Hold on, this gets weird.

Now we come to the end of my series on modes of the major scale, and this is a tough one. The Locrian mode is the least used, and probably the most misunderstood out of all of the modes of the major scale. This one isn’t tough to play, though. It is just a C major scale like the others, but this one starts on the letter B…
C major: C  D  E  F  G  A  B  C
B Locrian:                          B  C  D  E  F  G  A  B
Or we can say:
Major:   1 2     3  4  5   6    7
Locrian: 1 b2 b3 4 b5 b6 b7
Yeah, a lot of flats to remember!

Here is a great way to play this mode using 3 notes-per-string:

Notice the strange unfinished quality of this mode. It is almost as if it resists having B as the tonic note, because the ear really wants the notes to resolve. The problem with this mode comes from its use in Western harmony. In Western (or classical) harmony, music is about tension and resolution, the way we hear a G7 chord resolve to C major.

Now diving into a little chord theory, the B diminished chord contains the notes B, F, & D. It also wants to resolve to a C major:

The reason the G7 & B diminished hold the same sort of tension is because they are almost the same chord! G7 is a B diminished chord with an added G: G B D F. G7 is the V chord in C. B diminished (or its 4 note sibling, a Bm7b5) is the vii chord in the key of C. So we can say that both the V chord and vii chord need to resolve back to the I (C major). Many players substitute a Bm7b5 for a G7 in a chord progression, but hey, this isn’t about chords right now- back to the mode!
Now the problem with this Locrian mode is that it has this same unresolved quality. The chord it is played over is unresolved. If it goes to a C, you are not really playing in B locrian, but C Ionian, since that is where the harmony is going. You also can’t use B Locrian over the Bm7b5 and C Ionian over the C. Again, you are not ‘hearing’ the mode itself since the overall harmony dictates C Ionian.
We can further hear this when we build a chord progression on the unstable-sounding B diminished chord (or Bm7b5):
Bm7b5 – G – Am – F

Sounds weird, huh? This is why the Locrian mode is sometimes called a ‘theoretical’ mode: it isn’t used much in our Western harmony system. Yes, there are a few composers who have used it, but both rock and jazz prefers chords to resolve, more than anything. One use is the bass line in the Bjork song Army of Me.
This is one way to practice this mode that doesn’t sound quite as strange: Use a constant eighth-note rhythm bass note, playing a B. Then add some chords from the key of C major on top:

Now I will play a solo using B Locrian over the top. This still sounds strange, but strange is good, right? It isn’t as weird as the first chords I played, and it seems like the tension of this mode is softened (just a little) this way.

All recordings done with an Alnico II Pro set.The Alnico II Pro comes in neck and bridge versions. I used them split for the rhythms, and full on for the solo.

Funny, while doing some research for this article, I came across several blogs that mentioned songs like YYZ, Enter Sandman, and the song Black Sabbath as examples of Locrian, but other than the flat five note common in each one, they are all built on single note riffs (pretty awesome ones at that) but with no chordal harmony suggesting the Locrian mode.
Remember, unique sound of each mode is dictated by the chord progression it is played over. In other words, practicing modes by themselves – not practicing them over chords – is more of a finger exercise than a lesson in how the modes sound and their application. Cool thing is that any scale can have modes- we call the 5 modes of the pentatonic scale ‘boxes’. Modes of the harmonic and melodic minor scale get pretty strange names too. But in the end, playing in a mode on guitar has as much to do with the structure of the chords behind the solo as the notes in the solo itself. In other words, you aren’t ‘using modes’ if the harmony in the background of your cool riff doesn’t point to a specific mode, or there is no harmony at all. For more about the modes, I would recommend any books or videos (or old magazine articles, if you can find them) by Frank Gambale.
Hopefully this series on modes have helped some of you readers that might have been confused on what exactly these mode things are. They are not too hard to understand, and it only works if you can practice them over chords.
So do you ever think about modes or scales when you play solos or just wing it? Both approaches have worked well for lots of guitarists in the past. Do you work out solos crafting exactly the right notes or do you tend to improvise more?