Reharmonization 101 — Chromatic Progressions with Passing Diminished Chords
By Masashi Y.
“The jazz guitar comping I’ve been transcribing has chords that aren’t in the original lead sheet.” “I can play the standard progressions — now I want to add a bit more color to my comping.”
The tool for both of these is reharmonization (usually shortened to “reharm”). Keep the melody and the overall shape, but swap or insert the chords underneath to add motion and color — it’s a cornerstone of arranging across jazz, pop, and film scoring alike.
This article is aimed at guitarists. It walks through the reharm techniques we’ve already covered and then introduces a new tool: the passing diminished chord. Passing diminished chords are all over jazz guitar comping — with just one chromatic passing chord, you can change the feel of a standard progression. It’s one of the highest-return-per-effort techniques you’ll learn.
What Is Reharmonization?
Reharmonization means swapping chords in an existing progression, or inserting new ones between them, to re-color the harmony underneath the melody.
It breaks into two broad approaches:
- Substitution: replace a chord with a different one (e.g. replace V7 with the ♭II7 tritone sub, or replace I with VIm).
- Insertion: add a new chord between existing ones (e.g. add V7/II before II, or insert a passing diminished between I and IIm).
Since the melody doesn’t change, the listener still recognizes “this is the song,” but the harmony gains depth and directional movement — that’s the appeal of reharm.
A Map of the Techniques We’ve Already Covered
Here’s a short recap of the main reharm techniques covered on this site. Keep this as a reference for combining with the passing diminished later in the article.
Secondary Dominants (V7/X)
Treat any diatonic chord as a “temporary I” and insert its V7 right before it.
- Original: Dm7 → G7 → Cmaj7
- Reharmonized: A7 → Dm7 → G7 → Cmaj7 (A7 = V7/II pulls strongly toward Dm7)
Dm7
G7
Cmaj7
A7
Dm7
G7
Cmaj7
See the full guide: Secondary Dominants — Guitar Voicings, Tensions, Scales, Deceptive Cadences.
Related IIm7 (ii-V Decomposition)
Insert a IIm7 right before any standalone V7, rewriting it as a “ii-V pair.” Where secondary dominants “add a V7,” this is the mirror image — “add a IIm7.”
- Original: G7 → Cmaj7
- Reharmonized: Dm7 → G7 → Cmaj7 (add the IIm7 that sits a fourth below G7)
G7
Cmaj7
Dm7
G7
Cmaj7
See the full guide: A Guitarist’s Guide to ii-V — Breaking Down V7 with Related IIm7.
Tritone Substitution
Replace a V7 with another V7 a perfect fourth away. The bass line descends chromatically.
- Original: G7 → Cmaj7
- Reharmonized: D♭7 → Cmaj7 (G7 and D♭7 share the B/F tritone)
G7
Cmaj7
D♭7
Cmaj7
See the full guide: Tritone Substitution on Guitar.
Deceptive Cadence
Redirect the target of a V7 from the expected I to a nearby tonic-substitute chord.
- Original: G7 → Cmaj7
- Reharmonized: G7 → Am7 (V → VIm — “sounds resolved, but isn’t quite”)
G7
Cmaj7
G7
Am7
See the deceptive cadence section in the secondary dominants article.
Slash Chords (Bass Line Shaping)
Keep the upper chord intact, but change the specified bass note to create a smooth bass line.
- Original: C → Am → F → G
- Reharmonized: C → G/B → Am → F → C/E → Dm7 → G (bass moves smoothly C → B → A → F → E → D → G)
C
Am
F
G
C
G/B
Am
F
C/E
Dm7
G
See the full guide: Slash Chords on Guitar.
The Passing Diminished — A New Tool
Here’s the main topic. The passing diminished chord (also “passing dim7”) is a technique for inserting a diminished chord between two adjacent diatonic chords — a chord that doesn’t belong to either one.
What Is a Diminished 7th Chord?
A diminished 7th chord (dim7) stacks four notes a minor third apart. Because every interval is the same (minor third, i.e. symmetric), the chord has no directional pull and sounds unstably “floating”.
- Example: C♯dim7 = C♯ - E - G - B♭
All four notes share a special property: each one is a semitone away from a chord tone of a neighboring chord. This is what makes the passing diminished work.
C♯dim7
Basic Patterns
The typical use is to insert a dim7 wherever the bass moves by a single fret chromatically.
Ascending (bass moves up by a semitone)
| Original | Reharmonized | Bass motion |
|---|---|---|
| C → Dm | C → C♯dim7 → Dm | C → C♯ → D |
| F → G | F → F♯dim7 → G | F → F♯ → G |
| G → Am | G → G♯dim7 → Am | G → G♯ → A |
| Dm → Em | Dm → D♯dim7 → Em | D → D♯ → E |
C
C♯dim7
Dm
Descending (bass moves down by a semitone)
| Original | Reharmonized | Bass motion |
|---|---|---|
| Em → Dm | Em → E♭dim7 → Dm | E → E♭ → D |
| Am → G | Am → A♭dim7 → G | A → A♭ → G |
Em
E♭dim7
Dm
In every one of these, the key feature is a smooth semitone bass connection.
Why It Works — Ascending and Descending Are Different
Here’s a distinction that matters. Ascending and descending passing diminished chords don’t come from the same mechanism.
Ascending: A Rootless V7(♭9) to the Target
An ascending passing diminished is the rootless form of the target’s secondary dominant V7(♭9).
- C♯dim7 notes: C♯ - E - G - B♭
- A7(♭9) notes: A - C♯ - E - G - B♭ (R - 3 - 5 - ♭7 - ♭9)
Omit the A (root) and the top 4 voices of A7(♭9) = C♯dim7. In other words, C♯dim7 functions as “V7/II (♭9) headed to Dm7,” carrying real dominant pull toward Dm7. The same principle holds for every ascending case (F♯dim7 → G equals D7(♭9), G♯dim7 → Am7 equals E7(♭9), and so on).
Descending: Not a Dominant — A Chromatic Passing Chord
By contrast, descending passing diminished chords are NOT substitutes for V7(♭9).
- E♭dim7 → Dm7: E♭dim7 (E♭ - G♭ - A - C) shares no notes with A7(♭9) (A - C♯ - E - G - B♭), the V7 pointing to Dm7.
- A♭dim7 → G: same story — no note-overlap with D7(♭9) (D - F♯ - A - C - E♭), the V7 pointing to G.
Descending diminished chords aren’t dominant pulls. They’re chromatic passing chords whose voices all slide down together by semitone — you take the sound of the previous chord (e.g. Em7 before E♭dim7) and step the whole thing down a semitone on the way to the next chord. It’s a parallel-motion chromatic approach.
Common Ground: Every Voice Moves by a Semitone or Whole Tone
Even though the two mechanisms differ, the smoothness you hear is identical. Because dim7 is a symmetric chord built entirely in minor thirds, every note is one semitone or one whole tone away from a tone of the neighboring chord.
Looking at voice motion from C♯dim7 → Dm7 (a practical guitar Drop 2 voicing) in the ascending case:
- C♯ → D (semitone up, to R)
- E → F (semitone up, to ♭3)
- G → A (whole tone up, to 5)
- B♭ → C (whole tone up, to ♭7 — this is where the 7th appears)
Two voices move by semitone, two by whole tone, and they land on a complete Dm7 (D-F-A-C: root, ♭3, 5, ♭7 all present). You get the same “arriving home” feeling as a V7 → I resolution, reinforced by the chromatic bass.
Passing Diminished vs. Secondary Dominant (Ascending)
If an ascending passing diminished is equivalent to V7(♭9), what makes it different from a secondary dominant? The answer is the strength of the pull, which hinges on whether the root is present.
| Technique | Example (before Dm7) | Pull | When to use |
|---|---|---|---|
| Secondary dominant | A7 (→ Dm7) | Strong (root A spells out “V → I”) | When you want a highlight moment |
| Passing diminished | C♯dim7 (→ Dm7) | Subtle (no root, passing-chord color) | When you want to slip through it naturally |
If a secondary dominant is a “strong pull,” a passing diminished is a “casual pull.” It’s the first thing to reach for when you want to keep a standard progression mostly intact but add “a hint of jazz color.”
Putting It Together — Step-by-Step Reharm of a Standard Progression
Combine reharm techniques, and a single progression starts changing its expression layer by layer. Let’s take the classic C-major cycle Cmaj7 → Am7 → Dm7 → G7 → Cmaj7 and reharmonize it step by step.
Step 0: Original
Cmaj7 → Am7 → Dm7 → G7 → Cmaj7
Standard I-VI-II-V-I cycle. Stable, but the motion is quiet.
Cmaj7
Am7
Dm7
G7
Cmaj7
Step 1: Secondary Dominant (Replace VIm with V7/II)
Cmaj7 → A7 → Dm7 → G7 → Cmaj7
Swap Am7 for A7 to create strong pull toward Dm7.
Cmaj7
A7
Dm7
G7
Cmaj7
Step 2: Swap In a Passing Diminished (Even Lighter)
Cmaj7 → C♯dim7 → Dm7 → G7 → Cmaj7
Replace A7 with C♯dim7, smoothing the bass into C → C♯ → D.
Cmaj7
C♯dim7
Dm7
G7
Cmaj7
Step 3: Tritone Sub the Final V
Cmaj7 → C♯dim7 → Dm7 → D♭7 → Cmaj7
Replace G7 with D♭7. The whole bass line is now C → C♯ → D → D♭ → C, rising and falling chromatically.
Cmaj7
C♯dim7
Dm7
D♭7
Cmaj7
Step 4: Deceptive Cadence for a “to be continued” Feel
Cmaj7 → C♯dim7 → Dm7 → D♭7 → Am7
Replace the final Cmaj7 with Am7 (tonic substitute), keeping the sense that the music is still moving forward.
Cmaj7
C♯dim7
Dm7
D♭7
Am7
Note: This shape is a double reharm — “redirect the tritone sub D♭7’s target, then apply a deceptive cadence to VIm.” The bass jumps at the end (C♯ → D → D♭ → A), so compared to the classical deceptive cadence (G7 → Am7), the tonality goes ambiguous and the result sounds modern and floating. If you want the more grounded classical deceptive cadence instead, revert Step 3’s D♭7 back to G7 — “Cmaj7 → C♯dim7 → Dm7 → G7 → Am7” works beautifully.
Play Step 0 and Step 4 back to back. The melodic skeleton is identical, but the motion and the color have become a completely different thing.
Practical Tips
- One move at a time: Don’t mix multiple techniques immediately. Stack them one at a time — “first add a V7/X, then insert one passing diminished” — so your ear can tell which move is doing the work.
- Check for melody clashes: Always verify that your reharm chord tones don’t clash by a semitone with the melody. Passing diminished chords are dissonant, so the rule is pass through them briefly (linger too long and they float loose).
- Let the bass line decide: When you have multiple reharm candidates, pick the one that gives the smoothest bass line. Since the purpose of a passing diminished is “fill in the chromatic gap in the bass,” this criterion lines up with it directly.
notave — Instantly Find Reharm Voicings
notave lets you type a chord name and see voicing options on the fretboard instantly. Reharm-specific chords like C♯dim7, A7(♭9), D♭7 are just as easy to pull up — same workflow as any other chord.
- Instantly shows voicings for diminished, altered, and other specialized chords
- Enter the surrounding chords and it recommends voicings with smooth voice leading
- Save voicings as TAB/staff notation; play them back to hear the sound
Everything from reharm ideation to finalized fretboard shapes in one place.
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