theory is just there to guide n play around with. notice all de best guitarists arent boxed in by theory but rather manipulate it to get de desired effect.
there are some great guitarists who know nuts about theory. Nuno Bettencourt for instance can't even read tab, i think he mentioned too that he doesn't know much theory..however theory and good knowledge of scales and the fretboard can make improvisation on the fly really much easier, make u more confident in soloing too..and definitely aids in songwriting or solo construction..
I think theory can be very very useful. But it's still up to your creativity to make full use of it. Read somewhere that Paul McCartney can't read music scores? Correct me if i'm wrong...
but would it be better if u knew ur theory besides juz moving ur fingers around the fretboard?
take for example if u or ur band plays a song wif chord progressions and den some stranger who so happens to step into the jamming studio and comments on ur song saying dat it's very good and den he ask u wad key is the song in.certainly it would be better to answer his question for example telling him ur song is in the key of G from the chord progressions instead of beating around the bush rite?
another example would be let's say u're playing a E minor harmonic scale on ur guitar and ur fren asks u wad is a E minor harmonic scale.would it be better to tell him dat the 7th note note of a harmonic scale is raised by one semitone/step in addition to the sharps involved in E minor scale
okay maybe as a pianist myself , i feel that i can't live without theory and it sure helps me a lot and not juz anyhow banging my fingers on the keyboard juz to get the right kinda sound.
basically wad i personally feel is dat theory is important in every aspect of music and of course it certainly saves u from much embarrassment as well :lol:
besides u can use theory to boast to ur frens dat u're a serious musician and they will be like ,"what the hell is he talking about this wad harmonic scale crap?! but hell he sure sounds pro to me!!!!"
actually u dun really have to go to Yamaha to learn theory.in fact all music schools in singapore teach theory alone.there are also private music teachers around whether being guitar/piano/violin/drum teachers , they still teach theory as a subject alone.
all u need to do is go scouting around for music schools and private teachers for their monthly fees and select the best deals out of it