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Music Production;
Audio mixing is done in studios as part of an album or single making. The mixing stage follows the multitrack recording stage and the final mixes are normally submitted to a mastering engineer. The process is generally carried out by a mixing engineer (a mixer), though sometimes it is the musical producer who mixes the recorded material.
A mixer working on a commercial release would normally for spend 1-3 days mixing a single track, although times might vary greatly depending on budget, quality of the recordings and the complexity of the production.
Audio mixing on a personal computer is also gaining momentum. More and more independent artists are starting to use their personal computers for digital recording and mixing their work. Audio editing on the computer is also easy and generally preferred.
Post-production:
During the post-production stage of a film or a television program, audio mixing takes place in a studio (or a theater) once the final cut is produced. Normally the engineer will mix 4 main elements:
- Speech (dialogue, ADR, Voice-Overs, etc.)
- Ambiance (or atmosphere)
- Sound FX
- Music
A 20 minute television program might be mixed in around 16 hours. A full-featured film might spend more than half a year in the mixing.
Equipment
Mixers:
A mixer, or mixing console, or mixing desk, or mixing board, or software mixer is the operational heart of the mixing process. Mixers offer a multitude of inputs, each is fed by a track from a multitrack recorder, mixers would normally have 2 main outputs (in the case of two-channel stereo mixing) or 8 (in the case of surround).
Mixers offer three main functionalities:
- Mixing – summing signals together, which is normally done by a dedicated summing amplifier or in the case of digital by a simple algorithm.
- Routing – allows the routing of source signals to internal buses or external processing units and effects.
- Processing – many mixer also offer on-board processors, like equalizers and compressors.
A mixer has numerous rotating controls (potentiometers0 and sliding controls (faders which are also potentiometers) that facilitate the manipulation of levels, the addition of effects such as reverb, and frequency content (equalization) of audio signals. On most consoles, all the controls that apply to a single channel of audio are arranged in a vertical column called a channel strip. Larger and more complex consoles such as those used in film and television production can contain hundreds of channel strips. Many consoles today, regardless of cost, have automation capabilities so the movement of their controls can be recorded, and then played back automatically, like a player piano. A recent trend is to use a “control surface” connected to a computer. This eliminates much of the electronics in a conventional console as the actual automation work is done digitally by the computer.
Outboard gear and plugins:
Outboard gear (analog) and software plugins (digital0 can be inserted to the signal path in order to extend processing possibilities. Outboard gear and plugins fall into two main categories.
- Processors – these are device are normally connected in series to the signal path, so the input signal is replaced with the processed signal 9e.g. equalizers).
- Effects – while an effect can be considered as any unit that affects the signal, the term is mostly used to describe units that are connected in parallel to the signal path and therefore they add to the existing sounds, but do not replace them. Examples would be reverbs and delays.
Common Classes:
- Processors:
- Faders – used to attenuate or boost the level of signals.
- Pan pots – used to pan signal to the left or right and in surround also back and front.
- Equalizers – used to manipulate the frequency content of signals.
- Compressors – used to manipulated the dynamic content of signals. Among many applications they can even the level fluctuations of a singer, or reshape dynamic envelopes of percussive instruments (e.g. adding attack to a snare).
- Gates – used mainly to attenuate low-level signals, for example, the kick spill on a snare recording.
- Effects:
- Reverbs – used to simulate the boundary reflection created in a real room, but that adding a sense of space to other wise ‘dry’ recordings.
- Delays – most commonly used to add distinct echoes as a creative effect.
Additional information yet to be edited
Mixer
A device with two or more signal inputs and one common output. The two primary classes are linear (additive) and nonlinear (multiplicative) mixers. Linear mixers are used to add or blend together two or more signals, nonlinear mixers mainly to shift the spectrum (center frequency) of one signal by the frequency of a second signal.
Linear mixing is the process of combining signals additively, such as the summing of audio signals in a recording studio. This operation can be accomplished passively by simply using a resistive summing network. Although this approach appears very economical, there is a loss in signal strength and an interaction of the signal amplitudes as the gains are adjusted.
Inexpensive integrated circuits have improved this application dramatically. Operational amplifiers of reasonably high quality that will eliminate the adjustment interactions and also provide gain are readily available. The input signals are summed into the virtual ground summing node at the input of the operational amplifier. There is a sign change in the output, but that is a small drawback compared to the advantage of having the virtual ground provided by the operational amplifier. See Amplifier, Integrated circuits, Operational amplifier
Perhaps the most familiar application of nonlinear mixers is in radio and television receivers. They are widely used in such applications as amplitude modulation (AM) and demodulation, frequency demodulation, phase detection, frequency multiplication, and single-sideband (SSB) generation. The incoming information to a receiver has been transmitted and received at a frequency far too high to permit efficient amplification and processing. Therefore the signal is translated or frequency-shifted or heterodyned by a mixer to a lower frequency, known as the intermediate frequency (IF), where amplification and processing are performed efficiently by an IF processor, sometimes referred to as the IF strip. See Amplitude-modulation detector, Amplitude modulator, Frequency-modulation detector, Frequency modulator
A second application of a nonlinear mixer is frequency synthesis, where a stable but not easily changed signal at a high frequency is made tunable by mixing it with an easily tunable signal at a low frequency, which, perhaps, can be varied in precise increments of any size. The utility of the method is limited by the ability to filter or separate one frequency term from another, thereby determining the minimum practical value of low frequency for the application.
A mixer is an integral part of an AM-radio integrated circuit which contains virtually all AM-radio functions except filters. A particular type of mixer, the quadrature detector, is included in the frequency-modulation (FM)-radio integrated circuit.
There are four main components of a basic sound system: audio mixer, amplifier, speaker, and microphone (more info below). In addition, you might need other equipment including turntables, an iPod console and more depending on the event.
Audio Mixers (Sound Boards)
Audio mixers - a "mixer" - is an electronic device that allows multiple audio equipment to be connected to the sound system. This is a necessary item comprised of multiple inputs each with a volume control used to control audio levels.
The number of input required on your mixer will depend on the number of items (microphones, turntables, an iPod, etc.) that will be connected to the sound system.
Mixers geared toward DJ's include additional features include a cross fader used for transitions between connected audio equipment.
Mixers are highly recommended when using a microphone in order to have better control of the volume, feedbacks and quality of the sound.
Amplifiers
An amplifier - "amps" - is a device that increases the amplitude of a signal (the voltage or current) sent to the speakers. In laymen's terms, amplifiers are absolutely necessary to produce sound.
Amplifiers can be separate or built in to a speaker. See below for the pros and cons of "Powered (Active) versus Unpowered (Passive)" speakers.
Speakers
There are two types of speakers generally used at most events: unpowered (Passive) and powered (Active) speakers. Powered speakers (active speakers) have a built in amplifier.
Advantages
- Can be connected directly to a mixer. - Avoids the necessity of speaker to amplifier matching
Disadvantages - Electrical source required for each speaker - Increased number of cables required for connection to each speaker - Often less powerful and less durable then unpowered speakers.
Unpowered speakers (passive speakers) requires a separate amplifier.
Advantages - Reduced number of cables required for connection to each speaker - Often more powerful and more durable then powered speakers
Disadvantages - A separate amplifier is required for use with speaker
For a more robust sound (found commonly in nightclubs and dance parties), Sub-bass speakers should also be considered. This is a speaker dedicated to low-frequency sounds and adds a distinct presents of low end sounds.
Microphones
There are three basic kinds of microphones: traditional, wireless and lavaliers.
Traditional microphones have a wire that can vary in length that connect to your mixer.
Advantages:
- You don't have to worry about loosing connectivity during a speech/presentation. Disadvantages:
- The wires and limited mobility.
Wireless Microphones are similar to a traditional microphone but with a cord. Microphone but it has a chord.nal microphones have a wire that can vary in length that connect to your mixer Advantages: - Increased mobility Disadvantages - Risk of poor reception or unexpected interference - Batteries required
A lavalier microphone is a small piece that clips on to your clothing
Advantages: - Increased mobility - Hands Free operation
Disadvantages - High risk of feedback - Lower level of sound
Other Equipment: - CD Player - Turntables - iPod Console - Equalizer - Compressor - Limiter - Gate - Crossover - Processor
When most users think of a sound system, they think of the visible endpoints: microphone or the loudspeaker. But  neither of these passive components can create any sound without active components between them. Microphone signals require a preamp, signal processing, and
amplification before the loudspeaker can do its job.
For small sound system requirements, there's nothing more convenient than combining some of these tasks into a single component, and that's where the mixer/amplifier (or powered mixer) really shines.
Mixer/amps are most commonly used by solo musicians, or for smaller venues such as clubs, coffee houses, and even school/church multi-purpose rooms. But they are equally useful in any building where a sound system might be temporarily set up in different rooms (or outdoors) on different days. In some cases, portable mixer/amps are even permanently installed, despite their ultra-portable nature.
Advantages And Disadvantages
Mixer/amplifiers usually combine a mixer, equalizer, and amplifier all into one unit. They typically range from six to 20 inputs, and up to 1,200 watts total power output.
For portable applications, the advantages are obvious. Most manufacturers provide units with built-in carrying handles to take full advantage of the compact size and feature combination. Since all three components are included, there is only one box to carry instead of three. There is also less set up required, since you don't need to interconnect the components.
There are some disadvantages with powered mixers for permanent installations, however. For one thing, a high-quality mixer/amp can cost as much or more than its separate components. Also, if one part of the mixer/amp fails, you need to replace the entire unit in order to get your sound system up and running. And since the equalizer is always exposed (as opposed to being in a separately located rack somewhere), it is susceptible to tampering by unqualified (or curious) hands. Some of the more sophisticated features that are available on separate mixers may not available on mixer/amps (such as mute, subgroups, more than two or three Auxiliary sends). How To Choose A Mixer/Amp:
Here are some of the more popular features, and the decision you need to make before choosing the right one for your  application.
Mic/line/instrument inputs: How many microphones will you be using? Don't forget to include direct inputs from DVD players or musical instruments. And keep future expansion in mind.
Equalization: This can range from simple treble, mid, bass control to multi-band graphic or parametric equalizers. It depends on how much control over tone shaping or feedback you think you'll need.
Direct Outs/Inserts: If you'll be using external sound effect devices or other signal processing, you'll want input/output access to individual channels.
Onboard Effects: Some small mixer/amps include impressive builtin digital effects like delay and reverb.
Mono or stereo: Stereo amplifiers are important for high-quality music, but it's also useful for sending different output levels to each loudspeaker.
Monitor outs: For musicians, separate monitor outputs can be essential. But it's also useful for sending signal to outboard amplifiers for control over multiple loudspeaker zones.
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