Digital technology is a complex subject but it's not difficult to understand the basic concept.
Digital recording works through sampling - slicing up analogue signals (the natural sounds we hear such as voices or instruments other than synthesisers), and giving each slice one of a number of predetermined mathematical values. The theory is that if you use a large enough range of values and take enough samples - or, in digital parlance, use a high bit and sampling rate - the digital signal will be indistinguishable from the original. Compact Disc technology, for example, uses a 44.1kHz sampling rate, which means that the signal is measured 44,100 times every second.
Why bother, you might reasonably ask? Well, digitising sound offers both theoretical and practical advantages over analogue processing. Analogue recording runs into problems with deep bass and high treble signals, and analogue media, such as vinyl records and cassette tape, suffer from inherent noise. In theory, neither of these problems affects digital. In practice, though, a well-tuned ear can find fault with the performance of digital systems, although designers have made great progress addressing their problems. Compare the sound of a ten-year-old CD player with one of today's machines and you'll hear a huge improvement.
One distinct advantage for digital comes when copying recordings. All else being equal, digital to digital recordings should display none of the degradation apparent when making analogue copies of recordings, where each copy introduces more noise and distortion into the signal. With a CD player equipped with a digital output socket and a MiniDisc recorder, you can make virtually identical copies of your CDs to play while you're jogging or driving.
Despite its apparent robustness, however, digital technology - or rather its implementation - is not perfect. The cables used to connect digital equipment can introduce errors if they're inappropriate types. The digital-is-just-numbers brigade will tell you that error-correction circuits will correct any such problems caused by missing or corrupted bits of data. What they don't mention are the audible effects these devices have upon other parts of the circuitry. As always, listen before you buy. The spec sheets don't tell anything like the whole story. Give two CD player designers exactly the same components and they'll come up with two entirely different sounding players. Let your ears tell you which design works the best.
Once you've made your choice some simple guidelines will help you to achieve the best results with digital equipment. Remember that CD players, MiniDisc recorders, DVD machines and so on all use mechanical
components. These are all susceptible to unwanted vibration and microphony (unwanted signals produced by
the physical movement of electrical components). Use an isolation platform or equipment rack to counter this
problem. When connecting digital equipment (particularly when connecting one digital component to another)
use appropriate, high quality cables and keep them as short as possible. Be careful of where you position digital
equipment and cables: try to avoid placing your CD player next to your tuner, and don't run digital cables close
and parallel to analogue interconnects.
So, what's the next big thing in digital technology? That's anyone's guess. It's a fast moving field and new
technologies don't always live up to the marketing people's expectations - DAT and DCC never took off. There's
talk of "super CDs" but wait until your local record store is full of them before you invest in a new player. DVD,
however, does look like being a stayer and it should certainly boost the uptake of Dolby Digital surround sound,
which is good news for anyone who is really serious about home cinema.
Related Topics: CDs, Dolby Digital/DTS, Recordable CDs