You will always need to consider what bow speed to use in order to play musically. For example, too much bow for one note, may cause you to play it with too fast a speed making it too loud for the phrase.
Bow distribution is how much bow you give each note. If you don't figure out how much bow to give each note in a phrase, you may either run out of bow or cause some notes to be too loud or too soft because you are playing with the wrong bow speed.
Bow speed and bow distribution are both necessary skills to develop in order to play a phrase musically.
There are exercises you can do to learn how to control your bow speed. A metronome is essential to give you feedback. You may also need to put stickers on your bow to identify where you are in the bow. Without stickers, it can be hard to know if you are getting to a certain point within a certain time as you learn how to control bow speed.
Christopher Bunting gives some good bow speed exercises. An easy one to begin with is 8,6,4. Set your metronome to 100. Put some stickers on your bow stick at the middle and each quarter. Using full bows on each note of a one octave scale, move the bow evenly for 8 clicks, then switch immediately to 6 clicks/bow, then to 4 clicks/bow and back to 8. See if you can do this using constant loudness throughout.
The faster the bow speed, the louder the volume if the pressure and placement remains constant. So if you want to change bow speed and keep the volume the same, you'll have to adjust your arm weight (which is where your sensing and imagination can help you.)
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