Design And Construction Of A 3-Channel Microphone Mixer

ABSTRACT

An audio mixer is an electronic device for combining, and modifying audio signals. The modified audio signals are summed to produce some combined output signals. This project is titled design and construction of a 3-channel microphone mixer. A microphone mixer is an electronic console that is used to mix different recorded tracks by changing their volume levels, adding effects and changing the timbre of each instrument on the tracks.

Mixers are most often used by recording studios but are also typically used in live situations by live sound engineers.

There are two types of mixers, digital and analog, and both are commonly used by the same recording studio to achieve different results.

In this work, an analog audio mixer using common electronics components, such as resistors, capacitors, potentiometers and operational amplifiers (Op-Amps).

The aim of this work is to design and construct a 3-channel microphone mixer which can accept three different microphone at the same time and mix their different tracks by changing their volume levels, adding effects and changing the timbre of each instrument on the tracks.

CHAPTER ONE

INTRODUCTION

Microphone mixer is an electronic device for combining (also called “mixing”), routing, and changing the level, timbre and/or dynamics of microphone signals. A mixer can mix analog or digital signals, depending on the type of mixer. The modified signals (voltages or digital samples) are summed to produce the combined output signals.

Microphone mixers are used in many applications, including recording studios, public address systems, sound reinforcement systems, broadcasting, television, and film post-production. An example of a simple application would be to enable the signals that originated from three separate microphones (each being used by vocalists singing a duet, perhaps) to be heard through one set of speakers simultaneously. When used for live performances, the signal produced by the mixer will usually be sent directly to an amplifier, unless that particular mixer is “powered” or it is being connected to powered speakers. Among the highest quality bootleg recordings of live performances are the so-called soundboard recordings that are sourced from this mixer output to the speakers.

Prior to the emergence of digital audio workstations (DAWs), the process of mixing used to be carried out on a mixing console. Currently, more and more engineers and independent artists are using a personal computer for the process. Mixing consoles still play a large part in the recording process. They are often used in conjunction with a DAW, although the DAW may only be used as a multitrack recorder and for editing or sequencing, with the actual mixing being performed on the mixer.

1.1                                             OBJECTIVE OF THE PROJECT

The objective of this work is to design an audio device which have and can accept four different microphone inputs then with only one output. And the level of each audio input is controlled with potentiometer.

1.2                                         SIGNIFICANCE OF THE PROJECT

The role of a music producer is not necessarily a technical one, with the physical aspects of recording being assumed by the audio engineer, and so producers often leave the similarly technical mixing process to a specialist audio mixer. Even producers with a technical background may prefer that a mixer comes in to take care of the final stage of the production process.

Microphone mixing is done in studios as part of creating an album or single. The mixing stage often follows a multitrack recording. The process is generally carried out by a mixing engineer, though sometimes it is the musical producer, or even the artist, who mixes the recorded material. After mixing, a mastering engineer prepares the final product for reproduction on a CD, for radio, or otherwise.

1.3                                         APPLICATIONS OF THE PROJECT

Public address systems use a mixing console to set microphones to an appropriate level, and can add in recorded sounds into the mix. A major requirement is to minimize audio feedback.

Most bands use a mixing console to combine musical instruments and vocals.

Radio broadcasts use a mixing desk to select audio from different sources, such as CD players, telephones, remote feeds, or prerecorded advertisements. These consoles, often referred to as “air-boards” are apt to have many fewer controls than mixers designed for live or studio production mixing, dropping pan/balance, EQ, and multi-bus monitoring/aux feed knobs in favor of cue and output bus selectors, since, in a radio studio, nearly all sources are either prerecorded or preadjusted.

Dub producers/engineers such as Lee “Scratch” Perry were perhaps the first musicians to use a mixing board as a musical instrument.

Noise music musicians may create feedback loops within mixers, creating an instrument known as a no-input mixer. The tones generated from a no-input mixer are created by connecting an output of the mixer into an input channel and manipulating the pitch with the mixer’s dials.