Frequency Divider Waveform

[Hairy Harry]

Hello Mitch (et al)

The 3/2 or 2/3 ratio makes PERFECT fifths and fourths...
think C-G or C-F.  Fifths and Fourths are inversions of each
other...

Perfect means zero beat. If you go around the "circle of fifths"...
C-G-D-A-E-B-F#-C#-G#-D#-A#-E#-B## (which should be = C)... you will
find that you are sharp by about a 1/2 step. This difference is called
the "Pythagorean Comma".  This excess is eliminated by making all fifths 
flat, spreading the error term EQUALLY among all intervals.
This is EQUAL TEMPERMENT... and is what all normal analog synth VCOs
follow when you play them.

The Perfect Fifth sound nice and "synthy"... but you cannot use this
technique to get very far from the fundamental or horrible mistunig
will result.

Using division techniques to get the other intervals usually requires the 
original frequency by very high (2-5MHz) and then dividing down
by integer sets... usually three digits. Top Octave Generator chips like the 
now defunct Mostek (number forgot). You will not get this from an octave 
divider...

So Fifths, Fourths and Octaves are the usual limit.

The 2:1 is an octave

H^)  harry

PS: I say only NICE things about suboctave gens. Not like the BBD etc...  
:^)


>From: Mitchell Hudson <mitch at sirius.com>
>To: EFM Synth DIY <efm at xavax.com>, Synth DIY <synth-diy at node12b53.a2000.nl>
>Subject: Frequency Divider Waveform
>Date: Mon, 31 Jul 2000 01:11:54 -0700
>
>     So the frequency divider is working! The amateurs have successfully
>modified a module!  Here I will insert a Thank you to the list for all
>of your advice and commentary. I have built a few modules so far now I
>want to modify all of them!
>
>     I have to thank Mr. Blacet, the FD is one of the most useful modules
>I have built before the modifications. I have three of them now. I use
>them to fatten up sounds and as a CV source. I often chain them together
>and use the out as a sort of sequencer and then use the /n outs as a
>sort of square wave LFO to sync everything together.
>
>     Now that I am playing with the frequency divider I am curious what
>is happening with the wave form that is coming out of the FD. Is it a
>chord? or is it a more complex single tone? I am not sure how to
>describe what I am thinking here. But is the output like hitting
>multiple keys on the piano or is it like playing a single note on an
>instrument that has overtones?
>
>     On this same note so to speak what are the divisions that create the
>other notes of the major scale? For example if /1.5 creates a major
>fifth what division would create a minor third or other interval?
>
>--M
>

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