Confused about how to know the chord progression for each scale

Question

Take this D major backing track for example

The thing is, in this case, the D minor pentatonic doesn't sound very good if I play over that backing track. Although it sounds great if I play the D major pentatonic (which as far as I know I think it's "the same" as S# minor pentatonic?):

Then we have this one which sounds great if I use the E minor pentatonic, but doesn't sound really well with the E major pentatonic.

Ok, great. Minor for minor and major for major, I guess I get that.

Buuuuuut then we have this, which is "E blues":

Both sound great, the minor sounds perfect and the major has a more "happy" sound and both combined have a more "bluesy" sound (I hope you understand what I'm trying to say xD)

I'm assuming that all this happens because of the chord "progression" (I don't know if that's how it's said), each one of those backing tracks is using different chords (at least in some parts) and that's what "causes" this.

So my question is, which chords are those backing tracks using? One of the videos actually says the chords but I'm wondering about how do you "form" the chord progression for any key.

All I know about this is that if I want to play in say, A, I have to find it's I, IV, V chords (which would be A, D, E) and then play I7, IV7, V7 (so A7, D7 and E7). If I do so, then the A minor pentatonic sounds good.

But how does this work? Is this progression (I7, IV7, V7) in any of these videos or not at all?

Basically what I'm wondering is what "formula" should I use to know the chord progression if I want to solo with the major pentatonic, which for both at the same time and which for the minor pentatonic (I'm assuiming the I7, IV7, V7 is used for the minor pentatonic :/).

And generally speaking, what type of backing tracks are ok if I want to play with both scales? Should I search for "E blues backing track" rather than "E backing track?"

Anyways thanks for your time and have a nice day!

Answer 1

The first 2 backing tracks make use of major and minor triads. That is, AFAIK, they make little, if any, use of the 7th chords. So, like you said, playing a D Major Pentatonic over the D Major chord or an E Minor Pentatonic over the E Minor chord sounds nice and makes sense.

However, the Blues backing track is a Blues Shuffle. This means that, if in the Key of E, you will hear this

E5 (E B  E) + C#
A5 (A E  A) + F#
B5 (B F# B) + G#

(he also threw in a C chord every now and then)

In other words, the backing guitarist is playing an E5 'power' chord and, usually with the small finger, adding in the C# to give that shuffle feel. Same with the A5 and B5.

With those 'open' 5ths (i.e. E + B, an interval that is a perfect 5th, or an open 5th since it does not have a 3rd in between the E and the B), the soloist is more free to play, either E Major pent. or an E Minor pent. Both have the E and the B and both 'land' on the root, E.

Now the E Major pent. has the same notes as the C# Minor pent., which can give it an advantage over the E Minor pent since the E Minor pent does not have that C# 'shuffle' note. However, the E Minor Pent, as you have experienced, can also sound really nice over the E5 since the Minor 3rd ('G') in the E Minor pent does not 'clash' with the 'G#' that you would normally hear if the backing blues guitarist was playing an E Major triad (E G# B). Also, that Minor 3rd 'G' helps create the "blues sound" since it is considered a "blue note".

https://en.wikipedia.org/wiki/Blue_note

So, in short, for the 1st backing track that progresses:

D A Bm G

Feel free to make use of the D Major, A Major, B Minor and G Major pentatonics.

But for the 3rd Blues Shuffle backing track that (mostly) progresses

E5 A5 B5

Feel free to use, either the E Major, C# Minor or E Minor pentatonics over the 1 chord and then continue is similar fashion for the following chords (i.e. A, F#m, or Am over the A5 and B, G#m or Bm over the B5). You have more freedom over that Blues Backing track.

And, as always, play what sounds best.