DigiTech RP255 - Manual (Page 9)

3
Display shows
note played
Top LEDs indicate
note is sharp
Green LED indicates
note is in tune
Bottom LEDs indicate
note is flat
In Tuner mode, you can change your tuning reference. The default factory setting is A=440 Hz
(displayed as A=440). Rotating Knob 1 selects alternate dropped tunings. Alternate tunings are A
= Ab, A = G, and A = Gb. The display window briefly flashes the current tuning reference.