Partial bass range
In churches the scales played were limited. So that the most frequently used range could be played half-tone by half-tone, unnecessary notes from the lower range were omitted on old pipe organs. There was also a period when the lowest octave was arranged in a way that could be described as incomplete, with only one black key (C, D, E, F, G, A, B♭, B, and C). Because pipes become thicker and longer as their pitch gets lower, those of the bass range cost more to produce, so this was a pragmatic approach.