"killer octave:

[Phil Bondi]

Boy..I have to admit that my conception of this 'octave' was all wrong.

For some reason, I was under the impression that the 'killer octave' lied somewhere
between C6 and E7, depending on the piano. The reason for the 'extended' range
is because this is the area of a piano that is the most unstable, hence the
nickname.

Thanks to all for making this as clear as mud for me!

Rook