Hey all,

I'm aware of what interval the tritone is (flatted fifth...) and where it naturally occurs in the major scale (7th/leading tone)

BUT I'm still having trouble understanding exactly what a Tritone substitution is....

Could someone please give me a brief explanation AND an example that I can listen to (i.e, a standard...)?

Thanks!

--Legs
I'll try to explain this as best as I know how...

so a tritone is either an augmented 4th interval or a diminished 5th interval (same thing). So if we have an E note, a tritone above E is Bb. So a tritone substitution for an E7 chord can be a Bb7 chord, for example.

In an example here: in Footprints by Wayne Shorter the trunaround for it is
F#-7b5, F7b5, E7#9, A7#9

What you can do is do a tritone substitution with the A7#9 so you can play a chromatic chord progression (it can just make life easier) so..
F#-7b5, F7b5, E7#9, Eb7#9
especially nice to do if you're soloing over the progression

hope that helps somewhat
A tritone sub is substituting a dominant 7th chord for another 7th chord which shares the same tritone between the third and 7th (enharmonically).

In C, V7 is G B D F

B-F is a tritone

Respell that enharmonically you get

F, Cb

Which is the 3rd and 7th of a Db7 chord.

In a dominant seventh chord there is a tritone between the major third and minor seventh of the chord.

The tritone is a dissonant interval. That dissonance adds to the tension of the V chord.

The tension inherent in this dissonant interval can be resolved by moving each voice inward by a half step to give us a major third interval.

The interesting thing about a tritone is that is splits the octave in half exactly. You can invert a tritone and it is still a tritone. Any other interval will invert to a different interval. This is the only interval that has this property.

It is these characteristics that make the tritone substitution possible.

You see when we have a V7 chord resolving to an I chord the tritone in that V7 chord is resolving into a major third of the major tonic chord.

For example D7 is D F# A C when this resolves to the G chord (G B D) the F# moves up a half step to G and the C moves down a half step to B.

But if we know that the tritone will resolve this way what if we use another dom7 chord that has the SAME tritone in it and resolve that tritone in the same way?? In the D7 the F# is the third and the C is the minor seventh. If we make the C the third then the root would be Ab and the minor seventh would be Gb (enharmonically Gb is the same as F#).

So we could use the Ab7 chord to resolve to a G major tonic chord by utilising that same tritone resolution.

Another way to look at it would be like this...

A tritone resolves by each of the tones moving inward by a half step. So since the notes of the tritone are the same distance from each other in both directions then they could resolve by both moving toward each other by a half step in either direction.

A tritone of E to Bb for example could resolve
a) by moving the E up a half step to F and the Bb moving down a half step to A (as in an F major chord)
OR
b) it could resolve by moving the E down a half step to D# and the Bb up a half step to B (as in a B major chord)

That tritone (E - Bb) is found in the C7 chord (E is the third Bb is minor seventh) and also in the Gb7 chord (Bb is the third and Fb is the minor seventh).

Notice that the roots of those dominant seventh chords (C7 and Gb7 are a tritone apart??

So the tritone substitution is basically a common tone chord subsitution. The rule is that you can substitute any functioning dominant seventh chord with a dominant seventh chord with a root a tritone away the original chord. so basically bII7-I.

Pick up your guitar and play

V7-I and listen to it
then play
bII7-I and listen to that.

It is different but it has that same resolution of the tritone.

The dom7 chord you are substituting could be a secondary dominant. So insted of II7 V7 I you might do bVI7 V7 I. Try both of these out to see how they sound.
Si
Ah wow never realised there was a tritone interval in the dom7th chord
^^ what these guys said!

I love using it as a secondary dominant in minor keys, e.g. Ab7 - G7 - Cm, kinda like 20Tigers mentioned at the end of his post
Quote by Xiaoxi
The Byzantine scale was useful until the Ottoman scale came around and totally annihilated it.

Can you please give me an example to listen to?
at the end of the chorus of Roadhouse Blues by The Doors (the "let it roll part")
The harmony goes B7 - C7 - B7... the C7 is acting as a secondary dominant (C7 - B7 - E)
Quote by Xiaoxi
The Byzantine scale was useful until the Ottoman scale came around and totally annihilated it.
Tritone-subbed blues, for example: replace the IV and V with a dominant 7th chord a tritone away. If we're doing a C blues, that means that F7 becomes B7 and G7 becomes Db7.

More generally, whenever there is a V/I relationship, or a secondary dominant, you can substitute a dominant 7th a tritone away (which will voice-lead as a b2 above whatever you are targeting/approaching).

So, ii V I in C with 7th chords would normally be: Dm7, G7, Cmaj7. If we tri-tone sub on that G7, instead we get: Dm7, Db7, Cmaj7.

Wonderful sound.
Here's a simplified form:

In a diatonic Major key, a 7th chord is built from the 5th chord of that keys Major scale.

So let's write out the key of C, just the notes in the C Major scale.

C D E F G A B C

Count to the 5th letter, notice it's a G?

OK, without boring you with the theory side, let's call that a G7 (this is what i mean by the 7th chord...the G note forms a G7 in the key of C....if I were talking "shop" with other theory people, I'd write it as the V7 in the key of C, for this illustration)

So this G7 is the chord where we build the tritone substitution. We are going to make a DIFFERENT or SUBSTITUTE for the G7, in the key of C

THEORY ALERT - you need to know intervals and at the very least notes on the neck or something of that nature to understand this next part.

Moving from G you need to find the note that makes a TRITONE away from that G note. Interval wise, it's a b5 away from the root G.

THEORY ALERT - That note is a Db - if you don't know that, you might want to study theory.

So NOW let's use that Db and make that the new SUBSTITUTE - by adding a 7th. Db7, is our Tritone substitute for the G7

So if I had C Am F and G7 in a progression...

I could make that into C Am F and Db7 - that Db7 is a Tritone Substitution for G.

Interesting experiment: If you formed a tritone substitution off that Db7, what would you end up with?

Best,

Sean
Last edited by Sean0913 at Feb 25, 2012,
Tritone-subbed blues, for example: replace the IV and V with a dominant 7th chord a tritone away. If we're doing a C blues, that means that F7 becomes B7 and G7 becomes Db7.

Isn't the distance between F7 and B7 a Perfect Fourth? You mean a tritone away from the Dom7 chord you are Discarding, correct?
Quote by Brainpolice2
Tritone-subbed blues, for example: replace the IV and V with a dominant 7th chord a tritone away. If we're doing a C blues, that means that F7 becomes B7 and G7 becomes Db7.

Isn't the distance between F7 and B7 a Perfect Fourth? You mean a tritone away from the Dom7 chord you are Discarding, correct?

The distance isn't a perfect 4th at all. its a +4 - Do this, write out a F Major scale (the letter names of the notes) and count 4 away.

By the way I'd call the tritone off F a Cb to be correct, naming wise; but calling it B in interacting with real people is acceptable.

Best,

Sean