Q: Is it possible to do “full bends” on a chromatic.

A: It depends on what you mean by “full.” I can bend notes on a chromatic by as
much as three semitones, depending on the note.

On a diatonic, or on any harp where both the blow and draw reed are free to
vibrate, the two reeds interact, and create a system wherein the
higher-pitched reed can be bent and the lower pitched cannot. As the pitch of
the bent note gets lower, the lower-pitched reed also begins to sound at the
same frequency, and eventually takes over the vibration completely from the
higher-pitched note. The effective limit to bending in such a system is
slightly less than a semitone above the lower of the two notes.

For instance, in Hole 4 of a diatonic in C, the draw note is D and the blow
note C. The draw note can be bent down to just a little below Db. By the same
token, in Hole 10, C is the blow note and A the draw. In this case, the blow
note is higher in pitch, and can be bent down to just a little below Bb.

When two reeds interact like this it gives a very different sound from one
reed bending by itself. If you go back to Hole 4, put your finger on the blow
reed, and bend the draw note again, you’ll find that you can bend the note
much farther (it also requires more care to control), but it sounds sort of
“dead.” And if you put your finger on the blow reed, you can bend the draw
reed, which is not possible when the draw reed is available.

On most chromatics, the valves prevent any of the draw air from reaching the
blow reed, and vice versa – like putting your fingers on the diatonic reeds.
Thus any reed bent is bent by itself. This removes the range limit placed on
bends in the system described above, and also prevents that “live” bluesy bend
sound, but a casual listen to Larry Adler or Toots Thielemans will amply
demonstrate that it is a very effective sound nonetheless — “FULL BENDS ON
A CHROMATIC?” 17 Feb 1994 WY