Archive of the former Yahoo!Groups mailing list: Yamaha CS80

Re: David Rogoff's excellent Hz/V observations, This is a great time to share something that David Wilson of the New England Synthesizer Museum told me about Hz/V...

If you look at the control voltage signal that would be sent from a 1V/Octave keyboard controller and an Exponential VCO, if you sacle and offset the control voltage the results are:
When you offset (add to or subtract from) the voltage, you transpose the sounding pitch of theVCO
(for example, I can play an "A" on the keyboard and a "C" note might sound, but octaves played on the keyboard still sound an octave apart
and
When you scale (multiply or divide) the voltage, you disrupt the tuning(scaling) of the pitch of the VCO (for example, octaves played on the keyboard will no longer result in octaves sounding from the VCO.)

Well, when these operations are performed on the control voltage signal that is sent from a Hz/V keyboard to a Linear VCO, the results are reversed(!):
When you offset (add to or subtract from) the voltage, you disrupt the tuning(scaling) of the pitch of the VCO (for example, octaves played on the keyboard will no longer result in octaves sounding from the VCO.)
and
When you scale (multiply or divide) the voltage, you transpose the sounding pitch of theVCO
(for example, I can play an "A" on the keyboard and a "C" note might sound, but octaves played on the keyboard still sound an octave apart.

Maybe its just me, but I always found this observation/symmetry/reversal fascinating.

Regards,

Kyle Jarger

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