Making V-I More Interesting Part 2: The V Side 2

In the last part of this tutorial, I deliberately left out a concept that is commonly known as tritone substitution of dominants. Many people have a general understading of how to use it but the musical background on this usually is a little bit foggy. Also, the application of this concept in a more "film musical" context seems tricky, so I'll try to clear up a few things here.

After the vote about how advanced the contant here should be turned out in favour of being more advanced, I tried to structure this post in a way that it lays fundamentals in the first part and digs really deep towards the end so that hopefully everybody can take something out of it.

The inherent property of a dominant chord like G7 that makes it want to resolve is the inherent instable interval of the tritone between the third (B) and the seventh (F) of the chord:

https://soundcloud.com/robin-hoffmann/v-i_tritone/s-4Ibp34LHcBr

The general and traditionally accepted property of a tritone is that it wants to reslolve to a more stable interval. However, a tritone can resolve in two directions: Either by moving both voices a semitone outwards to form a minor sixth or by moving both voices a semitone inwards to form a major third:

https://soundcloud.com/robin-hoffmann/tritone-possible-resolutions/s-2WIC7cUrkpT

If we now fill these up into full chords again, it means that a G7 could either resolve to a C major triad or to a Gb major triad:

https://soundcloud.com/robin-hoffmann/g7-both-resolutions/s-DHqRmx63Jlh

The consequence of this is that if every dominant chord has two possible target chords that it could resolve to, then every tonic chord would need to have two different dominant chords that it could follow.

In case of the tonic of C major, these chords would be G7 and Db7 which both containt the exact same tritone:

https://soundcloud.com/robin-hoffmann/cmajor-both-dominants/s-SlsSm3XUh6D

So this is the dry and basic theoretical approach behind the concept of Tritone Substitutions. The approach would be that you can substitute any dominant chord with a chord that is a tritone away from it (G to Db for instance).

There are two more ways to quickly find a possible tritone substitution:

Exchange the function of the chord tones that form the tritone: in G7 the B is the third and the F is the seventh of the chord, in  Db7 the B is the seventh and the F is the third. While this doesn't seem like an easier way than just doing the maths of finding the chord a tritone away, it creates a bit more understanding of this progression

The easiest approach would be to simply form a dominant chord on the note that is a semintone above the root note of the TARGET tonic (Db being a semitone higher than C)

Up to this point, this concept usually is well known among musicians, however I know that a few misconceptions about this approach are pretty wide spread even with experienced musicians that I'd like to clear up here:

1. Tritone Substitutions are a Jazz thing and are tricky to apply in  "non Jazz" contexts

While it is true that this form of substitution is often used in Jazz, it by no means is exclusive to it. The approach was well known even centuries ago. Here's an example by Haydn (which from the perspective of Jazz could be considered ancient) that uses a quite exposed tritone substituted dominant:

https://soundcloud.com/robin-hoffmann/haydn-tritone-substitution/s-i3vFE5qaKq3

The target chord of D major in the very last bar is not reached by the "traditional" dominant of A7 but rather through its tritone substitued version of Eb7.

2. Tritone Substitutions need to be Dominant 7th chords

While it is true that only "full" dominant seventh chords will include the tritone that resolves, our ear is so trained to this that even a major triad could work to create that "dominant feeling". In the following loop the Db functions as a tritone substitution for a G chord:

https://soundcloud.com/robin-hoffmann/triad-as-dominant/s-pJnVug2Z8aq

3. Tritone substitutions very often sound weird and forced and usually don't work too well

There is some truth to this, but only if you don't put effort into this. In fact the example by Haydn above is perfect to demonstrate how great such a substitution can work if you set it up properly. Observe the great voice leading in the cello which sets up that Eb perfectly before it appears. The moment where the substitution appears and resolves feels musically very attractive as it creates a pleasant surprise without being too on the nose and feels very logical in this context.

This is an essential point you should take away from this. Even though theoretically it is perfectly fine to simply subsitute the chord, it works way better to properly set up the substitution by leading towards it (as seen in the Haydn example).

4. Either the regular or the Substituted Dominant

There is no rule that says that they both are mutually exclusive. In fact, they can even form a chord progression:

https://soundcloud.com/robin-hoffmann/both-dominants/s-vNdKazM2R7b

Of course "regular" chord colorization like sus4 or added tensions are possible as well.

5. Tritone Subsitites are a Voice Leading Nightmare

It is definitely true that a chord progression that shares no common tones (like going from Db7 to C) is tricky to voice lead. Particularly the fact that from Db to C a lot of voices will move in parallel motion (including their fifths) if you don't put effort into it, things might become musically unpleasant very quickly. So yes, it is not easy to voice lead a tritone substituted V-I easily but that shouldn't be a reason to not use it as with a bit of effort it is definitely possible to avoid annoying parallelisms that are clearly audible.

There is one more essential point to address here: While it seems quite understandable that the regular and the substituted dominant share the same tritone, these chords are even more alike than you might think.

Jazz piano players learn very early on that you can use the same right hand voicing for an extended harmony of the dominant and its tritone subsitution and simply change the bass note:

https://soundcloud.com/robin-hoffmann/right-hand-voicing/s-dOZAzEO8kip

While the G13 voicing from a musical standpoint seems quite "standard" for anybody who often deals with extended harmony, the interesting part happens when you apply this voicing to its tritone substitution as it transforms into a Dominant 7th altered voicing.(If you don't know what this is, just stay tuned for an upcoming tutorial about scales that will clear these up). From bottom to top the Db7alt. right hand voicing contains the third, b13, 7 and #9

While the natural "reflex" when seeing an altered chord is that you feel like it creates a lot of new colour with all these "non standard" tension notes, when applied to a tritone substituted dominant it in fact smoothens things way more.

Compare the supposedly weird altered voicing to a rather straight forward dominant9th voicing of the same chord:

https://soundcloud.com/robin-hoffmann/db7-chord-comparison/s-lkeBzQj0djp

It seems like in this context, the musical flow from the altered voicing to the tonic feels more natural than the supposedly "simpler" voicing.

The reason for this becomes rather clear when you compare the possible scale material:

While the Db mixolydian has a lot of different notes compared to the target of C ionian, the Db Altered scale shares almost all tones with the target scale which of course smoothens the transition tremendously, particularly when writing melodies on top of it. While of course in some cases it might not be desirable to smoothen this progression as you might want the tritone substitution to stand out, in cases where you want the transition to be more "organic", the choice of going for altered might be the better one. And of course you don't need to establish the entire altered chord as harmonic support in this bar but your choice of melodic notes on top of it will already imply that scale and have the "smoothening" effect.

With these strategic approaches it is possible to embed a tritone substituted V quite easily into a chord progression without having it stick out. It is still nothing that is every day business in media music but when placed at the right moments can create a fantastic effect.

In the next part we will have a look at what we can do to the I side of a V-I to make it more interesting.