Almost nobody's progression is wrong. What makes an amateur track sound amateur is voicing — the same four chords, played in root position, jumping around the keyboard instead of moving by a semitone or two. This page measures that. Press Cheap and then Expensive below and watch the number change: identical harmony, 68 semitones of movement against 12.
Build a progression, then change how it is voiced without changing a single chord. The lines in the display are the individual voices — when they run almost flat, the progression sounds expensive. When they leap, it sounds like a preset demo.
Same chords, same key, same rhythm. The only difference is inversion, spread and which notes you leave out.
Three progressions in the library get a bigger number from the Expensive button, not a smaller one — Phrygian techno, Suspended stabs and Chromatic climb. That is not a bug and it is worth understanding. All three move their roots by a semitone, so root position was already about as smooth as smooth gets; the number rises because the button adds sevenths, and more notes means more total travel. Those progressions get their power from the interval itself, not from voice leading, and the measurement is honest enough to tell you so.
The measurement. The number top-right is the total distance every voice travels across the loop, in semitones. It is not a quality score — some music wants leaps — but in house and techno, low is almost always better. Under 20 for a four-chord loop means the voices are behaving. Over 50 means each chord is being played from scratch with no thought about the one before it, which is exactly what root position does.
All eight of these are A minor 9. Same notes, same harmony, completely different instruments as far as your ear is concerned. Click any of them.
The one to internalise is rootless. If your bass is already playing an A, the chord does not need one — and removing it frees a voice for the 9th, which is the note that makes the chord sound like a record rather than a music lesson. Almost every "how do they get that lush house chord" question is answered by "they left the root out and added a 9th".
Everything here loads into the lab in the current key. Roman numerals are relative to the minor tonic, which is where most of this music lives.
The notes above the seventh. They are the difference between a chord and a colour, and there are rules about which ones you may not use.
| Extension | Interval | Works on | What it does |
|---|---|---|---|
| 6th | 9 st | Major, minor | Softens and dates a chord — instantly 1970s. Replaces the 7th rather than joining it. |
| 7th | 10 or 11 st | Everything | The single most important addition. A triad is folk music; a seventh is dance music. |
| 9th | 14 st | Everything | Lush, open, "expensive". The default extension in house. |
| 11th | 17 st | Minor only | Hollow and modal. On a major or dominant chord the natural 11 clashes hard with the 3rd. |
| #11 | 18 st | Major, dominant | The fix for the above. Floating, Lydian, cinematic. |
| 13th | 21 st | Dominant, minor (Dorian) | Rich and jazzy. On a dominant it is the sound of gospel house. |
| add9 | 14 st, no 7th | Everything | Open and modern. Ambiguous because there is no 7th to tell you the function. |
| sus4 | 5 st, no 3rd | Everything | Removes major/minor entirely. The techno stab: neither happy nor sad, just tension. |
Each mode is defined by one or two notes. Change that note and you have changed the genre.
| Mode | The note that defines it | Characteristic chord | Where it lives |
|---|---|---|---|
| Aeolian (natural minor) | b6 | i – VI – VII | The default. Melodic techno, trance, most house. |
| Dorian | natural 6 | i – IV (major) | Deep house, Detroit, garage. Minor but not sad. |
| Phrygian | b2 | i – bII | Dark techno, industrial, hard groove. Immediately menacing. |
| Mixolydian | b7 over a major 3rd | I – bVII | Disco house, funk, French house. Bright but not resolved. |
| Harmonic minor | natural 7 | i – V7 | Psytrance, hard dance, anything wanting drama. Easy to overdo. |
| Lydian | #4 | I – II (major) | Ambient, breakdowns, anything floating. |
How to actually use this. Do not "write in Dorian". Write in minor, then raise the sixth in one chord and hear what happens — in A minor that means using D major instead of D minor. One chord tells the listener which mode they are in, and it usually only needs to appear once every eight bars.
Learn the four-chord loop, then stop collecting progressions. There is no shortage of chord sequences in the world and no track was ever rejected for using a common one. The scarce skill is making four ordinary chords sound like they were played by someone who knew what they were doing, and that skill is entirely in this page's second section.
All sounds synthesised live in the browser. Roman numerals are relative to the minor tonic. The voice-movement figure is the total absolute semitone distance travelled by all voices across the loop.