The 11 drawbar stops are based on the Hammond organ model X-66, representing the following stops and harmonics. Stops are given as "footages" where 8' is equal to a fundamental's pitch, 16' is one octave lower, 4' is one octave higher, etc. The fractions used are based on the denominators 3, 5, and 7 and are related to the
major scale degrees, respectively. Thus an 8/9' is related to a
that is three octaves higher than the fundamental 8' (i.e., -1 octave=16', 0 octave=8', 1=4', 2=2', 3=1', and 4=0'). However, in the waveform graphs, the octaves are all adjusted down one octave to allow the most harmonics to be defined based on the lowest drawbar being treated as a fundamental. Thus the table below is to be used as a relative reference to what is implemented in this Demonstration. Note that drawbars 10 and 11 are unique in combining two stops each, with the second stop's amplitude equal to half of the first stop's amplitude. Thus one value is applied to both stops and harmonics simultaneously. More control can be achieved with the harmonic waveform viewer if desired.
S. Irwin, Dictionary of Hammond Organ Stops: A Translation of Pipe-Organ Stops into Hammond Organ Number-Arrangements
, 4th ed., New York: G. Shirmer, 1970.