A digital or analog mixer serves as the control center for live sound. The mixer receives inputs (direct line or XLR ) from instruments, microphones and external hardware processors (compressors, limiters or expanders). Some, depending on the size, also will include an equalization feature for each channel. Mixing consoles also include knobs for panning and low-cut filtering adjustments. High-end digital mixers are equipped with software to monitor sound levels during a live performance.
Speakers and amplifiers provide the actual sound at a live performance. There are two configurations. First, the amplification of an instrument or microphone through a speaker and the speaker system. Amplification provides a sound boost. For example, most microphones use a pre-amp or amplification box to boost output through a speaker system. For live sound systems, amplification units are connected to speakers to improve and boost the quality of sound.
Microphones are used for speaking or singing, but some are used on speaker systems. Regardless of the application, the microphone projects sound into an amplifier or speakers through the mixing board for output. There are various types, but the microphone most used for live sound configurations are dynamic microphones. Dynamic microphones are built to capture the range of a human voice or an instrument.
Sound engineers treat live sound as a science. They know what decibel levels will work in certain spaces and can balance the sound and use tools to fight problems such as feedback, echo and distortion. A typical sound engineer will have "side chain" equipment to monitor sound peaks, clipping or low volume. A sound engineer also uses metering equipment to determine where the points of sound travel through a building. For example, sounds can be trapped in the center of a building with a high ceiling. A sound engineer solves the problem by using a component such as an expander to fix the problem.