Ok JohnPR and other theory experts...

[Davis Webb]

Jamming in a song in D major. Looked for a good country riff to embellish the chorus. Using the 3rd fret of the D string to create that great bluegrass sounding riff off the D chord. Found that the A major pentatonic was great. Why does A major pentatonic sound so great using D chord to resolve to?

Riddle me this. Well, actually, I really want to know!

Cheers
D.

[Hotspur]

Well, always start by looking at the notes:

Notes of D major scale: D E F# G A B C#

Notes of D major chord: D F# A

Notes of D major pentatonic: D E F# A B

Notes of A major Pentatonic: A B C# E F#

So let's note the obvious:

Every note in A maj pentatonic is in D major. Two of the notes of A major pentatonic are chord tones of D major. There is only one note different between A maj pentatonic and D major pentatonic: A major pentatonic has the leading tone (relative to D major) of C#, whereas D major pentatonic has the root.

So when you're playing in A major pentatonic over a D major chord, one could argue that you're really playing in D major pentatonic, except that you're letting the chord cover your tonic and you're throwing in the leading tone (which is a great tool for, uh, leading, to the tonic). Thing might be a little strange because you have a hard time making strong resolutions without a D melody note, but maybe that's where some of the bluegrassyness comes from - that's not a genre of music I've really dug into.

[JonPR]

Originally Posted by Davis Webb

Jamming in a song in D major. Looked for a good country riff to embellish the chorus. Using the 3rd fret of the D string to create that great bluegrass sounding riff off the D chord. Found that the A major pentatonic was great. Why does A major pentatonic sound so great using D chord to resolve to?

Assuming you're not actually using it over the D chord, but resolving to the D, A major pent is standing in for the A chord. It's an A triad arpeggio (A C# E) plus two good passing notes (B, F#).
Ie, if you're playing A major pent followed by a D chord, it will sound like an A chord resolving to D.

It's standard bluegrass/country style, for riffs, fills and solos, to use the major pent of each chord, usually adding the b3 to slide up (or hammer on) to the M3.
Ie, in D major:
D chord = D major pent, plus passing F (resolving to F#) - eg frets 3-4 on the D string
G chord = G major pent, plus passing Bb (resolving to B)
A chord = A major pent, plus passing C (resolving to C#)

The three pents together spell out the whole D major scale (no outside notes), but in three 5-note subsets that work well on each chord. The passing b3s add the "blues" effect.

If you were using A major pent actually on the D chord, that's quite a different, non-bluegrass sound. As Hotspur says, most of it is compatible with D, but the C# gives you the maj7 of the chord. If you don't resolve that note, it's a very sweet, jazz/ballad sound - not bluegrass at all.
If you were to resolve the C# up to D immediately (treating the C# as a passing dissonance, not a chord tone), that's different, but then it's not really A major pent - the D chord will make it sound like D major pent with passing C# .

[DupleMeter]

Two reasons: All the notes are diatonic to the key of D (that means they're part of the scale of the key) & your hinting at the V7 chord (A7) when you do that so it feels really satisfying to have that V7 > I cadence.

As we learn in Theory 101: a dominant 7 chord's expected resolution is down to the I chord. This is defined as dominant motion (a half cadence in theory terminology). One of the most satisfying sounds in western music.

D Major with the notes from A Major Pentatonic in bold):
D E F# G A B C#

[Davis Webb]

Originally Posted by JonPR

Assuming you're not actually using it over the D chord, but resolving to the D, A major pent is standing in for the A chord. It's an A triad arpeggio (A C# E) plus two good passing notes (B, F#).
Ie, if you're playing A major pent followed by a D chord, it will sound like an A chord resolving to D.


If you were using A major pent actually on the D chord, that's quite a different, non-bluegrass sound. As Hotspur says, most of it is compatible with D, but the C# gives you the maj7 of the chord. If you don't resolve that note, it's a very sweet, jazz/ballad sound - not bluegrass at all.
If you were to resolve the C# up to D immediately (treating the C# as a passing dissonance, not a chord tone), that's different, but then it's not really A major pent - the D chord will make it sound like D major pent with passing C# .

Wow, this is exactly what I found, it is serving as the A chord in a progression. You folks have taken it a whole level further! I sincerely appreciate all of the info, still reading, but had to stop to say...THANK YOU!

[macmanmatty]

Originally Posted by Davis Webb

Jamming in a song in D major. Looked for a good country riff to embellish the chorus. Using the 3rd fret of the D string to create that great bluegrass sounding riff off the D chord. Found that the A major pentatonic was great. Why does A major pentatonic sound so great using D chord to resolve to?

Riddle me this. Well, actually, I really want to know!

Cheers
D.

3rd fret of the D string don't you mean 4th fret? Cause what the heck is a "F" note doing in a bluegrass country "D major" song? That's probably one of the last notes I would use in key of d major.