Sharp 4th sounds good in major scale lick/progression?

Question

As part of my practice session today, I was exploring using CAGED chord shapes up and down the neck while incorporating licks in order to make melodic passages. While playing in A major, I improvised the following resolution that uses double stops borrowing from its diatonic chords:

   F# G# F# E F# E   F# E  D  A   
E|----------------------------x
B|--7/9--7--5/7\5----7--5--3--2
G|--6/8--6--4/6\4----6--4--2--2
D|----------------------------2
A|----------------------------0
E|-----------------------------

I borrowed chord tones from G# F#, E, D, and of course A, so it is a 7-6-5-4-1 falling resolution to the root.

I liked the way it sounded, so I played that part a couple times and realized one of these notes (the D# at the 8th fret on the G string) is not actually in A major. However, I am borrowing it from a G# major chord (as it is the 5th), which is in fact in A major.

I tried to find a similar melody that is purely A major, but this was the closest I got, basically just moving that G# half a step up to turn it into an A (it doesn't sound good to me):

  F# A  F#  E F# E   F# E  D  A   
E|-----------------------------x
B|--7/10--7--5/7\5----7--5--3--2
G|--6/9---6--4/6\4----6--4--2--2
D|-----------------------------2
A|-----------------------------0
E|------------------------------

So ultimately, my question is:

Is it okay to "borrow" that D# despite it not being in A major since it is a chord tone of G# which is in A major? Is this faulty logic? Why does it sound good? Am I just playing in lydian at this point with the sharp 4th? I don't think I am since I am also using a perfect 4th - B string 3rd fret - when playing the D chord right before the resolution.

Note: Please forgive me if I am interchanging or using incorrect terms or phrases. I am still pretty new to this whole music theory thing. Thanks!

Answer 1

Bottom line, if it sounds good to you then it’s OK!

You’re referring to the stacked 4ths as chords, which I consider to be a bit of a stretch since they really don’t have any sense of quality, with the exception of your final A chord. I suppose you can think of them as inverted power chords, or 5 chords. I would tend to think of this passage more as a melody harmonized in parallel 4ths.

As for your D#, it does briefly imply Lydian but you are not really in Lydian mode as you have a D natural on the next to the last “chord” which implies a IV-I cadence. The reason the D# works is it maintains the 4th intervals. If you were to swap it for a D natural in order to be diatonic (7/9 instead of 8/9 on the second group) you would have a dissonant tritone interval. The 9/10 in the second example also works musically but if you don’t like it as much there’s no need to consider it.

One thing you can do if you want to avoid the Lydian D# sound is have the second group of notes be in 3rds, or 9/9 (E/G#) instead of 8/9 (D#/G#). Try it out and see what you think. There are many instances where nice harmonies can be created by combining and alternating 3rds and 4ths.

I’m curious, is there a bass note or bass notes that you are hearing under this series of moving 4ths?