Audio Video Recording And Editing 4(1+3)

Lesson 05: Different Sound Equipments and Their Parts

Audio Mixers

Audio mixers (Fig. 7.11) are instruments that are more complex than the audio faders. The complexity is also a boon since they help us perform the following functions:

• Control the volume of signals coming from various inputs (micro­phones, audio players, etc.-l using faders. The faders help in regulating the input levels of sound sources coming from various sources (mics or audio players).
• Combine and balance the inputs coming from various sources, while us­ing one fader up or the other down. For example, in an audio mixer with six inputs, we connect six microphones to record a musical score. Fading up or down each fader helps in balancing the input of each instrument.
• Equalize, that is, manipulate the characteristics of input sound. Equalizing involves controlling the audio signal by increasing some wanted frequencies and decreasing the unwanted ones. For example, you can reduce the hiss in speech by equalizing the input.
• Auxiliary send is used to send the output to other external devices such as an effects generator. The output from the Aux Send is again taken back into the audio mixer, mixed and routed through the final output.
• Route the mixed and equalized audio signals to a specific output (re­corder/speaker /headphone).
• Enable monitoring of all the functions mentioned above through speakers/headphones as they are being recorded/broadcast.

Audio mixers are known by the number of inputs and outputs they pro­vide. For instance, a 6 x 2 audio mixer has six inputs and two outputs. Similarly, a 24 x 4 audio mixer has 24 inputs and four outputs. This means that you can connect 24 microphones/players, balance, and equalize those inputs to get four outputs.

Audio mixers come in handy both in live and post-production situations. In a live situation, audio inputs are first balanced and equalized and the recording done. In post-production situations, an audio mixer is used on linear editing suites (non-linear suites have built-in audio mixers). Inputs/ outputs have to be manually adjusted for balance and equalization. You will learn more about it when we discuss editing.

Professional audio mixers have a provision to connect a headphone or a pair of speakers to monitor the output. Some audio mixers are also capable of providing the phantom power supply to microphones when needed. It is al­ways better to purchase audio mixers that can provide phantom power supply.