Random but important theory

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Over on Facebook, I am running a daily quiz where I ask a theory question and pick a winner at random each day. I am doing it to promote my Music School and every winner gets to enroll in a class for free.

A lot of people are participating over there and the conversation is heated sometimes. Even when I post a question that I consider pretty cut and dried, it seems like someone wants to argue with me. That is fine of course and it is not like these questions are about trivial facts that are not useful in real life music. They are actually things worth discussing and arguing about.

Here are some of the questions and my take on the answers.

There are technically 12 diminished 7th chords possible. But practically speaking, how many diminished 7th chords really exist?

There was not much debate about this one. There are really only 3 diminished 7th chords that can each be inverted into 4 different positions. In other words, C, Eb, Gb and A diminished 7th chords are all just inversions of the same four notes. Same is true for C#, E, G, and Bb as well as D, F, Ab and B.

Why is this important to understand? Probably the biggest benefit is that it just makes the chords easier to learn and use.

Name 1 of the 2 chords that most naturally can be substituted for C7.

Now there are a lot of possibilities here but my question is which are the most natural. First of all, it is most likely that the C7 will be used in context of a V chord in the key of F. Knowing that, there are two chords that very naturally substitute for a V chord: ii and vii. The most natural variations of those chords? The ii is usually a minor 7th and the vii is usually half diminished. They are most natural because they are diatonic.

So, translating those numbers into chord names gives us Gmin7 and E half diminished.

Many people answered with F#7 which is the common tritone substitution. That is a fine substitution but I would not call it natural.

What is the most natural and common substitute for a I chord?

Most people said vi. I think iii is more natural because iii and I are functionally equivalent. That being said, I did say which is more natural AND common and since I can’t prove which is more common, I counted both answers as correct.

What is another name for this chord: Cm7(b5)?

I was looking for C half diminished. Strangely, people really over-analyzed this, but many did get it right. A lot of them notated it as “C half diminished 7” and things got a little heated when I stated that saying “half diminished 7” was redundant because a half diminished chord HAS to have a 7th in it. Hey, I am right about that but is it worth arguing about? No…. Sometimes, a Facebook break is a good thing.

What is the #11 in a F#7 chord?

The answer is C. The easiest way to think of a #11 is as a tritone away from the root. There are only 6 tritone intervals (C-F#, C#-G, etc). Memorize them and this gets easy.

But sigh, there was the debate about whether you should call that note C or B#. Technically, B is the 11th so the #11 should be B#. But let’s get real. Is it easier to read C natural or B#? When I am writing, I am going to write C natural to make things a little easier for the readers. But that is just my opinion.

You are in the key of C and play a C triad. You want to add a 7th to it. What is the note you are most likely to add? (Hint: there are two possible 7ths)

I am most likely to add a B natural because that is the diatonic choice. I chords like to be major 7ths and about half the time, I turn them into major 7ths. That being said, there are occasions where you would use Bb, making the chord dominant. I do this often when the next chord is going to be a IV chord. Adding a Bb turns the chord into a secondary dominant V/IV.

But again, my question was worded imprecisely and because I could not say which one is used more often, I ended up counting both B and Bb as correct.

In the key of Eb, what chord would be classified as the V/iii?

I thought this would be easy. When I write V/iii, I am referring to a secondary dominant called a “five of iii.” To find this chord, you simply go up a fifth from the iii chord. The iii chord is g minor so that makes the V/iii a D chord.

Now, in my world, a secondary dominant is always a dominant chord (meaning a major triad with a minor seventh added). It is just expected. But several people are arguing with me about that on Facebook and I have had to repent and concede that you don’t have to make that chord a dominant. It can remain a boring major triad if you want to and over history, many times, that has been the case.

So, I ended up accepting either D major or D7 even though I prefer D7. Dominant chords resolve down a fifth much better than major triads.

Some classical purists are taking me to task because they claim that I need to be explicit in my use of Roman numerals. In other words, they say that I was looking for D7, I should have said V7/iii.

I don’t agree. That is not the way we do things today. Modern writers are more likely to write V and give the performers the flexibility to play that V in any way they want. In my case, if I see a V, I am definitely going to add the 7th and probably one or two other color notes as well. According to some of my classical friends, that apparently makes me a bad person 🙂

If this kind of discussion is interesting to you, come join us. I am posting a new question every day for the next few weeks.