The strengths of Yamaha Synthetic reeds correspond closely to those of conventional cane reeds. So, to start, we recommend that you choose a strength which is the same or similar to the reeds you are currently using.
If the strength you normally use isn’t quite right, try adjusting the resistance by moving the reed slightly higher or lower on the mouthpiece. Higher makes the resistance higher, lower makes it lower.
Beyond that, the Facing and Tip Opening of a mouthpiece can help determine what strength of reed will work best. The Facing represents the length of reed that will vibrate when playing. A longer Facing produces more resistance and bigger sound, while shorter Facings give less resistance. Tip Opening is the distance between the tip of the reed and the mouthpiece. The bigger the distance is, the more resistance and bigger sound it produces, and vice versa.
Generally speaking, a mouthpiece with a shorter facing and smaller tip opening will use a higher strength reed. A mouthpiece with a longer facing and bigger tip opening will use a lower strength reed. If you’re not sure about the details of your mouthpiece, please check with the manufacturer or your local music store.
The Yamaha 4C mouthpiece has a relatively shorter facing and smaller tip opening, enabling beginners to produce sounds more easily. Therefore, 3 or 3 1/2 are good strengths for most players using a 4C.