Confusion about blues scale and chords

Question

I have no real knowledge about music theory, so my question may be nonsensical. Before my question I need to state an assumption which may be wrong and gets me confused: when playing a song in a certain scale, usually all chords will only contain notes in that scale?

So I look at the pentatonic (minor) blues scale for C which contains: C, Eb, F, F#, G, Bb, C

When I look up a 12 bar blues in C I get the chords C, F and G. I can't get it how these chords are played only with the tones in the scale. What am I not getting?

When playing 12 bar blues in C. Is the solo supposed to be in the C blues scale?

Answer 1

As for your initial assumption, that "when playing a song in a certain scale, usually all chords will only contain notes in that scale": that's actually untrue! See Does playing in scale mean only using notes from that scale? You can (and eventually will) have pitches outside the scale, but often these are best done following particular stipulations that we can't outline in a single answer.

As for the blues scale and chords, they're just two different animals.

The twelve-bar blues in C is based on chords built on C, F, and G. Sometimes there are extensions, and sometimes there are other chords inserted, but that's the basic twelve-bar blues. These chords are used to create the harmonic background of the blues.

Meanwhile, the C blues scale, which you accurately described, is typically used to solo, not to create the harmonic background. In other words, the pitches of the blues scale can often fit on top of the twelve-bar blues, even if they aren't always a part of the twelve-bar blues progression. (But note that you can use other scales/concepts to solo, not just this one.)

It's a bit like baking a cake, maybe. You don't usually put sprinkles in the batter (the basis of the cake), but they sure are good sprinkled up on top.

Answer 2

Blues is a musical form that enjoys a somewhat loose relationship with theory, and perhaps this should be taken as a lesson to all musicians that over-explaining music with theory should be, for the most part, avoided. That does not mean that you should take a pass on learning some music theory and applying it to your music and playing; knowledge of theory is extremely useful. It is great that you are asking questions like this as you attempt to better understand the music.

In music that is based around a harmonic progression, it is perfectly fine to form the melody from notes which are not found in the underlying chords. These notes provide some tension, and are frequently resolved to a note that is a chord tone.

Taking the chords C - F - G mentioned for a blues in C, and considering a C pentatonic minor scale with them (C E♭ F G B♭), the scale contains the 1st and the 5th of C (and also the ♭3 of Cm), it contains the 1st and the 5th of F, and it contains the 1st of G.

You could just play the 1st and the 5th on C chords and F chords, and the root on G chords, in this way playing only notes from the scale that match the chord of the moment.

But, the E♭ and B♭ are the blue notes of the scale (and the F♯ in the blues scale you mention is also a blue note). These are tension notes that are usually played bent upwards a bit. So, the scale has C, E♭, and G, where the E♭ exists in a tense relationship with the C chord, and the scale also has a G and B♭, where the B♭ exists in a tense relationship with the G chord. The missing A (for F) and D (for G) don't keep the scale from relating to the chords, and you could add an A when playing over an F chord, and a D when playing over a G chord, if you like.

It is also worth noting that good players very often do not play a single scale over a set of chord changes (blues or otherwise). Instead of playing the C blues scale over 12 bar blues changes, you could play A pentatonic minor over C, D pentatonic minor over F, and E pentatonic minor over G (this is equivalent to C pentatonic major, F pentatonic major, and G pentatonic major). Or you could try any number of other scales that "fit" with your chords.

The take-away should be that it is important to not just choose a scale that fits a chord progression and then to run that scale over the progression. Even when you do have a scale that fits over several chords, listen to the chord that you are playing over, and try to make what you are playing fit that chord, or play something against that chord (generating tension).

Answer 3

If it helps, think of the scale as the series of notes that match the chord (not the chord being formed of notes that match the scale.) If it helps, think of a chord progression like 'Too Close' in Cm

• Cm
• Eb
• Fm
• Ab
• G
• Cm

It's in C minor, but it's playing both a Bb (in the Eb chord) and a B (in the G chord). That doesn't make sense if you're thinking in terms of a single scale.

But if you're thinking in terms of scale being the notes that fit the current chord, suddenly the Bb vs B makes a lot more sense. The Bb is part of the Eb major scale, and the B is part of the G major scale.

Now move things forward into your 12-bar blues progression. When you're on the G chord, you can play a C#, even though you're in the key of C. Why? Because a C# fits the G minor blues scale.

Hope that helps things make sense :-)

Answer 4

There are three sets of chords you might like to try with the C minor blues scale you describe.

1. You can try Cm, Fm and Gm, which would fit in with your theoretical understanding, as these belong to the Cm scale, from which the C minor blues scale is derived. This will give a powerful but melancholy feel.

2. You can also try Cmaj Fmaj and Gmaj as you describe in your question. This also works very well. What you are doing is substituting the minor chords for their parallel majors. (You may also try using C7, F7 and G7.) This will also give you a powerful, bluesy minor solo, overall the music will be happier sounding than the previous one.

3. Finally, you can try EbMaj, AbMaj and BbMaj. These are the relative majors of Cm, Fm and Gm. The result is music with a jolly, rock and roll feel.

You can also mix all three of these together. For example Cm, Fmaj and G7 sound pretty funky when used together in a standard 12 bar blues progression.

Playing major chords with a minor scale per paragraph 2 is very common in rock as well as in blues. Playing minor chords with a major scale is rather more unusual.

Answer 5

As a terse definition, blues is played in 8 or 12 (or other) bar patterns, comprised primarily of dominant 7 chords on the I IV and V (which does not fit in one diatonic scale) with melodies in minor or major pentatonic scales (from the I chord) and often both with blue passing tones. It is this juxtaposition of minor scales over major chords, dominant 7 where major 7 normally would be, and blue notes, among other things like sliding notes, that give blues it's unique and ubiquitously recognizable sound.