M3/m3 ratios (cross posted)

Ron Koval drwoodwind@hotmail.com
Wed, 19 Feb 2003 20:59:25 +0000


Hello cyber-land techs....

New on the tuning front is the focus on the ratio between the major 3rd and 
minor 3rd of a chord. Jason Kanter wrote about this last month, and has 
included some experiments on his website. (www.rollingball.com)

I began tuning alternate temperaments years ago out of curiosity.  After 
attending a class taught by Ed Foote, I had the tools to begin graphing the 
temperaments to try to predict how they would sound.  Along the way, I've 
come in contact with a few people who have helped me to gather enough 
information to ask questions to continue the learning process.  I began to 
wonder how the major third and the minor third that co-exist in a major 
triad interact.  I used a spreadsheet to start looking at the m3-M3 beats, 
as well as the m3/M3 beats.  As I was focusing on the subtraction, Paul 
Bailey was looking into the division, or ratio between these intervals.  
Along came Robert Wendell, who has the math skills to do a lot of 
calculations in his head when creating temperaments. A few of us were 
searching for a really nice mild temperament, while others were developing 
tunings with much more contrast.  What was discovered is that there are a 
few ratios of m3/M3 that create a pleasing beat sychronicity.

Let's look, for example at a C chord. (C-E-G) the interval of C-E is called 
a major third, while the E-G is called a minor third.  In equal temperament, 
one C-E beats around 10bps, while the related E-G beats around 17bps.  
Combining those two beats gives......lots of beats! (27/second)  Imagine a 
drummer tapping 10 times with the left hand and 17 times with the right 
hand. Only the first beats in each hand would fall together. This, I think 
is the source of the ever present "shimmer", or "waver" used to describe 
equal temperament, by alternate temperament technicians.  Dividing those 
beat rates gives us a ratio of around 1.7

What happens if we could keep the major third beat @10 times/sec, while 
change the m3 beat to 20 times/sec?  Each beat of the major third would be 
matched with a beat of the minor third, with a minor third beat coming in 
the middle. (adding up to 20/second)  Dividing these beat rates gives a 
ratio of 2. Ooooooohh, we added beats to one interval to come up with less 
beats combined.  Coool!  Another way to get 20beats/second is the 
combination of M3=10 and m3=15,(triplets vs. duplets) with a ratio of 1.5.

This synchronizing of beats was noticed randomly appearing in historical 
temperaments, but not used to create new temperaments until  recently.  
Robert Wendell just discovered (his words) a temperament that has all the 
M3/m3 ratios set to either 1.5 or 2.  He describes it as just falling into 
place, once he got started, kindof working backwards from F#. (I don't 
pretend to understand how he got there!)

For those of you willing to try this mild well temperament, here are the 
offsets from equal temperament.

Wendell Natural Well temperament:
(M3rds range from 7.4 – 17.6 cents from pure thirds)

C 	4.24
C#	-1.59
D	2.41
D#	2.32
E	-2.08
F	2.29
F#	1.83
G	3.74
G#	0.37
A	0
A#	4.28
B	-0.12

There is a little retrograde progression (D-A) to make the ratios work out.

Also, since the modern ear seems to be very sensitive to the thirds between 
17 and 18 cents wide of pure, he has altered the above temperament to fix 
the retrograde progression and lessen the widest thirds a little. This 
effects the ratios.  Though they do not equal 1.5 or 2, they remain very 
close.

Wendell Very Mild Well
(M3rds from 7.8 to 17.2 cents from pure)

C     4.24
C#    -0.83
D    3.04
D#    3.08
E    -1.65
F     2.69
F#    2.27
G     4.29
G#    1.13
A      0.0
A#    5.04
B     0.31

These are worth a listen.... Hope you get a chance to try them!

Ron Koval
Chicagoland








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