Pioneer DVJ-X1

A CDJ is a specialized digital music player for DJing. Originally designed to play music from compact discs, many CDJs can play digital music files stored on USB flash drives or SD cards. In typical use, at least two CDJs are plugged into a DJ mixer. CDJs have jog wheels and pitch faders that allow manipulation of the digital music file similar to a vinyl record on a DJ turntable. Many have additional features such as loops and beat analysis that are not present on turntables. Additionally, some can function as DJ controllers to control the playback of digital files in DJ software running on a laptop instead of playing the files on the CDJ.

Many pro audio companies such as Gemini Sound Products, Numark Industries, and Denon produce DJ CD players, but Pioneer DJ CD players are the most commonly found in dance clubs and are seen as the industry standard by many DJs.

The Pioneer CDJ-400, CDJ-800, CDJ-1000, CDJ-900, and the CDJ-2000 have a vinyl emulation mode that allows the operator to manipulate music on a CD as if it were on a turntable. Models released prior to the CDJ-1000 lack this feature. Pioneer CDJs released after the CDJ-400 can play from USB sticks as well as CDs. Pioneer integrates its software rekordbox with the CDJs to prepare music with cue points, accurate BPM, and search/playlist functions.

The CDJ-100S is a CDJ model that was released in the early 1998. The CDJ-100S is a basic CD player with a pitch controller and three sound effect options.

The CDJ-200 is the discontinued budget model CDJ CD player released in 2004. It is similar in size to the CDJ-100S, however features such as MP3 playback capabilities and loop functions have been added or improved. Both the CDJ-100S and the CDJ-200 have similar options to manipulate the CD, however they lack the vinyl modes of other models.

The CDJ-400 was released in the late 2007. It is similar in size to the CDJ-200, but comes with scratching abilities and effects, as well as being Pioneer's first model to have a USB input. This makes it possible to play MP3 music from a USB memory stick.

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