Conn 54I Wonderphone Bell Front Bb Euphonium
Date: 1929. Owned by Jim Blood
Interestingly, the 1924 and 1926 catalogs disagree with each other when it comes to the Wonderphone family of single bell Euphoniums. So what follows is the 1924 catalog's version of things, since that agrees most with the pictures I have.
The Wonderphone family of single bell front Euphoniums consists of the 48I/49I (see separate listing), 50I/51I and the 54I/55I (pictured here). The 48I/49I are three valve top action instruments. The 50I/51I are three valve front action instruments. The 54I/55I are four valve front action instruments. Even numbered instruments are low pitch, odd numbered instruments are high pitch.
What Conn said in 1924:
A mellow quality is added to the tone of the Euphonium by means of the curved or "Wonderphone" bell with which the models shown on this page are built. The rich, sweet quality of the Euphonium is greatly enhanced by this feature, and in addition, the bell, being adjustable as to position and also entirely detachable, enables the performer to throw the sound in any desired direction as well as to conserve space in transportation. While these instruments are entirely different in proportions from the straight bell models, owing to the difference of the bell, in all respects as to ease of playing and light action they are identical to the other models.