Every signal source used by your mixer has its own individual channel. Each channel has its own input port and set of controls. The most common inputs are XLR and ¼-inch TRS. You connect your microphone, instrument or playback device to the mixing board through these. Your devices may require converters if their outputs are not compatible. You can easily find XLR or TRS input and output converters at a local electronics retailer.
The channel input features a basic, channel-specific gain control. The gain control is usually a rotating knob you can adjust to amplify your signal to a functional level. This differs from volume control, which uses a sliding button to fine-tune your signal's decibel output during your mix. Turn this knob up and down until your signal registers clearly.
Each channel on your mixing board features its own equalizer and volume control. The volume control is usually a sliding button known as a fader. Slide the fader up and down to control the channel's volume output. The channel may also have buttons to mute its signal or isolate it for solo playback.
The equalizer is a row of rotating knobs that control the bass, treble and midrange frequency output of your channel's signal. Each knob controls a frequency range referred to as a band. The bands denoted with lower hertz (Hz) values control bass, also referred to as low-end. The bands denoted with higher hertz values, usually marked kilohertz (kHz), control treble. Bands in the center of your equalizer row control midrange. Turn the band knobs up and down to amplify and decrease each frequency output accordingly.
VU or peak meters display the output levels for each channel. Depending on the model of your mixing board, you may also have these meters for other levels within each channel such as individual band frequencies. The meters show when a signal's volume is too great by an escalation of colored bars or a rotating needle. This allows you to identify in real time when a signal becomes too loud, which overloads the channel's processor and causes distortion.