The members of the recorder family differ in size which is well illustrated by the Renaissance - Consort.This family includes the sub bass (lowest tone F) up to the sopranino (lowest tone f2).There is also the huge contrabass which has a very low and breathy/?smokey sound and the tiny "Gar Kein Flötlein"?hardly a recorder which has a high and squeaky sound. These two recorders are seldom played.
The illustration on the right shows how the frequency of the lowest tone is halved with the octave register, while the the length of the instrument is doubled: for example, the tenor recorder is twice as long as the soprano. Its lowest note (c1) has half the frequency and thus sounds an octave lower. On the other hand the great bass in c is twice as long as the tenor recorder and consequently the frequency of its lowest tone is only half as high. The great bass sounds a octave lower than the tenor and two octaves lower than the soprano.
The same principle applies to the instruments in f: sopranino (f2), alto (f1), bass (f), and sub-bass (F).