Sounding off on PC audio

Windows details everything you wanted to know about speaker sets, sound standards and we even put four of the latest two-channel speakers to the test.

At its very core a ‘speaker' is an electromechanical transducer device that converts the electrical signals it receives from a source device - such as a DVD player or a PC's sound card - into the audio that reaches our ears.

A speaker will generally, depending on the cost, contain a number of ‘drivers' that are usually round in shape and these are made from paper, plastic and metal.

It is these drivers that are actually responsible for creating the sound we hear and there are a number of different types of drivers, each designed to tackle certain audio frequency ranges.

‘Subwoofers' are drivers that are designed to produce very low frequency sounds, ‘woofers' handle standard low frequency audio, ‘mid-range' drivers take care of middle frequencies whereas ‘tweeters' are setup to handle high-frequency audio.

In some cases high-end speakers also employ ‘super-tweeters' and these are specifically engineered for sounds that are outside a regular tweeter's frequency range.

A quality speaker generally employs each of these drivers in order to produce the most accurate audio whilst being able to run at high sound-pressure or volume levels.

Speakers that use a combination of drivers have an internal filter setup, so the electrical signals from the source are sent to the right driver. This filter is known as a ‘crossover'. Crossovers can be either passive or active.

A passive crossover is an electronic circuit that uses resistors, inductors and non-polar capacitors. These components form a network and are placed in between the amplifier and the speaker's drivers so that they can divide the signal into the relevant frequency bands and supply the signal to each driver. These crossovers function without any additional power and are regularly installed within a speaker's cabinet.

An active crossover is an electronic filter circuit that divides the source electrical signal into individual frequency bands before it is amplified. As a result, an amplifier is needed for each individual driver.

Active crossovers require external power but in terms of advantages these offer more precise frequency separation and are capable of serving high output purposes. Passive crossovers convert some of the source signal into heat when they function and are thus not the best choice for high power output satellite speakers.

Low-cost speakers forgo using the drivers mentioned above and instead use a different driver entirely. These are known as ‘full range drivers' and as the name suggests, these are designed to handle a wide range of audio frequencies.

These are mostly designed to produce clean output at low volumes but speakers equipped with this type of driver cannot compete with multiple driver speakers in terms of sound quality and accurateness. Speakers with full range drivers also lack a built-in crossover network as this is largely unnecessary since only a single driver is responsible for producing all the audio.

As a result, it is possible to produce this speaker type relatively inexpensively since a single driver is cheaper than several and the lack of a crossover network also helps to save cost.

The most basic speaker system you can buy is a 2-channel system. This will include left and right satellite speakers and is enough to produce basic audio. Most entry-level PC systems will ship with 2-channel audio systems. A 2.1-channel speaker set is superior to these because in addition to featuring left and right satellite speakers, a subwoofer is also present.

The subwoofer will enhance the overall quality of audio heard because it will handle low-frequency audio exclusively (if a proper crossover is in place).

Beyond these speaker configurations, you can also find surround configurations that are designed to envelop the user in audio. In its most basic form you could buy a 3-channel speaker system though these are now outdated.

This speaker configuration has two forward channels (left and right) and also includes a rear, centre speaker, which will be used to create surround effects. In this case the speakers should be placed an equal distance away from listener and in level with his ears.

For a better surround experience you can also opt for a 4- or 4.1-channel audio system (also known as quadraphonic). With the former you get four satellite speakers (two forward, two rear) whilst the latter also includes a subwoofer for better low frequency audio performance.

The most common speaker configuration type for high-end PC sound systems or even home theatre audio setups is 5.1-channel, which includes five satellites and a subwoofer. The satellites are separated to include three forwards (one left, one centre and one right) and a rear left and rear right. This speaker configuration can also be referred to as a 3-2 stereo system.

In recent years audio vendors have gone beyond 5.1-channel systems for homes and there are now 6.1-, 7.1-, 10.2- and even, at the ultra-high-end, 22.2 channel surround. 6.1 systems feature three forward satellite speakers, two ‘side' surround satellites, one rear satellite and a subwoofer. The side speakers in this sort of system are designed to be placed at the left and right side of the listener.

7.1-channel expands upon this further by including two rear speakers rather than just one. Whereas 6.1-channel systems haven't really taken off in the consumer market space, 7.1-channel speaker sets are becoming increasingly popular in homes.

10.2- and 22.2-systems are both very new to the market. A 10.2 audio system includes five forward satellites, five surround channels, two subwoofers and two ‘height channels'. In total the system offers 14-different audio channels.

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