how to avoid disharmonic chords with the melody?

[MadBrain]

[...]
Is there a simple answer why it can be said that melody is in F scale?

We have notes from F major scale: F G A Bb C D E F. We have all the triads. But isn't F maj (F A C) also a part of A minor scale A B C D E F G A?

With kind regards,
Mateuz

You kindof feel it... in particular, when you hear the root note (F), you can feel that it's the root. You can also feel it in the chord progression - generally, when a song is in F, the chord progression will have lots of cadences leading to F (Gm7 C7 F; Bb C7 F; Db Eb F; Gb F; etc...). And songs in F usually have melodies that end with F as well. And a lot of songs start on the root chord (so the first chord in the song or the first chord after the intro might well be F). Essentially, the whole chord progression is built around F.

The actual notes used aren't that important... F major will have F G A Bb C D E, and F minor will have F G Ab Bb C Db Eb, but in practice you can sorta mix up major and minor together. For instance, a classic blues in F will typically use the chords F7, Bb7 and C7 (F7 has Eb and Bb7 has Ab which are outside of F major). And the melody can either be in F major blues scale (F G Ab A C D, which has Ab outside the scale on purpose), or even in F minor blues scale (F Ab Bb B C Eb, with 3 out of scale notes - Ab B Eb). And if you get creative with chord progression, you can have chords like Db7 or Gb7.

Yes, all 12 notes can appear in a song in F major... what makes it in F is the structure.

[jancivil]

The answer to the question in the thread title IS: you get to know what you're doing. I recommend locating a solid basis and coherent path over canvassing the internet and taking the information strangers provide you as a foundation. For instance:

- Melody should be in the same scale as chords...
- Melody should not play notes that are a minor 9th over chord notes for too long. In Jazz terminology, they are called "avoid notes". For instance, F cannot be one of the accented notes over a C major chord because it forms a minor 9th with the E in the chord. Likewise, Ab cannot be accented over a C minor chord because it forms a minor 9th with the G in the chord.

I never heard of "avoid notes" as a term. This, everything, is contextual. Note very well. The reason to avoid F as a substantially present tone over C major is not the same thing as Ab on a G7 dominant to C major. In fact, if the piano player sees that thing on the chart, the chances are fairly good she's going to finger Ab like it's not any kind of problem. It's a cliche these days, "if it sounds good it is good", but I would prefer that advice, I mean to a stranger, before stating rules in this fashion. Particularly as later the rules are set aside...
Forget it, it's the internet, Jake.

So that's kind of an odd thing to see, a proscription against "minor 9th" per se, then the following sentence posits "Jazz terminology" as authority. It is a kind of jazz thing not to have the ♮11 over a major chord, especially not the I chord. Although one may find a way to do it beautifully, I came across that recently, though my sieve of a memory didn't hold onto the name of the thing or anything. It wasn't so much "jazz"... But that's jazz thinking; there is no universal principle of "no ♮4 or 11 over major triad" for too long". What is too long? Whoop, there it is, context.

Now, I expect the OP is not looking to do anything too avant-garde but something fairly pedestrian at this juncture, but I would not advocate strong discouragement along the lines of "Ab cannot be accented over a C minor chord..." for even a beginner but particularly as these things are somewhat more widely perused than that narrow a focus. NB: Ab as accented over eg., C minor may well be simply an appoggiatura; which will resolve to G soon enough, but what school teaches "cannot accent a non-chord tone", in any style?

In the appoggiatura thread, I pointed to Stevie Wonder's Cause We've Ended As Lovers for a tune where an accented note resolving stepwise down is the whole thing. Four beats of the tension and resolve.

[jancivil]

to understand why melody is described to be in specific scale although it mixes chords from different scales/keys.

The word scale corresponds with key here. In the simplest sense, the F major scale is not 'the' A minor scale, even as the chord is VI in A minor. Just noodling about on the F maj scale is liable to lend the sense of F major as a key, that is if the note F is central to your awareness. When it's 'the tonic note', the home or spot that's 'at rest' in your feeling. If those seven tones are bandied about and your central consideration is one of the 7 tones other than F, that's probably going to turn out 'modal'. IE: if your central chord thing is A minor, you're thinking, your vibe is rooted in A minor and you are noodling around with those 7 tones, you have 'A Phrygian' at hand. So your assessment 'it's more about feel than a strict rule' is basically right.

[ImNotDedYet]

You made a good point here. But believe me - I'm a mechanical engineer - I can't work without solid basics I don't want to follow the music theory, but I need it to know where can I start. Just a little bit

Why not? If you took the time to try to learn the theory first, you'd know the answers to these questions. (and it surprises me to hear you're an engineer and have no interest in theory - because a LOT of musical theory is based on math, which you're obviously good at - as am I )

And you're thinking about it wrong. You seem to be thinking that the chords are what defines the musical key or feeling when in fact it's the scale of the musical key that defines the scales. Major scales have the same sequence of steps in between all the notes in the scale, as do natural minors scales. The chords are only based on the musical notes in those scales - at least for triads.

Chords are, as you've found out, applicable in multiple musical scales because each adjacent musical scale differs only at one point in the scale either adding or subtracting a sharp or flat as you go around the circle of fifths.

And my jazz piano teacher uses the term avoid tones/notes all the time to whoever had never heard of that, so who knows...it could be a matter of your teacher and who taught them.

[jancivil]

I'm a mechanical engineer - I can't work without solid basics I don't want to follow the music theory, but I need it to know where can I start. Just a little bit

The solid basics you need in order to really know what you're doing is not trivial. It makes no sense to state you need your solid basis while indicating you aren't very interested in the, ah, mechanics of it. I think you're beginning to get the picture, though.

[jancivil]

And my jazz piano teacher uses the term avoid tones/notes all the time to whoever had never heard of that, so who knows...it could be a matter of your teacher and who taught them.

It doesn't matter, it's just words which are supposed to signal an idea. I don't like it but that doesn't matter. I made points about what that concept did in the thread. 'Avoid an F over a C major with its E because the minor ninth.' Not so much, as apparently the flat nine per a dom. seventh is pretty prevalent as a chord. As opposed to a "disharmony". That specific 'avoid' is about... well, it involves the style and its expectations and how that particular chord is not beautiful in the usual situation. Context. Maybe a flat nine over that third is not the same as one over the root.

[jancivil]

Here's a quartal voicing of C^7(9 #11) with a minor ninth present in it: C F# B D G. I wouldn't avoid it by some dogma. Jazz to me is not the domain of the conservative so happily.