Hi, I am a theory novice and am trying to work out the theory behind a song I composed.
The verse progression uses 3 chords progressing from Amaj-Cmaj-Gmaj. I can't figure out what key this is! C? G? maybe some borrowed chords? help!
The bridge then uses Amaj, Asus4, Dminor is this a key change?

any help appreciated, thanks!

it depends a lot on how you emphasize the chords but in a way it makes most sense to view it as A or G since you begin and end on those respectively. then again that D minor that supposedly plays some role is only naturally present in C. so I might say C major/A minor with a borrowed A major. that's the easiest way to theoreticize it with the least amount of ad-hoc substitutions.

heh. I guess my point is you shouldn't care too much about key. it could resolve rather nicely into a G major/E minor as well. when playing around with your chords I really feel an urge to either stick a D major in there and resolve to E minor, or just switch the A major to A minor. B flat could do some nice things to establish the D minor. F could strengthen C.

sorry for incoherent ramble. I'm not in top shape.
Last edited by qa2pir on Sun May 20, 2012 6:02 pm; edited 3 times in total

Hmm, the key is really going to depend upon the context in which you use the chords and how you resolve them. The relationship between the A major and C major chords is called a chromatic mediant relationship, which can really occur in many contexts, especially in today's music. However, I'd need to see more of what your doing to say the exact key -- what you've supplied can be resolved in a number of ways. If I had to say a key (and I'd rather not without seeing more), I'd venture G major or C major, as your progression resolves quite easily into them if you throw in another chord, but that doesn't have to be the case. Really, there are a lot of possibilities, and both of the progressions you've provided can do a number of different things.

Unfortunately, the same is true of the second progression you've listed; the context is going to be important as to what key you are in. However, the relationship between chords here is much simpler, since it's a simple V --> I progression. It may be a new key, it may not. If taken with the previous paragraph and we venture the first key as G, then D is the fifth (a very natural destination from G), but here, the expected mode of D is not present, instead substituted for it's parallel minor.

If you'd like, pm me more info or send me a copy of what you've written and I can analyze it a bit more for you, as there currently isn't enough here for a definite answer.

Note: edited a few things.

well that was a better reply than mine.

but I hope you can toss them together for ultimate profit.

Also, as a suggestion, try Asus4, then Amaj to D. You don't have to do this depending upon your goals, or if you just like what you've already written, but I suggest this for the following reason:

If we just look at A --> D in isolation, this is a dominant/tonic relationship. The C# is in this case functioning as the leading tone to D (it is an active tone that is only one half-step away from D, and it wants to move to D). So in your Asus4 chord, have the D move down to the C# in the Amaj chord, and then have the C# move to the D in the D chord.

In short, this is better voice-leading, and it will in general lead you to better results when moving from chord to chord.

You had a fine response, and I agree moving into e minor sounds really nice with the addition of the appropriate chord.

And to bobathan, if you haven't finished writing yet, do that first before worrying too much about the key and anything anyone has told you or mentioned, that way you don't confuse what you've been doing/make changes that you don't like before you're ready to make them. There are a number of possible progressions I could suggest, but without seeing what you've written, they could possibly conflict with what you've already done.

could you possibly supply us with the melody? that often helps guide the ear toward the key.

Let's see.

The first part is

| A | C | G |

I think you have a modulation here. The A is in the Key of A Major (I degree). The C and G are in the C major key (I and V degrees).

In the second part, you have the same modulation, just using diferent chords.

| A | Asus4 | Dm |

The A is in the A major key (I), But the Asus4 acts like Am, (VI in C Major key), and finaly, Dm is the II in the key of C Major.

absent you giving the rhythm, or the tune, I would suggest these answers are guesses.

it's not complicated though. If you feel that A is 'home', or the Dm is home, those are your 'keys'.
does A C G turn around to A, repeat it, and that's your basis for a 'verse'? if so, you can say 'it's in A' and be safe from correction.

'Dm is ii of C' if C is I. There is no particular evidence of that. If this functioned according to a classical sort of paradigm, and Dm functioned like a ii chord does in that functional harmonic paradigm, that will tend to be a true statement. But, Dm is also 'iv of A'. A and Asus are V of D minor. Absent the tune and/or rhythm, no one knows for certain.

C and G surrounding an A as I, tonic chord, is not evidence of modulation. There would be more chords needed to even suggest the possibility and there are none given.

The Asus does not necessarily act like Am. Probably not. It goes to Dm, following an A major, V of D minor.

To the OP: do not heed these guesses. This is just someone showing they believe they have some information about chords that belong to keys, and that they belong to this or that key per se for some reason. There is no completely reliable evidence of key here. This information may not, and probably does not apply.

Amazing answers! can't believe how quick the responses were, such an amazing resource! I had initially thought A, then got confused & thought G or C. Based off your replies I'm again thinking A with borrowed 3 & 7 from Amin for C&G.
This borrowing of Amin seems to fit nicely with the Amaj Asus4-Dmin prog too so maybe still in Amaj at this point using I-I-IV but with the I-I substituted for Amin & Asus4 and the IV D substituted for its parallel minor as KBSoundSmith said?

This logic also seems to fit with the chorus progression I forgot to mention of Amaj-Cmaj-Dmaj-Csus4

A few of you have requested more info/melody so I have uploaded what I've did. Please keep in mind, I am a novice and could only score it through sibelius' midi, so be kind!! (the vocal line is an experiment at this point)
Any advice to improve appreciated
[http://s1175.photobucket.com/albums/r624/bobathan1/]

My "guesses" are the most basic analisys. You can play a C major scale over a C major chord. It works.
Even if Dm is the "home", you still play in the C major scale. It's Dorian mode.
You tonal center are A, but you need to modulate for C major over the other chords. If you stay in A major, you got a mess.

Play a C# note (major third of A) over the C major chord... It drives you to F harmonic minor!
Try the G# (major seventh of A)... mess!

SO, the basic aproach here is


A chord - Play A major scale (A B C# D E F# G#)
C and G chords - Play C Major scale (C D E F G A B)

Asus4 and Dm chords - You still in the C major scale notes (even if your enphasis stay in Dm), so pay in C major scale.

After quickly looking through what you wrote, I'm definitely saying it's A with borrowed chords with a very heavy dose of mode mixture (intended or not). It isn't traditionally tonal, but that doesn't matter. The insistence of the return to A is what's important. Part of why you were probably confused is that musical lines with more active figuration are in constant disagreement with the intended harmony, creating (what I'm guessing, since you're here asking questions) unintentional harmonic ambiguity.

I can give a little bit of advice, but it's going to be quick little obvious things; for anything meaty you'd have to pay me for lessons.

First off, find out what normal score ordering is (order of instruments on the written page) and follow it; it will make your writing much easier to read (and to write!).

The piano parts shouldn't be separated; frankly, with just slight adjustments, this can be written for one piano, not two; the Treble clef should be on top, and the Bass clef below.

For the vocal line, I assume this is for more than one voice. Is it for more than one voice type? If so, that typically will be written on separate lines for each voice type. One thing I'll say is that typically, unless you are dealing with advanced vocalists, you don't want to get too crazy with the line. Vocalists don't get to press a button and have the right note come out--they have to hear it in their head before they sing the note. If the vocal line is not in agreement with the harmony (which isn't necessarily a bad thing), you have to make sure that the notes they sing are easy to access; better yet, don't have the vocal line disagree with the underlying harmony. In general, be conservative with vocal lines.

One other thing: in terms of harmony, I would try to do short exercises (no longer than 16 measures) using simpler, more traditional harmony without conflicting lines. This will help you have better control over your harmonic language, as well as develop more focused melodic writing. This will make writing a bit easier for what you're trying to do.

Thank you so much for the advice & tips, priceless! I'm coming to a new understanding of music theory, so much to learn though! I think I'll try to simplify the tonality for now, I'm not that advanced yet!

There is no evidence the OP is playing scale of A major over what is very likely the so-called borrowed chords which you want to be evidence of key of C.

EG: a C# over a C major chord will be, given the context of some simple changes here, a discord and not more. There is no evidence of scalar application in the OP. Two chords coincident with C major is no evidence of a modulation to that key. It seems you don't quite have what a modulation is. Asus, A, D minor, could well be a modulation but you're not having it because you really want C major for some reason.

There is no sense I can see to implying F harmonic minor or F of any kind. There is no evidence of it. A modulation to F minor will be managed quite otherwise than making the mistake of A major scale over a C chord, I assure you. C# does not belong to F minor. That will be a Db and there's a difference for the distinction. You reveal numerous problems of your understanding of this information.

This is supposed to justify your ad culum guesses as if educated. Frankly it's a display of a lot of undigested information completely out of context. You seem like you've looked at the internet an awful lot in lieu of musical practice.

Sorry to be brutal and nothing at all personal, but you have little to no idea what you're on about.