The Yamaha Heavyweight Series
YAC HR30-GPR
17.08 mm (.672"); standard contour; standard thickness; standard cup (double-cup); throat 4.40 mm (.173"); semi-narrow backbore; Holton MDC with smaller rim diameter. Smaller inner rim diameter than the 31. Smaller inner rim diameter than the 31. All-around type. Shallow "U" cup facilitates high notes, while a deep "V" makes low notes easy.
YAC HR31-GPR
Cup diameter 17.28 mm (.680");standard contour; standard thickness; standard double-cup; throat 4.40 mm (.173"); semi-narrow backbore; Holton MDC Medium rim configuration provides flexibility for difficult passages. Relatively large throat delivers a heavy, somewhat dark tone with extra volume.
YAC HR32-GPR
Cup diameter 17.48 mm (.688"); standard contour rim; standard thickness rim; standard double-cup; throat 4.40 mm (.173"), semi-narrow backbore; Holton MDC with larger rim diameter. Larger inner rim diameter than the 31. Authoritative low notes. Large cup volume for a rich, mellow tone.