Theory details what intervals make up a chord or a scale. This can be visualised using emuso’s clock-instrument, independently of musical instrument, to understand the intervals involved. You effectively look at one or more octaves of notes, all collapsed onto the twelve hours (0 AM to 11 AM) of the clock face. Replicating these intervals on a musical instrument involves selecting these intervals from the anchor, and placing them in various octaves … this is what you need to know for performance, and what emuso’s chord and scale libraries do for you. But this is a lot more detail than required to understand the note relatonships between chords and scales, chords and chords, and scales and scales.

Let’s take a look…

Now let’s have a look at the Rel-X tool.  Don’t worry about the scale and chord names used below.  Pay attention to the graphics discussed below.

Here is what Rel-X looks like when you follow steps 1 to 11 below (click it to enlarge (make the lesson fullscreen first)).

Notice there are two sets of labels above.  One set has the usual labels showing the intervals on the clock (semitones (clock time 0 – 11 AM), or interval symbols) representing what’s on “guitar” at that time.  The other set of labels appear at the outer end of spokes.

When a chord or scale is loaded onto the spokes, initially the corresponding spokes are aligned with 0 AM of the clock.

The outer spoke label at 0 AM is labelled 0 (semitones) or 1 (interval symbols).  The other spokes are labelled with the interval they each make with the spoke labelled 0 AM. (In other words, the intervals for the chord or scale, if it was rooted at 0 AM).  When the spokes are rotated, these labels rotate with them, so you can see where the chord root or scale tonic is currently aligned against the chord or scale showing on the clock (reflecting what’s on “guitar” or “piano” or “bass”).  Keep an eye on the spoke with outer label 0 (or 1 with interval symbols) as you rotate the spokes.  When a full match occurs, look at the clock time that coincides with this spoke.  You then know that the spoke contents can be created out of what’s on-instrument, starting at that clock time (interval).

Below you’ll find the above chord can be created rooted at the first and second scale notes (times 0 and 2), and other scale notes as well.  Once you know the sus4 chord and a few of its voicings, you’d just align it appropriately e.g. if you were playing rhythm for someone to solo over using the scale below.

After step 3 below, the clock shows the intervals of the mixolydian scale. Its start note (also known as the tonic) is aligned at 0 AM.   After step 6, a set of twelve dim, coloured spokes appear, initially empty.

On completing step 9,  the chord’s intervals appear on the spokes, with the chord root also aligned  with the scale start note (0 AM).  The spokes at 0, 5 and 7 AM are lit up indicating the intervals found in the sus4 chord, relative to the chord root.  Where a chord note matches a scale note, the spoke shows orange, so you can see this chord exists in the scale, when rooted at the scale start note.

The “Rotate” buttons can be used to move the chord root aganst the scale, to see if it matches elesewhere in the scale.

1. CTL-left click on the 3rd fret of the bass string to move the anchor.
2. Press “Toolkit”, select “major scale and modes” from “scale families”. Click “Scale” and select “Mixolydian”.
3. Click button “Rel-X” in the toolkit.
4. Now we’re going to look for any “sus4” chords that exist in this scale …
5. Select “seventh and sixth” types from the “chord families” dropdown, ready for step 9.
6. Click “Explorer” in the Rel-X gadget.
7. Click on the dropdown arrow next to the button labelled “Choose search”
8. Choose “from Chord menu”. Notice the button changes color to orange, as does the Chord button in the Toolkit, to remind you that any chords will be sent to the explorer, and not the instrument.
9. Click on the Chord button in the Toolkit and select “sus 4”. (The “sus 4” chord is made up of interval symbols 1, 4, and 5, or semitones 0, 5 and 7)
10. If needed, type “=” so the labelling changes to semitones in range 0 – 11.
11. Notice the spokes at times 0, 5 and 7 have all lit up orange. This shows the intervals for the chord are found if the chord is built starting at the scale start note (0 AM).
12. Click “Rotate+” on Rel-X. The spokes rotate by one position. None light up orange. The scale does not have the right intervals to build a sus4 chord there.
13. Click “Rotate+” again. The spokes rotate so the chord root aligns with the second note of the scale (at 2 AM). The spokes light up. We have a match.
14. Keep rotating. You’ll find another match at 5 AM, 7 AM and 9 AM.
15. You’ve found that the sus 4 chord can be built rooted at the scale notes located at 0, 2, 5, 7 and 9 semitones above the scale start note.  In other words, at the 1st, 2nd, 4th, 5th and 6th notes of the scale.
16. Click Rel-X button to dismiss Rel-X

Now let’s look for a scale called “major pentatonic” (its semitone intervals are 0 2 4 7 and 9).

1. Click Rel-X to turn it on and click Explorer.
2. Click on the dropdown arrow next to the button labelled “Choose search”
3. Choose “from Scale menu”. Notice the button changes color to orange, as does the Scale button in the Toolkit, to remind you that any scales will be sent to the explorer, and not the instrument.
4. If needed, type “=” so the labelling changes to semitones in range 0 – 11.
5. Select “basic scales” from the “scale families” dropdown.
6. Click on the Scale button in the Toolkit, scroll down, and select “Major Pentatonic”. (This has semitone intervals 0 2 4 7 and 9)
7. Notice that the spokes at times 0 2 4 7 and 9 all light up orange. So, the mixolydian scale contains this pentatonic, starting at the first note of the mixolydian scale.
8. Keep rotating, and you will find matches at times 5 and 10 as well. The pentatonic can be built from the mixolydian scale pitches located at times 0, 5 and 10.
9. Click the Rel-X button to dismiss the Rel-X tool.
10. Click the “Small clock” button to locate the clock back in the upper right of emuso.

Scales that are “roughly” right for a chord are often used for aural effect. Rel-X can be used for this, and also to find chords within chords.

Use “Settings > Customise fretboard and interval colours…”

Use the “Rel-X” button to change the background colour , “Clock Label” for the text just outside the clock, and “Spoke Label” forthe text outside the spokes.

For example: