FlatFive shows you a chord symbol. You play it. That is the whole app — everything below is about shaping which chords come up, how they are written, and when they change.
The drill screen
The chord fills the middle of the screen. Underneath it, when you have switched them on, sits the instruction for this card — both hands · 2nd inversion.
Below that is the next chord, greyed out. It is there so you can get your hand ready before the change, which matters once the tempo is up. You can turn it off in Settings → Display → Show next chord; in manual mode it is hidden automatically, since you already control when the card turns.
At the bottom: the tempo wheel, the session countdown if you have set one, and Start.
Advancing: metronome or manual
Settings → Practice session → Advance.
Metronome
A count-in plays, then the chord changes on the downbeat every one, two or four measures (Measures per chord). The click is generated on the audio clock, not a timer, so the flip and the beat land together and do not drift apart over a long session.
Set the tempo three ways:
- Spin the wheel. It is an endless wheel — there is no “full” or “empty”. One turn is 30 BPM, so the whole 40–240 range is about seven turns. Fine adjustments are easy.
- Tap the number and type a tempo.
- − and + for single steps.
Changing the tempo mid-session is fine and takes effect immediately. Everything else waits for the next start.
Manual
No metronome at all — no tempo, no count-in, no beat dots. Tap Next when you are ready for the next chord. Good for slow work: sitting on an awkward voicing until it is right, rather than being dragged on by a click.
Choosing chord types
Settings, scroll to the chord sections. They are grouped:
| Group | Contains |
|---|---|
| Triads | major, minor, diminished, augmented, sus2, sus4 |
| Sevenths | maj7, m7, 7, °7, ø7, m(maj7), m7♯5, maj7♯5, 7♯5, 7♭5, 7sus4, 6, m6 |
| Extensions | maj9, m9, 9, 6/9, m11, 13, maj13 |
| Altered dominants | 7♭9, 7♯9, 7♯11, 7♭13, 7alt |
Each group has All and None. By default the five core sevenths are on, plus plain major and minor.
Beside each chord type you can see every spelling it will be written with — Cm7 C-7 —
so you know what to expect on a card.
Keys and weights
Settings → Keys. Every key is a row: a toggle on the left, a weight on the right.
A weight is a multiplier on how often that key comes up, from 0.0 to 2.0 in tenths:
- 2.0 — comes up twice as often as a key at 1.0
- 1.0 — the normal share
- 0.5 — half as often
- 0.0 — reads as never, and the key leaves the deck entirely
This is the feature to reach for when a key is giving you trouble. Turn G♭ up to 2.0 and leave the easy ones at 1.0, and you will spend your session where the work is.
Two details worth knowing:
- D♭ starts at 0.1. It is rarely a key centre in jazz, so by default it barely appears. Turn it up if you want to drill it properly.
- Weights apply to random order only. The circle of 5ths and chromatic orders visit every key in turn, so there only 0.0 changes anything — it removes the key from the cycle.
Reset weights appears once anything differs from the defaults.
Order and direction
Settings → Keys → Order.
- Random — a weighted draw, never the same chord twice running.
- Circle of 5ths — ascending is C, G, D, A…; descending is C, F, B♭, E♭…
- Chromatic — ascending is C, D♭, D…; descending is C, B, B♭…
The two cycling orders have a Direction setting and show a preview of the order they will actually use, with your switched-off keys removed.
Inversions
Settings → Inversions. Off by default; the cards simply do not mention voicing.
Switch it on and every card names one: root position, 1st, 2nd or 3rd inversion, and the next-chord hint carries it too in short form (2nd inv).
Choose specific inversions with the chips, or choose random to let each chord use whatever it has. The two are alternatives — picking one clears the other.
A triad has only three voices, so it has no third inversion. It will never be asked for one, however the chips are set.
Hands
Settings → Hands. Off by default.
Switch it on and each card names LH, RH or both. Pick any combination.
Hands and inversions combine on one line — left hand · 1st inversion — and both appear in the next-chord hint, so you have warning before the change.
Presets
A preset is a whole setup saved under a name: chord types, keys and their weights, order, inversions, hands, advance mode, session length, tempo, meter.
To save one: set the drill up the way you want it, then Settings → Presets → Save current settings and give it a name.
To switch: tap the name at the top of the drill screen and pick another. Loading a preset stops a running drill, since the chords are about to change.
To change one: load it, adjust something, and a dot appears beside its name. Settings
then offers **Update “
To rename or delete: swipe the preset in Settings.
Each preset shows what it drills, so the list stays readable:
ii–V–I workout Cmaj7, Cm7, C7 · all keys · random · random inversions · LH/RH/both · 20 min
Timed practice sessions
Settings → Practice session → Length — 5 to 60 minutes, or No limit.
The countdown sits above the Start button, and the drill stops itself when the time is up, showing time’s up until you start again.
Stopping part way pauses the clock rather than starting over, so you can adjust a setting mid-session and carry on. Changing the length always begins a fresh session.
In manual mode there is no Start button, so the clock begins on your first Next — the session starts when you actually start playing.
How chords are written
Chord symbols are set in Petaluma, a hand-lettered font drawn in the style of the Real Book copyists.
Every spelling, not just one
A chord type is written every way charts write it, mixed with roughly equal weight:
| Chord | Spellings you will see |
|---|---|
| minor seventh | m7, -7 |
| major seventh | maj7, Δ7 |
| half-diminished | ø7, m7♭5, -7(♭5) |
| diminished seventh | °7, dim7 |
| flat ninth | 7♭9, 7(♭9) |
The point is to read all of them fluently, not just the one you happen to be used to.
Sharps, flats, and what is actually writable
Settings → Display → Accidentals: sharps, flats, or random (the default), which picks per card so you read both.
Your preference gives way to correct notation. A chord is only ever shown spelled a way it
can be written without double accidentals — so a flats-only session still shows F♯°7,
because G♭°7 would need a B double-flat. For the same reason, a half-diminished chord is
never built on D♭.