digital master oscillator (1)

The use of frequency dividers in electronic organs has been known for many years. The usual procedure is to use divide-by-two stages to divide down the notes of the highest octave to obtain the lower octaves. Until recently it was normal practice to use twelve independent master oscillators for the twelve notes of the top octave. The disadvantages of this approach are that twelve oscillators have to be adjusted when tuning the organ, a procedure that requires ·a skilled ear. Since the oscillators are independent, supply voltage variations, temperature changes and component ageing can all make the organ go out of tune. A digital master oscillator, in which the notes of the top octave are derived from, and are all locked to, a single clock generator, suffers from no such disadvantages. Tuning is accomplished simply by altering the clock frequency, and if the clock frequency does drift this will not be noticed when playing solo, since the relative pitch of the notes will remain the same.