Do you avoid parallel octaves/5ths when writing parallel supporting Melodies? For example when harmonizing a vocal melody I have a plugin that by default adds a 3rd and 5th underneath. Should I change it to a 6th and 3rd? I read you shouldn’t have a parallel 6 3 chords more then 3 times in a row. So should I automate it to use the 3rd and 5th once in a while. Also. Let’s say I have a chord underneath and the 6 3 chords that are following the melody creating non chord tones with the harmony. Is that okay? Kinda like bichordal stuff. I’m confused with parallel supporting melodies.

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    I don't know what kind of music you're doing. Yes - if you use too many parallel chords of any kind the music can get dull. Yes - try the 3rd and 5th: a variety of chord-shapes is probably more interesting. Don't let the plugin change the harmony on every single note-change in the tune: some notes are better as non-chord tones. But as I said, I've no idea what this thing of yours sounds like. Got a screenshot? Commented May 20, 2020 at 5:08
  • A 6 3 chord is one in 1st inversion, with its 3rd underneath. Serial usage of those is similar to parallels.
    – Tim
    Commented May 20, 2020 at 8:50
  • One of the 8-bit Fire Emblem themes associated with Marth is harmonized purely with perfect 5ths and, at least to me, has an unsettling effect. I find it's the ugliest of the themes associated with Marth.
    – Dekkadeci
    Commented May 20, 2020 at 14:58

2 Answers 2


I often avoid it, but it depends what the song is asking for. Sometimes, a 1:1 fifth or third melody on top of a melody is just what the song needs and is less intrusive to other parts that may be harmonizing less linearly. Ultimately it's up to you! There are no rules, just suggestions ;)


There are some "rules" or guidelines about this in classical harmony theory. First parallel movement is generally considered less desirable than counterpoint or oblique movement but this is really a matter of preference. However, when it comes to having 5ths and octaves without a note in between one reason to avoid it could be resonance. These are considered "perfect" intervals. They contain a large number of matching overtones or harmonics. As such the intensity of sound will build higher than a harmony with 3rds even if the players or singers are not increasing their individual volume. For this reason it's avoided, however rules were meany to be broken and they have been. It is not uncommon in modern music to play parallel 5ths and octaves.

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