Research into the evolution of the double bass reveals a tangled web of several hundred years of changes in design and fashion in the dimensions of the instrument and consequently in its stringing and tuning. The picture is further complicated by the simultaneous use during any one period of different forms of bass in different countries. The earliest known illustration of a double bass type of instrument dates from 1516 but in 1493 Prospero wrote of 'viols as big as myself.' Planyavsky (1970) pointed out that it is more important to look for an early double bass tuning rather than for any particular instrument by shape or name. A deep (double- or contra-) bass voice is first found among the viols. There existed simultaneously two methods of tuning - one using 4ths alone, the other using a combination of 3rds and 4ths ('3rd-4th' tuning). Agricola wrote of the contrabasso di viola as being the deepest voice available. He was referring to an instrument comparable with that made by Hanns Vogel in 1563 and now in the Germanisches Nationalmuseum, Nuremberg. This ornately and beautifully decorated bass is fitted with gut frets like other viols and tuned G'-C-F-A-d-g. This high '3rd-4th' tuning was given by Praetorius (Syntagma musicum, 2/1619) for a six-string violone (a name also confusingly used in the 16th century to denote the bass of the viol family). He listed several other tunings, both high and low, for five- and six-string violoni. Most interesting of all is the low tuning D'-E'-A'-D-G, only one step removed from the modern E'-A'-D'-G instrument. Orlando Gibbons scored for the 'great dooble base' in two viol fantasias. Whether a low '3rd-4th' tuning was used or a higher one cannot be certain.
Some fine basses, many of which were probably converted from their original form in to three- or later four-string instruments, date from the late 16th century and early 17th. A notable three-string bass, originally built as such, is that by Gasparo da Sal?, owned by Dragonetti and now in the museum of St. Mark's, Venice. A beautiful six-string violone of much lighter construction by Da Sal?'s apprentice Giovanni Paolo Maggini is in the Horniman Museum, London. This is of violin shape, with a flat back, and makes interesting comparison with the viol shaped violone by Ventura Linarol (Padua, 1585) in the Kunsthistorisches Museum, Vienna.
During the early 17th century the five-string bass was most commonly used in Austria and Germany. Leopold Mozart referred in the 1787 edition of his Violinschule to having heard concertos, trios and solos played with great beauty on instruments of this kind. The earliest known playing instructions, by Johann Jacob Prinner (Musicalischer Schlissl, 1677, autograph US-Wc) are for an instrument tuned F'-A'-D-F#-B. Much more usual, however, is the tuning F'-A'-D-F#-A cited in 1790 by Albrechtsberger, for a violone or contrabass with thick strings and frets tied at every semitone round the fingerboard. Michel Corrette's 1773 M?thode throws much light on the bass techniques and tunings in use during the 18th and early 19th centuries when the bass was enjoying some popularity as a solo instrument. Many of the virtuoso pieces from the Viennese school of that period and later abound with passages of double stopping and, in view of the tunings required, were thought by early 20th-century authorities not to have been written for the bass at all. Later research revealed that the instrument has in the past been tuned in some 40 or 50 different ways; although the repertory is quite practical with the tunings the composers envisaged (e.g. one of the '3rd-4th' tunings), much is unplayable on the modern conventionally tuned instruments. There are in fact numerous solo concertos from this period.
In Italy an early tuning (cited by Planyavsky, 1970) is Adriano Banchieri's of 1609 for his 'Violone in contrabasso', D'-G'-C-E-A-d. Later the number of strings was reduced, and three-string instruments were preferred. Even during the early 18th century a three-string bass tuned A'-D-G or G'-D-G was normal. It had no frets and with the growth of the symphony orchestra it was logical that his more powerful instrument should supersede earlier models. Not until the1920s was the additional E' string expected of most professional players. Until then any passages going below A' were transposed up an octave, resulting in the temporary disappearance of the 16' line.