A boombox is a transistorized portable music player featuring one or two cassette tape players/recorders and AM/FM radio, generally with a carrying handle. Beginning in the mid-1990s, a CD player was often included. Sound is delivered through an amplifier and two or more integrated loudspeakers. A boombox is a device typically capable of receiving radio stations and playing recorded music (usually cassette tapes or CDs usually at a high volume). Many models are also capable of recording onto cassette tapes from radio and other sources. In the 1990s, some boomboxes were available with MiniDisc recorders and players. Designed for portability, boomboxes can be powered by batteries as well as by line current. The boombox was introduced to the American market during the late 1970s. The desire for louder and heavier bass led to bigger and heavier boxes; by the 1980s, some boomboxes had reached the size of a suitcase. Some larger boomboxes even contained vertically mounted record turntables. Most boomboxes were battery-operated, leading to extremely heavy, bulky boxes.