How To Choose a Subwoofer

Before you choose which cabinet is the best for your subwoofer, it's worth doing a little research to understand exactly how a subwoofer works. In this article we'll be explaining just that; how subwoofers function and which design might be best for you.

It's all about the bandwidth

Generating high levels of bass over small bandwidths is easy. That is exactly what low price subwoofers do. In comparison, a higher output that covers a wider bandwidth without a huge amount of distortion while simultaneously keeping the dimensions down to a reasonable size isn't easy at all. Studio quality, low-frequency replay needs to move a lot of air. We need a powerful amplifier, a considerable bass driver (or as an alternative several smaller drivers) and considerable diaphragm displacement.

One common method of achieving high efficiency is by placing the driver inside a so-called 'band-pass cabinet'. In plain English, this is a resonant, tuned box, where the driver hides inside and the sound escapes through a single or multiple ports. These are often found on low-priced home theatre systems and as 'boom boxes' in cars. While really loud, this design usually sounds too 'boomy', with a kind of single-note response which may sound great for film crashes and explosions but doesn't really help us hear the individual notes being played by the bassist.

Check out the reflex                                                                                                           

Most subwoofers use a form of 'reflex' design, combining practicality and efficiency with adequately wide bandwidth, and are usually encased in reasonably sized containers. The principles of the design have been tried and tested thoroughly and entails the front end of the driver radiating directly while the rear contributes volume through the closed cabinet by way of one or multiple ports. While naturally, some subwoofers are better than others, most studio speakers share exactly this design.

Less common is the 'closed box' design where the cabinet is completely sealed and the only sound heard is contributed via the front side of the driver. This design is relatively inefficient and it places considerable performance demands on the driver and the amp. But when it comes to specific factors like distortion, timing and phase response, the design has distinct advantages. The 'transmission line' design is a close variation on the same theme. It aims to bring together all the advantages of sealed and reflex cabinets and while these two designs can be quite costly, they are renowned for reproducing the most accurate sound and tend to be the easiest to integrate and align.

Size is not important

When it comes to subwoofers, size shouldn't be the dominating factor in your choice of purchase. While bigger does usually mean louder and possibly comes with a more efficient extension of low frequency, smaller systems can provide a clearer, crisper sound with superior definition.


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