speaker boxes. WinISD is a well-regarded Windows-based choice that also has a downloadable Mac version (see References).
Enter your copied data (from Step 1) into the speaker-building software to produce the box and cutout sizes for your bass-reflex enclosure.
Print the data and take all measurements with you to aid in cutting when you purchase the wood for the speaker enclosure.
- More than 5,000 speakers are listed in the Thiele/Small online database.
- If you don't want to download software, you can use the online calculator provided by AJ Design Software (see References).
Ron Roberts has combined personal fitness with health-care copywriting since 1995. He developed weight-training and nutritional plans for private clients, as well as plans for Nautilus Fitness Centers. He is also a skilled and experienced investor, having surfed the investment waves of several technological trends. Roberts earned his B.A. in English from University of California, Los Angeles.