Quick Tip: “I D P L M A” Key Signature Guide

Quick Tip: “I D P L M A” Key Signature Guide

on Jul 13th 2012 with 9 comments
Tutorial Details
  • Difficulty: Beginner/Intermediate
  • Time: 10 minutes

Are you tired of using either major or minor scales in your compositions? Have you ever heard of modes or modal scales? For those who want to bring something interesting to their compositions, try using the notes from one of the modes and you will immediately hear the difference. For more information about what modes are or how to use them, visit Ryan Leach’s premium tutorial “An Introduction to Modes“.

In this quick tip I want to give you a little guide on how to figure out the right key signature for the specific mode. The only thing you have to remember is this row “I D P L M A”, which refers to 6 most used modes: I – Ionian, D – Dorian, P – Phrygian, L – Lydian, M – Mixolydian, A – Aeolian. I purposely skipped the last one – Locrian mode because it is considered more of a theoretical mode and it is hardly ever used.

Whether you are preparing yourself for a music theory exam, or you are about to compose a piece using one of the modes and you are not sure what key signature or notes you should use, this quick guide may help you.

In our example we’re going to look at the key of G and its different key signatures when it comes to the particular modes.

I – Ionian mode

Let’s start with a G Ionian mode. This mode is the same as today’s major scale, so G Ionian mode uses the same key signature as G Major (1 sharp) and the notes are: G, A, B, C, D, E, F#, G.

G Ionian mode:

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D – Dorian mode

Now let’s say you want to compose a piece in a G Dorian mode. Take a look at the “I D P L M A” row. Letter “D” is the second in a row, which means you have to use the same key signature as F Major (1 flat), because F is a major second below G, so the G Dorian mode uses these notes: G, A, Bb, C, D, E, F, G.

G Dorian mode:

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P – Phrygian mode

If you want to use the G Phrygian mode, you have to use the same key signature as Eb Major (3 flats), because Eb is a major third below G, so is the letter “P” third in our row (I D P L M A). G Phrygian mode uses these notes: G, Ab, Bb, C, D, Eb, F, G.

G Phrygian mode:

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L – Lydian mode

The rest of the modes work in the same manner. G Lydian mode uses the same key signature as D Major (2 sharps), because D is a perfect fourth below G, so is the letter “L” fourth in our row . G Lydian mode uses these notes : G, A, B, C#, D, E, F#, G.

G Lydian mode:

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M – Mixolydian mode

G Mixolydian mode uses the same key signature as C Major (0 flats/sharps), because C is a perfect fifth below G, so is the letter “M” fifth in our row. G Mixolydian mode uses these notes: G, A, B, C, D, E, F, G.

G Mixolydian mode:

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A – Aeolian mode

The sixth in our row is the letter “A”, so if you want to use a G Aeolian mode, you have to use the same key signature as Bb Major (2 flats), because Bb is a major sixth below G. G Aeolian mode uses these notes: G, A, Bb, C, D, Eb, F, G.

G Aeolian mode:

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You can use the same method for every single key.

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Lukas Kobela is a Slovak film composer. He scored the feature film "Lóve" (2011), the student short film for The Los Angeles Film School "Perdition" (2010) and composed music for the project "Hockey Heroes of Slovakia" (2010). He currently studies composition in Bratislava, Slovakia.  

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  • jack

    Are you sure this is correct? I thought that the different modes use the same notes of the scale. So if your in G then all modes in G use the G scale just starting on a different note.

  • Bob Sacamenno

    This is wrong. Modes have nothing to do with swapping key signatures. If I was going to play G in all of it’s different modes, I would change the tonic, not the key signature. I think somewhere along the line, the author became confused about how modern modes work. I believe he may be right about the melodic intervals of the modes, but because he insists on keeping G as the root, he’s wrong by modern definition. For example, everyone knows that the 6th mode, Aeolian, is really just the relative minor of whatever key you’re in. Most people who know music theory understand that the difference between a major key and its relative minor key is that you switch tonics to the sixth scale degree. The key signature stays the same! I would still have F# but I would start the scale on the E. The melodic progression becomes the natural minor: W-h-W-W-W-h-W, where the W’s are whole steps and h’s are half-steps.

    Fix your post man!

  • Bob Sacamenno
  • http://adriantry.com Adrian Try

    Hi guys. The points you’re making is valid, but I think you’ve failed to understand the purpose of Lukas’ quick tip.

    As you say, if you’re playing through modes on your guitar in the key of G, then all of the modes have the same key signature – one sharp – because you’re playing in the same key.

    But Lukas is a film composer. If he decides to compose an entire song in a mode rather than just a major or minor key, he needs a way to determine the key signature for the score. His quick tip gives you a simple way of doing that.

  • Jim Korioth

    The post is correct. I think the confusion here in the comments arises from the fact that the author is starting every mode on the G, which does require a different key signature for each. In the examples offered here in the comments, it is a correct that a Dorian mode is played by beginning on the second note of a major (Ionian) scale – but the modal scale takes its name from the first note played. Keeping G major to illustrate the point, a Dorian mode scale can be constructed using the notes of the G major scale by starting on A, and the resulting scale will have the same key signature as G major – but the scale is called an A Dorian scale. To create a G Dorian scale, the scale must begin on the second note of some other major scale. This is where the tip comes in: in a G Dorian scale the G is the second note of a major scale that beging a major second below G – F, just as the post indicates. An F major scale has 1 flat in its key signature, and the G Dorian scale using the same notes as the F major scale) has the same key signature as the F major scale – 1 flat.

    It’s definitely confusing. To keep it straight just remember, G major and G minor are really just G Ionian and G Aeolian – and G major and G minor have different key signatures.

  • Lukas Kobela
    Author

    Thanks Adrian and Jim for making it clear!

    • http://adriantry.com Adrian Try

      Your welcome, Lukas. Great quick tip!

  • ezrashanti

    This was explained terribly. I understand that basically as you move forward in the IDPLMA you move down two half steps, but basically you gave us no way to remember this and didn’t explain the purpose of the modes or anything. This helped me not at all. Can I use every single mode of G in the same song? Probably not. You also explained each one separately (what a time waster) and never really said the formula for conversion, instead just telling us the notes for each mode. Worst article I’ve read on tutplus so far.

    • Chow Fan

      I see u posted that 5 months ago so i dont know if this will help..

      These are not all of the modes. These are only 6 of the church modes and i believe this article is poorly explained because going into modes deeply would involve intense music theory studies. O_O. When i refer to the church modes, I like to look at 7 of them: Ionian, Dorian, Phrygian, Lydian, Mixolydian (those 6 were included), and Locrian. They can be rememberred by I Drank Punch Last Monday After Lunch (IDPLMAL). To remember that Locrian is at the last L, just think that Lydian comes right before Mixolydian which would be the Last and Monday. These are Gregorian modes.

      Another way to remember them is by the arrangement of half and whole steps between the notes.

      Ionian/Major Scale: C, D, E, F, G, A, B, C

      Dorian: D, E, F, G, A, B, C, D

      Phrygian: E, F, G, A, B, C, D, E

      Lydian: F, G, A, B, C, D, E, F

      Mixolydian: G, A, B, C, D, E, F, G

      Aeolian/Natural minor scale: A, B, C, D, E, F, G, A

      In each example, there is half steps between the E-F and B-C notes. All the other notes half whole steps in between them. I thinks these sites are ok refrences. If you want more in-depth explanation, just respond.

      http://musictheoryblog.blogspot.com/2007/01/modes-of-major-scale.html

      http://www.teoria.com/reference/g/gregorian.php

      http://www.churchmusic.ca/BOP5.html
      Happy to help,
      Chow Fan