At first glance, the Yamaha CS series clarinets and SE series clarinets may appear somewhat similar. However, there are several important design differences that result in sonic variances, too:
As shown in the illustration on the right, the CS bore is more cylindrical than the SE bore and less “under- cutting” (and more upper) than SE tone holes.
The right-hand chimney tone hole illustrations below show the difference between the tone hole shapes, and the sectional view of the two models shows the difference in bore (note also that the CS has a thicker wall than the SE):
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