Finding primary chords within a scale

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Posted by Ray_Chappell on May-26-2008 22:54:

Finding primary chords within a scale

I'm new to formal music theory... I have a question regarding primary chords within a scale. Music Theory for Idiots lists the primary chords for Major scales, but not minor scales. So, after Googling around, I found something that said in order to find the primary chords you count 5th from the tonic up, and 5th from tonic down to get the primary cords.

So, if I'm doing this correctly for Em scale, 5th up from tonic (E) is B, and 5th down is A. So, am I correct that the primary cords would be E, B, and A? And would those be I, IV, and V chords, in that order?

Appreciate any help!

Posted by DigiNut on May-26-2008 23:09:

Correct.

Although I'm not sure why they'd tell you to count down a 5th. The primary chords are I, IV, and V, so you count up a 4th and up a 5th. Isn't that a lot more intuitive?

Just so there's no confusion, even though the root is always I, IV, or V, the V chord is different depending on whether you're talking about the harmonic, melodic, or natural minor scale.

Posted by Ray_Chappell on May-26-2008 23:23:

Appreciate the response.

So, if I'm counting up a 4th and 5th, wouldn't that make the IV cord A (up 4), and V chord B (up 5) (knowing, as you said, the V chord can change)?

When I count up then down, I end up with the IV cord B (up 5) and the V chord A (down 5)?

Hopefully I'm not making this more complicated than it should be... just want to be sure I get it right so it is easier in the future.

Thanks!

Posted by cryophonik on May-26-2008 23:26:

It gets a little trickier with minor chords because they can be built on one of three minor scales, but you're on the right track.

You should probably brush up on the differences between the natural (pure), harmonic, and melodic minor scales to understand why the chords are different as I explain it below. This webpage explains it clearly:

http://en.wikipedia.org/wiki/Minor_scale

First, the general convention for referring to chords is to use upper-case Roman numerals for major chords and lower-case Roman numerals to refer to minor chords. That will make it easier for you to follow along:

the primary chords in a natural minor scale are i, iv, and v (all minor chords); therefore, in the key of E minor, the primary chords would be E minor, A minor, and B minor.

In the harmonic minor scale, the primary chords would be i, iv, and V. Note that the dominant V chord is used because the seventh note in the harmonic minor scale is a half-step higher than that of the natural minor scale - that note is also the third note of the V chord (aka the dominant 5th) and determines whether the fifth chord is a major or minor chord. Therefore, in the key of E minor, the primary chords would be E minor, A minor, and B major.

Ready to be totally confused (if you're not already)? The melodic minor scale has different notes for the ascending scale than it does for the descending scale. The descending scale is identical to the natural minor scale, so the primary chords would also be the same: i, iv, and v (E minor, A minor, and B minor). However, the ascending scale of the harmonic minor has a raised sixth note and seventh note (relative to the natural minor scale). So, the primary chords that are built on the ascending scale are i, IV, and V (or E minor, A major, and B major).

One last point - it's not uncommon to use more than one of the three different minor scale variations in a given piece, depending on the style of music. However, I think you'll find that most trance songs use only the natural minor scale/chords.

HTH.

Posted by Ray_Chappell on May-26-2008 23:46:

VERY helpful - appreciate it! This will help make a bit more sense of what the music theory book is saying and puts me on the right track.

Thanks!