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AC #38 Intervalics 101 (5ths – [Perfect 5ths / Power Chords])

Intro / Op-Ed

Of all the intervals we’re covering, perfect 5ths are among the strongest and most versatile!

Perfect 5th is lifting weights

The interval is so strong that, with only 2 notes, (almost like a triad having 1 of its 3 hands tied behind its back!), it can hold its own as a “power chord” and sonically cut-thru and even overshadow chords that have a much higher note density. The use of this interval on pianos, as an “anchoring” type of “power chord”, can be heard in the LH boogie-woogie stylings of pianists like James P. Johnson and Sammy Price, and also in the sheer power of either hand of Dorothy Donegan and in the LH bomb-dropping, sonic-booms of McCoy Tyner.

The interval’s versatility is shown by its chameleon-like ability to comfortably blend in with both major and minor tonalities. This special ability is due to the fact that “power chords” lack 3rds, which is one of the reasons that the perfect 5th is an ever-present tool of “top-40” poppers as well as slammin’ hard rockers! Its use and presence in playing situations is easily revealed to people with trained ears.  Its use and presence are also evidenced on many of today’s pop music lead sheets and piano scores that are populated with chord symbols like C5, F5, and G5… musical shorthand that signals a perfect 5th is to be played where those chord symbols appear.

Now with all of that being said about perfect 5ths and “power chords”, I want to make sure I say a few words about the following:

Is the “power chord” really a chord?

“It takes a minimum of 3 notes to make a chord” is a point that’s taught in music theory classes.

In many instances, in its role as a “power chord”, the perfect 5th is further strengthened by doubling its root note with an octave (see *2 – just below). This reinforcement adds a third note which bolsters and gives credence to the notion of referring to these intervals as chords. However, even with an added 3rd note, “power chords” still remain classified as an interval! Why? Let’s consider the consistency and congruency of the following three scenarios.

1 – Consider middle C. Add 2 more Cs to it in ascending octaves. You’ve got 3 notes! Is it a triad?

Illustration of example 1 on piano and treble staff

If you said yes, you’ve got one of these  Professor Matthews' Red X coming your way with an invitation to stay after class! If you said no, you’ve got one of these Professor Matthews' Green Checkmarkcoming your way with an invitation to skip class today!  Three Cs spread over 3 consecutive octaves is not a triad. It’s a triple octave unison! 

*2 – Consider C perfect 5th (C and G or 1 and 5). Add another C exactly 1-octave above the root.

Illustration of example 2 on piano and treble staff 

You have 3 notes! Is it a triad? No! You have a Perfect 5th interval with a doubled root!

3 – Consider C major triad (root position, 1-3-5). Add another C exactly 1-octave above the root.

Illustration of example 2 on piano and treble staff

You’ve got 4 notes! Is it a 7th chord? No! It’s a triad with a doubled root, a 4-note triad if you will.

Octave-doubling any note(s) of an interval or a chord does not change the entity’s classification.  The rule that says “it takes a minimum of 3 notes to make a chord” governs chord classification and the 3 notes must be 3 different notes, not an octave doubling of an original unit member.

So although perfect 5ths are also known as “power chords”, by definition, they are not chords. They are intervals, and it is my hope that that you’ll get to know these intervals a little better through the work you’re doing in this series. 

Construction of Perfect 5ths from the scale steps of Pentachords/Pentascales

Pentachords and pentascales (synomous terms), are the first 5 notes of a diatonic scale. Major pentachords and/or major pentascales are comprised of major scale notes 1 thru 5.  Extracting only the 1st and 5th notes of this major scale subgroup yields a perfect 5th interval.

Major Pentachord/Pentascale Legend
1-5 = scale steps
w = whole step (major 2nd)
1/2=  half step (minor 2nd)
w  w  3 1/2  4 w 

If you start with C and follow the schematic’s instructions, step-by-step, the C major pentascale will  reveal itself on your piano’s white keys. Play the pentascale in the keys of G, D, A and E too.

Construction of Generic 5ths from the 7-Letter Musical Alphabet


1. Select any letter from the 7-letter sequence
(In doing that you’ve established the interval’s letter name and root… think of it as scale step “1”.)

2. Skip over the next 3 scale steps.
(In doing that you’re skipping over scale steps 2, 3, and 4 because your mission is to make a 5th.)

3. Now, having skipped over scale steps 2, 3, and 4, select the very next letter in the sequence.
(In doing that, you’ve selected scale step “5” as the interval’s upper note and then you extract scale steps 1 and 5.)

That’s it! You’ve constructed a 5th… a generic 5th*.
*(All accidentals are excluded In generic intervals. Only letter names and staff position matters.)

5ths – These intervals may be identified by their letter names because both letter names are the 1st and 5th letters of an alphabetically sequenced 5-letter string (pentachord or pentascale).

When written in standard music notation, 5ths will have exactly 3 unoccupied staff steps in between the interval’s lower and upper notes–a space/line/space, OR, a line/space/line. Also, three alphabetically sequenced letters will be skipped over.

Harmonic and melodic intervals on a treble staff

Keep the following points in mind:

1. The staff represents a piano’s white keys only. The black keys are notated by accidentals. (Staff steps, unmodified by accidentals, are whole steps, except for the half steps at E to F and B to C) (One staff step = the distance from any staff line to the very next staff space or vice versa, up or down)

2. Every staff line and every staff space correlates to a specific white key on the piano.
(This point applies to all ledger lines and ledger spaces.)

3. If 3 consecutive staff steps are skipped over, 3 correlating piano keys are also skipped over!  (This “skip-over/fly-over” concept and analogy is illustrated in the key of C in the photos just below.) (Your eyes skip-over the 3 staff steps while your fingers “fly-over” the 3 correlating piano keys.)

Illustration of notes being skipped and flown over

Perfect Intervals: (This section is reposted from AC #37… slightly revised. Click to view)


Perfect Intervals: What are they? Why are they called “perfect”?

Part of the answer to both questions has to do with the overtones and harmonics that only this particular class of intervals produce. Many piano tuners rely on perfect intervals in their craft. However, since the details that explain overtones and harmonics go far beyond the scope of this post, I’ll simply tell you which intervals are “perfect” and I’ll mention a distinguishing and affirming “key” characteristic of perfect intervals, (“Key” pun intended).

Which intervals are perfect?

There are only 4 of ’em! They come directly out of the major scale. Memorize ’em! (1-4-5-8)

1-1 Perfect 1st or Perfect Unison – (The 1st note of a major scale doubled directly upon itself)
1-4 Perfect 4th – (The 1st and 4th notes of a major scale)
1-5 Perfect 5th – (The 1st and 5th notes of a major scale)
1-8 Perfect 8th or Perfect Octave – (The 1st and 8th notes of a major scale)

Here’s an optional verification process you can use to confirm an interval’s “perfect” status.

Perfect Interval Evaluative Characteristics Affirmation Test (P.I.E.C.A.T.)
(OK! I confess! I just made-up this tongue-in-cheek acronym but many cats have been known to eat non-cat-like foods. I had a cat that loved vinegar potato chips! Anyway, here’s how the test works…)

A “purr-fect” interval is affirmed when the upper note of any given interval is also found in the major scale that begins on that interval’s lower note, AND, the lower note of that interval is also found in the major scale that begins on that interval’s upper note. Here’s another way to say it…

If your interval’s top note is present in its bottom note’s major scale, AND, its bottom note is present in its top note’s major scale, voilà! You’ve ID’d a “purr-fect” interval via “P.I.E.C.A.T.“!

a pretty cat is about to eat some pie with a fork!

“Did somebody say pie cat? Yummy! Mmmm! Got Milk?

  (The video below shows how you might use LH Power Chords to anchor and drive a groove.)

The most commonly used accidentals are shown in the lineup just below followed by examples of the most common occurrences of 5ths in the key of C.

  = natural
= sharp
X = double sharp
=  flat
♭♭ = double flat

Perfect 5th = C to G (The 5th note of a major scale remains unmodified)
Augmented 5th = C to G (The 5th note of a major scale is sharped once)
Minor 1st *(N/A)
*(Minor functionality isn’t allowed on any perfect interval.)
Diminished 5th = C to G **(The 5th note of a major scale is flatted once)
**(Perfect intervals become diminished with only one flat)

This link will open an Acrobat/Adobe flash type of applet where you’ll be asked to correctly match ten intervals via a drag-n-drop process. Doing the exercise at least 4 or 5 times will give you an introductory workout on identifying and matching the intervals in C and other keys.

Study well and have fun,

See you next post,