Over the same chords, what makes a melody good changes depending on whether a voice or an instrument plays it. Bodies and instruments are built differently.
Part four closes with the difference between modes. ChordMelo separates "vocal melody" and "guitar lead" because this difference is substantial.
What a vocal line needs
A voice covers roughly an octave and a half comfortably. Beyond that it breaks into falsetto or simply will not come out. Breaths are required, so rests have to go somewhere. Repeated leaps make pitching unreliable, so steps get mixed in.
What a guitar line needs
A guitar covers a wider range than a voice and never needs to breathe. It moves fast, so it can carry more notes. Leaning towards easily-fingered shapes such as pentatonics makes it both playable and idiomatic.
- Generated as a vocal melody
Am | F | C | G
- Generated as a guitar solo
Am | F | C | G
- Range — narrow for voice, wide for guitar
- Rests — required for breathing, optional on guitar
- Leaps — modest for voice, large on guitar
- Note count — as many as words allow, or many more on guitar
- Note choice — pentatonic leanings make guitar lines playable and idiomatic
The span between the lowest and highest note available. Voices manage about an octave and a half; instruments usually more.
Generate a guitar solo over the same progression. The contrast with the vocal version is unmistakable.
Generate a guitar soloVoices have narrow range and need breaths; guitars have wide range and move fast. Write for the one you mean.