Pedal Tone

The pedals in the organs before 1950 were generally considered weak and uninteresting. An obvious, but very expensive solution would have been to have a keying and drawbar system just like the Great and Swell manuals. But the organ simply didn't have room for more than two pedal drawbars, 16' and 8', and the nine contacts and busbars per key would have been very expensive to implement. In the late 1940's an effort was made to develop an improved pedal tone system that wouldn't greatly increase the cost of producing the organ. The goal was to increase the harmonic content of the pedals while retaining the two drawbars and eight contacts per pedal. In patent 2,508,514, granted 23 May 1950, John Hanert and Laurens Hammond describes a significant revision to the PedalTone generation system including wiring changes and changes in the lowest octave of tonewheels.

The wiring changes allowed each pedal to blend the fundamental ToneWheel for that pedal with the a portion of the outputs of six higher tonewheels which formed the even harmonic series for that pedal tone. The first twelve tonewheels would be ComplexToneWheels rich in odd harmonics and producing an output very similar to that of a square wave. This would be blended with even harmonics generated by other tonewheels. For example, the lowest C pedal would blend the 1st townwheel (C0) with the 13th (C1), 25th (C2), 32nd (G2), 37th (C3), 41st (E3) and 44th (G3) tonewheels in progressively decreasing amplitudes. The fundamental tonewheel in each pedal (again, rich in odd harmonics) is keyed directly and only to the 16' drawbar. The even harmonics are blended between the 16' and 8' drawbars. Adding more 16' drawbar would increase the odd harmonic content and a portion of the even harmonics and adding more 8' drawbar would increase the higher even harmonic content of the pedals.

While this greatly improved the pedal division, Hammond ConcertOrgans featured additional generation techniques to further improve the pedals, including 32' vacuum tube generators, octave dividers, etc.