Originally Posted by Niro5150
If a riff went : 6" 7" 9" 6" on the low e string
I would look for scales in which these notes are found??
Those notes are A# B and C#.
They occur in the following scales:
B and F# major;
B harmonic and melodic minor;
G# harmonic and melodic minor;
A# half-whole diminished.
All those scales have 7 modes (except the diminished, which only has 2 modes).
You would choose which scale is best by trial and error - seeing which one has other notes that sound like what you want.
As for the mode, that will depend on what the root note (keynote or tonic) of your scale is.
If it's A# (if that's the note you end on as well as start on, or if that's the root of the chord you play the riff over) then - as amerok says - it's probably phrygian (A# phrygian) - although it could just be locrian (less likely).
You could get more interesting modal sounds on an A# root by using the notes of those harmonic or melodic minor scales:
B harmonic minor with A# root = A# ultralocrian (locrian b4 bb7) A# B C# D F# G A#
B melodic minor with A# root = A# superlocrian (locrian b4, aka jazz "altered" scale) A# B C# D E F# G# A#
G# harmonic minor with A# root = A# locrian natural 6: A# B C# D# E Fx (double sharp) G# A#
G# melodic minor with A# root = A# phrygian natural 6: A# B C# D# E# Fx G# A# (maybe easier to think of as Bb phrygian nat 6: Bb Cb Db Eb F G Ab Bb)
Remember the sound
of the root note is what's important in these modes. A# has to sound like the "home" note, which can be tricky.
E.g., if you play A# locrian, that's likely to just sound like the B major scale - because B is the natural and familiar keynote of that set of notes.
In fact all these scales would be far simpler to spell and think about if you just raised or lowered your 3 notes by one fret!
If the above is making your head explode, try using frets 7, 8, 10, 7, which is B, C, D, B.
Now (assuming B is your root) your scale options are:
B phrygian (G major scale) = B C D E F# G A B
B locrian (C major scale) = B C D E F G A B
B ultralocrian (C harmonic minor) = B C D Eb F G Ab B
B superlocrian (C melodic minor) = B C D Eb F G A B
B locrian natural 6 (A harmonic minor) = B C D E F G# A B
B phrygian natural 6 (A melodic minor) = B C D E F# G# A B
B half-whole diminished = B C D Eb F F# G# A B (8 note scale. Not a lot of use for composing stuff, but could be fun to try out)