In general, polyphony describes music with two or more parts playing at the same time. More specifically, the term refers to the number of actual notes an electronic instrument may play at one time. For instance, the original MiniMoog synthesizer was monophonic (it could only play one note at a time), while the ARP Odyssey could play two, making it duophonic. Most early samplers were capable of playing only eight notes at any time (or four notes if the sample being played is in stereo, as that requires two notes of polyphony). When instruments can play multiple notes at one time, they are considered to be polyphonic. Today, most synthesizers and samplers can play far more notes, in some cases up to 128 (and even more if a personal computer is being used as the sound source).