What's in the box?

When it comes to choosing loudspeakers, there are many designs to pick from. Neville Roberts discusses what different cabinet enclosure types offer

One of the first issues that many people consider when choosing a speaker is its size and how it fits in their room. Size may be the factor that determines whether you choose bookshelf, standmount or floorstander. However, the design of the enclosure can have a significant impact on the sound.

The main use of the enclosure is to house the bass driver to control its resonances and acoustically couple it with the room. Midrange drivers need their own chamber separate from the bass to minimise interactions between the two. Tweeters are usually self-contained so don't need enclosures.

An important point to note is that to reproduce bass, you need to move lots of air. That means you need a larger area cone and enclosure than for higher frequency notes. Physics tells us that a sound of low frequency is heard with less intensity than one of a higher frequency of the same amplitude (ignoring the characteristics of the human ear and such things as Fletcher-Munson curves). The amount of energy in a wave is directly related to its amplitude and frequency. To transmit a bass note with the same energy as a high-frequency one, the bass needs to have a larger amplitude. This means that a small speaker and bass driver can't accurately reproduce low bass notes.