In
audio engineering, a gain stage is a point during an
audio signal flow
Audio signal flow is the path an audio signal takes from source to output. The concept of audio signal flow is closely related to the concept of audio gain staging; each component in the signal flow can be thought of as a gain stage.
In typical h ...
that the engineer can make adjustments to the level,
[Thompson, Dan (2005). ''Understanding Audio''. Berklee Press. .] such as a
fader on a
mixing console
A mixing console or mixing desk is an electronic device for Audio mixing (recorded music), mixing audio signals, used in sound recording and reproduction and sound reinforcement systems. Inputs to the console include microphones, signals fro ...
or in a
DAW. Gain staging is the process of managing the relative levels in each step of an audio signal flow to prevent introduction of
noise
Noise is unwanted sound considered unpleasant, loud or disruptive to hearing. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrations through a medium, such as air or water. The difference aris ...
and
distortion
In signal processing, distortion is the alteration of the original shape (or other characteristic) of a signal. In communications and electronics it means the alteration of the waveform of an information-bearing signal, such as an audio signa ...
, feeding the inserts, such as equalizers and compressors with the right amount of signal, particularly in the analogue realm. Ideal gain staging occurs when each component in an audio signal flow is receiving and transmitting signal in the optimum region of its dynamic range.
[Davis, Don (2013). ''Sound System Engineering''. Focal Press. .]
In an audio system containing both microphones and loudspeakers, the total amount of gain in the system can exceed 100 dB. This is usually broken up into a number of smaller steps, called ''gain stages,'' where the signal is amplified or attenuated as needed before reaching the loudspeaker.
In a signal flow beginning with an acoustic sound source (such as a musical instrument or singer), the
Microphone preamplifier
The term microphone preamplifier can either refer to the electronic circuitry within a microphone, or to a separate device or circuit that the microphone is connected to. In either instance, the purpose of the microphone preamplifier is the same.
...
is typically the first electronically adjustable gain stage, where the signal is amplified by as much as 95 dB in exceptional cases . Before reaching the microphone, the sound source is subject to the
Inverse-square law, which states that sound intensity diminishes as distance between the sound source and the microphone increases. This means that (1) moving the microphone closer to the sound source increases the signal level produced by the microphone, and (2) moving the microphone farther away from undesirable noise sources will diminish the amount of noise in the microphone signal. Microphone placement is therefore an important aspect of gain staging .
Following microphone placement and the microphone preamplifier, the audio signal has been amplified to
Line level
Line level is the specified strength of an audio signal used to transmit analog audio between components such as CD and DVD players, television sets, audio amplifiers, and mixing consoles.
Line level sits between other levels of audio signal ...
, and can be processed by a device capable of accepting a line-level signal.
References
Sound recording
Audio mixing
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