Learn the Ionian ♯5 Mode
Major but unsettled. The #5 disrupts Ionian's sense of completion; it sounds like the major scale is reaching for something just beyond its grasp. Bright, augmented, and slightly surreal.
Try Ionian ♯5 interactivelyWhat makes it sound this way
The #5 replaces the perfect 5th, making the tonic triad augmented instead of major. This single change destabilizes the otherwise solid major scale, creating a funhouse-mirror version of Ionian where something feels slightly 'off' despite the major brightness.
Overview
Ionian #5 is the third mode of the harmonic minor scale. It looks like the major scale with a single alteration. the raised 5th. but that one change fundamentally alters its stability. The tonic triad becomes augmented, removing the grounded quality that defines Ionian. It is the harmonic minor family's answer to the question 'what does major sound like without a perfect 5th?'
Why it sounds the way it does
The perfect 5th is the most consonant interval after the octave. Replacing it with an augmented 5th (eight half steps, symmetrically dividing the octave with the major 3rd) creates inherent instability. The root, 3rd, and #5 form an augmented triad. a chord with no clear tonal direction because of its symmetrical structure. The rest of the scale is pure Ionian, creating a disorienting effect: familiar brightness with an uncanny twist.
Chord fit
Ionian #5 serves maj7#5 chords, but it keeps the natural 4th (an avoid note over the major 3rd), which makes it slightly less versatile than Lydian Augmented for this purpose. In practice, most players choose Lydian Augmented (from melodic minor) for maj7#5 chords. Ionian #5 appears when the harmonic context is specifically derived from harmonic minor.
Practical improvisation use
This is a specialty mode. You would use it when analyzing or playing within an explicitly harmonic minor framework and the harmony lands on the bIII chord. It is not a first-choice improvisation scale for most situations. If you encounter a maj7#5 chord in a jazz standard, try Lydian Augmented first. it usually sounds smoother.
Guitar practice angle
Raise the 5th in your Ionian shapes by one fret. The augmented triad arpeggio is the key pattern to internalize. Because augmented triads are symmetrical, the same fingering shape repeats every four frets. this makes the scale geometrically interesting on the guitar neck even if you do not use it frequently in performance.
Compare it to...
Ionian has a perfect 5th. stable and grounded. Lydian Augmented raises both the 4th and 5th, eliminating the avoid note and creating a more versatile scale over maj7#5 chords. Ionian #5 sits between them: one note different from Ionian, one note different from Lydian Augmented.
What to listen for
Play a C major triad and raise the G to G#. The shift from stable major to unstable augmented is the Ionian #5 signature. Compare it against Lydian Augmented (also add F#) to hear how removing the natural 4th further brightens the sound.
Practice suggestion
Play through all seven modes of A harmonic minor, pausing on each to explore its sound. When you reach C Ionian #5 (the third mode), spend extra time comparing it against C Ionian and C Lydian Augmented. This contextual approach. hearing it as part of a family. is more useful than practicing it in isolation.
When to reach for it
- •Over maj7#5 chords in harmonic minor contexts
- •Augmented major passages
- •Compositional and analytical applications
- •The bIII chord in a harmonic minor key
On the fretboard
- •Take your Ionian shapes and raise the 5th by one fret. the augmented triad shape is the foundation
- •Practice the augmented triad arpeggio (1-3-#5) across string sets. it repeats every four frets due to symmetry
- •Compare it directly against Lydian Augmented (also raise the 4th to #4) to hear which you prefer over maj7#5
Common mistakes
- •Confusing it with Lydian Augmented. check whether the 4th is natural or raised
- •Practicing it extensively when more essential modes need attention first
- •Not recognizing it as part of the harmonic minor system
Test yourself
If you can answer these in your own words, you have the concept. If not, revisit the sections above.
- What is the parent harmonic minor scale for C Ionian #5?
- Why is Lydian Augmented generally preferred over Ionian #5 for maj7#5 chords?
- What interval makes the tonic triad of Ionian #5 augmented?