Where can I find a part (UK) in Nuts and bolts Posted August 7 On 16/06/2021 at 18:09, Tony Newnham said: The missing low C# is simply because before organs were tuned to equal temperament (or another well tempered temperament) chords based on C#/Db were unusable because of the tuning. Any piece in Db major could use the low C# (AKA Db) in modern tunings. Keep in mind, though, that D Major is a commonly used key in early music and the C# is the bass note of the first inversion of the dominant chord. C# is beautifully in tune with the A in quarter-comma meantone as it is tuned pure to the A. (The E is less happy in the chord because the A - E fifth is narrow and thus beats rather fast and is noticeable when not taken into account by the player in their spacing of chords when playing continuo.) I believe that short octaves for organs were more about keeping costs down by not included less needed notes rather than because particular notes were unusable in early temperaments. This cost benefit is obvious in organs given the size of the pipes for the low D#, C#, A# and G# omitted in one short octave arrangement. But harpsichords also utilized short octaves where the cost benefit is not as pronounced. It does result in a smaller instrument, so would that have been more of a factor when people's housing was more limited in size?