As Wagner, Nielsen, Mahler, and others sometimes write a low A1 it is useful to be able to cope with it easily.
Insert a cardboard tube 23 cm. in length and 4 cm. in diameter; mine came from a roll of kitchen paper towels (in England: "kitchen tissue"). In order to make it secure in the bell, I coated about 2 cm. from the outside of one end with a latex based glue (Copidex). When it dries, this has a rubbery texture which keeps the cardboard tube firmly in the bell.
It makes a very fine low A1 with the fingering for low B1-flat. In fact our contra player admitted that it was a finer and fuller A1 than he can produce on his instrument. (Editor's note. Mr. Strachen is a frequent correspondent with the editor and is a very fine amateur player of the Buffet/Crampon bassoon in England. This tube fits his Buffet and works well, as he points out. I am sure that with a little experimentation with tubes of various lengths and using a glue of the type mentioned, German-system bassoonists should be able to fashion an equally successful low A1 "bell.")