Figure out a key - The easy way!

Evo

Hi guys and gals, Here's a little tip for those of you that sometimes struggle to know a key just by looking at a chord progression. I won't go into too much detail over why this works unless anybody is really interested or asks nicely but here's a quick way to work out which scale to use. Firstly, take your progression. In this case, let's use F, Am, G, C Then look for any two chords of the same gender (either both major or both minor) in your progression which are alphabetically next to each other. This time, the chords we're after are F and G. These are chords 4 and 5 in your key, so by working backwards, you can find chord number 1. 5-G 4-F 3-E 2-D 1-C If you spot two major chords next to each other (like F and G) then they are chords 4 and 5. If you spot two minor chords next to each other (like Am and Bm) then they are chords 2 and 3. Just bear in mind that whilst the chords need to be next to each other alphabetically, they can appear anywhere in the chord progression and not necessarily in the right order. Hopefully this might help someone out there. If there's any questions or you'd like more detail on this, comment away and I'll go into more detail All the best!

viz

Just on those particular chords, I IV V vi :

BigMonka

So what key would Sweet Home Alabama be in? 

http://3.bp.blogspot.com/-bwLdF_eZmoo/TgOJTGrZD4I/AAAAAAAAHyM/Eerwb7s286E/s1600/can-o-worms.gif

Evo

C and D being your two chords next to each other, puts sweet home Alabama in G major. Never understood why people struggle with that.

Also, the chord progression I outlined would be a 4, 6, 5, 1 in C. Not quite the four chord wonder in the axis of awesome vid which is a 1, 5, 6, 4 in E ( E, B, C#m, A)

viz

Yes sorry I didn't mean to imply the order was the same, nor that your example and theirs was in the same key; just that the axis songs also had I, IV, V, vi, all following your little tip of the IV and V neighbours pointing to the I being the key. Thought it would make you smile I've changed my post

One thing to add to your tip - of course those 2 neighbouring major chords in your example could point to the relative minor of the key mentioned in the original post, in other words be the VI and VII not the IV and V. So for example in your Fm A G C example, C major might be the key, but so might A minor - for example The Passenger (Am F C G), which is i VI III VII, not vi IV I V. The "i" is the A, and the song is in A minor. I'm sure the OP knows this and obviously the key signatures are the same, but thought it worth writing, just for the sake of completeness

Regarding SHA, I think the D crowd would say it's in D mixolydian, so the key signature would be 1 sharp like G major, but the tonal home would be D, if that's where they felt it was, therefore no inconsistency between your view and theirs, from a key sig perspective at least.

Just as a point to note, and again as I'm sure the OP knows, for songs that are diatonic but are not written in Ionian, like Satriani's Flying in a Blue Dream, where the two neighbouring major chords (C and D) don't point to the song being "in G" but "in C Lydian" - in keeping with your tip, the sig would normally be written with an F sharp, ie as G major, notwithstanding the tonal centre being C (though some might favour writing it as though it were in C major and raising every F to F# - both are possible.)

Non-diatonic songs like The Damned's "I think I'm wonderful" which has a I and a II, may not have a IV and a V, so you'd have to be careful of using your tip for this or other songs with such non-diatonic progressions and borrowed chords.

Evo

Non diatonic tunes are most definitely a big no-no with this approach. So if you're into anything atonal or weird and freaky then you're going to need to start looking a bit deeper into your theory.

The modal stuff is all bang on like Viz says. Whilst this trick will point you at the right notes, it might not necessarily give you the correct tonal centre. Someone mentioned "another brick in the wall" on another thread and that's a good example of this. While most guitarists play this in D minor, it's actually in C major/A minor but focusses its note choices around D. Which is called playing in D Dorian. I'm sticking to my guns on SHA being in G though as 2 out of the 4 bars in that chord progression (and therefore half the whole song) is G. Seems like a good tonal centre to me, just seems like people can't shake that "first chord is the key signature" mentality.

So yes, while this trick works, there is a bit more to the theory side of it. But if you only want to know which notes to play and aren't too bothered about what to call it or why it's called that then this should do the ticket :-)

viz

Sha - I am 49% with you on that one. But I ask you this: what is ACDC's Back in Black in?

Evo

Now you're talking!

Back in Black is a tricky one to call, you can justify a couple of different answers but taking everything into consideration I think the best compromise is E mixolydian. Gives you the b7 for the D5 and the G doesn't sound too odd because of "blues rules" ;-)

viz

I agree, it's a 1 b7 4 4 progression, like Fleetwood Mac's "Don't Stop Thinking about Tomorrow", Journey's "Anytime" or J Geils Band's "Centerfold".

Here they are, if anyone's interested in what a true 1 b7 4 4 sounds like:

Back in Black (in E)

Don't Stop Thinking about Tomorrow (in E)

Anytime (in E)

Centerfold (in G)

Lots of fun can be had discussing whether SHA is a 1 b7 4 4, or a 5 4 1 1. But that's for another thread, preferably one that's been closed.

Col_Decker

Last chord in the progression = close enough for rock n' roll

Evo

Fleetwood Mac has another clue later in the song with the B7 but dominant chords are for another thread ;-)

GuyBoden

Good stuff, spotting the Fourth and Fifth chords seems like a good idea for finding a Key with traditional harmony (the stacking every third note in a Major or Minor scale tradition), but obviously it's no use for Modal and more modern harmony stuff.

TimmyO

Col_Decker said:

Last chord in the progression = close enough for rock n' roll

And if it's Rock n roll, that's probably E or A ... 

Evo

Modal is hunky dory. It'll give you the the correct scale, just not the necessarily the correct name for it. For example, if you looked at a D major to C major vamp as being in G major then you'd still be playing the same notes as if you thought of it as C lydian. The lydian scale is more correct, but that wasn't really the purpose of this thread

GuyBoden

Ambiguity in harmony is sometimes (purposely) created by playing Major triad chords when in theory they are seventh chords.

C E G = C Major Triad Chord
C E G Bb = C7 chord

The Bb note in C7 gives the chord the 7th sound, otherwise it sounds the same as a C Major triad. Personally I find C7 sounds a bit boring, because it anchors you to a key with no ambiguity.