Conn 28K BBb Sousaphone Grand
Date: 1928, owned by Greg Butcher
The 28K is the four valve version, the 26K is the three valve version. It was produced between at least 1919 and 1928.
What Conn said in 1926:
This model of the Sousaphone Grand was designed especially for the benefit of those accustomed to Eb basses. It is quite as effective as the BBb model both in tone and appearance. Although it weighs nearly six pounds less, the Eb is only a quarter of an inch shorter than the BBb, and the bell diameter varies by only one inch, so this instrument adds to the appearance of the band or orchestra in which it appears quite as much as does its deeper-voiced brother.
The entire Sousaphone family was created in the Conn factories, the first one having been built especially for the brass section of Sousa's band, and consequently the present models are the result of many years of practical experience with this type of instrument. The tonal qualities of all models are pure and the scales are accurate and even.