Effects of cabin volume on speaker enclosure design

One characteristic of bandpass enclosures which is universal is that they exert greater control over cone motion over a wider frequency band than conventional designs. As such, it is not always possible to make blanket statements as to the performance benefits and drawbacks of bandpass enclosures in general. As if that is not confusing enough, within each bandwidth range, the designer can also manipulate box parameters to shift the range of operation up or down the sub-bass range which also has an effect on efficiency.ДЄs you can see, bandpass enclosures can have very different sound characteristics based on the designerвЂ™s choice of box parameters. Intermediate bandwidths can also be designed which create a compromise between all these characteristics. When box parameters are adjusted for a narrower bandwidth, the efficiency of the subwoofer system within that bandwidth increases and can reach gains of up to 8dB (sometimes even higher.) As box parameters are adjusted for wider bandwidths, very impressive low frequency extension can be produced from extremely compact enclosures at the expense of efficiency and good transient response. So what? CouldnвЂ™t the same thing be accomplished by placing a low pass crossover on the subwoofer system? Yes, it could, but a bandpass enclosure can produce significant performance benefits in terms of efficiency and/or deep bass extension that would not be possible in conventional designs of equal size.Д«y adjusting the volumes of the front and rear chambers and the tuning of the port or ports, significant performance trade-offs can be created.

The name вЂњbandpassвЂќ is really pretty descriptive in that it refers to the fact that the enclosure will only allow a certain frequency вЂњbandвЂќ (range) to вЂњpassвЂќ into the listening environment. This ported front chamber acts as a low pass filter which acoustically limits the high frequency response of the subwoofer system. In a bandpass enclosure, the front of the speaker fires into a chamber which is tuned by a port. In a conventional sealed or ported subwoofer system the low frequency extension is controlled by the interaction of the speaker and the enclosure design, but the high frequency response is a result of the speakerвЂ™s natural frequency response capability (unless limited by a crossover). Instead, the entire output of the subwoofer system is produced through the port or ports.

In a bandpass box design, the woofer no longer plays directly into the listening area. Many home sub/satellite speaker systems currently use bandpass designs for low frequency reproduction.Д¬an pass lots of output through a small opening The first patent for a bandpass enclosure was filed in 1934 by Andre dвЂ™Alton. It would probably surprise many people to know that this is a very old design. These enclosures have, at times, been popular in the car audio world.

Effects of cabin volume on speaker enclosure design