"Major" progressions & "Modal" voicings (tonal vs modal) when building chords & progressions

Question

im not asking "what i can or cannot play" as all music is subjective, but im asking for "theory" or "technical" reasonings.

people often say that they replace the 4/11 over a Major chord, primarily with the tonic Major chord, with the #4/#11, so to avoid the tension between the M3 guide tone. so what they are really saying, in technical terms, is that they prefer a Lydian sound over an Ionian sound?

My confusion comes from the fact that if we build a tertian harmony sequence of diatonic notes, over a CMaj scale chord, in the key of C, you will have the "avoid note" of [F] as the diatonic 11th (ie; C-E-G-B-D-F). Its as if the chord is its own worst enemy, if that makes any sense lol The tonic chord is meant to be "at home", yet if built up until the 11th is reached naturally, it creates this conflicting sound.

This is mostly regarding the tonic Major, as the other true Major chord of the scale is the subdominant (IV), which is naturally the Lydian chord of the scale. So technically, the (IV) cannot be voiced in such a way to naturally create this "avoid" note scenario, if one were to use just the notes of the corresponding parent scale. (ie; using the notes of C Ionian or F Lydian, etc.)

However, if in the key of CMaj, you decided to play [F Ionian] over the [IV] chord, you would then be intentionally creating the "avoid" note 4/11 scenario?

So, if you have a typical [1-5-6-4] pop or rock progression in CMaj & you voice the 1 chord as having the [11], that means you are strictly implying an "Ionian" sound? However, if you voiced it to have a [#11], you would imply a Lydian sound, just over that 1 tonic chord, although the entire progression or piece would still be considered a CMaj key?

If a progression was "modal" on the other hand, such as a [C Ionian] progression, then that means you would SPECIFICALLY use notes like the [4/11] & the [7]... not only over the [I] chord, but as often as needed over/under other chords in the progression as well? For example, a pure Ionian progression could be [CMaj(add11)-> FMaj-> CMaj-> bdim]?

So when other sites & sources describe the [4/11] as an avoid note, they are perhaps speaking from a primarily "tonal" chord voicing or progression standpoint & are simply saying, in reality, they prefer a Lydian sound, rather than an Ionian voicing?

I know nothing is stopping us from using a CMaj(add11) chord, in a "tonal" progression, as mentioned above, though... if it sounds good to you, that's all that matters, but Im simply trying to understand things from a theory, technical or "historical" point.

thanks

Answer 1

I'm not fully sure what you're asking here, but I think I've considered some of these problems myself. First of all, from my understanding, avoid notes aren't referring to chords built on every degree of a scale. The avoid note for C major is only for the C major chord. These are notes to avoid when soloing over specific chords, rather than applying to the whole key. I came across this concept on my own sort of. I wanted to figure out what makes some harmonies sound bad (to me). I ended up finding that I can put every note of a key into a "chord" and it sounds good, up until the F (in C major or A minor). That note only sounded good to me as a passing note or a suspension note resolving down. That's essentially the avoid note concept, I think. I started trying to rationalize it in other way too. Those notes are related by 5ths built up from the root. For example, C-G-D-A-E-B. The next note is not F but F#. In fact, even though F looks close to C on the circle of 5ths, it's actually the very furthest note when you go up by 5ths like that. To me, this helps explain why a #4 sounds much better than the natural 4, because the relation by consonant intervals (5th being more consonant than a 4th) is much more distant. Another "side effect" of this that I notice is that if the 4th is emphasized too much, it can sound like it's the actual root of the chord, thus making it sound less like a I chord and more like a IV chord, because that creates the 5th relation with C, but now C isn't the lowest note in the chain of upward 5ths.

This might be inaccurate or unhelpful, but this is basically my personal experience with the concept from my own perspective. It's actually a huge part of my concept of harmony, because it has helped me learn to build the chords I like and what notes go well over them.