ESA1996
Active Member
As long as you don't have any 2nds, 7ths or tritones in the harmonies, and both harmonies are within the scale you're in, you're fine (Both rules can be broken while still sounding good, but holding on to those makes things easier. The Blooddrunk verse riff for example doesn't really follow any scale). I don't think there's anything more to it than that; Alexi came up with a riff, and decided to harmonize it, but instead of going with a normal harmony, he decided to go wild and see what happens. If both variations of the riff (Original and the harmony) sound good on their own, and they don't have any clashing intervals (2, 7, tritone), then they should sound good when put together (Assuming there is no chord beneath the riff of course. If there is a chord beneath the riff, then you have to make sure the harmony doesn't clash with either the original melody/riff, nor the chord beneath it, which limits what you can do a lot. The verse in Blooddrunk doesn't have any chord stuff going under it so Alexi had free reign to do whatever he wanted with the harmony).