The band that I play with always plays everything tuned down 1/2 step. When I set my GR-55 system settings to down tune shift -1 the tuner recognizes this setting so that the tuner shows an E even though it is hearing an Eb. When I set the GP-10 down tune shift to -1 the tuner still shows what the guitar is actually sounding. Playing an tuned down E string results in an Eb on the tuner. What does this GP-10 down tune setting do and is there a way to get the tuner to operate like the one on the GR-55? Didn't see an explanation in the OM. Thanks.