Audio signal flow

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Audio signal flow is the path an audio signal takes from source to output, including all the processing involved in generating audible sound from electronic impulses or recorded media.[1]

Analog recording[edit]

An analog console, also known as a mixing board, is a device for routing the multitude of audio signals present in a recording into various outputs. These boards allow the audio signal to be controlled, split, filtered and otherwise adjusted internally and by other devices in the electrical environment. Analog mixers are usually the central piece of equipment in a recording studio or live sound venue. Recording artists using analog consoles had to record using tape decks. Two factors that allowed engineers to distort the audio are in relation to the tape’s width and the speed at which the song was played back.[2]

Digital recording[edit]

Digital audio recording is a very recent and efficient innovation in the music industry. It has allowed a huge expansion in the ability to manipulate the audio after it is recorded. In digital recording, the audio signal is converted into digital information that a computer can process. Our computers use DAW (digital audio workstations) to turn the digitized music into the product of an audible sound.[3]

Signal flow chain[edit]

To start off the signal flow chain there must be a microphone line. This line is a direct transfer of the audible sound to the mixing board. Microphones work as transducers and convert the audio into an electrical current.[4] Speakers are also transducers as they convert the electrical signal to an audible sound. Microphone lines give no effect to the audio; they provide the most basic and clean sound.

The auxiliary send provides a space for plug-ins to be activated. Plug-ins allow the recording engineer to insert a special effect on the audio signal. Many engineers use reverb or delay to create a unique effect on a singer’s voice or even insert a loud distortion on the lead guitarist’s riff. The auxiliary send is another part of mixing that enhances the audio’s personality, but is not required. It is also important for the audio engineer to realise the amount of processing power required by the host CPU to manipulate the audio. It is more efficient to use time modifier plug-ins such as reverb, delay etc. in an auxiliary send - as an insert on the channel strip would require that portion of the signal to be modified dramatically, instead of a split of the signal which would in turn be sent to the auxiliary send.

The on/off switch gives the engineer the option to either activate or bypass the function. The fader only controls the tracks volume but is essential to the entire mix. The fader is gauged by decibels and it is very important. It becomes critical to understand the decibel output of the audio track before recording the signal. A very loud signal can blow the speakers and greatly damage the recording equipment.

Often, when listening to music, it is possible to almost pick out where the instrument is being played in the music. The pan knob allows engineers to “place” the instruments mentally and give the music a great feel. Human ears hear through binaural localization and can tell the difference between right and left sounds.[3] The sound engineer's main goal in using the pan knob is to create a sonic soundscape of instruments, this would create clarity and transparency within the mix, essentially allowing each individual performer to be heard. They want to paint a picture for the listener to make the music more appealing. Often engineers follow the pattern of how you may hear the instruments if the performance were live.

After all these selections have been adjusted to personal preference there are a few final steps. To ease the job of adjusting levels, sub groups may be assigned. This is when a group of microphone lines can be synchronized together so that only one knob controls them all. Sub group assignments are very helpful for an instrument like the drums. A drum set often has microphones on close to every drum and can be very hard to adjust each drum head individually. By assigning the drums to a group, the engineer will be allowed to move the output volume with one knob instead of six lines, for example.

When all audio has been sent through each step, a master mix is in place.

See also[edit]


  1. ^ Steven Roback (2004). Pro Tools 6 for Macintosh and Windows (2nd ed.). Peachpit Press. p. 303. ISBN 978-0-321-21315-0. 
  2. ^
  3. ^ a b Alten, Stanley R. Audio in Media, 8th Edition. Wadsworth CENGAGE Learning, 2008.
  4. ^