1. Rim Diameter:
- The 12C has a larger rim diameter compared to the 6.5AL. A larger rim provides more surface area for the player's lips to rest on and can be more comfortable for players with larger lips.
2. Cup Depth:
- The 12C has a deeper cup compared to the 6.5AL. A deeper cup provides a darker and more resonant sound, with more low-end warmth and projection.
3. Throat Size:
- The 12C has a larger throat size compared to the 6.5AL. A larger throat facilitates greater airflow and allows the player to produce a louder, more powerful sound.
4. Backbore:
- The 12C has a different backbore design compared to the 6.5AL. The backbore design can influence the resistance of the mouthpiece and the overall response and feel of the trombone.
5. Overall Effect on Sound:
- The 12C produces a darker, warmer, and more resonant sound compared to the 6.5AL. It is considered a more versatile mouthpiece suitable for a wide range of playing styles and genres.
- The 6.5AL produces a brighter, clearer, and more focused sound. It is preferred by some players for jazz and lead playing due to its articulation and projection capabilities.
Ultimately, the choice of mouthpiece depends on the individual player's preferences and playing style. It's recommended to try different mouthpieces to find the one that best suits your needs and provides the desired sound and feel.