Re: JI oscilloscope images (Digest 83 Message 16)

Hi John,

On Sat, 6 Mar 1999 14:21:54 -0500, John deLaubenfels
<102074.2214@compuserve.com> wrote:
>I have an oscilloscope, nothing fancy, left over from when I dabbled in
>digital circuit design, and I find it a terrific tool for demonstrating
>the beauty of Just Intonation.

I know there's something to using an oscilloscope to demonstrate just
intonation, or any periodic waveform. So-called "Lissajous" curves are used
to analyze waveforms.

As a matter of fact, Justonic's Pitch Palette uses an oscilloscope to create
Lissajous curves. Per http://www.justonic.com/screen2.htm:

Oscilloscope: Shows the harmonic purity of a chord
with "Lissajous Curves". Great for a
visual comparison of pure harmony to
equal temperament.

(They also show a sample screen shot of the oscilloscope at that web site.)

>I run the output of my Korg M-1 synth to the scope: left channel to
>horizontal and right channel to vertical (or the reverse; it doesn't
>matter)...

That should give some interesting pictures, although it's hard to comprehend
what the pictures would look like. In your case, you're using relatively
complex waves as inputs. I am only familiar with using simple waves (sine
waves) as input. If X and Y are sine waves an octave apart, a "figure 8"
would be displayed. If it was a slightly mistuned octave, the figure 8
would slowly spin.

I can only surmise that what you're getting with the more complicated waves is:
For just intonation: a "still picture" (possibly "Spirograph"-looking).
For equal temperament: a motion picture/tangled web/full of static.

--Mark

P.S.: Could someone find a way to demonstrate this on a web page or something?

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| Mark Nowitzky |
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