Cm7/G - What is a Slash Chord?
In jazz piano and other music when a chord symbol is followed by a slash and another note, we have a slash chord: Cm/Eb for example.
Slash Chord Broken Down
This could be a very short article because there are only two rules to slash chords, and they are:
1. the chord is to the left of the slash
2. the bass note is to the right of the slash.
Jazz pianists: play the chord on the left side of the slash and include the root of the chord (such as a C in a Cm7.) Do not play the note to the right of the slash unless you're playing solo piano where it would be the bass note (left hand.)
Bass Players: Play the note after the slash, the bass note.
Here's what a simple Cm7/G looks like in sheet music. Notice that we're playing the root of the chord, the C, in the right hand chord voicing (wikipedia link and see below). Play a G in the left hand, and C-Eb-G-Bb in the right hand:
If the bass note is repeated for several bars with the chords on top changing, it's called a pedal (wikipedia link) and is used to build tension in the music. I'll talk more about building tension in music in a moment.
More on using the root in your right hand chord voicing: breaking the rules?
Normally jazz pianists play rootless voicings, chords without the root (the C in a C7 chord.) The reason we don't need to play the root is because the bass player is doing that, or in solo piano it's our left hand. However when I see a slash chord I normally add the root somewhere in the chord voicing because it needs to be in the harmony and the bass player is covering a different note, the note after the slash, such as the G in a Cm7/G slash chord.
Slash chords often don't sound right unless you include the root somewhere in the chord.
The Argument Against Slash Chords
The main argument against using slash chords is that with effort and some creative theory, you can spell out any chord without a slash. Instead of saying Bb/C, you could say C9sus4, however...
There's a reason for that slash chord.
Even though you can almost always spell a chord out scientifically, note for note, number for number, exactly as it "should be" from a jazz theory point of view, that doesn't mean you should. Jazz is art and science, and as a musician dedicated to the energy of live performance and creating an atmosphere of skin tingling groove, I never want science to come before my art.
For example, take a look at the Fm6/C chord below. It could also be written as a C11(b13) but I decided instead to use Fm6/C because the sound of an Fm6 is what the music calls for.
The first step in improvising over slash chords is playing over the chords (improvising on the chords), not the bass notes. You can find more information on improvising over slash chords below.
The Reality of Slash Chords
In the example above, the chord can be written both ways, as an Fm6/C or as a C11(b13). As a composer, what determines the use of a slash chord is the harmony you want at that point in the music.
I chose the slash chord because in that part of the song the harmony is alternating between an F minor sound and a C7 sound (a common 5-1 relationship.) In the bigger picture, I just wanted that sound of an F minor flat 6 at that moment in the music.
On the other hand, if I had something else in mind like resolving to a CM7 chord, the chord would undoubtedly be written as a C11(b9) because it would put the musician mentally in the key of C for that part of the music, giving the musician the best opportunity to jam on the music as possible without any confusion.
As a jazz pianist/jazz musician these things become more natural as you are exposed to them.
During the process of learning more songs and further developing the ones you already play, you will eventually know the architecture of jazz so well that you play the sounds you are hearing in your head without having to think at all about how.
Why Do Jazz Pianists Use Slash Chords?
Slash chords and especially pedal tones are useful when you want to calm the music down or go the other way and build up to a transition in your performance, to raise the potential for some kind of awesome splash-down that will drive the audience crazy.
A great example of using a pedal to work things up is Monty Alexander and his trio with John Clayton on bass and Jeff Hamilton on drums playing "The Work Song" by Nat Adderly at the Montreaux Jazz Fest in the late 70's.
Take a deliberate listen at the 11:05 mark of the vid below if you're not swinging out of your mind by then as Monty sets up a pedal tone that they hold for 8 bars while Monty does his thing. Then they move up a half step and build more tension. He goes through the keys until eventually picking one to be the 5th of the next key he wants to go in. He doesn't care about keys, it's music, man, if it's time to jump into the groove it doesn't matter if it happens to be in a different key than you started. If you're too tight to be OK with changing things up like that, your music is going to sound tight.
Just when you thought there couldn't be any more tension, any more delicious anticipation, Monty revs it up one more notch before the band explodes into a heavy swing and annihilates a chord progression they were repeating earlier.
Where Do I Use Slash Chords?
As a jazz pianist you have a lot of opportunities to use slash chords. You have 10 fingers, 88 piano keys and pretty much any 5-1 chord progression (and derivative thereof, such as a 2-5-1) can be turned into a slash chord/pedal tone.
Take a look at the tune "Beautiful Love" (a standard we should all know!) It opens with a 2-5-1 in D minor.
To give it a different sound, the entire first line (above) can be played with an A pedal. Here are chords I might play in a solo piano situation. The chords include melody notes along with the harmony, so be sure to bring out the melody, that is, make the melody louder than the rest of the notes. Record yourself playing this and listen to it, make sure the melody comes out.
You can do the same thing in the next four bars by using a C pedal.
Note: I didn't pick those bass note pedals out of thin air. Did you notice that the pedal note was the 5th of the key center? The same 5th that would be in the 2-5-1 chord (link goes to LJP 2-5-1 lesson) progression of the same key.
In the first four bars the key center is D minor, the resolution of the 2-5-1. The 5th of D minor is A, and because the 5th is very friendly with other chords and notes it can be used as pedal tone in many situations. The more you experiment with it and practice tunes that use it, the more you'll learn where you can use it.
Practicing and Improvising Jazz Piano Over Slash Chords
No matter how you feel about slash chords, the fact is you have to play them and improvise over them. Don't get caught up in the semantics of how you're going to spell the chord, argue about how the chord should be spelled and if it should have a slash or not, instead get caught up in is how to make your music the best it can be by jamming over the sound of that slash chord as it pertains to the music. Jam it like you own it.
The first thing you do when you see a slash chord is figure out how it relates to the music around it. That's part of always knowing what's happening ahead of you in the music and how it relates to what you're playing at that moment. This is so you can get an idea of the harmony (which may or may not be obvious) and play appropriately.
When you are improvising you must know what the harmony is ahead of you and what the harmony is behind you while also focusing on your improvisation so that what you're playing is going somewhere and leading the listener to the next harmonic center in a musical way.
If you're having trouble figuring out the harmony over a slash chord (or any chord) try checking altered notes in the melody, notes that have sharps, flats, or naturals. Often these notes will be the reason the chords have alterations like a C7b5 or F7#9. Examine the Beautiful Love snippet above. The song starts on an Em7b5. The reason for using this chord symbol is that the A in the first measure is the flat 5 of the E minor chord, so we add the flat 5 to the chord symbol.
Playing notes over a chord is easy, playing notes over a bunch of chords while compositionally preparing to resolve to a new key is what you are striving for.
Jazz Piano Improvisation Tip
If you don't know what notes will work when you're improvising over a certain slash chord; some of them can be tricky, then play the melody or just stop improvising and listen.
The notes you play when improvising are only as good as the space you put around them.
It's OK to stop for a moment, find your balance and sound, and then start playing again. It's worse to play through some harmony using guesswork; the audience knows when you are BS'ing and anyway, you don't have to fill up every moment with notes. Keep in mind that the notes you play during improvisation are only as good as the space you put around them.
Jazz piano improvisation is like a painting- you can't see anything in the painting unless the artist puts some space around them. If you play without any space, filling it all up with notes, then none of those notes will mean anything or be anything more than background noise because nothing will stand out. Use space (no playing) to give your audience a chance to digest what you just played, they need it, and it will help them feel about your music the same way as you.
Hope this helps. Feel free to ask any questions!
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