The six examples are all probably pitched in C (D-Leipzig, 1538; B-Bruxelles, 940; US-MA-Boston, 17.1879 (unstamped); US-NY-New York, 89.4.2345 (unstamped); F-Paris, E.760, C.550; I-Roma, 617). The first four examples have five brass keys: S, A, Ab/Eb,F#/C#, and E/B as found on soprano clarinets with the S and E/B keys positioned on the back for the left and right thumbs. There are six sections: mouthpiece, curved section similar in shape to the Greek letter omega (Ω), barrel, body section with finger holes and one thumb hole bored at an oblique angle, bell base, and bell flare. The length and bore of the long serpentine body produce a sound an octave lower than the soprano clarinet.

Three of the six Papalini bass clarinets (B-Bruxelles; US-MA-Boston, ca. 1825; US- NY-New York, ca. 1825) show a later design. They have a boxwood barrel with horn ferrules connecting the omega sections to the main body. The two halves of the body and omega sections […] are connected with […] iron pins. […]

The E/B key is now positioned for the right-hand thumb, the Ab/Eb key moved so that the touch is placed for L4, and there are nine oval finger holes, including one for each thumb, with finger holes L1 and R3 doubled for playing f1/c3 or f#/c#3 and g/d2 or ab/eb2. The shape of the body enables the finger holes to be placed closer together, but the fingering of some notes has become awkward. The tip of L1 covers a single or double hole, and the lowest joint covers the hole on the outside of the curve. The tip and a lower part of the first joint of the right-hand ring finger (R3) are required to cover the large double holes. The instrument in Boston is unstamped except for “1” or “I” on the bell, and the instrument in New York is unstamped; both are attributed to Papalini.

Rice, From the clarinet d’amour to the contra bass, 284,285.