Boss Chromatic Tuner TU-2 Owner's Manual page 18

Tuning in Bass mode
* If you wish to change the standard pitch, do so before you begin tuning (page 20).
1. Press the MODE select switch several
times to make "BASS" light.
18
If you are using flat tuning (semitone
down) make " " light. If you are using
double flat tuning (whole step down)
make " " light.
Flat tuning
Double flat tuning