In order to begin understanding how a sound system works, it’s important for us to understand how sounds are generated. In order to be able to reproduce sound, sound systems need a source that generates (or picks up) the sound.
There are a variety of sources for sound. Here are a few of the most common:
- Microphones – All microphones are designed to take sound waves (acoustical energy) and turn these waves into electrical signals. The majority of sound today is created with real instruments using microphones. Microphones pickup virtually anything you can hear, and they are an important system input device. There are numerous types and uses of microphones, and we’ll dig more deeply into them in the Microphones sections.
- Playback Devices – Audio playback devices are another common input to a sound system. There are a variety of playback devices that include CD players, tape players, iPod & MP3 players, computers, and a variety of video playback sources with an audio output. Generally these playback devices are used to playback sounds that have already been created elsewhere.
- Digital and electronic instruments – Today, many instruments create sounds using sensors and pickups (like an electric guitar or electric bass) or have some sort of sound generating electrical components in them (such as digital pianos and synthesizers). Often these systems can plug directly into a sound system without the use of a microphone. For older, classic instruments (such as guitar amps) microphones are still used to help capture the unique sound of the guitar/amp combination.
The Mixing Console:
The mixing console is like the brains of a sound system. All of the audio as well as the primary controls for the system are all contained in the mixing console. It’s called a mixing console because the inputs (from one to several hundred depending on the size of the console) are all “mixed” into a single output that plays back through the loudspeaker. In a typical rock band, you might have 2 or 3 guitars, a bass, drums, keyboards, and several vocal channels. An orchestra or other performing arts event can have many more. All of these inputs are then mixed down and played back out of the speakers. A mixing console lets you control and tweak all of the inputs to craft an overall mix.
Once the sound is mixed, it is then sent to the amplifiers. The amplifiers take a line-level (very weak) signal and amplify it to a speaker level output. Amplifiers take the signal and effectively make it really loud, and then send it on to the loudspeakers where it is converted back into acoustical energy.
The final step in the typical signal chain for a sound system is the loudspeaker. The loudspeaker is designed to take the electrical signal and convert it into actual sound waves that we can hear with our ears. The speakers take the mixed signal and convert it into vibrations that we can hear.
A sound system is designed to take several input sources and combine them together using a mixing console. This combined signal is then sent to the amplifier where it is boosted and sent to the loudspeaker that converts it back into sound waves that we can hear. Whether you have a small system with one or two speakers or a huge system multiple inputs and loudspeakers, these basic functions are the core of any sound system.
Often the jobs of the mixer and amplifier or the amplifier and the loudspeaker are combined into one unit. Loudspeakers come as active speakers (with an amplifier already built in) or as passive speakers (without an amplifier built in). Likewise some mixers are powered mixers meaning they have an amplifier built right in. Although these systems combine several pieces together, it is important to remember that all the pieces are still present, they just working together within the same device.