Ways to practice fast and tricky passages
We encounter a fast passage and it doesn't seem to get much better even though we spend a lot of time on it. We trip on the same tricky passage every time and we don't know how to improve on that. I will explain some of the ways to practice that will help you get out of that frustration.
Stop on each note before you go to the next
This is the first thing you should do if you cannot play a passage right. Stop after each note, and think about the next note as much in detail as you can. To play the notes correctly, our brain has to receive the correct information in advance. This includes the note itself, fingering, position, angle of your hand and arm, distance of shifting, etc.
Physically prepare everything before you play the next note. Your finger needs to be on the next note, the shifting has to be completed, the string crossing has to be completed before you play the next note. Basically, you get to the next note and wait. Do not wait to change your position or put the finger down until you play the next note. Everything needs to be done before you move your bow for the next note.
Let me explain more with this example.
First, practice stopping after each note. This passage involves shiftings. Do not shift as you play the next note; shifting must be done before you play the next note. Think about how far you need to shift, how you might have to change the angle of your hand, etc. We need to figure them out while you are stopped. You play the next note only after you know exactly what and how you will play it.
Also, this passage requires quick string crossings. Just like the shifting, do not cross strings as you play the next note. Make sure that your bow is waiting on the next string before you play. To execute string crossings successfully, we need to know the exact angle of your bow, the height of the bow arm, and how far your bow needs to move from one string to another.
Practice with added accents. For instance, you can place accents on every 4 notes, all down bows, or all up bows.
Place accents on every 3 notes when notes are originally grouped in 4. This will throw off the sense of beats, which will make you think harder which note you should play when and how:
Make up rhythms
You can come up with rhythms to make the passage more complicated. Add dotted rhythms instead of straight 16th notes.
One thing I'd like to mention about practicing with dotted rhythms; make sure that the short notes (the 32nd notes in the examples above) are extremely short. Do not make it into a triplet. We are practicing for dexterity when we add dotted rhythms. We need to learn how to go from one note to the next note quickly. Otherwise we are not really utilizing the benefit of the dotted rhythm practice.
Similarly, you can come up with more random rhythms.
It is more effective to come up with rhythms where the pattern of the created rhythms do not line up with the pattern of the original notes. In the above examples, the 1st one is assigned a 5-note pattern while the 2nd one is a 6-note pattern. This will throw off the sense of beats. This will make it more difficult to practice but you will gain more in the end because you have to think more about the coordination between the right and left hands/arms.
Make up slurs
Come up with slurs. Make 4-note slurs into 3-note slurs, add slurs to all separated notes, etc..
Just like the accent practice, it's more effective to practice with slurs that do not line up with the beats.
To play many notes in one bow
Sometimes we feel that we don't have enough bow to fit in all the notes in one bow as suggested in the music. In such a situation, try this practice method.
In the example above, practice by stopping the bow after each note, and use as little bow as you can while doing so. You should be able to play all of the notes in each measure with less than half a bow when you do it successfully. When practicing this way, a moderate tempo should suffice. It does not have to be fast.
Then play with all of the notes connected but with as little bow as you were using before. Once you can do that, now you can use more bow for a better tone. You will feel that you have more than enough bow to play all the notes, and you no longer feel choked trying to get all the notes in one bow.
Practice faster gradually with a metronome
Start at a tempo that you can play. Then, raise the metronome by 2 or 3 notches each time. You hardly notice the difference each time when you go faster, but after practicing for 10 minutes, you realize that now you are playing 20 notches faster than when you started, which is a big difference in tempo.
You will less likely to develop a bad habit as you play faster when you practice this way because you feel that your playing is always under control before you raise the tempo. When we suddenly change tempi, we do strange things physically just so we can keep up with the tempo, which leads to a bad habit, and you will hit a wall where you cannot play any faster no matter how much you practice.
Why these practice methods are effective
These practice methods force you to think about each note, and coordination between the right and left hands. By exercising this way, you stop playing notes automatically. You will start to play each note because you are telling your body exactly what to do at an exact moment. In result, everything you are playing now becomes under control.
One of the main reasons why we cannot play a passage is because our fingers and the bow arm are moving on their own. When they escape our attention and control, we are not managing that part of the passage, and we make a mistake.
Also, these practice methods will teach you to understand what should happen next before they do. When you know what is going to happen next and your body is ready for it, you have a much better chance of playing a passage faster.