Channel Strips and Mixing Desk Layout
Thursday, January 18, 2024
Channel strips and mixing desk layout are central to the operation of a live sound system. They allow audio engineers to control various aspects of the sound from each input source. While I'm unable to provide images, I can describe the typical layout and functions of a channel strip on a mixing desk:
Channel Strip:
A channel strip is a vertical set of controls on a mixing console that processes a single input source. Here's a breakdown of a typical channel strip from top to bottom:
1. Input Section:
- Gain/Trim: Adjusts the level of the incoming signal, setting the stage for proper gain structure.
- Pad: Attenuates the signal by a fixed amount (e.g., -20 dB) for very loud sources.
- Phantom Power: Supplies +48V power for condenser microphones.
2. Dynamic Processing:
- Compressor/Limiter: Controls dynamics by reducing the volume of loud sounds that exceed a certain threshold.
- Gate/Expander: Reduces low-level noise by cutting off the signal when it falls below a set threshold.
3. Equalization (EQ):
- High-pass Filter: Removes low-frequency rumble and reduces stage noise.
- Fixed or Sweepable EQ Bands: Typically, a 3- or 4-band EQ with low, mid, and high-frequency controls. Some have sweepable mids (also called semi-parametric EQ) for precise frequency shaping.
4. Auxiliary Sends:
- Pre-fader Aux Sends: Used for monitor mixes or effects that need to be independent of the main mix's fader level.
- Post-fader Aux Sends: Typically used for effects like reverb or delay that should follow the main mix levels.
5. Pan/Balance Control:
- Pan: Positions the channel's signal within the stereo field of the main mix.
- Balance: Adjusts the level between left and right for stereo input sources.
6. Routing Section:
- Subgroup Assignment: Allows channels to be grouped and controlled together before reaching the main mix.
- Mute/Solo: Mutes the channel or isolates it for solo listening.
7. Fader:
- Fader: A vertical slider that adjusts the channel's volume in the mix.
8. Channel On/Off:
- On/Off or PFL (Pre-Fade Listen): This engages the channel in the mix or allows the engineer to listen to the signal before it reaches the fader.
Mixing Desk Layout:
A mixing desk is typically laid out with all channel strips side by side, allowing the engineer to access multiple channels simultaneously. The layout can be divided into several sections:
- Input Channels: The bulk of the mixer, where each channel strip is dedicated to a specific input.
- Master Section: Usually located on the right side, this section controls the overall output of the mixer, including the main mix faders, master auxiliary sends, and master processing.
- Group/Subgroup Faders: Allow for collective control of assigned channels, useful for managing groups of instruments or vocals.
- Auxiliary Returns: Separate controls for the levels of effects or additional inputs returning to the mix.
- Monitoring and Communication: Controls for the engineer's monitors, talkback mic, and communication with performers or stage crew.
Understanding the layout and function of each element on a channel strip is crucial for live sound engineers, as it allows them to shape the audio effectively, manage the mix, and respond quickly to the dynamics of a live performance.