Home Recording Basics(Audio)

When it comes to recording audio, you may hear the words 'signal chain'. This is the series of devices that the signal goes through before it reaches the recorder itself - perhaps a microphone plugged into a mixing desk and then a recording device on the end.

For the most part think of the signal chain like a door frame. When you're setting up the signal chain, you want to keep the signal as far as possible from scraping its feet on the floor, without it banging its head the top of the door frame.

The top of the frame is the loudest signal that any device can cope with before it begins to distort. Every device has a limit like this - it's the point where the signal gets so loud that the electronics run out and can't follow the loud bits any more. At that point, the peaks in the signal get chopped off and the result is distortion.

The floor is noise. Every device, however simple, adds noise to the signal chain. You can't get rid of it, all you can do is drown it out by keeping the wanted signal as loud as possible.

Most audio devices have some kind of indication that the signal it too loud. Either there'll be a meter with a red area to show that the signal is too loud, or simpler devices might just have a single light which comes on when the signal is beginning to distort. You set the level so that it is just short of this point.

Setting up the signal chain for the ideal level is known as 'getting a level.' Usually it'll only take a few minutes but then the human element comes into play. When you tell a singer or musician that you're actually recording, rather than getting a level, they usually try harder. That means that they'll play or sing louder and so you have to start all over again.

Signals come in two basic flavors. 'Line level' is a standard level for electronic instruments. Anything like drum machines, synth modules or the line outputs from guitar amps that you plug straight into the mixer or recorder without needing a microphone. Line level signals are generally pretty easy to set up because you can control the levels from the instrument's front panel knobs.

Microphone levels are bit trickier. The same mic stuffed into the bell of a saxophone will give a lot more signal level than one that's placed near a quiet instrument like a violin. And two different types of microphone placed near the same instrument may give different levels too.

To get around this, microphones are put through a device called a mic pre-amp. This is designed to cope with all of these differences and bring all the different signals up to the same sort of level. Generally speaking, when you're starting out you'll be using the mic pre-amps built into your mixer, recorder or computer sound-card.

Source: BBC





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