I was reading a theory book and it's talking about "Modal Interchange." The key is in C Major and I can't understand how BbM7 went to CM7. Isn't BbM7 a secondary triad Sub Dominant? And as I know, a secondary triad Sub Dominant can't just skip to the Primary triad Tonic.. So what is happening here?
What's this idea that one chord CAN'T skip to another? Bbmaj7 demonstrably CAN go straight to Cmaj7. Do you like the sound? Good. Add it to your bag of musical resources. If you subscribe to some system of 'theory' that says it can't be done, find a better sysyem of theory!
Theory describes. It does not give permission.
I'm going to keep saying this until it sinks in! Seems to be taking a long time :-)
i 'm studing a theory book that talk about the bVIIM7 function.These chords are non diatonic chords inherited from the Myxolidian mode.Their function us a SUB-DOMINANT function. For instance in G Major you can find an FM7 because in G mixolydian the F is not #, as in a G7 chord. The bVIIM7 chords tend to resolve on I. But as a sub-dominant chord, you can find it in a IV-V-I cadence where the bVIIM7 take place of the IV. This the case in the pop song i'm studying where FM7 (bVIIM7) is preceded by a C (IV) and followed a D7 (V7) and a G (I). This emphasizes its a SUB-DOMINANT function ( I Need you by America - 1971) Cheers !