Octave and Fifth Quantizer

[jorgen.bergfors at idg.se]

<< Wait a minute, did I get the fifths thing wrong? The interval between C and G is a fifth, right? G is 7 semitones up from C, right?  >>

>Yes, it is.  But you need to raise the voltage by 7/12th's of a volt to get that pitch.  You raised it by 6/12th

>The correct voltage increase would be 0.5833 volts, not 0.5000.  (thanks to our wondrous exponential converters, it's always .0833 volts per half-step)

Aahh... I was trying to be too smart with the calculator I probably mixed up linear and logarithmic math. Actually I had it at 0.5833 volts at first, but then I got the impression that it was wrong. So my quad VCO module is actually built with 0.5833 volts. No wonder it sounded right then...

<< Or am I thinking wrong here? I'm not a maths guy. >>

>No, *I'm* not a maths guy!  I'm REALLY not a maths guy.  Believe me, you are >Albert Einstein by comparison.

>Anyway, it's good that you can adjust it to the pitch you want.  The flatted >fifth may be a better idea, because it is exactly half-way between the >octaves.  Then you can make your fine tune knob's range symetrical around >zero.  With the perfect fifth, the plus side of the fine tune knob would need >to go up five half-steps to reach the next octave, but the minus side would >need to go down seven half-steps.   (or you could go with the perfect fifth, >and have the fine tune pot go plus/minus seven steps)  Either way is good, I >think.

>Michael Bacich

Thanks a lot for pointing this error out. Isn't posting things to this list an excellent way to find errors that you might not have thought about? It has helped me a lot.

By the way, what do you other DIYers think is most useful? A flatted or normal fifth?

/Jorgen