This morning I was practicing double stops on the violin. I always seem to have more trouble playing double stops on the violin than on the viola because of the strong presence of difference tones in the upper register. Sometimes I feel like I have to "fight" a great deal of "noise" just to get them to resonate evenly.
Then, out of the blue, I got an email message from David Mendes, a person who reads this blog, with a link to a dissertation about Lucien Capet. Capet's analysis of the way the bow works is fascinating, and also extremely useful. This image, however, proved to be a revelation for me.
[You can click on it for a larger view.]
The gist of the image is that when playing different double stops it is best to put the weight of the bow in different places in order for them to sound properly. It has nothing to do with the musical direction of a phrase, or voice leading, though sometimes a nice coincidence does happen. It has everything to do with the ease of getting both pitches of a double-stop to sound and resonate.
When you play the interval of a second, you put more weight on the lower string (or pitch).
When you play the interval of a third, you also put more weight on the lower pitch, but you don't need quite as much as you do for a second.
A fourth is only slightly weighted to the lower pitch, and a fifth is exactly even.
For sixths, the weight goes toward the higher pitch, and for octaves even more weight goes toward the higher pitch. The most weight goes to the higher pitch for ninths and tenths.
I just tried this with solo Bach, and found the results remarkable. It really makes you think and feel. It's so much easier to make music when the double-stops come out sounding clearly.
There's a German edition of Capet's La technique supérieure de l'archet in the IMSLP.
Thank you, David.