I just had a couple simple questions. The questions I am about to ask might sound like I don't know a thing about music theory at all. But I actually know a lot (not as much as a lot of others out there, but a decent amount lol). More on the classical side. I am interested in creating rock type songs. All the questions are really based around riffs using all there different scales (pentatonic major/minor, mixolydian, phrygiran, etc...), an how they relate to other instruments in the mix/arrangement.
-for example say you have a riff in A minor pentatonic scale.
1. Does all the other instruments: bass, keyboards, synths, melodies/vocals, etc... have to relate to the A minor pentatonic scale?? i kind of know they have to relate....but how much??
2. Say the riff (in A minor pentatonic) is playing A C E, can I have the melody/vocals or basically anything (bass/keyboards/synths/pads etc...) playing A major A C# E melodies, chords, riffs, or whatever with/along side the A minor pentatonic riff??
Would that be stupid and the C in the riff would not sound right with the C# of the A major?? is that unusual to do it that way?? is it more common to just keep everything in A minor pentatonic so it all sounds/blends better??
thanks a lot.