Guide Tone Lines Explained: The 3rd and 7th Through Any ii–V–I (Free 12-Key PDF)
A guide tone line connects the 3rd and the 7th of every chord. In a ii–V–I the 7th of one chord falls a half step to the 3rd of the next, and the 3rd stays where it is to become the next 7th. Play only those two notes and the whole progression is there, with no root at all. The free sheet below has it in every key.
What guide tones are
A seventh chord has four notes, but two of them do most of the talking. Here are four common chords with those two notes in blue.
The blue notes are the 3rd and the 7th: F and C in Dm7, B and F in G7, E and B in C△7, C♯ and G in A7. The keyboard above each bar shows all four keys you play, with the root in red.
Why these two? Because they decide what kind of chord it is. The root is shared by every chord built on it, and the 5th is the same in all three of these types. The 3rd and 7th are not:
In a band the bass player already has the root. If you play the 3rd and 7th, the listener hears exactly which chord it is.
The ii–V–I line
Now drop the root and the 5th and keep only the blue notes. Watch what happens at each chord change.
That is the whole cadence: two notes, two half steps. Each time, one note holds and the other steps down. You can also start with the 3rd on top (C–F, then B–F, then B–E) and the same thing happens with the voices swapped. The free sheet has both positions in every key.
A longer line
Put A7 in front of the ii–V–I. A7 to Dm7 is another root movement down a fifth, so the line simply keeps going.
Now listen to the top voice alone: C♯, C, B, B. A line falling by half steps, made only of 3rds and 7ths. The bottom voice moves G, F, F, E. Put the two together and you have a smooth two-part line through four chords without one root.
Four common mistakes
1. Jumping around. If you play F–C on Dm7 and then grab B–F an octave higher on G7, the line is gone. Always take the nearest note: hold one, step the other.
2. Missing the half step on V. The 3rd of G7 is B, not B♭. The tritone B–F is what pulls the ear to C. In other keys, read the key signature carefully on the V chord.
3. Adding the root anyway. With a bass player, your root only muddies the low end. Trust the two notes. Playing solo piano is the exception: put the root in the left hand.
4. Treating it as a chord exercise only. Guide tones are also the safest landing notes in a solo. Put them on beats 1 and 3 and fill in the space between, and your lines will follow the changes.
How to practise it
Print the sheet. Each line is one key. The left half has the 7th of the ii chord on top, the right half has the 3rd on top. Work through it like this:
1. Play both notes as written, slowly, with a metronome on beats 2 and 4. Name the moving note out loud at each change.
2. On a single-line instrument, play only the top voice as long notes, then only the bottom voice.
3. Sing one voice while you play the other. If you can sing it, you can hear the changes.
4. Add one passing note just before each new guide tone, then two. That is the first step from a guide tone line to a solo.
Pianists can add the root in the left hand while the right hand plays the pair. On guitar, find each pair on two neighbouring strings and keep your hand in one position.
FAQ
What is a guide tone?
Usually the 3rd and the 7th of a chord, because they decide whether it is minor 7, dominant 7 or major 7. Some teachers use the word more loosely for any chord tone you aim for on a strong beat.
Why does the 7th go down to the 3rd?
When the roots move down a fifth, as in ii–V–I, the 7th of each chord sits a half step or a whole step above the 3rd of the next one. Stepping down to it is the smoothest possible connection, and from V7 to I it also resolves the tritone.
Does it work in minor keys?
Yes. The same rule holds, the 7th steps down and the 3rd holds or moves by a half step. Only the spelling changes, so start with the major ii–V–I on the sheet first.
How does this connect to shell, drop 2 and quartal voicings?
A shell voicing is the root plus these two notes. Drop 2 and quartal voicings add colour around them. Learn the guide tone line and every other voicing gets easier to find.
Every example on this page was written in Band Session Note, the iPad notation app I make. The pictures are the app’s own screen.
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