Music theory and chords

[Clef_de_fa]

I know quite a few people who were very good in music harmony/theory lectures/classes but underachieved/failed miserable as musicians.

I could also say : I know quite a few people who know next to nothing in music theory and they are stuck in a 3 chords rut for the past 25 years

See ... it goes both ways and generalization like that lead to nothing

 

[Clef_de_fa]

I like the cut of your jib.

Glad you like it, my life is now complete

 

[RWRLV]

"""If I play a chord, must all the notes be in key"""
NOTE! A chord has 3 notes or more & chords (ex: A minor7) can be found in multiple keys.

A power chord (ex A&E 1&5 or Root 5th) or groups of them will not define a key nor do they offer a chord quality so the melody would need to be considered.

"""or does only the root matter when it comes to staying in key?""

No! If your just playing roots one can go in & out of key using passing tones or put other notes of the chord in the root. It all depends.

I'll suggest looking at some classics like Stairway to Heaven (the opening descending bass notes & over all chord qualitys), Little Wing (the F chord), the Beatles-Yesterday (check the chords & melody vs the key of F) or Del Shanon's Runaway (it is written using both A min & A Maj keys). Or even some real simple things like Ac/Dc tunes. They love using the Maj3rd /Min 3rd thing, 5ths or 3rds in the bass line , Sus 4 & passing tones in the bass all the time. Off the top of my head Back in Black & Are you Ready (intro & bridge section) have these quality's.

With all this Cb vs B discussion Im surprised I didn't get called out for --- Maj3rd /Min 3rd thing--- rather than #9

 

[Icculus]

Oh good lord, I was trying not to confuse the issue! Throwing in concepts like Cb wasn't exactly going to help.

And while we're still at it, you might see Cb notated in a piece of music, but in 25 years of playing, I've never once heard a musician refer to that pitch as Cb, regardless of the key we were in. Ever. That's as esoteric as it is elitist.

You were confusing the issue even more.

- they're, their, there
- to, two, too

Sound the same? Sure. Mean the same thing? Hell no. Get the point?

 

[bass geetarist]

Op I'm guessing so far you're learning to be scared to play in Db (or at least scared to talk about playing in Db)...

To answer your original question, no, it's not just the root note that matters when it comes to staying in key (this doesn't mean you always HAVE TO stay in key, but it is good to understand when you're in or out).

Jimmy K had it right when he said that whatever sounds good against the chord is right, but it's worth learning enough theory to understand what is "right" according to diatonic theory. That way, you'll at least develop an understanding of the basics, and you'll be able to decide whether you want to go "outside" the key or not, instead of just guessing. I'd recommend learning all the modes of the C major scale to start. This would mean learning C major (aka ionian), D dorian, E phrygian, F lydian, G mixolydian, A aeolian, B locrian. I won't spell them out for you, but you can find them easily online.

If you do try this, you'll notice that you're actually playing all the same notes for each scale, just starting in a different place. I think it's a good grounding for understanding how we move through chord changes while staying in the same key.