As students of music we aim to train our ears to hear each note on its own terms, and when we improvise, to intend each note on its own terms. To many of us, especially jazz students, scales can be crutches that work against the goal of musical intent because relying on rules like “every note in a lydian scale sounds good on a major 7 chord” can allow the student to avoid the work of hearing each note before it is played. A related risk is that the student gets bogged down in nomenclature and/or comes to mistake the nomenclature for the music itself. I expressed reservations along these lines in an earlier post about my analysis of a wonderful fill played by Brian Charette.

But despite the unfortunate role they can play as crutches and morasses of nomenclature, scales can also serve good and useful purposes for us as students of music: They are a good shorthand for talking about the ways that different collections of notes sound, and for introducing our ears to sounds that are new to us. “Experiment with the sixth mode of melodic minor on half-diminished chords” can be very fruitful guidance as long as we don’t stop there and instead use the guidance as a stepping stone to putting intent behind every note. It’s in that spirit of useful shorthand that I aspire to use the notion of scales when I discuss improvisation.

Some time back I was listening to “Sugar Ray” as played by Phineas Newborn, Jr., Roy Haynes, and Paul Chambers, and in his improvised solo I heard Newborn do something I really liked, something I hadn’t heard other players do in such an overt way: Over a dominant chord, he plays a run on the blues scale of a whole step below. For example, at 2:20 over a G7 chord, he plays a descending F blues scale run:

At 2:32 over a C7 chord, he uses the same idea, playing a descending Bb blues scale run:

When I say “blues scale,” this is what I’m referring to:

In the runs Newborn plays, he omits the fifth degree of that scale, i.e., the C natural in the F blues scale and the F natural in the Bb blues scale.

Because of the reservations about too strong a focus on nomenclature that I referred to above, I definitely don’t suggest that giving something a name in any way represents understanding that thing. Nevertheless I find it interesting to highlight relationships between what Newborn does in these runs and other ways of making note choices for improvisation over dominant chords. So let’s digress for a moment and then we’ll bring things back together.

You’ve probably encountered the notion of tritone substitution before. It comes from the observation that each tritone occurs as the third- and seventh-degree chord tones in two different dominant chords. For example, the B-F tritone occurs in a G7 chord and also in a Db7 chord (questions of spelling aside). And because the tritone accounts for so much of how a dominant chord functions in western harmony, it’s often very musical to substitute one of those chords for the other anywhere that they occur.

If we think of scales as ways of guiding note choice for improvisation, of course we wind up considering the relationships between chords and scales. In major-scale harmony, the fifth mode of the major scale (called “mixolydian”) connects with the dominant chord: G mixolydian contains all the chord tones of the G7 chord. Modes of the major scale can be played entirely on white keys, so it’s for more than one reason that we might say mixolydian is the whitest-sounding scale to play over a dominant chord. It contains no alterations: the fifth degree (D natural) is unaltered, and even the higher-degree chord tones — ninth (A natural), eleventh (C natural), thirteenth (E natural) — are all unaltered.

Now let’s look at white-key mixolydian tones through the lens of tritone substitution. What scale degree alterations does the G mixolydian scale give us with respect to a root tone of Db? F natural is the major third and B natural (Cb) is the flat seventh, so of course we’re still in dominant-chord territory. There’s a G natural, so we’re dealing with a flat fifth, a raised fourth, or a sharp eleventh, however you choose to think of it. There’s an A natural, which is a sharp fifth or a flat thirteenth, giving us an augmented dominant chord sound over a Db root. There’s a D natural and an E natural, so we have both flat ninth and sharp ninth. In short, everything that can be altered is altered; quite a contrast to the white-bread mixolydian sound. A dominant chord with all those alterations is usually succinctly called an “altered dominant chord” as opposed to being explicit about “flat 9 sharp 9 sharp 11 flat 13.”

So we might be tempted to say, “Play the G mixolydian scale over Db7 for an altered dominant sound.” But there’s one problem: The G mixolydian scale doesn’t contain a Db, so it’s not ideal as a bag of notes to choose from for Db7. We want our note choice to give us the option of emphasizing the root of the chord, and instead of the Db, the G mixolydian scale has a C natural, i.e., the natural 7th degree in the key of Db major. That natural 7th can be a useful tone in improvising on a dominant chord, but let’s just say it sounds like a very bold decision except when we use it as a passing tone, and we all know there’s a fine line between sounding bold and sounding unintentional or wrong. So what if we’re willing to trade away this least orthodox of notes, C natural, to get the Db that we want? Then we end up with this (notice the change in key signature from earlier examples):

Commonly called the altered scale, that bag of notes is often heard in jazz improvisation on dominant chords, and as we’ve seen above it embodies the most straightforward answer to the question: “What scale sounds like altered dominant and/or tritone substitution?” There’s no way to transpose that scale so it sits entirely on white keys, so clearly we’ve departed the realm of major-scale harmony. Where are we instead? We’ve landed in melodic-minor (specifically ascending melodic minor) territory: You can probably recognize that scale (spelling aside) as the seventh mode of the ascending D melodic minor scale. By the way, you probably already know that other modes of the melodic minor scale are heard often in jazz improvisation, too.

OK, now let’s tie this back to Phineas Newborn’s trick.

At 2:20 in “Sugar Ray,” Newborn plays over a G7 chord, so let’s look at the G altered scale. Just as the Db altered scale is the 7th mode of D melodic minor, the G altered scale is the 7th mode of Ab melodic minor (notice that now we’re back to the key signature of the tune):

Compare that G altered scale with the notes in the run at 2:20 in “Sugar Ray.” The run consists entirely of notes from the F blues scale, as we said right in the beginning, but look! It also consists entirely of notes in the G altered scale! And even though it’s basically a blues-scale run, it captures most of the “juicy” altered notes: The flat 9th (Ab), the sharp 9th (Bb), and the flat 13th (Eb). Besides those three notes, it contains only the third (B natural) and the seventh (F natural).

Scales and this kind of analysis aren’t an explanation of why a particular idea works musically; Newborn’s idea works because it sounds good, nothing more, nothing less! But by exploring the relationships between his idea and different scales, maybe we can get some inspiration for musical intentions to bring forward in our improvisation — hopefully intentions of our own that will sound good, too. As we can see here, one suggestion you might take away is to experiment with your bag of blues-scale licks — especially ones that don’t use the fifth degree of the blues scale — on dominant chords a whole step up when you want an altered-dominant sound.