linear vs exp FM

[jorgen.bergfors at idg.se]

>>important if the FM is DC, ie detuning. Linear
>>detuning in most cases sound far better than exponential, because the  beating rate will stay the same, no matter what
>>note you play.
>Sorry, but I do not understand what you mean. A Detune is an _constant_  >offset and there is no relevance for logarithmic or linear thinking becaus  >you dont have differential aspects.

Yes, that's what you might think. But remember that with exponential FM, the FM voltage is added to the keyboard voltage. Suppose you have two oscillators tuned to the same frequency and have added a very small voltage to one oscillator, so the frequency diffrence is 1 Hz. If you now play the keyboard one octave highter, 1 volt is added to this. Because of the exponential response, the small voltage that caused 1 Hz increase before, now increase the frequency 2 Hz. Remember that a fixed voltage always give the same musical interval, no matter what octave you're in. So the beat rate doubles, and that is probably not what you want.

/Jorgen