Rocktron Reaction Tuner - Manual (Page 10)

Calibration:
To match the pitch of any instrument or audio source
(like an old piano or tape player) press the “Calibrate”
button while simultaneously playing the note on the
instrument. (Note: you might have to first tune one
string on the guitar or bass by ear to match the actual
note if the piano is out of standard tuning or if the
tape player you are playing along with runs slower
or faster than normal). Once you have one note on
the guitar tuned to the source - simply play that note
on the guitar - while the note is “ringing” press the
Calibrate button. The tuning pitch of the tuner will
automatically be shifted to match the pitch of the au-
dio source. Release the button and tune the remaining
strings as normal with the tuner The tuner at this
point has automatically adjusted the tuning range to
match that pitch. To reset the tuner to standard 440Hz
pitch turn off the tuner and then back on again with
the footswitch (see controls - point 6).