Modes are scales that start on a different note of the original scale. For example, if we start on a different note than C, but play the same notes that are in the C Major scale, we have a different mode. The modes have different names that come from ancient Greek words.
Here is a list of the modes in the diatonic scale:
The modal scales are called by their origin note. The Dorian scale above is called the D Dorian. The Aeolian is called the A Aeolian.
They all contain the same notes, but these modes all have a different flavor. As long as the starting note or ending note of each scale is used more frequently, then you will hear the difference. For example, if you start and end on the D notes, the C Diatonic scale will sound more like a D Dorian than a C Ionian even though they are both made up of the same notes. This is because the order of semitones and whole-tones is different for each one, as you can see in the chart above.
The above scales can be subdivided into three types: major, minor, and diminished. The major modes are the Ionian, Lydian, and Mixolydian. They are major because the root note forms a Major third interval with the third note. This affects their overall tonal quality.
The minor modes are Dorian, Phrygian, and Aeolian. They sound minor because the root and the third note form a minor third interval.
The diminished mode is the Locrian. The Locrian is a diminished mode because it has a minor third and a minor fifth interval in it.
That noted, the Ionian is considered the primary "major" scale and is the one people talk about most often when they say "major scale." The Aeolian is the primary minor scale, and is usually just referred to as the "minor scale."
After the Ionian (or Major) scale, the Aeolian (or Minor) scale is the most frequently used. It is used so frequently in fact that musicians often speak of it as the “relative minor key.”
The relative minor key is the Aeolian of a Diatonic scale. Most of the time when music modulates from one key to the other within a piece of music, it is from the major key to the relative minor. So they are often memorized in pairs. For example, the relative minor of C major is A minor.
This list explains all the major keys and their relative minor keys:
Playing the Modes
Good news. Because all the modes contain the same notes that are in the major scale, we already know where to find them on the PSG. Just use the same 2 positions discussed in the KEYS section. The only difference is which note starts and finishes the scale and is emphasized more. In order to play the modes, we just have to extend the scale notes a bit from our two positions.
This image shows all the notes of C Major at both positions:
Here is the notation for all the C Diatonic notes at both positions. The C notes are marked with arrows:
Starting on different notes in each of these patterns will yield the various modal scales.
Below are the 7 modal patterns shown as part of the larger major scale pattern positions colored in green and yellow. The required pedals are in the 2 diagrams under each PSG Mode Diagram. The notation for each mode is found below each of the modal diagrams. As a reference, here are the pedal locations again: THE COPEDENT