There are lots of techniques that cellists typically find challenging. Playing fast, playing high...playing double stops.
Double stops are present in all the advanced and showpiece repertoire. We have to get good at them. And yet, how many of us repeatedly mess them up? Or get them more or less right in the practice room, but then mess them up in concert? Why are they such a bugbear to so many of us?
Success in performance is determined by successful practice. Double stops are no exception to this. Under the right conditions, anyone can master them reliably and effectively.
Two of the best ways to work on double stops are the daily practice of scales in thirds, sixths, and octaves, plus etudes that focus specifically on double stops, such as Etudes 9, 13, 17, and 34 from David Popper's High School of Cello Playing.
Most of us have spent long stretches of our lives working hard on these etudes. And yet, how many of us still struggle to get double stops in tune?
It's not a lack of hard work. It's just that in many cases, we've taught ourselves to play double stops out of tune.
There's a famous story about a great virtuoso who was approached by a fan after a concert. The fan gushed "How is it that you never seem to play any wrong notes, Maestro?" "I only practise the right ones," growled the virtuoso.
This is so simple it almost sounds like a joke, but it's true. What we need to be good is a practice method that repeats what's right, and doesn't allow what's wrong. Using this four-step method, any advanced cellist can nail those hard double-stopped sections reliably every time.
Step One: Know How You Want To Sound.
In order to have the goal of playing in tune, you must first know what it actually means to play in tune.
You can read about this in Chapter Three and Chapter Six of Cello Practice, Cello Performance.
For further reading on just intonation, check out How Equal Temperament Ruined Harmony (And Why You Should Care) by Ross W. Duffin, and to learn how you can apply this to string instruments, read A Violinist's Guide for Exquisite Intonation by Barry Ross (there's plenty in there that we can apply to the cello).
Once you've read the principles of intonation in all the keys from Cello Practice, Cello Performance, plot out an intonational analysis of the double-stop passage you want to master, figuring out which notes can take advantage of the sympathetic resonances of the cello's open strings, which notes should be pitched slightly sharp, and which should be slightly flat. Here's an example from Chapter Six of how I plotted out the intonation for the first two measures of Popper's Etude No. 9. (A full explanation of my symbols and what they mean can be found in Chapter Three.)
Step Two: Know How You Sound Now--And Own It.
You can't improve if you don't know what needs improvement. It's not enough to complain that you're out of tune--make a video of yourself playing a problematic passage and assess the problem honestly. Do you tend to be sharp or flat on certain notes, or is the intonation problem seemingly random?
Here's an example of an assessment you might have made:
Step Three: Practice in Small Sections, Figuring Out What Works.
Don't waste your time running a long section, deciding the whole thing is out of tune, and starting over with a resolution to do better. You're just teaching yourself to be habitually out of tune.
Instead, break the section down into two- or three-note excerpts. In the first stages of note-learning, you may wish to use a slow tempo. (Check out page 94 of Cello Practice, Cello Performance for additional strategies for learning double-stopped sections.)
Questions to ask yourself as you move from double stop to double stop:
1. What conditions must be in place for playing the first double stop successfully? What about the second one?
2. What conditions must be in place for transitioning from the old position into the new position? (For example: is my hand, my wrist, my elbow, or my shoulder tense? How can I release tension? What degree of pronation does my left hand need to comfortably move from one position to another with an economical amount of movement? What part of my finger tip or pad needs to touch each string? Is my arm's elevation working for me?)
Here's an analysis I made of these questions for the first three double stops in Popper No. 9.
Step Three is the hardest of the four steps, because sometimes we have literally no idea what's going to work, even with a teacher's guidance. All arms and hands are different. All cellos and bows are different. This level of experimentation can be mentally exhausting. Don't give up.
Step Four: Remember What Worked, and Repeat It.
The trick to mastering a skill is to repeat it until you have taught yourself to replicate it reliably every time.
The key concept here is to make sure you don't repeat wrong things. How many of us are wasting time in the practice room by hashing through a double-stop section, landing on one out of tune, "noodling" the note until it's in tune, then going on?
When you do this, you aren't really fixing the problem, you're teaching yourself to do it wrong.
Say goodbye to the intonation noodle, the wrong-note shuffle, the stop-and-fix-it-then-go-on. They're sabotaging your success.
The other top mistake cellists make is to get a hard spot right once, decide that it's fixed, and move on. Just once isn't going to work. Chances are you did it wrong twenty times before you did it right once.
If you got it right just the once, go back to Step Three and ask yourself: "What conditions were in place that enabled me to do it right that one time?" Don't let up until you've figure out the answer to this question. Figure it out, memorize it, and...
...repeat it right, a thousand times. Two thousand times. Ten thousand times.
As I stated in Cello Practice, Cello Performance, "Far from being some mysterious gift bestowed upon the lucky few, [effective cello performance] is a learnable skill that any advanced cellist can acquire through efficient practice."
That's all this is. Reject the wrong thing. Embrace the right thing. Repeat the right thing. Repeat it. Repeat it.