External cartridge CD changers
External cartridge CD changers have two or more CD cartridges, each loaded with five to 10 CDs and inserted into the changer. The changer can retrieve and play one CD at a time. Cartridges can be bought separately, but usually have to match the size and capacity of other cartridges.
Internal cartridge CD changers
Internal cartridge CD changers also use cartridges, except that they are fixed permanently inside the changer. CDs are stored and retrieved through a single slot in the changer. They usually hold five to 10 DVDs. This capacity may be adjusted by adding cartridges, although installation is more complicated than in external cartridges.
Carousel CD Changers
Carousel CD Changers hold three to seven CDs on a rotating platter that can be ejected from the player. The platter can usually rotate when ejected, allowing users to change or load CDs while another CD is playing. They usually take up more space and are often built into large audio component players.
Computer-based CD Changers
Computer-based CD Changers have standard-size disc drives that capture the contents of each CD and save them onto the hard disc or an online database. Their capacity is limited only by the computer or database memory. A typical system can hold as many as 200 CDs' worth of music. They also offer advanced playback and music management features, such as creating playlists, song searches, and displaying album art.
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