Thursday, December 4, 2008

High level basics about Sound Boards (Mixing Console)

This picture is of a sound system install we did at a church.

A sound board is a mixer as was discussed in previous post with the ability to enhance or augment the source signal(s). You can find these devices commonly used in  recording studios, public address systems, sound reinforcement systems, broadcasting,  and television studios among other things.

If you have ever wondered how the level of a singer or speaker is controlled and that of the live or prerecorded accompanist this device is how.  When used for live performances, the signal from the board is typically not sent for post processing rather it is sent straight to the amplifier (unless it is a powered sound board) meaning the amplifier is built in.

The board is usually divided into these sections:

  • Channel Gain
  • Input Jacks / Microphone preamps
  • Basic input controls
  • Channel EQ (High, Mids and low)
  • Routing Section including Direct Outs, Aux-sends, Panning control and Subgroup assignments
  • Input Faders
  • Channel monitor level
  • Subgroup faders
  • Output controls including Master level controls, EQ and/or Matrix routing

As you can see from picture these are often color coded consistently (there is that word again) across each channel to make their purpose east to identify. Each channel typically has most of these controls to allow the operator the ability to uniquely tailor the various levels. An example using the above is the system speakers receive all output from all channels but the monitors (near the organist and the choir) have been set so that the choir does not hear themselves while they are singing.  Additionally in many newer systems a channel that is used typically by a single person can be set for level once and a single push button used to make the channel live or kill it.

The input controls (pots) are typically rotary knobs with marks around them denoting relative level of intensity. The input serves to buffer the signal and reduce the amount of extra noise in the system noise

Each channel typically also have basic equalization (Bass, mid low, mid high, and treble) Some systems also have Parametric equalization to allow the control internal band-pass filter sections (amplitude, center frequency and bandwidth)  

Subgroup and main output fader controls typically on the right side of the mixer (that is right since most people are right handed the boards are typically designed to accommodate right handed people)

Sounds boards also have VU (Volume Unit) or peak meters to monitor output levels for each channel or for some smaller boards just the master outputs to help reduce source and output signal over driving (also known as overmodulating or clipping). 

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