Disk Jokey (DJ)

A disc jockey, also known as DJ, is a person who plays recorded music for an audience. Originally, "disc" (sometimes spelled "disk", although this is now uncommon) referred to phonograph records, not the later Compact Discs. Today, the term includes all forms of music playback, no matter the medium.
There are several types of disc jockeys. Radio DJs or radio personalities introduce and play music that is broadcast on AM, FM, shortwave, digital, or internet radio stations. Club DJs select and play music in bars, nightclubs, or discothèques, or at parties or raves, or even in stadiums. Hip hop DJs select and play music using multiple turntables to back up one or more MCs/rappers, perform turntable scratching to create percussive sounds, and are also often music producers who use turntablism and sampling to create backing instrumentals for new tracks. In reggae, the DJ (deejay) is a vocalist who raps, "toasts", or chats over pre-recorded rhythm tracks while the individual choosing and playing them is referred to as a selector. Mobile DJs travel with portable sound systems and play recorded music at a variety of events. According to a 2012 study there are approximately 1¼ million professional disk jockeys in the world.

Turntablism is the technique of manipulating sounds and creating music using phonograph turntables and a DJ mixer. One of the few first hip hop DJ's was Kool DJ Herc, who created hip hop through the isolation of "breaks" (the parts of albums that focused solely on the beat). In addition to developing Herc's techniques, DJs Grandmaster Flowers, Grandmaster Flash, Grand Wizard Theodore, and Grandmaster Caz made further innovations with the introduction of scratching.
Traditionally, a DJ will use two turntables simultaneously. These are connected to a DJ mixer, an amplifier, speakers, and various other pieces of electronic music equipment. The DJ will then perform various tricks between the two albums currently in rotation using the above listed methods. The result is a unique sound created by the seemingly combined sound of two separate songs into one song. Although there is considerable overlap between the two roles, a DJ is not the same as a producer of a music track.



In the early years of hip hop, the DJs were the stars, but that has been taken by MCs since 1978, thanks largely to Melle Mel of Grandmaster Flash's crew, the Furious Five. However, a number of DJs have gained stardom nonetheless in recent years. Famous DJs include Grandmaster Flash, Afrika Bambaataa, Mr. Magic, DJ Jazzy Jeff, DJ Scratch from EPMD, DJ Premier from Gang Starr, DJ Scott La Rock from Boogie Down Productions, DJ Pete Rock of Pete Rock & CL Smooth, DJ Muggs from Cypress Hill, Jam Master Jay from Run-DMC, Eric B., DJ Screw from the Screwed Up Click and the inventor of the Chopped & Screwed style of mixing music, Funkmaster Flex, Tony Touch, DJ Clue, and DJ Q-Bert. The underground movement of turntablism has also emerged to focus on the skills of the DJ.

A typical modern DJ mixer generally has between two and six stereo channels for connecting and mixing audio sources. Each channel usually has a phono input with RIAA equalization for turntables and one or two line level inputs for sources such as CD players. Controls for individual channels are arranged in vertical columns (channel strips), starting with a switch or a knob selecting between the inputs. Below the input selector is a gain (or trim) control, used to match signal levels between channels. Next follows an equalizer section, used to fade parts of tracks in and out; a common basic technique is to kill the bass on one channel while mixing so the basslines of two tracks don't clash. A typical mixer features separate knobs for the low, mid and high frequency ranges. Some more controls may follow, such as a balance knob, built-in sound effects and aux-sends for external effects units. Below there's normally a cue switch sending the signal to the headphones, letting the DJ preview and beatmatch a track without sending it to the master output, but on some mixers there's a different way to select the cued source. The channel strip ends with a fader which sets the channel's signal volume in the final mix. The signal may pass through a crossfader. On simple mixers there are normally two channels assigned opposite ends of the crossfader, sometimes with a button to reverse the crossfader's direction. More advanced mixers have assignable crossfaders in which each channel can be assigned to either end of the crossfader or to bypass the crossfader entirely. Many scratch mixers have a crossfader curve control that effectively changes the distance the crossfader needs to travel to open the channel fully, letting to shorten it to a millimetre or two, which is useful for speedy scratching.

Additionally, one or two microphone inputs may be present to accommodate MCs. These can be configured either as additional inputs to main channels or as special microphone channels which are similar in structure, but normally have fewer controls and are often monaural. Most DJ mixers feature peak meters to aid matching levels between channels and monitor the signal for clipping. Usually there are peak meters for master mix and cued mix, though sometimes per-channel meters are present. A DJ mixer has one or two headphone connectors and a headphone volume control. Headphones are normally used to monitor a cued channel, but on some mixers other variants are possible, such as split cue where cued channels are sent to the left headphone channel and master mix to the right, or a way to select between cued channels and master mix. Normally there are two or more outputs for the master mix, used to send the signal to an amplifier or another mixer for the public address system, to a loudspeaker in the DJ booth for monitoring the mix, or to a tape recorder or a computer for recording. There may be one volume control for all outputs or separate controls for each outputs. Sometimes a recording output doesn't have a volume control.

A Computer DJ is defined as a DJ who uses a computer or laptop to play digital music encoded audio files, to a public crowd. Originally due to file size storage issues, this was usually using lossy codec files (e.g. .mp3/.aac), however as drive space increased, this improved to using original uncompressed PCM files (e.g. .wav/.aiff) which do not offer support for metadata, hence why latterly the metadata included and smaller file-sized lossless codec files (e.g. .flac/.m4a, ALAC) are used.
As well as a laptop or computer, MIDI controllers are also used to provide a more tactile and useful interface for control of DJ software by providing physical controls similar to those of record decks or CDJs and DJ mixers. External hard disk drives and audio interfaces (sound cards) are also commonly utilized. By using a sound card with multiple stereo outputs, or two sound cards, a Computer DJ can use a conventional DJ mixer by routing one software deck out of one sound card into one channel of the mixer, and likewise for the other deck. Some DJ software packages allow a single stereo channel to be broken into two mono outputs which correspond to two player decks.
Most DJ software allows the integration and manipulation of external audio inputs, and this has encouraged many DJs who have previously only used vinyl or CDs to integrate a laptop into their setup. Computer controllers can also be plugged in via a USB port for the convenience of their moving controls like knobs and sliding buttons in order to control the software in realtime. The setup allows for a single audio output from the sound card to the amplifier/powered speakers. The controller is beneficial also with scratching, smoother pitch & crossfading adjustments, and overall ease of performing functions as opposed to mouse-controlled DJ software operation.
A CPS (Computerized Performance System) can be programmed to manipulate audio and/or video, symbols, perform complex and repetitive mixing procedures quickly, precisely and reliably for recorded or live performance. CPS systems don't jump like traditional Compact Discs.
In 1998, manufacturers joined with computer DJing pioneers to offer professional endorsements, the first being Professor Jam (aka William P. Rader), who went on to develop the industry's first dedicated computer DJ convention and learning program, the "CPS (Computerized Performance System) DJ Summit". Computer DJing has since become popular with many professional electronic artists, though there is still considerable debate as whether or not the dependence on a computer in performance renders it ineligible for inclusion in the humanities. Producers like Magnetic Man, deadmau5 and Daft Punk use computer technology.



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