EP-133 K.O. II Applied Music Theory

I got carried away making notes for a video and decided to clean it up to post it as a supplement to the video (whenever it’s done)

Please add more ideas and chord shapes. And please correct me, ask questions, suggest better explanations, etc! I’d like to make this thread as helpful as possible.


When using the pads on the KO II it’s pretty easy to make a decent-sounding chord progression by mashing buttons. You don’t have to take a fully deliberate approach, but hopefully this gives you ideas of some chord shapes, how to use them to create progressions, and how they can sound different between different modes.

The Number Pad

By default the KO II’s scale is set to 12T, which I find very helpful for editing but not playing.

7-9:  Gb G  Ab
4-6:  Eb E  F
1-3:  C  Db D
.-E:  A  Bb  B

These examples and explanations start with the pads set to C major.

In the C major scale, C is our tonic note and is set to the 1 pad by default. This is very helpful as it allows us to identify scale degrees by number.

In C major, our scale on the KOII looks like this:

7-9:  B  C  D
4-6:  F  G  A
1-3:  C  D  E
.-E:  G  A  B

Major & Minor Chords

Major and minor chords have 3 notes: the root, the third, and the fifth. This means that, when making a major or minor chord, you’ll play every other pad after the root note.

To make a C major chord, play pads 1, 3, and 5:

7-9:  B  C  D
4-6:  F (G) A
1-3: (C) D (E)
.-E:  G  A  B

The Three Basic Shapes

If we use the same approach of skipping every other pad we can make other chords in the key of C major.

It’s common to write down a chord progression using numbers relative to the key, starting with C as the 1. Upper-case Roman numerals indicate a major chord while lower-case indicate a minor chord.

If we apply the same every-other-key approach, we see the three basic shapes for major/minor chords on the KO II:

I: C major (C)

7-9:  B  C  D
4-6:  F (G) A
1-3: (C) D (E)
.-E:  G  A  B 

ii: D minor (Dm)

7-9:  B  C  D
4-6: (F) G (A)
1-3:  C (D) E
.-E:  G  A  B

iii: E minor (Em)

7-9: (B) C  D
4-6:  F (G) A
1-3:  C  D (E)
.-E:  G  A  B

Wait, if we’re in C major why are we using minor chords for D and E!?

Major and minor chords (again)

I’m glad you asked! It’s because we’re in the key of C major, so we’re making the chords we can make from those notes using our pattern of skipping every other pad.

When we use our pattern to get a chord starting from D, we end up playing D, F, and A.

There are two keys on a piano between D and F (D# and E) while there are three keys between C and G (C# D D#). The smaller jump is a minor third, while the bigger jump is called a major third, hence D minor and E minor fit into the key of C major.

More chord shapes

The chords we made starting from 1, 2, and 3 were C, Dm, and Em. We can repeat our pattern to make chords for F and G:

IV: F major (F)

7-9:  B (C) D
4-6: (F) G (A)
1-3:  C  D  E
.-E:  G  A  B

V: G major (G)

7-9: (B) C (D)
4-6:  F (G) A
1-3:  C  D  E
.-E:  G  A  B

But if we start from A, we run out of room.

Inversions

Let’s go back to our C major chord:

7-9:  B  C  D
4-6:  F (G) A
1-3: (C) D (E)
.-E:  G  A  B

If we play our G on the . pad instead of the 5 pad, we get different shape for our C major:

7-9:  B  C  D
4-6:  F  G  A
1-3: (C) D (E)
.-E: (G) A  B

It’s still a C major, but since the notes are in a different order it’s called an inversion.

On the KO II, you can play the 5th of a pad’s chord by playing the pad immediately below it. If we use this substitution for Dm and Em we get these shapes:

Dm inversion

7-9:  B  C  D
4-6: (F) G  A
1-3:  C (D) E
.-E:  G (A) B

Em inversion

7-9:  B  C  D
4-6:  F (G) A
1-3:  C  D (E)
.-E:  G  A (B)

Note that when you play an inversion it’s good to remember which pad is the root note.

More chord shapes

Now that we know how inversions work, we can get our 6 chord:

vi: A minor (Am)

7-9:  B (C) D
4-6:  F  G (A)
1-3:  C  D (E)
.-E:  G  A  B

But we run out of space again for our 7 chord. Thankfully there are more inversions available to us.

When we played inversions before, we played the fifth of the chord on the pad below the root note. If we play the pad to the bottom-right of that pad, we’ll get a different inversion which will allow us to play our 7 chord:

viio: B diminished (Bdim)

7-9: (B) C  D
4-6: (F) G  A
1-3:  C (D) E
.-E:  G  A  B

Wait, DIMINISHED!?

Diminished Chords

Every major chord is a major third and a minor third. For example, C major has a major third between C and E but a minor third between E and G.

Every minor chord consists of a minor third and a major third. D minor has a minor third between D and F but a major third between F and A.

Diminished chords are even smaller than minor, since they’re two minor thirds put together. B to D is a minor third (C C# between them) and D to F is a minor third (D# E between them). They’re often used to create tension in a chord progression.

Other chord types
A suspended chord has no 3rd. Instead you play the 4th or 2nd. These chord types can also be inverted.

Csus4:

7-9:  B  C  D
4-6: (F)(G) A
1-3: (C) D  E
.-E:  G  A  B

Csus2 (controversial chord name):

7-9:  B  C  D
4-6:  F (G) A
1-3: (C)(D) E
.-E:  G  A  B

7th chords have four notes: a root, third, fifth, and seventh. In other words you only need to add one more note to get a 7th chord:

Cmaj7

7-9: (B) C D
4-6:  F (G) A
1-3: (C) D (E)
.-E:  G  A  B

There are lots of inversions and ways you can move the notes around (including dropping the fifth) but here’s just one other example:
Cmaj7

7-9:  B  C  D
4-6:  F  G  A
1-3: (C) D (E)
.-E: (G) A (B)

Chord progressions

To make a chord progression in the key of C major, we can just use the different shapes above and see what sounds good through trial and error. Generally, starting or ending with the 1 is a good idea, and it’s common to play the 5 chord before the 1. These aren’t rules, though–just ideas to consider.

Practicing chord progressions

Now that you know shapes in the major scale, you might want to spend some time working out different chord progressions on the KO II’s pads, including inversions & sometimes substituting a different chord type.

Here are some progressions you could try:
1 6 4 5
1 3 4 5
1 4 1 5
5 4 1 1
2 5 3 1

The cool part: other keys & modes

If you change the KO II’s key from C major to F# major (System code 326; 320 changes back to C), the progressions will sound different but work just the same. No need to memorize which keys have sharps etc.

If you change the scale from C major to C minor (System code 312), the above progressions will sound drastically different… but they’ll probably still work!

This is a super oversimplified version of looking at modes:

  • If a progression sounds good in C major, try changing to C Mixolydian (316) or C Lydian (315). Each of those only change one note in the major scale.
  • If a progression sounds good in C minor, try changing to C Dorian (313) or C Phrygian (314)

There’s also Locrian mode but if you have to debate whether something can be used musically, I’m just gonna plan to not use it at all.

Pentatonic major/minor has a different layout than the modes of the major scale, so these shapes won’t work. Plus you probably don’t want to just make chords out of a pentatonic scale anyway.

Tangent about modes

The minor scale is technically a mode of the major scale, but I like to them of them as totally separate.

From this view, the Mixolydian scale is “C major but with a Bb instead of a B” and Lydian is “C major but with an F# instead of an F.” These do change which notes are played and change the name of some chords used, but they don’t differ as dramatically as changing from C major to C minor.

Similarly, Dorian in my mind is “C minor but with a major 6” and Phrygian is “C minor but with a minor 2”


Holy crap that was more than I intended to write.

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More about inversions
Inversions aren’t only useful when you run out of space.

In fact, they can give the same chord progression an entirely different feeling. In my last post I mentioned a 1 3 4 5 progression as one you could practice.

1 3 4 5 in C major would be: C Em F G. If you play them all as root position chords (not inverted), you’ll end up with these shapes:
1 chord (C major) root position

7-9:  B  C  D
4-6:  F (G) A
1-3: (C) D (E)
.-E:  G  A  B

3 chord (E minor) root position

7-9: (B) C  D
4-6:  F (G) A
1-3:  C  D (E)
.-E:  G  A  B

4 chord (F major) root position

7-9:  B (C) D
4-6: (F) G (A)
1-3:  C  D  E
.-E:  G  A  B

5 chord (G major) root position

7-9: (B) C (D)
4-6:  F (G) A
1-3:  C  D  E
.-E:  G  A  B

This is a totally legitimate interpretation of I iii IV V and will sound fine but, in my opinion, is a bit stale.

Using inversions we can give the progression a different feeling entirely. For example, we could keep the notes for every chord very close together by carefully picking our inversions:

1 chord (C major) second inversion (second because we moved 2 notes from the bottom of the chord to the top)

7-9:  B  C  D
4-6:  F  G  A
1-3: (C) D (E)
.-E: (G) A  B

3 chord (E minor) second inversion

7-9:  B  C  D
4-6:  F (G) A
1-3:  C  D (E)
.-E:  G  A (B)

4 chord (F major) first inversion (first because we’re only moving F from the bottom to the top)

7-9:  B  C  D
4-6: (F) G  A
1-3: (C) D  E
.-E:  G (A) B

5 chord (G major) first inversion

7-9:  B  C  D
4-6:  F (G) A
1-3:  C (D) E
.-E:  G  A (B)

Hopefully you can hear how different these two progressions sound despite having the same chords represented by the same numbers.

You can get as creative as you want–maybe the first 2 chords are close together while the last 2 chords are far apart from the rest.

You could even take the I iii IV V progression and play it moving DOWN the pads:

1 chord (C major) first inversion

7-9:  B (C) D
4-6:  F (G) A
1-3:  C  D (E)
.-E:  G  A  B

3 chord (E minor) root position

7-9: (B) C  D
4-6:  F (G) A
1-3:  C  D (E)
.-E:  G  A  B

4 chord (F major) second inversion

7-9:  B  C  D
4-6: (F) G (A)
1-3: (C) D  E
.-E:  G  A  B

5 chord (G major) first inversion

7-9:  B  C  D
4-6:  F (G) A
1-3:  C (D) E
.-E:  G  A (B)
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Thanks for sharing these – really helpful!

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I wanted this to be more applied but I just burnt out before I even got to the applied part. Hopefully this will serve as a helpful reference.

Videos coming someday… hopefully.

Understanding Scales & Modes

The KO II has 10 scales available. Here are the ones I’ll focus on, along with their respective system codes:

Major (311)
Minor (312)
Dorian (313)
Phrygian (314)
Lydian (315)
Mixolydian (316)

These are all variations of the major scale.

If we look at the distance between every note in the major scale and use H to represent half steps (i.e., the next highest black or white key on a piano) and W to represent whole steps (i.e., two black or white keys higher), we get this pattern:

 W W H W W W H
C^D^E^F^G^A^B^C

Imagine that pattern repeating indefinitely, much like the keys on a keyboard do:

W W H W W W H W W W H W W W H W W H W W W H

A mode of the major scale takes this same pattern but uses a different starting point. Like what if we made it so our first interval was here instead:

W W H W W W H W W W H W W W H W W H W W W H

If we take one octave starting from the first interval, we get:

W H W W H W W

If we started from C on a keyboard, the pattern gets us the following notes:

 W H  W W H  W  W
C^D^Eb^F^G^Ab^Bb^C

Which is also known as C minor. C Dorian and C Phrygian start from different points but aren’t that different from C minor–ultimately, they are “C minor with a raised 6” or “C minor with a flat 2.”

C minor (312):

7-9:  Bb C  D
4-6:  F  G  Ab
1-3:  C  D  Eb
.-E:  G  Ab Bb
 W H  W W H  W  W
C^D^Eb^F^G^Ab^Bb^C

C Dorian (313):

7-9:  Bb C  D
4-6:  F  G  A
1-3:  C  D  Eb
.-E:  G  A  Bb
 W H  W W W H  W
C^D^Eb^F^G^A^Bb^C

C Phrygian (314):

7-9:  Bb C  Db
4-6:  F  G  Ab
1-3:  C  Db Eb
.-E:  G  Ab Bb
 H  W  W W H  W  W
C^Db^Eb^F^G^Ab^Bb^C

In other words, C minor & C Dorian only differ on pads 0 and 6, while C minor & C Phrygian only differ on pads 2 and 9. Any chord progression or lead that doesn’t use those pads won’t sound different between the two scales.


C major has a similar relationship to C Lydian and C Mixolydian, where C Lydian is “C major with a sharp 4” and C Mixolydian is “C major with a flat 7.”

C major (311):

7-9:  B  C  D
4-6:  F  G  A
1-3:  C  D  E
.-E:  G  A  B
 W W H W W W H
C^D^E^F^G^A^B^C

C Lydian (315):

7-9:  B  C  D
4-6:  F# G  A
1-3:  C  D  E
.-E:  G  A  B
 W W W  H W W H
C^D^E^F#^G^A^B^C

C Mixolydian (316):

7-9:  Bb C  D
4-6:  F  G  A
1-3:  C  D  E
.-E:  G  A  Bb
 W W H W W H  W
C^D^E^F^G^A^Bb^C

So C major and C Lydian only differ on pad 4, while C major and C Mixolydian only differ on pads 7 and Enter.

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For those interested, here’s the first video I made from these notes: https://youtu.be/f0BE07e0VEs

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How does this work for the OG pocket operators?

Unfortunately, it doesn’t. :frowning:

The reason I’m writing this out for the EP-133 is because the layout works well for seeing intervals and chords in a way that won’t work with the original pocket operators.

Specifically:

  • The EP-133 has 3 pads per row, making it very easy to see thirds which is crucial for making chords. Pocket operators have 4 buttons per row which makes it harder to see thirds.
  • By default the scale starts on the 1 pad on the EP-133, making it easy to see degrees of the scale on the other numbered pads. Pocket Operators have their lowest note on pad 13 and follow a really confusing system for numbering from lowest to highest (13 14 15 16 9 10 11 12 5 6 7 8 1 2 3 4)
  • You can change the scale & key on the EP-133 but not pocket operators, so memorizing different chord shapes will only help in composing in one mode of one key.
  • I don’t think older pocket operators allow for the playback of more than one note at a time for the same sound (correct me if I’m wrong), so chord shapes would only be relevant for arpeggios anyway.

Understood. You are correct that you can only play one version of a sound at a time. (For reference, you can get around this on the sampler (PO 3x) pocket operators by copying a sound to multiple slots.) And anyway, you can create an arppegio even more easily on the smaller pocket operators by simpily playing notes in a vertical line. (eg: 13, 9, 5, 11) Thanks anyway.

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I originally posted this on Elektronauts but I’m also sharing it here:

I’m not sure if this will make it into my youtube videos, so I’ll share it here.

Thinking of the KO II like a guitar

  • It’s very common to approach the guitar/bass fretboard by learning different patterns to play 3 notes on each string
  • The KO II is similarly laid out: 4 rows (strings) with 3 pads (notes) per row. You can think of those 4 rows like the 4 lowest strings on a 6-string guitar, or the strings of a 4-string bass.

If you set the scale to major (311), key to E (324), and set the scale starting point to the . pad (key + .) you get this layout on the KO II:

7-9:  G# A  B
4-6:  D# E  F#
1-3:  A  B  C#
.-E:  E  F# G#

This is the same as the following scale on a 4-string bass (or the lowest 4 strings on a 6-string guitar), with each fret represented by a numeral:

G |--------------------1-2-4
D |--------------1-2-4------
A |--------0-2-4------------
E |--0-2-4------------------

For comparison, E minor would look like this on the KO II:

7-9:  G  A  B
4-6:  D  E  F#
1-3:  A  B  C
.-E:  E  F# G

And like this on bass/guitar:

G |--------------------0-2-4
D |--------------0-2-4------
A |--------0-2-3------------
E |--0-2-3------------------

Of course, the fretboard repeats and it’s common to change your hand position as you change chords. For example, if I’m playing a chord progression that goes from the 1 chord to the 4 chord, one option would be to shift my fretting hand to the 5th fret. I’ll continue to play the E minor scale, but now I’m reoriented so the lowest note in this position is the root of the 4 chord (does that make any sense…?)

In E minor, this would look like this on guitar/bass, basically just adding 5 frets (5 semitones) to each note we played in the E minor scale:

G |--------------------5-7-9
D |--------------5-7-9------
A |--------5-7-8------------
E |--5-7-8------------------

You can also do this on the KO II, though obviously it’s not as easy as on a guitar so you’ll have to change the scale’s starting point before you record the line in the new chord:

  1. Imagine that the . pad is the new chord, 4.
  2. Count up from the . pad until you get to 8. (e.g., count pads . 0 E 1 2 as 4 5 6 7 8)
  3. Hold key and press the 8th pad down

Basically, we’re answering “If I start on 4, where would the start of the scale move to?” In this case, the start of the scale moves to pad 2.

Here’s our new note layout:

7-9:  C  D  E
4-6:  G  A  B
1-3:  D  E  F#
.-E:  A  B  C

So if there’s a pattern of pads we liked playing on our 1 chord, we can now play that same pattern on our 4 chord using notes from the key we’re in.