reverse well explained (no graphs, only one number)

Ron Koval drwoodwind@hotmail.com
Wed, 25 Oct 2000 16:21:56 GMT


Ok, ladies and gents, let’s see if I can shed some light here….

No graphs, I promise.

In equal temperament, all like intervals measure the same, so in theory, all 
major thirds will measure 13.7 cents wide of pure.  We say that all thirds 
are the same, but we hear beats, not cents, so they don’t SOUND the same.  
In theory, (again in equal temperament) if one were to play major thirds 
ascending by half steps, the speed of the thirds increases equally at each 
step. Here is where tuners can get mixed up.  Even if a tuning has the 
thirds all increasing in speed, if they don't increase evenly from note to 
note, it isn't equal temperament. Now, pianos don’t like to conform to 
theories, so mathematical models, and aural tunings digress from each other 
in certain areas of the piano.

What we expect to hear in a well temperament, is that the speed of the 
chromatic major thirds will increase AND decrease in speed as the thirds are 
played.  In a Young’s temperament, the differences are large, and easy to 
hear.  In others, like the DiVeroli almost equal, there are groups of thirds 
that will progress like equal temperament, so the differences are not so 
easy to hear.  There is a pattern to the differences, and the pattern 
relates to the circle of fifths.  This musical chart shows the relationship 
of the different keys available in Western music.  C is at the top and 
progresses down to F#/Gb at the bottom.  The Well tempered tunings space the 
narrower (more pure sounding) thirds at the top of the circle, with the 
wider (less pure sounding) thirds at the bottom of the circle.

So to ‘test’ a well tempered tuning start with a C-E major third, and then 
play G,D,A,E,B,F#,Db,Ab,Eb,Bb,F,C  progression of thirds.  The intensity of 
thirds should increase to the middle and then decrease back to C.  Or, 
played up by half steps, C will beat slower than C#, which will beat quicker 
than D, which should be slower, or the same as Eb, which will be slower than 
E, which should be quicker than F, and so on.

A Reverse well would be just the opposite, with the key of C showing the 
most intensity, and F# being more pure sounding.  But the differences will 
not be obvious, because the reverse well will not be as ‘strong’ as 
something like the Young’s temperament.

To do a quick check for a reverse well temperament (check yourself!) play 
major thirds ascending and see if C is a little more ‘busy’ than C#, or even 
equal to C#, instead of an even increasing of the beats.  Check if the 
sharp/flat keys aren’t a little out of progression, instead of being exactly 
even in progression.

Of course, once you add the third note of each triad, there is a major 
third, a minor third, and a fifth all beating together (beats within beats) 
and influencing each other.  Sometimes all those beats together causes the 
chord which was predicted to sound very busy (just looking at the major 
third alone) to sound unexpectedly pure.  That’s what the equal beating 
temperaments try to use to their advantage.

I do know that the more I tuned in mild, unequal temperaments; the more I 
could hear the differences between the speed of the thirds. I became very 
sensitive to how small of a difference it takes to make a very real 
difference in the progression of thirds in a tuning.

I would urge tuners to not only stick with the Young, or the Vallotti Young 
in experimenting, because both are pretty strong.  A more mild temperament 
provides some tone color without the ‘jolts’ that can be found in those 
historic temperaments.

Hope this helps!

Ron Koval

Chicagoland

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