Jam-a-Lot User Manual

1. Playback & Live Performance Controls

Transport Controls

Located at the top of the interface:

• Play / Stop / Pause: Controls the playback state.
• Count-in: Select between 1 or 2 bars of count-in.
• Metronome: Toggle a metronome click on or off.
• User Menu: Sign in via Google OAuth or Email/Password, manage cloud library sync, give feedback via the Feedback modal, and view active user preferences.

Up Next — the Playlist

The Up next button stays in the bottom-left corner of the window wherever you scroll, playing or stopped. Press it to open the playlist; the band keeps playing behind it.

• The list: about 15 songs, scrollable, chosen from the song you're on — same feel and tempo, same composer, and every fifth song a change of feel.
• Click a song to play it now. × removes it from the list.
• Generate 15 more adds another batch with no repeats. New list replaces the list with different songs.
• Autoplay starts the next song when one ends. The song-end card and the list are the same queue.

User Account & Preferences Menu

• Join Beta Program / Account Button: Labeled "Join Beta Program" (with sparkles icon) when signed out. Toggles user profile menu when signed in.
• Guest Mode Notice Banner: Persistent notification explaining Guest Mode (3 demo tunes: Blues in F, Oleo, & Mr. P.C.).
• Cloud Library Sync: Back up custom charts and preferences to your personal Supabase account across browsers and devices.
• Give Feedback: Submit bug reports, feature requests, sound quality feedback, or general comments with interactive star ratings.

Bandstand Stage

The animated band graphic above transport controls allows screen theater mode expansion. Hotspot labels (bassist, drummer, comping style, room) cycle settings on click.

Performance Panel

Located directly below the transport. Split into four core tabs:

Practice Video — Slow Down and Repeat a Phrase

Open Song Info → Play Video. In Song Resources, press Play on a saved or discovered YouTube version to open the same controls; saved links stay unloaded until opened. Song Info opens the current song's saved video or canonical recording; attach a YouTube link for an unlinked original. Press Play video or the video's Play button to begin. Playback, seeking, speed and loop actions are grouped below the picture.

• Speed: choose a rate supported by this video; 1× · Original restores normal speed. The display follows YouTube's confirmed rate. Pitch-preserving slowdown is provided by YouTube; quality depends on its player and browser.
• −5s / +5s: seek five seconds and turn phrase looping off.
• Set A / Set B: mark the current phrase start and end, at least half a second apart. Moving A beyond B clears B. Times show tenths of a second.
• Fine tune A/B: a flat Phrase loop panel shows a timeline with draggable A/B trim handles and timestamps in hundredths. Type m:ss.ss or seconds; Enter or leaving the field applies, Escape cancels. Use − / + and Step segments for 0.01 s, 0.10 s (default), or 1.00 s adjustments. Fine edits preserve the other marker and active looping, stop at video limits and a half-second minimum, and update the selected duration beside the title. Up/down arrows adjust a focused timestamp; arrow keys adjust a focused timeline handle, with Home/End for its limits. YouTube seek accuracy may be coarser than the displayed precision.
• Loop A–B: toggle repetition and jump to A; press Play if paused. Go to A returns to the start; Clear A/B removes markers.
• Waveform…: opens a popup with shared playback controls and a local recording waveform (75 MB / 15 minutes maximum). Choose an original or authorized recording; Video offset (s) maps recording second zero to video time. Check alignment against a known attack, choose A or B and click the waveform, or drag existing handles. Zoom (1×–32×), Scroll waveform, Focus A / Focus B, timestamps and nudges help trim precisely. Set A before B. File, offset and zoom are temporary; marker edits use the saved video A/B. Close or Escape dismisses the popup.
• Calculate BPM: expand the calculator and press Tap beat on quarter notes at least four times while playing; Reset taps starts over. Pauses, speed changes and gaps over three seconds (extended at slow playback rates) restart tapping. Or mark A on a beat and B after the counted span, enter Quarter-note beats A–B and press Calculate from A/B. Four bars of 4/4 = 16 beats; four bars of 3/4 = 12; a dotted-quarter pulse in 6/8 = 1.5. B is the beat immediately after the counted span. Longer spans improve accuracy. Results show original BPM and effective BPM at the confirmed speed. This is manual measurement, not automatic audio analysis, and does not change the band tempo. Tap results are temporary.
• Markers and confirmed speed are remembered on this device per song/video. Reopening restores them with looping off and does not autoplay. If storage is blocked, controls still work for this visit.
• Starting a video pauses the band and other videos; starting the band pauses videos. Closing Song Info or changing tunes releases its players.

YouTube controls availability, ads and supported speeds; loops may have a short gap. An unavailable recording offers Open on YouTube ↗; you can also attach another version. Spotify keeps its existing provider player.

Solo Transcription — Private Improvisation Drafts

Open Toolbox → Staff Editor and choose Transcription in its header (the one Staff Editor icon also holds Melody and Bass patterns, and reopens on the one you used last), or the local-recording shortcut beside a Practice Video (it copies the video's A/B times into From / To). The panel is one window — header, a single toolbar, the score and a slim footer — and the header's Full screen button enlarges it to the whole browser window.

New transcription (microphone icon, open automatically when a tune has no draft): Choose recording… — your own recording or an authorized file, up to 75 MB / 15 minutes, kept in the browser — then set From / To to a 2–180 second passage and the concert-pitch Range, and press Transcribe. Audio is never extracted from YouTube.

The toolbar holds the transport — Play / Pause (Space), Back to start and the clock, with Notes · Original · Both to hear the transcription, the recording, or both together — then the Select / Add / Erase / Pan tools, Undo / Redo, Re-split staves, the notation tempo and meter, zoom and Save. A new transcription starts at the recording's own tempo, detected from the notes and the chart, because records are often played at double or half the tune's practice tempo; with the original recording available, Detect (and every new transcription) follows the recording's beat: it tracks each beat the band plays and puts the barlines on them, so the score speeds up and slows down with the band instead of drifting off the chords — a live band rarely holds one tempo, and a constant tempo that fits the first bars can leave the chords several bars ahead by the end. The status line shows the average and range, the printed tempo reads ♩ ≈, and a Following recording ✕ chip returns to a constant tempo (typing a tempo or changing the meter does too). Beat 1 moves onto a tracked beat, letting a chart sync point choose a neighbouring beat when the harmony clearly fits it better; a recording without a steady pulse is reported and left alone. ½× / 2× halve or double the tempo when every score bar holds two chart bars; they keep the followed beats, Beat 1 and every sync point whose barline still exists, so half/double clicks undo each other exactly. Without the original, Detect fits one constant tempo (from a chart sync point, the next 16 seconds from that known downbeat; an uncertain fit keeps the existing settings). Selected originals are saved automatically in a private browser recording library and restored with the study, so Original/Both work after reopening. Older studies need the original file once. Forget saved recording removes its library bytes while keeping the draft and current session playback. Storage failures are reported; clearing browser site data removes saved recordings. Originals stay on this device and outside study JSON/cloud sync. Clicking a note sets where Play starts; while playing, the cursor follows the notation beat grid and chord positions — the recording's own beats once Detect has followed them — including after ½× / 2×; orange notes are sounding at their original audible attacks, blue have played, and the score scrolls with it. The footer edits the selected note's pitch, start and length, and moves it to the other staff.

Keyboard editing (MuseScore layout). The Keyboard shortcuts button lists every key. ← / → step through notes (⇧ extends a range, ⌘ jumps a bar, ⌘A selects all); type A–G for the nearest pitch with that name in the key signature; ↑ / ↓ transpose the selection a semitone, ⌘↑ / ⌘↓ an octave, ⌥↑ / ⌥↓ move it between staves; 3–7 set the length (sixteenth to whole) and . dots it; Delete removes the selection and lands on the next note; N toggles the Add tool and Esc clears the selection. Each edit is one undo step, and Hear notes as you edit plays every note you select or change.

Swing notation. Eighth notes → Swing 8ths writes swung eighths as plain eighths, the way a lead sheet does, with Swing beside the tempo on screen and in the PDF; sixteenths, audio and saved timing are unchanged. New transcriptions that swing turn it on by themselves, and the footer's Beat shows the written beat.

Cleanup tools. The button reads Requantize all or Requantize N selected and reports changed timings or already-on-grid notes. Changing the grid alone does not edit notes. Requantize (toolbar, 1/8, 1/16 or Swing 8ths grid — Swing keeps each offbeat at the passage's own measured swing, key Q; no selection applies to the whole draft) snaps notes’ starts and ends to the grid from each bar's beat 1 and folds doubled notes — undoable, and the Notes playback becomes straight. / splits a note at the cursor, J joins the selection into one note, + ties a note to the next one of the same pitch, and ⌘C / ⌘X / ⌘V copy, cut and paste a phrase in rhythm at the cursor. The footer shows the selected note's Bar, Beat and Length in beats, all editable.

The score is piano sheet music with the title, composer and tempo at the top. The treble staff is one melody voice and the bass (F clef) staff holds everything else, switching to treble clef where the left hand plays high; weaker octave ghosts are removed after transcription, the footer (or ⌥↑ / ⌥↓) moves a note between staves, a melody note lowered under middle C moves to the bass staff by itself, and Re-split staves redoes the split. Short rests between notes are shown as held or tied notes, so isolated sixteenths read as phrases; every line holds at least two bars. New transcriptions default to Separate piano first (both hands): six-source Demucs isolates piano locally before note detection, with the full A0–C8 keyboard range. The online app needs the local helper (npm run solo:server after bash scripts/groove/setup.sh); development mounts it in Vite. Whole recording (no separation) transcribes the file in the browser and is selected automatically when the helper is not running; a requested separation that fails stops. Check the isolated piano player and download its WAV. Score view → Both hands / Melody only changes the staff and PDF without deleting notes. Beat 1 at (seconds) anchors barlines to a known downbeat within the passage; select a note and press Selected note = beat 1, or enter the time. Reset beat alignment restores passage start. Both hands, cursor, editing and PDF follow the grid while earlier notes remain in an opening partial bar and source audio timing stays unchanged. Save/download keeps the alignment; changing alignment, tempo or meter clears chart sync points. Melody only picks one note per displayed attack; Both hands keeps all candidates. Separation and staff splitting remain estimates; bleed and missed notes are possible. The tune's solo-form chords sit between the staves with rehearsal marks; click any bar's chord area to say which section (A, B…) or chart bar starts there. Each sync point holds until the next, so a performance that drifts can be re-synced section by section; without sync points alignment is automatic. The whole passage is one continuous score in the tune's key; systems reflow to the window, so zooming out (especially in full screen) shows the whole solo. Rhythm is rounded for display only. Click a bar’s chord area for Half bar / Normal bar / Double bar when this recording compresses or holds that measure. These private score corrections preserve tempo, source-note seconds, original audio and the tune chart; both staves and the PDF show the local meter, and later barlines use the actual lengths. Normal bar removes one correction, Reset bar lengths clears all, and Save/download keeps them. Global tempo/meter/Beat 1 changes clear them; Detect requests an explicit reset before fitting another global tempo.

Save (⌘S) keeps one private draft per tune in this browser; header icons open a study file, Download sheet music as a PDF, MusicXML to finish in MuseScore, Dorico or Sibelius (the score as shown, with chord symbols and the swing marking), or the private study file (no audio), or delete the draft. Every tune source supports solo studies, separately from composed tune melody; they stay out of cloud sync, sharing and catalog exports. No MIDI export.

Loop and slow down. Loop (or L) repeats the selected notes, or the whole passage when nothing is selected; Speed (100–35%) slows the notes and the original recording together, keeping the recording's pitch.

Bass Patterns — Your Own Cells, In Every Key

Toolbox → Staff Editor → Bass patterns writes your own bass cells of 1, 2 or 4 bars, written in C on the bass staff and played by the band in every key: each chord moves the whole figure to its root by the smallest step, keeping its shape and register. The library belongs to this device, not to one tune. Pick a pattern, Rename it after the section or variant it is for, change its length (longer repeats the cell, shorter keeps the opening bars) or start a new one with New: +1 / +2 / +4. Every staff editing tool works, and it is written as bass music is: it sounds an octave lower than shown. Choose it in Rhythm Lab → Microrhythm → Bass part under My bass patterns on any base rhythm — Minimal, Swing, Bossa Nova, Samba or Traditional. It replaces that base's own bass (on Swing, the walking bass) and moves with the timing clock.

Practice Routines

Click the dedicated Practice metronome icon in the top row. Build major or minor ii–V–I cadences, major or minor turnarounds, dominant cycles, or the reviewed four-bar Coltrane Countdown cycle. Choose a starting key, 1–12 key stops, 4 or 8 bars per key, tempo, and either a fixed semitone step (default +1) or random steps through distinct keys.

Load the chart and press Play. It is saved in the Practice collection as a regular tune, so Performance Plan chorus counts, solos, drum trading, Living Changes, the mixer, and tune editing all work. Rebuild refreshes the chart; Return to previous tune takes you back when available.

Solo Rhythm — Following the Form or Opening Up

Live controls (Use plan off): One row under the stage. 2-feel, In time, Double and a time multiplier (½× to 3×) work on every rhythm and hold until you change them, over the same chords. Trade 4s is one button, and End plays the tune's ending, then stops. Timing picks whether a change waits for the next chorus or the next 4-bar phrase.

Salsa bell drive: In Performance Plan → Rhythm, each Salsa section can keep its normal two-hit bell, use Loose quarter notes for four hits with an alternating eighth-note pickup, or use Quarter-note drive for four even hits. An explicit drive choice brings in the bell even at quiet energy levels; clave, tumbao, and tempo remain unchanged.

Under solos, choose whether the rhythm section follows the written form or switches to a single style (e.g. Swing) after N choruses:

• Follow written form: Every solo chorus plays section rhythms as written.
• Switch to [Feel] after N choruses: Plays written form for N choruses, then switches to selected feel for remaining solo choruses.

2. Chord Chart Views

Jam-a-Lot offers multiple layout modes to suit your practice setup:

• Standard Grid: Classic 4-column layout mapping bars evenly.
• Extended View: Authentic real-book lead sheet notation replacing grid lines with traditional bar markings, with every pass of the form written out in full.
• Repeat View: Collapses repeating sections using standard musical repeat brackets (|: and :|). First and second endings — written with 1/2 markers in the text editor, or inferred from two similar passes — fold into one body with numbered brackets after it, and the bracket that is coming up next lights up as playback enters that pass.
• Vintage View: Amber monospace layout displaying full form without repeat folding.
• Staff View: Every bar on a five-line staff, like a big-band chart. Bars with punches or breaks show the hits in real rhythm notation (slash noteheads, rests, ties, accents, triplets), with x noteheads for drums-only calls; other bars show time slashes, and chord symbols sit over their beat. Any melody you write or record appears on the same staff as a lead sheet, with any hits kept as accent marks under it; it is kept privately on your device on any tune, and only synced or shared for tunes you composed. The Staff shows bar above it switches the staff between the melody, a saved solo transcription (chorus by chorus), the band's live bass or piano part, or hits only, and opens the tool that fills each one: the melody editor (the same score editor as Solo Transcription, with a Tune melody / Solo study switch), the keyboard recorder, or Solo Transcription.

Collapsible sections: on long charts (over 32 bars) each section shows only its first line of bars, except the section being played (or the first one when stopped), which opens by itself. Use Show all N bars / Collapse under a section to open or close it. Choose Long charts, Always or Never under Settings → Look & Stage → Chart & Notation → Collapse sections.

Interactive Bar Seeking & Custom Range Looping

• Click to Play / Seek: Click any bar in the chord chart while stopped to start audition playback immediately from that exact bar without count-in delay. This includes the displayed intro and ending: an intro click stays in the intro, and an ending click stays in the ending. Click any bar while playing or paused to jump transport directly to that bar.
• Shift+Click & Drag Range Looping: Click a starting bar, then Shift+click an ending bar (or drag across bars) to highlight and continuously loop over that section.
• Loop Banner & Controls: Displays active loop range info with a ✕ Clear button (or press Esc) to cleanly return to full form playback.

Section Color-Coding

• Section A: Sky-blue
• Section B: Mint-green
• Section C: Soft-violet
• Section D: Warm-amber
• Section E+: Dusty-rose

3. Instrument Mixer & Quick Controls

Out of the box, all three instruments play at a calibrated level (expressed in decibels dB).unity 0.0 dB represents the calibrated baseline.

Tight kick at quiet energy: soft strokes keep their acoustic colour and remain audible alongside the upright, without a sudden jump into stronger strokes. Select Kick → Sound → Tight in the expanded mixer and adjust the existing kick level to taste.

Deep kick: Kick → Sound → Deep tunes the open kick down, darkens it and adds low end — a booming bass drum for records whose kick you feel more than hear. It plays at the same loudness as Open.

Phone / Mobile Sample Loading & Wi-Fi Prompts

• Streamlined Mobile Bundle (~31.7 MB): On phones (<= 640px), Jam-a-Lot preloads a streamlined ~31.7 MB instrument bundle: Acoustic Bass (0.8 MB), Steinway Grand Piano (26.0 MB), Synth Keys (0 MB), and the 1-layer Full Drum & Percussion Kit (~4.9 MB).
• Wi-Fi Recommendation Prompt: Before downloading the initial sample bundle on a phone, Jam-a-Lot displays a Wi-Fi recommendation prompt (with automatic cellular / Data Saver detection) offering Download on Wi-Fi (~32 MB) & Play or Data-Saver Synth Mode (0 MB).
• On-Demand Instrument Bank Loading: Alternate bass banks (Acoustic Natural, Electric Bass) and comping banks (Rhodes Mark I at 81.5 MB, Nylon Acoustic Guitar) remain visible in the sound selectors (including directly inside the Simple Mixer rows) marked with their download size and (Wi-Fi). Selecting an undownloaded instrument on a phone prompts to confirm Wi-Fi before downloading that bank on demand; rhythm style changes on a phone never auto-download unapproved banks in the background.
• Desktop-Only Workstation Tools: Workstation-heavy tools (Solo Transcription, Rhythm Style Lab, and SFZ Sample Import) are marked Desktop Only on phones.

Stage Plot & Stereo Panning

Importing Custom Piano Samples (SFZ)

1. In Piano card, click Import samples….
2. Select both your .sfz file and referenced .wav files together.
3. Audition C4 and click Import Kit. Saved to browser IndexedDB automatically.

Each Rhythm Style Remembers Its Mix

Your mixer faders are remembered per rhythm style, just as they are per drum kit. Balance the band for Bossa Nova, switch to Swing and set it differently, and your bossa faders come back when you return to Bossa Nova — whether you pick the style or load a tune that plays it. A style you have never adjusted keeps your current faders. Reset mixer clears every style's remembered mix.

Mix & EQ Studio

On desktop, Toolbox is a vertical icon toolbar centered at the left edge, with every available tool directly accessible. Hover for names and descriptions. Keyboard uses piano keys and Mix & EQ Studio uses an EQ curve, distinct from the mixer. At widths up to 1100 px, use the header Toolbox menu. The toolbar hides in full-screen performance view.

Open Toolbox → Mix & EQ Studio. It appears as a panel below the chart and its practice controls and stays open while you play until you press its Close button. Press Play to see the live RTA spectrum (with the EQ curve drawn over it) or the scrolling waterfall spectrogram, plus Peak, RMS and Crest meters.

• 6-band master EQ: low cut, low shelf, two bells and high shelf, high cut, with one-click genre curves such as Acoustic Jazz Club and Punchy Funk & Groove.
• Bus balance, room & glue compressor: drums, bass and piano levels and pan, room type, room presence and room bustle, master fader, and compressor threshold, ratio and makeup gain.
• Interactive EQ: drag colored dots for frequency/gain and scroll a bell for bandwidth; rotary knobs also support Shift, scroll, arrows and double-click reset. Linear · power law sits beside the genre presets and adds an adjustable −3…+3 exponent, default Kolmogorov −5/3 (about −5.02 dB/octave), with automatic stereo energy matching to avoid a volume drop and safe flat response at zero. Buttons beside the exponent knob select −1, −1/2, 0, +1/2, +1 or the Kolmogorov default. Its overlay aligns to the live spectrum; this drawing offset does not affect sound. Spain and Punchy merge as Punchy Funk & Groove.
• DJ Tools: automatically active when you open the tab, with six performance controls above the knobs and no enable checkbox. Four-stage low-pass ↔ OPEN ↔ high-pass filter, resonance, echo/time and stutter/rate knobs. Five momentary pads — Low-pass reveal, High-pass build, Filter round trip, Echo throw, Stutter burst — run for 0.5–16 seconds and restore your knob settings. Release / Stop, DJ sound edits or transport release cancel automation. Reset DJ Tools preserves EQ/dynamics. OPEN is transparent; times are seconds/Hz. Vinyl/tape/radio textures are retired.
• Instrument FX: separate Bass FX and Drums FX racks, both bypassed by default. Each has an on/bypass switch, Drive with clean blend, Low-pass (120 Hz–20 kHz, OPEN), Auto-wah, Chorus and Phaser (up to 65%), shared Mod rate (0.1–6 Hz), Delay (up to 60%), Delay time (60–1200 ms), Feedback (up to 65%) and Output (−18 to +3 dB). Times are independent of tempo. Presets: Nordic Bass · grit & wah, Drum Echo · rhythmic space, Floating Space · chorus & phase, and Clean / Reset. Nordic Bass, the second list entry, is the default for untouched racks; effects remain bypassed until enabled. Off racks collapse to their heading and toggle. Clean / Reset clears only its rack. New preset saves the current settings under a unique name in this browser; recall it from Preset, and edits are marked without overwriting. Reset preset restores the selected factory defaults or saved snapshot; double-click restores a single knob’s preset value. Selection and edits survive bypass, closing the studio and reloads. Bypass restores the clean level and mutes tails. The drums rack includes percussion. Settings persist globally with audio preferences, continue when the studio closes, and reach room sends, recordings and the listening reference. Knobs support the studio's drag, Shift, scroll, keyboard and double-click gestures. Inspired by e.s.t. interviews, not exact artist patches; chorus and phaser are creative additions. Research links are in About these sounds. Master EQ/DJ resets preserve these racks.
• Mono Check: folds the master to mono to check balance; it never adds texture and resets to stereo next session.

4. Rhythm Styles & Bossa Nova Fine-Tuning

Reference groove development (agent workflow): share a recording with the development agent and ask “Use $groove-from-audio to recreate this groove.” Its separate local workbench returns isolated stems, an editable beat/event grid, and a simple audible timing sketch. In the review page, compare Reference clip and Saved timing sketch, correct Meter / Quarters per detected beat / Bar one with Apply alignment, filter by Show bar / Voice, and Select, Update, Add or Remove hits. Play edited sketch and Include beat click audition edits; Download edited JSON saves the review for the agent, and Load edited JSON restores it. This is development tooling, not an audio-upload feature in the deployed app; listening review precedes a generalized style.

Bossa Nova comps on a nylon guitar: the Comping channel's sound picker now includes a Nylon guitar (a nylon-string classical guitar recorded by the University of Iowa Electronic Music Studios), level-matched to the Steinway, and Bossa Nova uses it by default. Your Comping sound pick is remembered per rhythm style: choose the Steinway while playing bossa and bossa stays on the Steinway; a pick made on Swing never stops Bossa Nova from using its guitar, and leaving bossa for Swing puts the piano back. On the guitar, the piano's two-hand split and connecting lines are switched off.

Automatic trio balance: all three built-in bass sounds and four comping sounds use phrase-level matching and tone shaping so the bass foundation, chord detail and reviewed drum mix work together. Nylon guitar includes low-frequency cleanup and pluck presence. Corrections follow the sound across rhythms; mixer faders and master EQ remain adjustable.

Bossa drum balance: the cross-stick clave leads the bossa groove, but no longer buries it — the kick, hi-hat and ride sit just under the clave at every energy level, with the shaker beneath them from Energy 2.

Bossa, Salsa and Bolero fills: Bossa uses brief two-stroke cross-stick cues, and Salsa uses up to three timbale fill strokes; Bolero uses up to two, without doubled strokes. Bolero section arrivals replace the existing timbale hit. Chorus pickups use eighth notes; cadenza endings use spaced strokes instead of rapid cascades.

Jam-a-Lot separates feel, rhythm style, and mixer sound. Accompaniment families include Swing, Ballad, Gypsy Jazz, Bossa Nova, Samba, Latin, Bolero, Tresillo, Waltz, Soul-Jazz, Funk, Blues Shuffle, R&B / Neo-Soul, Rock, and EDM.

Bass phrasing: Soul Jazz, Funk, Blues Shuffle, R&B and Rock build a four-bar bass statement and reply, with the opening figure returning before a turnaround. Energy 0 keeps each style's sparse bass groove. Electric and EDM octave figures reach the upper root, while bossa and salsa pickups follow the chord at a loop return. Swing, Ballad and Two Feel retain their walking or spacious jazz bass. A featured bass solo takes its solo line in every style.

Samba is the Rio groove behind bossa nova, played as a percussion section (a batucada) rather than a kit clave. Set the tempo in cut time (the samba beat is the half note: ♩ = 200 is a samba beat of 100; the style covers 150–300), or use a 2/4 chart at the samba-beat tempo. The pandeiro plays every sixteenth (thumb on the beat, quiet fingertip jingles, an accent on the last of four) and leads the section; the tamborim plays the two-bar teleco-teco; the kick plays the surdo with the weight on beat 2. Energy adds players one at a time: the pandeiro alone at 0 (bass on 1 and 2, two guitar strokes), the surdo and ganzá at 1, the tamborim at 2, the caixa snare, muted tamborim and open surdo at 3, the agogô and cuíca at 4, a second surdo and cuíca glides at 5 — and every instrument plays harder as it rises. Breaks: type samba break (or breque / paradinha), samba convenção (samba hits), chamada or virada in a bar, or bossa break / bossa hits on a bossa, and the band stops for that bar to play the figure together, coming back in on the next downbeat. The swingue is built in: the third and fourth sixteenths of every beat arrive a little early, the same at every tempo, in drums, bass and comping alike, and a Swingue slider appears next to the tempo for built-in Samba (0% straight, 100% the measured Rio feel, up to 200%; double-click resets). When Microrhythm owns Samba's clock, its λ replaces that slider. The agogô is a real two-tone bell and the cuíca answers it in the same high/low figure. Each instrument has its own fader under Drums → Percussion (Pandeiro, Tamborim, Cuíca, Agogô, Shaker), already balanced at 0 dB.

Tresillo layers a 3+3+2 rhythm across drum kit and hand percussion: kick and claves accent beat 1, the & of 2, and beat 4; hi-hat and snare keep time while congas answer. Select Tresillo in the rhythm style picker with the standard kit to hear both parts.

Soul Waltz is a modern funk / soul-jazz groove in 3/4, selectable under the Waltz family of Rhythm styles: straight sixteenths, the backbeat on beat 3, kick on 1 and the & of 2, and a push on the “a” of 3. Electric bass and Rhodes by default. Energy changes the whole band: eighth-note hat and rim-click at 0–1, sixteenth hat, ghost notes and extra kicks at 2–3, ride eighths with shaker sixteenths at 4, and a beat-2 snare answer, open hat and displaced kick at 5. Jazz Waltz stays the default for 3/4 tunes.

Soul 6/8 is the modern funk / soul-jazz groove in 6/8, in the same Waltz family. It is felt in two: the backbeat lands on the second pulse (eighth 4) and the kick on 1 and the 6 pickup. It fits the chart’s meter: a 3/4 or 6/8 bar is one 6/8 bar, 6/4 and 12/8 bars hold two, and on 4/4 it plays the 12/8 feel. The tempo always counts quarter notes, on 6/8 charts too (a dotted-quarter feel of 60 is 90). The bass stays on the root at every energy level, and the snare backbeat is an anchor rather than a metronome (it sits out or moves now and then). It is the default style for charts written in 6/8 or 12/8. Electric bass and Rhodes by default. Six energy levels: Low Light (hat and rim-click), Pocket, Backbeat (stick snare on 4), Neo-Soul (eighth hat, rare sixteenth ghosts), Afro Ride (the bembé bell on the ride with shaker) and Burn (full ride, floor-tom and kick commentary, open hat).

Soul 6/8 Brushes pairs natural acoustic bass and Rhodes with a brush kit. The bass develops an eight-cell phrase with held notes, late pickups, short chord-tone connections, quiet short plucks, deliberate pauses and a low-to-upper register reply. Bass Energy 0 leaves three bars of space on held harmony; 1 plays a root every other chart bar; 2 adds roots each bar and occasional pickups; 3 is the reviewed reference-like phrase; 4–5 add progressively more short replies and stronger touch. At 0–1, written chord changes interrupt a rest immediately, including mid-bar changes. Quiet spacing counts whole chart bars even in 12/8. Notes follow the chart and held roots honor written bass-note changes. Natural acoustic bass is the default; explicit mixer sound choices are respected. On drums, at energy 0–3 a brush stir with longer soft tails, occasional quiet three-stroke snare rolls, a light shaker weave, a kick that wanders and no kit hat or ride. Energy 0 uses sparse shaker eighths; 1–3 add soft sixteenth returns with rests. Adjust it in Percussion → Shaker; energy 4–5 bring in the bembé bell and the burn. Soul 6/8 stays the default for 6/8 and 12/8 charts.

Bolero modern is a second style in the Bolero family, at 50–110 BPM: bass always plays beat 1 and accented &2, with an optional beat 4. Kick and snare share &2; the standard kit leads with stronger kick/snare and hi-hat, featuring a clear, dynamic snare answer on beat 4, and an eighth-note ride cymbal wash entering at higher energy levels (Energy 3–5), alongside bongó and maracas, with congas and güiro joining from Energy 2. Acoustic piano leaves space with sustained chords and an eight-bar phrase. Energy 0 preserves the bass figure. Select it in Rhythm style, keep the standard kit, and balance the separate Kit and Percussion mixer trims. Unpinned sounds default to electric bass and acoustic piano.

Bolero uses an eight-bar piano phrase rather than a repeating one- or two-bar comp: bordoneo and tresillo statements open into partial-cell answers, a deliberate breath, and the full cinquillo at high energy. Each following phrase varies while written chord changes remain clearly stated.

Live Changes (formerly Living Changes)

Move Re-harm Level to reharmonize solo choruses without changing the stored chart. 0 plays the chart as written; higher levels change more bars and reach for stronger substitutions, up to the full Coltrane Countdown cycle. Recognized blues and Rhythm Changes forms use reviewed templates; other tunes receive destination-aware tritone, secondary-dominant, passing-diminished, backdoor ii-V, full tritone ii-V, and major-turnaround substitutions. These cadence rules work whether ii-V is written in one bar or two. Coltrane Cycle now defaults on and fits reviewed major-thirds cycles into complete two-, three-, or four-bar major ii-V-I cadences while preserving the final written tonic. Strict blues may borrow atomic Bird Blues phrases, and strict Rhythm Changes may borrow a complete ii-V-chain or tritone bridge; the Reviewed Library Families toggle controls those shared families. A reviewed major-seventh turnaround adds Fmaj7–A♭maj7–D♭maj7–G♭maj7 in F. Backdoor ii-V remains in the cadence draw alongside Coltrane. Above 180 BPM, generated substitutions use at most two chords per bar; the written chart remains intact. Same-root extensions are color, not Live Changes. Flow plans a stable proportion of compatible changes across the whole phrase: 0% makes none and 100% uses every non-overlapping opportunity.

5. Drummer Avatars & Human Feel

Select preset drummer profiles under Settings → Feel & Variation:

• Philly Joe: Swing-forward, traditional timing, and natural feel.
• Elvin: Loose timing, heavy syncopations, high comping intensity.
• Tony: Driving feel, ride-focused, razor-sharp timing.
• Max: Balanced swing, structured snare fills, melodic flow.

In Swing, the ride develops an eight-bar phrase while keeping the quarter-note pulse; selected skip notes rest and the final two bars lean into the arrival. Two-bar snare calls and answers leave room for the piano, and charted chord pushes on the & of 2 or 4 get kick and cross-stick accents. Quiet heads feather the kick; louder solos pair kick and snare. Acoustic section entries use short setup figures: bridges favor cross-stick and open hat, while returns and chorus arrivals move across the toms. The four drummer presets now give the ride skip, hi-hat chick, and snare their own timing placement. Your ride Sound pick remains the sound you hear, including bell.

Harmonic Imagination: Chord Families and Modal Minor

Under Settings → Band & Feel → Harmonic Imagination, two controls set how freely the piano, guitar and bass read the chord symbols. The chart always shows what you wrote.

• Chord families (on): a symbol names a family, and each time through the form the band picks a member. Major covers C6, C6/9, Cmaj7, Cmaj9 and Cadd9. Minor covers Cm7, Cm9, Cm11, Cm6, Cm6/9 and Cm(maj7); the minor-major seventh is never used on a ii chord. Dominant is two families: unaltered (7, 9, 13) and altered (7♭9, 7♯9, 7♭13, 7alt). A plain dominant goes altered only when it resolves down a fifth, most often into minor. Sus, half-diminished, diminished, augmented and ♯11 chords, and line clichés such as Cm Cm(maj7) Cm7 Cm6, stay exactly as written. The bass follows the same choice.
• Modal minor (So What) (30%): minor chords played modally. This means the So What voicing (three fourths with a major third on top); a call and response in which the grip is played short, then a step lower and held; and a bass that pedals the root. Low settings reach only minor vamps. From 35% it adds any whole-bar minor chord, and from 70% the ii of a ii–V. Salsa's montuno is never affected.

Bassist Avatars

Includes Standard Walk, Jaco, Eddie Gomez, Ray, Paul, and Ron profiles.

6. Library, User Tunes & Edited Standards

Locate standards by title, composer, tempo, or feel with instant search and A-Z jump indexing in the Library sidebar panel.

User Tunes and Edited Standards

• User Tunes & Collections: Organize original compositions, imported lead sheets, and explicit copies into User Tunes or custom folders. Editing a standard keeps its private chart in Jazz Standards, even after refresh or cloud sync.
• Moving & Copying Songs: Use the ⋯ menu on any song to move or copy it to an existing or new collection. Moving or copying a built-in or catalog standard automatically forks it into an independent User Tune under the target collection, keeping the pristine public standard untouched.
• Collection Management: Click the gear icon beside any custom collection to rename it across all songs, disband it safely (moving all songs to User Tunes without deleting them), or delete the collection and its songs.
• Editing Standards: Re-keying, editing chords, or changing section titles saves a private version under the standard's library entry. The public chart remains unchanged.
• Reset to Original: An edited standard displays a Reset option in the text editor to discard chart edits and return to the catalog default.
• Coda directions in text charts: Write to coda at last before a repeated section's first chord to enter the Coda before the final pass; write it after a chord when that chord should sound before the jump.
• Cross-Device Cloud Sync: Your user tunes, collections, and edited catalog standards sync automatically across all your signed-in devices (laptop, tablet, phone).

7. Creating, Editing & Sharing Songs

User Handles & Tune Sharing

Share chord charts, performance arrangements, and custom tunes directly with other musicians:

• User Handles: Set your unique username handle (e.g. @jazzbassist) in the User Menu. Other players can send tunes directly to your handle.
• Share Modal: Click the Share icon (fat curvy arrow) on any active tune:
  • Send to @handle: Transfer tunes directly to another registered user's inbox with an optional note.
  • Share Link: Copy a shareable link (app.jam-a-lot.org/#share=code) for instant browser preview and import.
  • QR Code: Display a scannable QR code on screen for bandmates to scan on their phone or tablet camera.
• Shared Tunes Inbox: Incoming tunes arrive in your top-bar Inbox (indicated by a red badge). Preview the chart before clicking Accept & Save.
• IP Safety Enforcement: User-original compositions retain custom lyrics and melody notes. Catalog standards automatically strip all lyrics and melody data before generating share payloads to preserve IP safety rules.

Typing Chords & Never Losing Work

• Shorthand is accepted: a lowercase root anywhere (dm7 → Dm7, bb7 → Bb7, c/e → C/E), the caret major seventh (eb^7 → Ebmaj7), music-keyboard signs (E♭7, C♯m, C–7), and quality words in capitals (DMAJ7). A lowercase letter on its own is still major — write cm or c- for minor.
• Unreadable symbols are never dropped silently: a typo with no readable root is named in the status bar with its line number, in place of "Valid Chart", and saving asks first — the default is to go back and fix it, because saving would leave that bar empty.
• Unsaved text is kept: the editor saves your typing to the browser as you go and offers it back if you close, reload, or lose the tab before saving. An Undo save button restores the text as it stood before the last save.

Tune Time Signature

The Chord Editor toolbar’s Time signature selector sets the whole tune, including 2/4, in text or grid mode. In text mode it updates the Time: header; click Save Changes to apply it. Grid changes preserve each chord’s share of its bar and keep explicit bar-level meters. Import previews show the parsed meter. In 2/4, count 1 & 2 &; a punch at 2.5 is the & of 2. Bossa Nova fits its full bass, drum and comping pattern into each two-beat bar, including its final pickup, at the displayed quarter-note tempo. Existing 4/4 playback is unchanged.

One Bar in Another Meter

In a 4/4 tune, write | Cmaj7 | 3/4 C7 G7 | Fmaj7 | to make only the middle bar three beats long. The following bar returns to 4/4. In the visual grid editor, use the meter selector beside that bar's number. For a two-beat C7 followed by a one-beat G7, write | 3/4 C7 / G7 |. Playback, seeking, metronome, notation and MusicXML export follow the shorter bar. Half bars and Double bars are unavailable while a bar has its own meter. Living Changes stays off on mixed-meter charts so fixed-length substitutions do not overwrite a short bar.

Half Bars & Double Bars

Two buttons in the Chord Editor toolbar change how many bars the same chords are spread over — the fix for a chart that came in with the wrong chord rhythm.

• Double bars: Inserts a barline between the chords of every bar, so | Dm7 G7 | Cmaj7 A7 | becomes | Dm7 | G7 | Cmaj7 | A7 |. A bar holding a single chord keeps that chord across both new bars, so the form stretches to twice the bars with the same harmony. A four-chord bar becomes two bars of two.
• Half bars: The reverse — merges each pair of adjacent bars into one, so | Dm7 | G7 | becomes | Dm7 G7 |. Half the bars, same chords, two per bar. Asks for confirmation first; a final unpaired bar is left alone.
• The two are inverses on a one-chord-per-bar chart, and repeat marks (|: ... :|) move with the bars they were drawn on.

Text Mode Editor Shorthand

The Chord Editor opens in text mode by default. Universal lead-sheet syntax:

8. The Listening Band (Microphone Input)

Open Listening in the header row to arm the microphone. The band listens in real time and adapts to your performance.

• Follows Energy: Moves the band anywhere from Energy 0 (stop playing) to Energy 5 (your loudest), measured against your own dynamic range. Strength from 80% up gives your playing full control. Response time is how many seconds of your playing the band averages (5 by default, down to Instant, which follows you every bar), and the Energy graph shows your playing and that average live. Set my range takes 13 seconds (play your softest, then your loudest) and is saved per mic, so the band reads you correctly from the first note.
• Phrase Answering: Fills gaps when you pause your solo line.
• Figure Catching: Locks onto repeated 1-bar or 2-bar rhythmic figures played into the mic.
• FFT Leakage Subtraction: Subtracts the band's audio from mic input bin-by-bin for clean speaker operation. Built for an amp and speakers: stay quiet for the first few bars and it learns your room with no calibration.

9. Screen Layout & Full Screen

Supports full-screen performance view (Esc to exit), dynamic chord resizing, and auto-scrolling to keep active bars in view. Scrolling the page yourself during playback pauses the auto-scroll so you can reach Stop or any control; tap Resume follow (or press Play again) to return to the current bar.

10. Background Audio Support

Jam-a-Lot keeps playing smoothly when you lock your screen or switch browser tabs, using Web Audio Web Worker timers for precision lookahead scheduling.

Rhythm Lab: Blend

The starting pair matches the chart meter: Jazz Waltz / Soul Waltz on a 3/4 tune, for example. Source A is available independently of an incompatible old B; choosing it keeps a compatible B or selects a partner. Source changes select the required Native/Phrase fit mapping. Choose compatible pair for … repairs a saved pair from another meter as a new draft, preserving the saved blend and chart meter.

Double-click Main balance or press Continuous sweep for repeating A → B → A, the selected number of full written choruses per direction even inside a shorter practice loop. The slider follows the audio clock; rhythm changes apply at future bar boundaries. Pause freezes phase and Resume continues; fresh Play after Stop starts at A. Double-click again or press Stop sweep to hold the current balance for manual adjustment. Starting a sweep clears part/timing overrides. Save and JSON retain the sweep setting and speed, but not its live phase.

Open Toolbox → Rhythm Lab → Blend, choose from the grouped Source A / Source B lists, and move Balance. Play blend selects the current recipe and starts playback; its pause icon pauses it. The colored button, Save blend and Load blend sit at the top. Save asks for a name; Load opens the saved chooser. Source A and Source B anchor the balance slider. Move the slider fully left or right to hear either source. On narrow screens the selectors sit side by side above the slider. Any EDM source selects Groovebox Synth for the whole pair at every balance; bass and comping selections stay fixed. Percentages describe algorithmic influence, not measured genre content. Advanced controls override Drums, Bass, Piano and Timing; untouched parts follow the main balance. Seed / Reroll chooses a repeatable realization. Previews never add saved rhythms or overwrite saved recipes. Older auto-named previews are hidden from the main menu but recoverable through Load blend; named and explicitly saved recipes remain visible. Reload a saved blend, or Export / Import JSON with both endpoint definitions. One transition per sets sweep speed from ¼ to 16 choruses (default 1); changing speed restarts at A. Speed is retained in Save and JSON. Changes reach upcoming unscheduled bars.

This prototype supports compatible native meters across families: Funk ↔ Swing, Funk ↔ Soul Jazz/R&B, Bossa ↔ Samba (including 2/4), Salsa ↔ Tresillo and Jazz Waltz ↔ Soul Waltz. On a 4/4 chart, choose Meter mapping → Phrase fit for Soul 6/8 (including Brushes) ↔ Swing: two six-eighth cells fill one bar, each compressed from three quarter beats to two. The fit description and onset preview show the mapping, and saved recipes retain it. In 4/4, all four electronic styles can blend with acoustic rhythms or each other using Native; their half-time authored bar spans two chart bars for all parts. They also pair with Soul 6/8 using Phrase fit. Which rhythms can blend? lists compatible partners for Source A; clicking one selects Source B and its mapping. Source menus label Ready, Ready (Native/Phrase fit), or Unavailable; source selection applies the required mapping. Expand Unavailable partners and reasons for explanations. Saved microrhythm and other unsupported cross-meter conversions are explained; BPM and chart meter are never changed implicitly. The onset preview shows authored drum material. Definitions are local plus JSON-portable; tune sync carries only an ID, and a missing definition is shown until imported. Timing studies retain their own provenance and are separate from complete styles.

Rhythm Lab: importing styles

In Toolbox → Rhythm Lab, the Import JSON panel has an Import files… button. Pick one or more rhythm style files — a single style, or one file holding several (for example every groove cloned from a recording, all-grooves.json). Each becomes one of your own rhythm styles; choose it as the tune's rhythm style or per section. If any file is invalid, nothing is imported and the panel says which style failed. Pasting JSON still works, and also accepts a list of styles.

Rhythm Lab: Microrhythm playground

Open Toolbox → Rhythm Lab → Microrhythm with the uneven-pulse icon. The Lab opens inline below the chart, like Mix & EQ Studio, keeping the chart and transport accessible.

Base rhythm chooses Minimal, a small kick/hi-hat/cross-stick groove with sparse coordinated bass and comping, or experimental Swing/Samba/Bossa Nova copies, or Traditional: each African and Réunion timing pattern played by an approximation of its own ensemble — Mandé bòn drums for Ngòn Fariman, the Khasonka dundunba bell, hook drum and jembe for Bire (the sSS lead over the measured bell clock), iron clappers and gumbrī bass for Sṭambēlī and Gnawa, and kayamb, roulèr, pikèr and sati for Maloya. One cycle per quarter note, so the tempo reads as cycles per minute; energy adds players; parts a tradition does not have (piano, and the bass in Mandé and Maloya) stay silent. A Bass part menu guides the bass: the tradition's own part, Anchor (tonic on the long stroke), Pickup (fifth on the swung last short), Bass drum line (doubles the cunba, hook drum or roulèr), a guembri-style Ostinato, one of My bass patterns (written in the Staff Editor, played in each chord's key), or Tacet — all placed on the pattern's own uneven strokes. These are reconstructions with the app's samples, not transcriptions. Two-interval Minimal patterns use two kit sounds; three/four-interval patterns use three. Selecting its timing pattern changes the main band’s accompaniment. Native copies retain their patterns, rests, accents and instruments. The base drives playback even when the chart stores another feel.

A highlighted Timing changes these players strip names Minimal’s kit, bass and comping; Swing’s ride; or Samba/Bossa Nova’s complete authored drum, percussion, bass and comping ensemble. Samba groups share 80% of the clock and 20% separately seeded variation. Minimal’s players share one exact clock. Generated embellishments retain their ordinary timing.

The Percussion band panel, right below the main controls, shows one card per player in the base’s band. Pick any player’s instrument (the original or one of 19: kit pieces, cymbals, toms, timbales, congas, bongós, cowbell, agogô, claves, güiro, shakers, pandeiro, tamborim, cuíca), take a player off to silence that part (tap its dashed card to bring it back), or Add player to double a part on another instrument. Reset band restores the base’s own band. Each base keeps its own band. Traditional studies default to a two-quarter-note pulse span.

Timing pattern lists compatible studies: four intervals for Samba and Bossa Nova, two/three for Swing, all studies for Minimal. Samba choices include Samba swingue, Escola de Samba da Cidade’s Samba de Roda, Gal Costa’s Aquarela do Brasil, Rogê’s Suingue de Samba, Chico Buarque’s Meu Caro Amigo, Innov Gnawa’s Chorfa, Muthallith, Sʿadāwī, Waaju’s Fangara and two Rollando passages. Screenshot-only choices are removed. The examples are compatible timing studies, not claims that every tradition is Samba. Rollando alternates measured odd/even pulses inside each bar; its contrast scales with λ. Rounded source percentages normalize to one pulse.

Interpolation / extrapolation λ now extends past A (0) and B (1), nominally from −1 to 2, stopping before an interval collapses. The top diagram extends the timing paths, shades the extrapolation regions, and labels both endpoint boundaries. Effect strength has been removed. For Samba swingue, λ=1/2 matches built-in Swingue at 100%/200%; its separate compact control stays hidden while the experiment owns the clock.

The vertical λ slider sits directly beside the first chart. Bars to simulate selects 1–128 bars (default 16), remembered locally and shared by the diagrams and playback cycle. Long realization plots scroll. Controls sit at the top (base, pattern, bass part, pulse, bars, play, new realization, source link), then the two diagrams, then the typed interval boxes and correlation slider. Explanations are hover tooltips plus a collapsible Notes on these controls inside the Research and listening guide; the strip naming the players the timing moves sits at the very bottom. On every base the Bass part menu also offers Style bass lines: Walking bass and the authored bass line of each built-in style that fits the chart's meter (Samba, Funk, Bossa Nova, Salsa, Rock, R&B, Shuffle and more). The base's own bass stays the default; a style line moves with the timing clock. Bossa Nova preserves its native kit, shaker, bass and guitar comping, all on the experimental clock. Edit interval weights A/B, pulse span (quarter notes), noise σ, across-bar Odd/even offsets and correlation. Four-interval studies default to a two-beat pulse; copied Samba fits into 2/4 automatically. Minimal is authored for the current meter. Samba defaults noise to zero; other studies default to 0 for the first interval and 0.5 percentage points for later intervals. Drag blue handles to edit symmetric ±1σ uncertainty. New realization advances the internal seed. Realized statistics include positivity and closure effects. Rollando rows show the first pulse while stopped and follow the sounding pulse during playback; its top diagram shows the mean.

Opening Microrhythm automatically selects Micro Minimal, Micro Swing or Micro Samba, and every edit applies to subsequent generated bars without a separate Apply step. Rapid slider moves are batched for efficiency. Play/Pause uses the main transport and already queued audio stays intact. The diagrams always follow playback: the active white onset dot grows and changes color in both plots while following the current bar. Auto-apply replaces that base rhythm's previous experiment and removes the obsolete synthetic grid study. Controls persist locally; Pattern editor JSON export/import retains the copied rhythm and its clock. Existing Human Feel and arrangement layers still apply.

When both the main chart and stage scroll out of view, a floating Chord changes panel shows the same continuously rolling chords as the stage, including played Living Changes, intros and endings. It follows the main transport throughout the app, including Rhythm Lab, freezes when paused, and closes when either chord display returns. Performance View uses its own chart. The panel also has Play/Pause and the tempo control.

The research guide distinguishes measured examples, illustrative studies and hypotheses, with sources for An Exploration of Microrhythm.