I'm trying to understand what key is the song 'Crush' by Dave Matthews in. It uses all the chords in Bm but it also uses F major and C major as well as D/F#; Why does the F and C sound right with this song?
First off, two links. One person's transcription of the chords for "Crush": http://www.azchords.com/d/davematthewsband-tabs-1009/crush-tabs-104305.html
And another person's "accurate Dave Matthews Band tablature": http://www.dmbtabs.com/song.php?sid=41
Those two seem to match pretty well and seem good to me compared to a live performance with just Dave and Tim Reynolds on acoustic guitars.
If we want to get a grip on what's going on here in some structural way, I can think of three immediate answers to your question:
- There's clearly a modulation to a different key going into the chorus. The different key for the chorus allows for some chords to used in different ways from the verse. There almost seems to be a kind of modulation right at the beginning of the verses.
- First year Western harmony theory is just scratching the surface of one system of musical structure. Just looking at the basics of jazz theory opens up a lot more chord possiblities, and there are harmony systems from outside of the Western (European) system that are completely different but can still inform modern music.
- Most importantly, this guitar part (like the other parts I've learned by Dave Matthews), seems composed on the guitar with a focus on the instrument and motion of fingering and notes. When I brainstorm on the acoustic guitar I find all kinds of chords that don't seem to make as much sense when I try to analyze them later.
If we look at the linked chord and tab transcriptions, we can really see what I'm talking about in point 3. I'm reminded of the chorus to "Satellite" where the guitar part seems to be more about moving one finger at a time or sliding chords up the neck than it is about creating a consistent harmony. Also, all the "suspended" (true suspensions and "sus" chords are not always the same thing) notes and extra notes (e.g., b6, 7th, 13ths) tend to soften the harmony of the base chord shape and open up a lot of consonant roles for the chord to fit in other keys. Finally, power chords (X5 chords like the C5 in this case) have much less harmonic content since they only contain the root and fifth of the chord and can fit into all kinds of harmonies.
So, what key is this song in? I'd say the chorus is solidly in C Major. If we consider all the F chords in the verses to be borrowed chords of some kind, and the E chords to be neither major nor minor, then we can make a good case for B Minor in the verse. And modulating a whole step up for the chorus make sense, so if we HAVE to pick keys, those are the ones I'd pick. At the same time, I wouldn't get too hung up on figuring out what keys songs are in. It can help for improvising, but for this kind of music it would be more effective to do modal improvisation (which is a whole nother topic).
I hope that helped. This kind of music is a lot more fund to play than to analyze, IMHO.