Available Tensions for Modal Scale Degrees

Question

I have a bit of a tricky topic here. I've been getting into bebop progressions, and I'm really enjoying myself. However the one thing I was missing was those nice lush chords you come by every so often. Hence me getting into tensions as of late. I've been understanding everything well as I usually do but I've only been able to find examples of tensions for major and minor scale chords. For example the available tensions for the I degree would be 9,13 then for the second degree 9,11 and for the III-7 chord you'd have 11. (Major scale, etc going onwards). Now my issue is that I don't exactly understand why these numbers change the way they do. I've found charts listing how every Minor 7 chord can have a 9,11, and other tensions in other modes etc. But they're different when they're of a certain degree of a scale. (For example tge III-7 only able to use 11) This is really throwing me off. I use a lot of modal interchange in my progressions, what would the tensions for the degrees of the other modes be? Why does one source tell me that minor chords can have these tensions when another tells me that if it's of a certain degree of a scale that they can only use these certain tensions and whatnot. (Not only just the minor of course, dominants, augmented, diminished, b5's, maj6's) I'm at a bit of a lose here. I'm currently halfway through a book on reharminization and several violin books and picking up another on tensions is what I'm trying to avoid, however the internet is full of "guitarists" and other "musicians" who don't know much about theory. Way back, finding anything on something as simple as a ii-V in a progression was hard to find on the internet. Any help will be appreciated, thank you very much. Amazing community here! Also, on a side note, if I were trying to figure out the tensions for a Dominant F7 chord in the key of Cmaj (being borrowed from the Dorian mode) how would I determine the tensions? Count up that scale with G as the tonic? I'm new to the figuring out tensions topic. Very confusing and there's nowhere to give me any insight on these things.

Answer 1

The short answer is: higher extensions (tensions, as I think you're calling them) have to fit within the tonic. That's the rule that you've come across. We'll look at a couple exams that meet this rule, and then we'll look at the exception you've described involving F7 in the key of C.

Let's say your song is a minor blues in Cmin. Since Cmin is the tonic, you can add any upper extensions you want to this i chord and it will fit in the tonic. You can treat the tonic as being in the Dorian mode, so that the 13th is A rather than A♭. When you reach the iv chord, Fmin, the A will be replaced with an A♭ (as often occurs in a minor blues), but otherwise, all of the upper extensions (the 9th/G, the 11th/B♭, the 13th/D) fit within the Cmin tonic. In this context, the reason why we can add any upper extensions to these min7 chords is because the upper extensions are in the tonic of Cmin.

It won't always be the case, though, that a minor chord will have higher extensions that fit within the tonic. Just as you've pointed out, let's consider the key of Cmaj and look at the iii chord (Emin). The upper extensions of Emin are F♯ (the 9th), A (the 11th), and C♯ (the 13th). The 11th is unquestionably in the tonic. The 9th is potentially in the tonic: it will sound more dissonant if the next chord is the IV (Fmaj) and it will sound less dissonant if the next chord is the vi (Amin). The 13th is definitely not in the tonic. Using these guidelines, we can make choices about which higher extensions will/won't fit within the tonic.

Now we can consider a scenario involving an F7 chord in the key of Cmaj. Given that F7 is borrowed from the Dorian mode of C, we can use extensions of the F7 chord that fit within C Dorian: G (the 9th), B♭ (the 11th), and D (the 13th). Of course, playing the 11th can create a sustained sound (though it doesn't have to).

In all cases, the overarching rule I'm using is: choose higher extensions that fit within the tonic. I believe this is what you've encountered, and this rule explains why some minor chords can have any extensions, while others cannot.

Answer 2

Thing is, anyone can write just about anything in a book, or on the 'net, and some readers think it's tantamount to the Bible! Obviously (?) it's not!

Apart, it's only theory anyway, and theory that hasn't passed into law. So someone is extrapolating something, and it reads like it's written in stone.

As has been said so many times, on this site in particular, what sounds good probably is, and vice versa.

We must all allow our ears, and those of our listeners, to be the deciders. there are no penalties for doing something musical that someone hasn't 'written in the statute book' - 'cos there isn't really one. What happens is that when something happens successfully a great number of times, mention is made of it for future musicians - a sort of 'this works, why not use it' approach.

You have to be your own guide here, and try certain extensions, some of which may appear to be brand new, but in reality can't be.When you've found a cluster of notes that fits in a particular place in your music, then that's the time to search for a name for it - and there may be two or three. But the ears have it, as the judge said...