Audio signal flow
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Audio signal flow is the path an audio signal takes from source to output.[1]
CD Playback Example
The following example will trace the signal flow of a typical home stereo system while playing back an audio CD.
The first component in the signal flow is the CD player, which produces the signal. The output of the CD player is connected to an input on a receiver. In a typical home stereo system, this connection will be analog and unbalanced at consumer line-level of -10dBV using RCA connectors. By selecting the proper input on the receiver, the signal is routed internally to an amplifier which boosts the signal voltage from line-level to the voltage required by the speakers. The output of the amplifier is then connected to speakers, which convert the electrical signal into acoustical sound.
Single Vocalist Signal Flow Example
The exact series of elements in a signal flow will vary from system to system. The following example depicts a typical signal flow for recording a vocalist in a recording studio.
The first element in the signal flow is the vocalist, which produces the signal. This signal propagates acoustically to the microphone according to the Inverse-square law, where it is converted by a transducer into an electrical signal. Other objects may also produce sound in the acoustical environment, such as HVAC systems, computer fans, traffic noise, elevators, plumbing, etc. These noise sources are also be picked up by the microphone. It is therefore important to optimize the acoustical signal/noise ratio at the microphone. This can be accomplished by reducing the amplitude of unwanted noise (for example, turning off the HVAC system while recording), or by taking advantage of the inverse-square law; by moving the microphone closer to the signal source and farther away from any noise sources, the signal/noise ratio is increased.
After the microphone, the signal passes down a cable to the microphone preamplifier, which amplifies the microphone signal to line level. This is important because a line-level signal is necessary to drive the input circuitry of any further processing equipment down the chain, which will generally not be able to accept the extremely low-voltage signal produced by a typical microphone.
For the purposes of this example, the output of the microphone preamplifier is then sent to an EQ, where the timbre of the sound may be manipulated for artistic or technical purposes. Examples of artistic purposes include making the singer sound "brighter," "darker," "more forward," "less nasal," etc. Examples of technical purposes include reducing unwanted low-frequency rumble from HVAC systems, compensating for high-frequency loss caused by distant microphone placement, etc.
The output of the EQ will then be sent to a compressor, which is a device that manipulates the dynamic range of a signal for either artistic or technical reasons.
The output of the compressor is then sent to a mix buss, where the signal will be combined ("mixed") with other signals, such as other singers or musical instruments.
The mixed signal is then sent to an analog-to-digital converter, which converts the signal to a digital format, allowing the signal to be sent to a digital recording device, such as a computer.
Band Signal Flow Example
See also
Notes
- ^ Steven Roback (2004). Pro Tools 6 for Macintosh and Windows (2nd ed.). Peachpit Press. p. 303. ISBN 978-0-321-21315-0.