Yamaha Horn Model No. Inner Rim Diameter (mm) Rim Contour/ Thickness Cup Depth Throat (mm) Backbore Playing Characteristics 28B 16.87 standard/ semi-thick semi- shallow (V-cup) 3.90 semi-wide Smaller inner rim diameter than the 29B. Ideal for Bb/HF horns. Smallest "V" cup in the line, but with a soft, mellow tone. 29B 17.07 standard/ semi-thick semi- shallow (V-cup) 3.90 semi-wide Fairly thick rim with a relatively small inner diameter for superior high tone. Medium throat for easy all-around playing. 29C4 17.08 semi-flat/ thick standard (U-cup) 3.98 semi-wide Smaller inner rim diameter than the 30C4. Ideal for Bb/HF horns. Relatively sharp shoulder and medium throat for clear tone. 29D4 16.88 semi-flat/ medium semi-deep (double- cup) 4.50 semi-narrow Double-cup combining medium and extra-deep "V" cups. Fairly small inner diameter, but with a large throat for rich tone. 30B 17.27 standard/ medium-thick semi- shallow (V-cup) 3.90 semi-wide Standard "V" cup model with a larger inner rim diameter than the 29B. Smooth airflow. Ideally matches horns with a very narrow bell. 30C4 17.28 semi-flat/ medium standard (U-cup) 3.98 standard Medium inner rim diameter and "U" cup for fast response. Standard type with ideal resistance and powerful, rich tone. 30D4 17.08 semi-flat/ medium semi-deep (double- cup) 4.50 semi-narrow Larger inner rim diameter than the 29D4. Exceptionally rich tone. Matches horns with a wide bell. Excellent stability on high notes. 31B 17.30 standard/ medium-thick semi- shallow (V-cup) 3.90 semi-wide Medium inner rim diameter with a "V" cup for a "traditional" soft horn tone. High volume over a wide range. A good match for horns with a narrow bell. 31D4 17.28 semi-flat/ medium semi-deep (double- cup) 4.50 semi-narrow Larger inner rim diameter than the 30D4. Heavy tone and high volume. Relatively flat rim of medium thickness for easy playability. 32B 17.67 standard/ semi-thick semi- shallow (V-cup) 3.90 semi-wide Even larger inner rim diameter than the 31B for outstanding low-note tone. Largest "V" cup in the lineup. Rich, mellow tone. 32C4 17.48 semi-flat/ medium standard (U-cup) 3.98 standard Larger inner rim diameter than the 30C4. Plenty of volume. Relatively flat rim of medium thickness for easy playability. 32D4 17.48 semi-flat/ medium semi-deep (double- cup) 4.50 semi-narrow Largest double-cup in the lineup. Also ideal for Wagnerian tuba. Large cup volume for a dark, heavy sound and easy low notes. 33C4 17.68 semi-flat/ medium standard (U-cup) 3.98 standard Largest "U" cup in the lineup. Can deliver a big, expansive sound. For advanced players. 34B 18.07 standard/ semi-thick semi-shallow (V-cup) 3.90 semi-wide Larger V cup in the line up. Happy sound and low notes. For the advanced player 34C4 17.88 semi-flat/ medium standard (U-cup) standard semi-wide Plenty of volume. U cup for powerful performance. 35C4 18.08 semi-flat/ medium standard (U-cup) 3.98 standard Larger U cup in the line up. Can deliver heavy sound. Suitable for large orchestras