Part of interesting and informative article by André Burguete (about Lutes) :
Already by 1500 there was a member of the lute family in use with an E tuning (the tenor lute: E – A – D – F# – B – e). This deep range was quickly exploited by composers and soon needed to be extended down by the interval of a second or a fourth (7 or 8 course lutes).
Lutes were built in at least four different sizes besides the tenor, and these served quite distinct purposes:
Descant lute in b natural (string length 48-52 cm) for ensemble use;
Alto lute in g or a (string length 56-60cm) for solo or ensemble;
Tenor lute in e (string length 67-72 cm) for solo or ensemble;
Bass lute in d (string length 74-78 cm) for ensemble;
Great bass lute in g (string length 88-95 cm) for ensemble.
The alto lute in g or a with its string length of between 56 and 60 cm played roughly the role in an ensemble that the violin plays today in a group of strings. Until around 1620 it was the favourite instrument for the performance of solo polyphonic works (Francesco da Milano, G. A. Terzi, John Dowland et al). The tenor lute in e, however, whose tuning is more or less identical to the guitar of today, can be most closely compared to the viola. It was used in ensemble and for song accompaniment; also for the less difficult solo pieces.
The considerably shorter string length of the renaissance solo instruments in comparison with today’s guitar was in line with hard physiological facts. A useful test for gauging the correct size of an instrument, to correspond to the size of their hands, for players of the alto lute was the stopping of a particular chord in A flat major in the first position (in guitar tuning an F major chord). This is a chord which appears in a prominent position in many pieces of the period and is made up of a barré at the first fret, which stops an A flat on the sixth course and an e flat on the second. On the third course a c’ is stopped at the third fret and on the top string a c’’ at the fifth fret. (On a guitar with the g string tuned down to F# this would give us the notes F, a, c’, a’). This small experiment might dissuade sensible people from having any ideas of a professional lutenist’s career.
Experience has shown that a string length of 56-60 cm on an instrument strung in 4ths is the most natural for managing the demanding solo repertoire and its most common left hand stretches. The mensuration of today’s guitars, averaging 65 cm is physiologically simply too long. 58 cm would make more sense. For an instrument in e tuning which is primarily involved in ensembles, on the other hand, it tends to be too short; 67 cm being the normal lower limit. In this sense, then, the gymnastic challenges facing a player of the “classical” guitar tuned in 4ths and with a mensuration of 65 cm – when compared with the background of the naturally sized instruments of the lute family – is rather like a violinist being forced to perform the solo violin repertoire on a viola tuned like a cello. But let’s return to the lute instruments.
The small volume of air in the little body of the alto lute led to its decline once the era of thorough bass began to make increasing use of a strong bass register, also in the solo plucked repertoire. Since the extension of the bass strings (a “theorboed” neck) on such small instruments only partially satisfied these demands, tenor and bass lutes, thanks to their larger bodies, began to gain in importance.