Every Erhu player has different arm and finger length. Some have short fingers and some have rather long fingers. The position of the Qianjin affects the amount of stretch needed to reach your notes.
But every Erhu player has different arm and finger length. A Qianjin position that works well for one player might be a struggle for another. Hence you need to vary the height of your Qianjin according to the length of your hand.
Before we go into how to do that, a little bit about how the position of the Qianjin affects the tone and playability of the Erhu:
The higher the position of the Qianjin, the louder and brighter the tone of the Erhu. The tension of the string also goes up, which means you need more effort to hold the string and do vibrato as well. A high Qianjin also means a bigger stretch for the fingers.
Vice versa, the lower the position of the Qianjin, the warmer and softer the tone of the Erhu. The tension of the string reduces, making it easy to hold the notes and vibrato. But you have to take extra care not to exert too much pressure else the pitch will go up. A low Qianjin means it is less of a stretch for the player, but your fingers might get kind of crowded at the high registers.
So here’s an old trick to find the optimal position for your Qianjin. You put your elbow on the resonator and line your arm along the neck of the Erhu. Your optimal position should be just above where you palm meets your pinky.
Should you have unusually long arms, you can shift the Qianjin position a little lower and should you have very short arms (like kids), you can shift the Qianjin position a little higher.
Here’s a video explaining what I have just explained.
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