I'm learning jazz and playing from lead sheets and am confused about how to handle triads that do not explicitly say what to do with the 7th. If the lead sheet I'm playing from just describes a chord as G, what are my guide tones for that? If I decide to just throw in a minor or major 7th, am I changing the function of the chord?

A plain triad sounds a lot different and either a major or a dominant chord, so I've been almost thinking of them as their own kind of chord.

  • Could you share the lead sheet? May 14 at 15:34
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    This wasn't for any specific lead sheet. I just notice that lots of the fake books I'm playing from have chords that don't mention 7ths. Here's one example: virtualsheetmusic.com/score/HL-21271.html. The C and G chords are plain triads.
    – kitfox
    May 14 at 15:40
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    'The C and G are plain chords'. And there's no reason at all that they should be anything else! Adding 7 (of any kind) changes the chord, and sometimes its function, so leaving a basic triad as is works absolutely fine. Don't get the idea that Jazz needs every chord changing! I played for a while with a guy who played every C maj. as C maj.7. Took a while to convince him it just didn't work well.
    – Tim
    May 15 at 7:40
  • But the C chords in your link are not all plain triads! One of them is a major 7th. That should strongly suggest to you that when a plain C is written, no 7th note is expected.
    – TonyK
    May 15 at 9:54

4 Answers 4


A basic, simple 'rule' is that we have Ⅰ, ⅱ, ⅲ, Ⅳ, Ⅴ, ⅵ, ⅶ° as the main triads diatonically.

The 7ths associated with those are as follows: ▵, m7, m7, ▵, dom 7, m7, °7.

When Ⅰ moves directly to Ⅳ, dom7 is appropriate. But above all, use ears. They will tell, in 99% of cases, whether the choice is good or not.

  • 6
    It took me a loooong time to parse "When I moves". May 15 at 8:54
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    @EricDuminil - sorry, blame the Romans...
    – Tim
    May 15 at 10:44
  • 1
    @Tim I blame fonts without serifs on the capital I. I've found myself instead using Unicode Roman Numerals, like Ⅰ
    – trlkly
    May 15 at 13:40
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    You could just rephrase to “when the I chord is followed by the IV chord” or something similar May 15 at 17:37
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    When I moves, I moves where I wants ta move. And when you moves, you moves where I wants ya ta move. May 16 at 10:37

Direct answers

Guide tones:

Major and minor triads generally are not thought of as having guide tones in the way seventh chords are, since they are considered stable within themselves; whereas seventh chords are considered inherently unstable and needing to resolve. The guide tones are the notes that most typically are the primary points of resolution: the third and the seventh.

To the degree there is (contextual) tension in a major or minor triad, the third of the chord is the first place to look, as it will often be the leading tone of the following chord.

Does adding a seventh change the function of a chord?

One should proceed as though it will. Turning a major triad into a dominant seventh, for example, potentially signals a modulation. It might or might now work depending on the musical context. Similarly, turning a dominant V chord into a major seventh weakens its function as a dominant chord.

Triads and seventh chords as separate entities

Music theory considers triads and seventh chords as separate entities. Further extensions (9ths, 11ths, 13ths) are generally interpreted in terms of the underlying seventh chord.


When a score calls for a triad, it should be played as a triad, without a seventh. Adding the seventh changes the sound and function of chords and risks clashing with the melody.

It is often okay to add a sixth to a triad, for color, because adding a sixth doesn't change the nature of the chord in the way a seventh does.

If the performer judges that a seventh can be played where a triad is specified, then one can follow @Tim's guidelines for major keys and the following for minor keys:

Minor key seventh chords

i = m7 (or mM7 if the seventh is raised)
iio = 7b5 (half-diminished)
III = M7
iv = m7
v = m7 (or V7 if used as a dominant chord / with raised seventh)
VI = M7
VII = 7 (i.e., dominant seventh)

Be careful, when adding sevenths, that you're aware of any modulations. For example, if one is in the key of C major, but encounters the triads F and Bb at a cadence point, then the minor seventh would be added to the F chord — creating an F7, the dominant of Bb — rather than the major seventh, which would otherwise be consistent with C major.

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    Have you met someone who has become a functioning jazz player through memorizing lists of logical rules, but didn't immediately hear when they messed up by adding the wrong kind of seventh? :) I have a hard time believing that such people could exist, but who knows, maybe. May 14 at 17:55
  • @piiperiReinstateMonica - when one has played using the 'lists of logical rules' for long enough, it becomes second nature. I rarely think about which 7th will work now, after years of just following 'rules'. And sometimes, the sound and feel within the piece will encourage those 'rules' to be broken - it just works. You don't do it and immediately hear, you just get the appropriate 7th first time!
    – Tim
    May 14 at 18:00
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    @Tim That sounds like a painful road - following lists of rules. I hope nobody has to learn music that way. I certainly didn't, and I'm glad for that. I strongly believe that music should be learned mostly by doing and feeling, with a little bit of intellectual guidance if absolutely needed. A lot of people in the Western world seem to seek a mainly intellectual approach to everything. This site is in a way a manifestation and product of that mindset. May 14 at 18:25
  • @piiperiReinstateMonica - I learned guitar and bass by trial and error, and won't let students waste their time following that path. True, it works - if you live long enough. But it's hardly enlightening, and knowing certain facts - and applying them appropriately - makes a lot more sense in retrospect. I could have saved literally years! And eventually did...
    – Tim
    May 14 at 19:03
  • @piiperiReinstateMonica I have not learned jazz (beyond a few basics), but the way my mind works is very attuned to understanding “rules” and structures and then extrapolating. So if I had learned jazz, it would likely have been similar to what you describe. One thing I’ve learned in ensembles is there are as many valid ways to learn and understand music as there are people in the world. May 15 at 17:41

In short: know what the simple written version would sound like if played literally like that, and then do whatever sounds good to you. You must develop your own sense and taste for what sounds good through practicing and trying things. Theory gives you ideas and tools for finding things to try, and to reason about what others play.

We could solve this question either by writing an endlessly long list of logical rules and checklists that even a deaf person could mechanically apply... or we could solve it like it's actually done: with ear and taste.

The only actual rule is: play whatever supports the melody appropriately for the occasion. If it makes you feel better, play it. If it makes your audience feel better, play it. If it makes you or your co-musicians confused, don't play it.

Chord symbols are written (by people) as guidance for accompanists (other people), and together with the lead melody, they describe the lead-sheet writer's view of what the most important idea of the song is, when described in simple, coarse terms. But it's just a starting point - all that can (and should) be jazzed up in various ways. Whatever chord symbol is written, it's just one possible idea, and each chord symbol should be read as meaning a rough umbrella term as a whole family of possible chords. And even then, you can ditch the whole rough idea and play something from a different family of chords, if you think that it suits your own idea better.

Quote from Jazz Piano Book by Mark Levine

The unhappy fact that the chord symbols C, C∆, Cmaj7, CM7, C6, and C69 all mean pretty much the same thing and are often used interchangeably can be discouraging to a beginner. In this book, I’ll use the ∆ symbol for all major chords.

So, in his book, he writes a "maj7" chord symbol, whenever he means any sort of non-dominant major chord. The actual realization of the described idea (IF you decide to follow that idea and not some other one) can even be a simple triad, or it could be a four-note or five-note chord, and it still fits the same general category. But dominant chords are a different family of roles, as you know.

However, lead sheets are not generally written like that - Levine just wants to say with this notation that many types of chords are interchangeable, and when you see any written chord symbol, you should generalize it in your mind to a wider overall chord family, and then play something within that general ballpark. You learn to do that by trying different things and messing with the songs.

Your example lead sheet of My Favorite Things, starts with four consecutive bars of "Em". It certanly cannot mean that you must hold the exact same chord for four bars, that would be boring, wouldn't it? Myself, I would be tempted to play a descending line: Em - Em maj7 - Em7 - Em6 - ... and on the next line, instead of the written Cmaj7, I would do the same over Am: Am - Am maj7 - Am7 - Am6 (depending on the occasion, maybe trying not to sound like Stairway to Heaven). But then there would have to be yet another change on the third line to get a change there... Maybe if the second line has to be a C based chord, I might alternate between Cmaj7 and D/C, to keep some motion going.

what are my guide tones for that?

Your guide tones are from the chord that you imagine. You might see four bars of "Cmaj7" written on the lead sheet, but if you want to play: C - D/C - C - D/C, then over the imagined C your guide tones are from C, and over the imagined D/C your guide tones are from D/C.

  • Quoting Levine means nothing - to me. He rarely backs up what he says convincingly..
    – Tim
    May 14 at 18:03
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    @Tim You read him wrong. :) Do you not agree that jazz players think of chords as interchangeable families? May 14 at 18:06
  • Having slept on your comment...True - depending on who/whatever else is playing, I may use different chords - not only from a close family (tts, etc.), BUT - surely it's easier to use those others have found to work well, rather than start from scratch, as you seem to advocate. Why re-invent the wheel? Just about every aspect of life relies on what others prior have succeeded (or failed) with before. But use that as a start point. Written chords are there because the composer wanted those in particular - in my own stuff, I write what I want (or would prefer) played - it's my baby! But...cont.
    – Tim
    May 15 at 6:36
  • ...cont. contrary to M.L. I don't see that Cmaj7 is a drect substitute for C6, or even that sometimes there is a sub. for basic C. His sweeping statements don't wash, and are rarely followed up with convincing examples (to me). So statements in what are supposed to be educational tomes are substantially weakened by that (for me).
    – Tim
    May 15 at 6:41
  • @Tim Levine describes a certain style, or styles, of playing employed by many players. You may not like the results of that style, but that's a different question. Chords being interchangeable means that a player considers swapping them for the sake of playing something different, but without breaking the harmonic story. Substituting a Cmaj7 with C7 can change the harmonic storyline in ways that a Cmaj7 <-> C6 switch probably won't - which is what Levine is trying to say by using the C∆ symbol for all non-dominant, non-altered major chords. I advocate taking theory-talk as hints, not rules. May 15 at 11:32

If it says G it might truly mean a G triad. Especially if a country or pop tune.

If that doesn’t sound quite right then it probably means GMaj7 or G6.

If neither of those sounds right then you should look at the chords before and after it and figure it out from the context. So if it is followed by C7, chances are it is a Gmin7, or if it is followed by C7b9 it is probably Gmin7b5.

If it is a 12 bar blues then they probably mean G dominant 7.

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