Conn 42K BBb Jumbo upright bell
Date: 1920's, owner unknown
The "upright bell" sousaphones are also called "raincatchers", for obvious reasons. The 42K came standard with a 26" bell, althouhh Ian Church's research indicates that sousaphones could be ordered with custom bells from 26" to 34". It has a 0.772" bore (about #11¾). Compare that to the about 0.719" (#10) bore of the 36K Fiberglass model or the 0.734" (#10½) of the 20K. The 42K is the three valve version, the 44K is the four valve version. It was produced between at least 1924 and 1927.
What Conn said in 1926:
As explained on [the opposite page], many band leaders prefer the original Sousaphone type as presented here rather than the Grand model, which is almost universally used for orchestra and ballroom work. Choice between the two models is largely a matter of taste, since there is no difference between them in tone, intonation, or ease of blowing. Each of these Conn models represents the highest type of development of that particular instrument, as no less a personage than Mr. Sousa himself has said.
The BBb model shown here is used in Mr. Sousa's own band, and is the improved counterpart of the first Sousaphone ever built, which was made more than a score of years ago in the Conn factories. It is used in most of the large concert bands today, and is conceded by band leaders generally to be a most necessary part of the instrumentation of any band of more than average size.
The adjustable bell makes it possible to direct the sound as desired, and since it is detachable it makes for great convenience in packing and transporting the instrument.