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Nexus by 2nd Up/Down

By May 18th, 2024Nexus System

Now, let’s look into the details of individual nexus patterns.

1. Nexus by 2nd


The 2nd nexus involves the smallest motion in root changes, providing a smooth and gentle impression. On the other hand, as all the chord tones are replaced, the change of harmonic color is strong.

It’s a very user-friendly nexus pattern—Just go to adjacent chords without much consideration and yuo can easily create an appealing chord progression.


Among them, I’m gonna introduce several popular chord progressions.


First and foremost, an essential timeless progression in rock and electronic music is the 4-5-6 progression, starting softly from the subdominant IV.

Functionally, it naturally follows the SDT cycle, making it very comfortable to the ear. The constant 2nd motion keeps the chord progression gentle, allowing you to focus on the melody and sound. Additionally, since many chord progressions form a loop of four chords, the 4-5-6 progression leaves creative possibilities for the final chord. Common options include progressing to the V for a consistent chain of 2nd nexus, going to IIIm for additional melancholy, or going to I to end with a bright tone.

2. About “Former Prohibitions”

2 is a commonly used progression in various genres, while 2 has two “former prohibitions”.

The connection V→IV

In both classical music and jazz, it is the common conception that the V is the point of highest tension, the climax. They say that the acceptable progressions from V are I or VIm, which have T function, or IIIm in jazz which is also considered as a T functioning chord.

On the other hand, the connection VIV, which can be described as “moderating the tension of the chords,” is not favored in classical or jazz contexts. In classical theory, many books give it negative words like “impossible” or “avoid it”.

Remember that the function of these intermediate harmonies is to lead toward V, not away from it—thus, I-IV-V-I or I-II-V-I but not I-V-IV-I or I-V-II-I.

Aldwell, Edward. “Harmony and Voice Leading (p.162)”.

Jazz theory doesn’t explicitly label it as a “prohibition”, but still describes it as “uncommon” or “retrogression.” Given these opinions, such descriptions are echoed in generic “popular music theory” as well1.

Use in Blues and Rock ‘n’ Roll

However, on the flip side, this progression has become quite common in blues born in 20th century US, and it continues to be used frequently in rock ‘n’ roll.

There is a history that this kind of progression, 1-1-4-1-5-4-1, was established and widespread as the basic fixed formats2.

These genre styles have been directly inherited by rock, and in genres that favor simple chord progressions, such as punk, these types of progressions are often seen.
There may have been composers and theorists back then who found this VIVI progression somewhat “inexcusable”, an “incorrect” way of harmony.


However traditional theory may deem it right or wrong, the fact remains that it was embraced by the masses, and rock ‘n’ roll exploded in popularity. That’s the reality.

Use in Reggae

Another genre commonly using VIV retrogression is reggae. For instance, a music scholar discovered that in a reggae song, the progression V-IV appeared twice as often as IV-V3. It’s far from “forbidden”, isn’t it?

From my own research, whhile you can naturally find functional prograde motion (TSDT), such as 1-4-5-1 or 1-6-2-5, at the same time, non-classical progressions like 1-5-4-1 or 1-4-5-4 indeed seem to be also prevalent.

Especially in relaxed and chilled-out styles like Hawaiian reggae, you can see that the retrogression of V-IV is effectively utilized. As Reggae is influenced by blues as part of its genre origins, it’s only natural that this progression would find acceptance within the genre.

And now, more than 100 years after the birth of the blues, this progression has become so commonplace in the vocabulary of popular music.

The impression of 5-4-1

The VIVI progression can be understood as reducing the strength of the sense of resolution that VI brings, making it more gentle. When VI feels a bit too energetic, IV inserted between them can act as a good “cushion”.


This progression works perfectly for expressing a calm and peaceful feeling.

The beautiful ballad “The Rose” by Bette Midler uses the progression IVIVVI in verse, showcasing the “cushion effect,” contributing to a soft and peaceful atmosphere.


Or successive descending progressions like VImVIV, there’s the contextual support of “keep going down from above,” making it very usable without any issues.

Naturally, this leads to a darker musical tone as it starts with VIm. Again there’s room for optional choices with the fourth chord in this progression such as 6-5-4-5, 6-5-4-3 or 6-5-4-2.

The notion that this progression is unnatural to ears is really a thing of the past!

IIIm→IIm Nexus

In classical theory, IIIm is typically allowed to progress to either VIm or IV, and no other options are generally accepted. However, due to the smooth transition to a neighbor root, it can be used without any special care in practice. A common progression is descending 4-3-2-1, or 4-3-2-6 for more darker sound.


Another example is the hit song “Cake By The Ocean”, which uses the progression 6-3-2-4.

There’s no noticeable discomfort, right?

In this manner, there are instances where the “prohibitions” of the classical theory are effectively broken. Ultimately, what matters is not whether the chord progression conforms to conventional theories, but whether it fits the content you want to express.

No matter how authoritative and established a theory may be, it can’t resist the changes of time. Our sensibilities are evolving over time.

So, when it comes to 22 connections, feel free to use them without worrying about the past prohibition stuffs. However, if you want to create a more classical-style piece, avoiding such prohibitions might lead to a more authentic composition.


  • The 22 progressions allow for a gentle and smooth chord progression due to minimal root changes.
  • Simultaneously, they create rich harmonic color changes with complete exchange of chord tones.
  • The once forbidden progressions of VIV and IIImIIm have a special effect of “restrained elevation” from Dominant to Subdominant.
  • Concerning the restrictions related to 2, even if you break them, the risk of bringing discomfort is low. They are commonly used in today’s pop music.