Chord substitutions

[BillMason]

Ok... how do these work again? I was taught towards the end of my second year of studying Jazz at university, but that was also just before I dropped out, so I forget how to do subs. Can someone please explain it to me? Speak slowly... :-)

[BassChuck]

A chord subsitution is when you play a chord that is different from the one that was used originally.

How and why you do that is a long and complex discussion.

There is an excellent book on chord subs by Andy Laverne, I recommend it. Check also the material that is sold by Jaime Aebersold (www.jazzbooks.com) he has lots of stuff on this.

If you are talking about jazz, then a couple of standard chord subs are: Replacing a V7 with (ii7 V7). For instance, instead of playing G7 to C, you would split the time spend on the G7 between Dm7 and G7 before going to C.
Another common sub is the (really, overused) "Tritone Sub". This involves replacing a V7 with a chord build on a root a tritone away (above or below makes no difference with tritones) from the original root. For instance, instead of the G7 to C, you would play, Db7 to C. Of course you could do the other sub I mentioned along with this and get Dm7 Db7 C. (play that on a piano, you hear its a common sound in jazz). Or you could play the ii7 of the tritone sub and have Abm7 Db7 to C.

Really, there is no end to this except to call in common sense and taste. You can sub every chord until you music is a total mess, so take it easy. There is even a form of Bb blues I've seen that never uses a Bb chord there are so many subs. But, that's what makes music so cool. Have fun.... it never stops.

[IanStephenson]

Mike Dimin's book on bass chords covers this stuff, specifically for bass. http://www.michaeldimin.com/

Ian

[DocBop]

The basic chord sub's are

For Major key
I can use iii or vi
IV can use ii
V can use vii

For Minor keys

I can use bIII
IV can use II or bVI
V can use bVII

Then not a sub, but chords being setup by preceeding them with the Chord's own V and something the chord's ii-V. So lets say a song has a couple bars of a F Ma7 chord. You might see it changed to C7 | FMa7 or even Gmin7 C7 | FMa7. Those aren't sub's it is just setting up the chords. When preceed using the V7 of the chord is also called Secondary Dominants, that is more for analysis.

Other things used is Parallel Keys, mixing chords from Key of same name (C Major and C Minor). Modal Interchange, similar idea. But these are tools used more in composition. Last not sure if a rule, but you'll see Minor chords changed to Dominants just because it sounds good.