Grex Music3 Conference

Item 63: Circle of fifths

Entered by carla on Mon Dec 17 05:13:01 2001:

Ok, if there are any of you out there that have a fundamental
understanding of the circle of fifths, I need some help.  I have a friend
that's trying desparately to get it to sink in but music theory is one of
those things that my brain shuts down upon.  Actually he is not only being
very patient with me, but doing a good job of explaining it.  It's just
very complex and interconnected and I had the thuoght that a different
perspective may help me.  I'm more visually oriented, it's hard for me to
think of things in terms of sound, which is why I changed majors to begin
with.
13 responses total.

#1 of 13 by orinoco on Tue Dec 18 01:33:21 2001:

What do you mean by 'understanding' the circle of fifths?  Are you just 
looking to be able to play in all keys?  Are you looking to learn some music
theory?  Do you (god forbid) want to understand the tuning issues it brings
up?


#2 of 13 by albaugh on Wed Dec 19 22:49:56 2001:

C G
G D
D A
A E
E B
B F#
F# C# (aka Db)
Db Ab
Ab Eb
Eb Bb
Bb F
F C


#3 of 13 by blaise on Thu Dec 20 04:21:14 2001:

Hmm.  The way I remember it is with F# converting to Gb (6 sharps = 6 flats).


#4 of 13 by rcurl on Thu Dec 20 16:52:56 2001:

Does this have something to do with the Comma of Pythagoras?


#5 of 13 by orinoco on Sat Dec 22 21:18:40 2001:

(Yes.  Twelve fifths are not _quite_ seven octaves, if you tune them justly.
The Comma of Pythagoras is the very slight difference between twelve perfect
fifths and seven perfect octaves.  In equal temperment, one-twelfth of the
comma is added to each fifth, so the circle of fifths ends up being a perfect
circle.)


#6 of 13 by rcurl on Sat Dec 22 21:29:37 2001:

So, is "Circle of Fifths" the same as "Equal Temperment". Or, what does
one do with the "Circle" in addition?


#7 of 13 by albaugh on Sat Dec 22 21:38:26 2001:

Re: #3: You are probably right.  Me, I didn't care *too* much where the
enharmonic substitution was made!  :-)


#8 of 13 by jor on Sun Dec 23 03:39:44 2001:

This response has been erased.



#9 of 13 by jor on Sun Dec 23 15:14:57 2001:

This response has been erased.



#10 of 13 by jor on Fri Dec 28 02:21:14 2001:

         Pythagorean Comma was how I remember it referred to . .
         But we are hardly any help to Carla.
  
         Back to our meta-questions: what is it you want to
         understand?
  
         If you keep ascending by a fifth, that is, 5 notes
         up the scale, you hit all twelve tones. We only have
         12 notes. Then you are back to your starting  point:
         like going around a circle. You can stop there, 
         if you want.
  
         But the real starting point is the harmonic series.
  
         Any uniform material, like a string or a column of air,
         vibrates in a series of frequencies called 'partials'.
  
         Let's say you have a string you can pluck or bow and
         it vibrates back and forth 100 times a second.  A low
         note.
         
         Each half is also vibrating independently, at
         twice the frequency (200 cps, cycles per second).
         Each third is also vibrating independently, 300
         times a second, aka 300 Hertz, 300Hz. And these
         partial overtones keep going, 400, 500, 600,
         theoretically to infinity, but they get quieter and
         quieter so it's really only the bottom dozen or so
         that we hear.
  
         Grab a guitar, pluck any open string and let it ring
         out. Now gently touch the string with your fingertip,
         at it's exact center. Hey! At the 12th fret!
         Touch it for the shortest instant.
  
         You will cancel out the bottom frequency, and cancel all
        the odd numbered partial overtones that are vibrating
        the string at that spot. For the even ones, that spot
        is right where they are not vibrating, so you are
        not damping them. So this subset of overtones will
        seem to jump out at you.
  
        This harmonic series, starting at any frequency X,
        and including 2X, 3X, 4X, etc., is where all our 
        scales and harmonies come from. There's stuff built
        into your ear, and your brain, and the cableing 
        in between, to help you notice that two different
        frequencies you are hearing happen to be integer
        multiples of each other. Is that going to happen
        by accident? Not often.



#11 of 13 by jor on Fri Dec 28 02:27:28 2001:

        I'll get it right someday.


#12 of 13 by gelinas on Fri Dec 28 02:29:06 2001:

(John? are you scribbling and reposting for a resaon?)


#13 of 13 by jor on Fri Dec 28 22:38:53 2001:

        mistakes.


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