Conn 24B Opera Grand (LP)
Date: 1925. Instrument owned by Paul Ayick.
Notice the copper valve casings. You see that on 22B and 24B models from 1924 and 1925. The presence or lack of copper valve casing doesn't indicate it is any particular model. Examination by Steve Hanson of one of these instruments with a copper valve casing shows that the valve casing is solid copper with brass threads soldered in. Also notice the lack of a right hand pinky ring. That isn't damage, it was built that way. The "small bore" described below is a #1 bore (0.438"), very common in models in the 50's and 60's. The 24B Opera Grand was built from 1921 to 1930.
What Conn said:
This model is built with a small bore and is known as the 24B. It was built especially for "jazz" or ball-room orchestras, and has proven its value for this character of music most successfully. It possesses a stinging, yet musical quality of tone and unusual carrying power. From the time this trumpet was placed on the market, it met with success and swept all other "jazz" behind it. It is extremely easy playing and is particularly noted for this feature. We do not recommend the Opera Grand for symphonic or concert engagements.
The instrument is 19½" long, weighs 2¼ lbs and has a 4 5/8" bell. The 24B is a "Low Pitch" version, the "High Pitch" version is called the 25B.