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I'm currently learning a 12 bar blues rhythm and am getting confused by it.

The solo is played over the A minor pentatonic scale.

And the underlying chord progression is A - D - E.

But isn't this actually a V-V-V progression with key changes? There is only one dominant seventh chord which sits with the mixolydian scale.

When i play the D minor pentatonic on the D7 and the E minor pentatonic on E7, it doesn't sound bluesy at all. But if i stay in A minor pentatonic throughout, it feels far more bluesy.

Why do they call it the I-IV-V progression isn't this technically incorrect ?

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4 Answers 4

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To be clear, a blues progression is called a I7 IV7 V7 progression rather than I IV V which implies diatonic chords (in Bb that would be Bb major, Eb major, F7).

Blues progressions actually do not conform to standard western musical harmony, you are correct by saying that improvisations will sound strange when playing diatonic major modes over the equivalent of chords.

Traditionally, blues progressions are almost always improvised over using a minor pentatonic or blues scale of the key that the blues is in. They are often very straight forward harmonically.

My personal approach to improvising over blues scales is to rely heavily on the key's minor pentatonic and blues scale, while adding in chord tones from the IV7 and V7 chord where necessary rather than using the other extensions of the scales that you would normally play over those chords (5th mode harmonic minor, etc) which can sound a little strange because they sound like they take you into other keys (bVII major over the IV7 chord etc).

If you are going down a slightly jazzier path, you can implement whole half and half whole diminished scales over the chords and as long as you end up resolving onto a chord tone of the current chord (I III V or VII normally, often the major 9th as well) you can get a pretty good sound.

Another thing to note is that you can basically play anything you want to on a blues as long as you take the above note into consideration, end up in the right place and play it with feeling. After all, blues songs are all about the feeling (not the complication of harmony).

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This is a good explanation. I would further say that what it means to "play with feeling" is actually to work on the phrasing. –  Michael Martinez Mar 14 at 19:06

You could call it a V-V-V with key changes, a IV-IV-IV , or whatever. The fact is that in a blues progression there are no key changes or modulations in a particular verse. The chords are related to each other,so in key A, with I, IV and V, it becomes A, D and E. Blues traditionally uses dominant 7th chords to get the 'feel', rather than a 7th just on the V chord as in most other styles of music. The 7th on the IV chord is probably the most telling, as it sounds like the music is going to modulate, but of course, it doesn't. Using Amin. pent. notes will also give a min 3rd against the maj.3 of the given chord. This again is the essence of the blues - although often that particular note is bent up to sweeten it, or not, as the whim takes.

Yes, you can play , say, the Dmin. pent. notes over the D7 chords, and Em pent over E7. This gives a few extra notes to play with. Note that some of Am pent. notes are duplicated in Dm pent.etc.

If the progression is indeed I-IV-V, then it's not a 12 bar, but just a 'three chord trick'.The standard 12 bar is the sequence for Rock Around the Clock, amongst thousands of other examples. There are many other answers to questions similar to yours on this site. Have a good look at the answers for more clues. There is no point in elaborating further in this answer.Keep playing, and work with the adage that if it sounds good, it is, even if technically some rule is saying 'you shouldn't play it like that'.

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It is just common practice to call a blues with chords I7, IV7, and V7 a I-IV-V blues, simply because the chords are built on the first, the fourth and the fifth note of the (mixolydian) scale starting on the I. And it is understood that all chords are dominant-seventh chords (unless you're playing a minor blues).

There are in fact lots of scales that can be played over a I-IV-V blues. It is not wrong to play minor pentatonic scales with roots I, IV and V over such a progression, even though especially on the IV chord it can sound a bit strange due to the b3 of the IV chord (which is the b6 of the I chord). Another straightforward choice is the mixolydian scale, again with roots I, IV, and V, depending on the current chord. And every time a chord can be interpreted as a V-chord for the next chord, alterations can be added (e.g. by using the diminished half-whole scale or the altered scale). And also don't forget the major pentatonic scale, which also works great over the blues!

A great example of scale choices and how they sound was given by guitar player Oz Noy in a clinic. Check out this blog post (plus video). Also see my answer to a related question.

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Because the way blues works is that the I7 is treated as a tonic, even though it's not tonic in the normal sense. But the V7 > I7 helps to reinforce that it actually is a tonic chord in the overall progression, because a V7 always has a dominant role, regardless of whether it resolves to a I7, Im7, Imaj7, I6, or whatever. Another way to look at it, is that you are constructing a I IV V, except instead of major chords, you're doing chord substitution on each.

To learn how to improvise on the basic blues, the best place is Dan Greenblatt's book "The Blues Scales: Essential Tools". In the first chapter he has you using I major blues scale on the I chord, and using I minor blues scale on the IV7 and V7 chords. Then, he expands on this later on and adds some additional things.

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