Mandolin are used. Usually, courses of 2 adjacent strings are tuned in unison. By far the most common tuning is the same as violin tuning, in scientific pitch notation G–D–A–E, or in Helmholtz pitch notation: g–d′–a′–e″. Note that the numbers of Hz shown above assume a 440 Hz A, standard in most parts of the western world. Some players use an A up to 10 Hz above or below a 440, mainly outside the United States. Other tunings exist, including "cross-tunings", in which the usually doubled string runs are tuned to different pitches. Additionally, guitarists may sometimes tune a mandolin to
Violone with the violin, but can't necessarily be described as genuine violin family instruments because their tunings, proportions and/or construction issues may be at odds with the other sizes. In the Renaissance and Baroque era and even in the 2000s, there are players who changed or adapted their instruments in unique ways. In this category we might find bass viols that are tuned in E (instead of D), or where the bottom string is tuned an extra step lower, to a C (a pitch found in numerous Baroque works). Or we might find a contrabass/double bass tuned in fourths, but with