Is a Blues in A really in A?

I wanted to bring up a topic of the Blues, at its quintessential level anyway, that is not really mentioned much anywhere at all. It has intrigued me now for a little while, and I suspect
it is somewhat strangely ‘hidden’ from many.

That is, that the basic Blues, in its purest I-IV-V dominant chord format, is a non-diatonic chord progression.
Of course, the base triads are diatonic, but the 7th chords are not.

So a “Blues in A” ( A7- D7- E7) is not technically in A at all. There are 3 keys involved in building these 7th chords. Same with any other key signature of this form.

So in A, only the V chord, the E7, is diatonic to the key of A Major.

The I chord, A7, belongs to D Major. It is the V chord of that key.

The IV chord, D7, belongs to G Major. It is the V chord of that key.

So, all built of the V chord of the respective key.

So technically, the 3 chords in a Blues in A ( or any key) actually come from 3 different keys; in the case of “A”, its actually D, G, and A major. There are no keys that contain 3 diatonic dominant 7 chords; melodic minor contains 2 dom7’s I think, but can’t think of any other scales that contain more than one.

Now, I had been studying the Blues methodically for about 9 months at the time, and music theory for over 2 years, when I read this in a coursebook some time ago; I was absolutely flabbergasted that I hadn’t noticed this, and no-one seemed to mention it either. It was like a ‘twilight zone’ moment that was hard to believe. Such a basic and core aspect of musical form and structure, hidden in plain sight.
In fact, I would suspect that the vast majority of guitarists would not realise this on a conscious level. It is an odd situation indeed. And I think its a product also of how the Blues is taught.

Now, the Blues is about the sound, not the theory, but I find it a most interesting topic nonetheless, with I think, real world implications.

What are the implications of this? Well, for me, it probably hasn’t altered anything greatly in the first 18 months or so of my Blues learning, as I’m still building the foundations.
But more recently, as I begin to explore a bit further, at least at a rudimentary level, it has opened up enormous possibilities regarding things like arpeggios etc, that belong to these 3 keys. And in particular, ‘jazzy’ cadences like the II-V-I etc, which can be incorporated into the Blues form; in some instances like a “melody within a melody”, and various others that can create a seemingly infinite array of possibilities.

I am curious if there are any others out there, who’ve been at this a little while, who have in any way explored the Blues in this way; or who may provide some additional clarity on the subject.

It has certainly provided some clarity for me in some more modern blues I’ve come across recently, and where some of these ‘outside’ sounds may originate from.

Cheers, Shane


Hi Shane,

Great topic and whilst I am unable to add anything intelligent to this it’s a very interesting point. I’ll be watching just to see the follow up comments :+1:

Griff Hamlin of Blues Guitar Unleashed always points out that blues are technically not in any key, because no key uses dominant 7th chords (or variants) on the I, IV, and V. He goes on to say that blues breaks all kinds of rules, so just don’t let it bother you.

A7 D7 E7

If you take the root and 7th of each chord…
…and rearrange them…
Voila! The A minor pentatonic!

Rules! What rules?
There are no rules, just theory. Blues plays around with the theory and makes the music it’s own.

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Cant say its really bothering me Mark. More of an open invitation for discussion, and how an understanding of it at more than a superficial level can open up playing opportunities.

Cheers, Shane

Hi Shane ,
You let my brain hurt … :grimacing:

It’s all going a bit too far for me this morning and probably the mornings in the coming year to fully understand what you want to say, but I saved this video 3 years ago after seeing it once when it came out and I wanted to watch it after the blim course, but I’m going to take a look at it next week… it has kept going through my head since…

and there is a very good chance that this is not at all about what you are saying here, but then you have seen something that an expert like Paul considers the most beautiful blues…so I hope you enjoy it …

I wanted to show you this earlier and I think now is a good time to show you ,

Edit:The man has the wrong sweater :grin:
(a brief look provides a lot of exercises for me)

Edit 2 : I couldn’t resist and looked at it in its entirety :smile:, from step 7 onwards, if I understand it correctly, it is very much about something you describe and that is certainly why it stuck in my head together with the idea of playing those 2 notes in the beginning (step 3) … :wheelchair: :hole:


You wrote theory and rules there. Knowledge and understanding can only enrich one’s playing and find good sounding things quicker or figure out where to look for (unless you have hours a day to figure everything by ear, old school).

Great avenues to explore, well worth the effort down the line. There wouldnt be all this i am stuck in a box all over internet if it werent like that.

@sclay Blues tonality – The Ethan Hein Blog


As I’m now starting out to look at Jazz these issues come up particularly in the choice of arpeggios but I’m still a beginner in the field.

I believe In the blues, the 7 chords are incorrect from a classical music perspective as a 7 will always want to resolve. But apparently our modern ears have become accustomed to it in the blues. I think the use is due to, in the major keys, the flat 7 being used a lot in the melody/tune. I believe this is mixolydian!

The solo I played in my recent blues AVOYP is predominantly major pentatonic but with flat 7 thrown in. But there again, the chords are all mainly 9’s except for the V where I stuck to the B7 subconsciously. And there again a lot of blues is in minor keys.

The more I look into it, the more the concept of sticking to one key and the chords therein goes out the window. Just have a look at some Bach piano pieces…


Yep, exactly. In this case using the 6251 of A to get back to the 1 chord.
I remember seeing this video some time ago ( I specifically remember the cool dude that Paul ‘found’).
A great shout out though on this video Roger, as a rewatch now is going to mean alot more.

I love how Paul plays the student role here, somewhat comically, as we all know his considerable guitar prowess. It allows the ‘cool dude’ to really get his info across though.

Cheers, Shane


Thats why i like this Ethan Hein idea of blues/tonality harmony being taught as a real thing and not just saying, oh, it breaks the rules (of classical) harmony/theory.

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Hi Shane,
Very happy with your comments and I’ll take even a closer look at it next week :sunglasses:

I have never gone into all of the theory side of Blues mostly because I think it could hamper creativity. In real terms if it sounds good it is good and my learning has mostly been down to listening and immersing myself in it then putting into practice what I’ve managed to absorb. Rules are there to be broken, if it works all well and good, if it doesn’t it’s back to the drawing board!


The ear is the final judge. Dont think knowledge can hamper creativity though.

I hadn’t watched Roger’s video link before I replied but having done so it confirms the use of the flat 7 to establish the blues tone. I have always thought of this as the blue note in a major key.

The rest of the video is taught in Justin’s lessons on “Jazzying up the blues” and “ Jazz walking bass” so is moving a bit away from blues towards jazz theory. It’s a great part of the journey.

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I had a quick look at this article (treatise?) and it looks awesome! The beginning is quite theory-heavy and will require some close study, but scrolling down, I see lots of history, examples and just all-around interesting stuff.

Thanks for sharing this.

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Thanks Rogier…
Not only did I watch the video (Why, when I’m not a ‘blues brother’? :thinking:) but was also curious what 42 gear street was, so watched an interview on that, which connects directly to the the Henning Pauly rabbit warren… :roll_eyes: :rofl:

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I’m not too sure we should let all this theory get in the way of our playing. It would be hard, in the middle of an improv, to think ‘I must do a dominant 7 or a diminished 7 arpeggio here’ as by the time you’ve thought of it, it’s too late. Instead, I guess, the ear gets used to the sounds through practice and uses them where appropriate.

For example “Need Your Love So Bad” and the John Mayall/Peter Green “Someday You’ll Be Sorry” use a 6 2 5 1 turnaround which is a standard jazz progression. There is an hour long live stream on YouTube with an analysis of Peter Green’s playing on the latter but I doubt the 19 year old Peter Green had studied jazz theory.

By the way, I’ve only learnt this kinda stuff about a week ago but I’ve played the songs longer without knowing the theory.

Hey Sly, you’ll have to allow me to disagree.
I used theory to to explain my observation but I didn’t write any rules!
Yes, theory is good to know, especially in communicating with other musicians, but music isn’t about theory - it’s about sound. It’s about feel, it’s about passion, it’s about emotion. No amount of theory will bring that out.

Oh, I wish I had hours a day to figure things out but I certainly don’t consider using my ear to be old school. My ear is my most valuable asset in trying to become a good guitar player.
Justin knows all the theory, but listen to what he says about those old blues boys not knowing much theory and using their ears.
Listen to what he says about theory in his Re-Active Listening lessons.
Some may say my thinking is superficial. Well I’ll take superficial and my ear any day of the week.

“Is a Blues in A really in A ?”
You go looking for some hitherto unknown key for it if you must.

Me? I’ll use my ear and play it in A :smiley: