I play on my piano alot and do improv solos by myself and one day I was messing around in the key of F#(6 sharps) and I hit a G and it sounded great. My question is why did it sound good. Is it part of some mode I don't know about?
Actually, it's not a Phrygian mode, Phrygian has a min3 and min6. One reason it sounds good though is probably because your used to hearing those intervals in relation to the relative minor, (in this case D#). Frequently "bluesy" sounding riffs will include the maj3 in a minor scale or riff, (think of the openning riff of Daytripper). In this case what your viewing as a R,b2,maj3, p4 of the F#major could also be heard as the min3, maj3, p5 and min6 of D#. Just one possible explanation. Hope it helps, Jeff