El Eje Player, User Guide

Part 1

Getting started

Install El Eje, open it once, and get your music in. The app stores its own data (collections, lyrics, EQ, cue points) on your Mac and never moves or edits your audio files.

Section 1.1

The window at a glance

El Eje is a single window. Learn these five regions once and the rest of the guide falls into place, there's no separate menu bar; everything lives here.

1. 1
   Preview (cue) deck, the bar at the top of the main column. Audition tracks on your headphones here while the room keeps playing.
2. 2
   Your set, the playlist you're building, stacked as sections: tandas, cortinas, performances and DJ mixes.
3. 3
   Main (Live) deck, the transport pinned to the bottom. This is what the room hears.
4. 4
   Right panel, slides in from the right and shows one of: your Library, Settings, or an Equalizer.
5. 5
   Toolbar, the gear opens Settings; the list opens the Library panel. (Hover the right edge and press Space to toggle the panel.)

Section 1.2

First use: add your music

You build your library by dragging music in from Finder, your files stay exactly where they are.

1. Open the right panel (click Playlists in the toolbar) and click the Music tab.
2. Drag a folder or audio files from Finder onto the Music list. Sub-folders keep their structure; loose files land in the current folder. Supported: mp3, m4a, flac, wav, aiff, aif, ogg, aac.
3. When the “Update added tracks?” prompt appears, choose Update & group to auto-fill lyrics, BPM/key and mood tags and group duplicate recordings, or Always do this, or Not now.
4. Watch the progress: an “Identifying tracks…” banner at the top, and a “Tagging…/Grouping…” bar in the panel.

After this, anything you add to a watched folder in Finder later, even while the app is closed, appears in the Music tab on its own.

Section 1.3

Add & fix metadata

El Eje reads each file's own tags (title, artist, year, genre) and can fingerprint-identify untagged tracks. When something's wrong, you fix it in one place and it follows the recording everywhere.

Edit one track

1. Right-click a track → Edit info… (or click the info button on its row).
2. In the Edit Track Info sheet, edit Title, Artist, Year, Genre, BPM, Key, Album, Comment, and pick a Color.
3. Click Save. Title / artist / year / genre changes propagate to every other copy of that recording; BPM, key, color and comment stay on that one file.

Let El Eje fill the blanks

• Select one or more tracks (or a whole folder), right-click → Update metadata. It identifies tracks and fills in missing lyrics, BPM, key and mood tags, never overwriting what you already have, so it's safe to re-run.
• If a track can't be placed automatically, right-click → Tag manually…, search the catalog, and click the right recording.
• Right-click → Make best version to choose which transfer of a song your tandas should use (it then shows a star , see §3.1).

Section 1.4

Import your DJ library

Already keep your collection in another app? El Eje pulls in the tags, cue/fade points, and the playlists you've built, from VirtualDJ, Traktor, or iTunes / Apple Music. Your audio files are never touched, and it only fills in what's missing, nothing you already have is overwritten.

1. Open Settings and find Import from another app.
2. Pick your app from the dropdown, then click the import button:

• VirtualDJ → “Import from VirtualDJ.” No file picking, El Eje finds VirtualDJ's database automatically on this Mac and any external drives. It brings in title, artist, year, genre, BPM and your cue/fade points, plus your VirtualDJ folders and playlists.
• Traktor → “Choose collection.nml…” and pick your collection.nml. Brings in title, artist, year, genre and cue/load/fade points; your music lands in Music by its folders, your playlists in Playlists, and tanda/cortina runs in the Tandas and Cortinas tabs.
• iTunes / Music → “Import from iTunes / Music.” El Eje finds your library automatically (if it can't, it asks you to point at your Library.xml). It pulls the richer fields DJs keep there, album, grouping, comments, BPM, rating and start/stop trim points, plus your playlists and folders.

Section 1.5

Settings

All preferences live in one panel, open it with the gear at the top-right.

• Theme, System or El Eje (coral), the brand dark theme.
• Text size, scales text across the whole app (Small → Extra large).
• When tracks are added, Ask each time, Always update, or Never (the enrichment prompt from §1.2).
• Show hints, the hover tooltips on icons; turn them off once you know the app.
• Mixer output & Preview output, the heart of DJ setup: send the room (master) and your headphones (cue) to different devices. See §2.1.
• Mixer volume & Preview volume, El Eje's own output level (separate from the macOS system volume, which can't reach a pinned device). Mixer goes to 150%; Preview to 250%, handy to boost the cue when the room is loud. Each has a Reset to 100%.
• Silence system sounds in Live mode, like Do Not Disturb, but only while you're Live: mutes macOS alert/notification sounds so they never reach your mixer.
• Refresh devices, re-scan for audio outputs you just plugged in.
• Delete destination, when you remove tracks from a group, their files are moved here (organized like your Music tree) rather than deleted, so nothing is ever lost. Defaults to Desktop/MovedMusic; Choose… to change it.
• Backup & improving El Eje, your edits back up automatically in the background (no audio). Restore from backup… brings them back on a new machine (the app relaunches).
• Library updates, El Eje quietly checks for author-vetted title/year/orchestra fixes; click Review updates to accept, reject, or undo each, your own edits always win.
• Import from another app, VirtualDJ, Traktor, or iTunes / Music (§1.4).
• Phone remote, pair an iPhone to control El Eje (§5.3).

Part 2

The two decks

El Eje has two decks: a preview deck you audition on headphones, and the main deck the room hears. Keeping them on separate outputs is what lets you cue the next tanda while the floor keeps dancing.

Section 2.1

The preview (cue) deck

The thin bar at the top of the main column, marked with a PREVIEW badge. It plays to your headphones only. Cue a track with its headphones button, or by double-clicking any row.

1. 1
   Headphones, marks this as the cue deck; it plays only to your Preview output, never the room.
2. 2
   Play / pause the preview.
3. 3
   PREVIEW badge + track, what's cued, so it's never confused with the Live deck.
4. 4
   Timeline + cue markers, drag to scrub; coloured pins are your Load / Fade-in / Fade-out points (drag to move, right-click to remove).
5. 5
   Time readout, current · −remaining (count-down) · total.
6. 6
   Waveform toggle, show/hide the zoomable wave for precise fading (coral when on).
7. 7
   Preview EQ, open the cue-deck equalizer; dial it in on headphones, then “Save to song”.
8. 8
   Add cue, drop a Load / Fade-in / Fade-out marker at the playhead.
9. 9
   Load upcoming, cue the next track from the playing queue.

After a cued track ends

One button in the preview bar decides what the cue deck does when the track you're auditioning finishes. Click it to cycle four modes, it stays neutral on the first and glows coral on the others, and your choice is remembered between sessions:

• Pause, “After this track: stop (no auto-advance).”
• Repeat, “After this track: repeat it.”
• Continue, “After this track: continue to the next in the list.”
• Shuffle, “After this track: play a random track from the list.”

The waveform & precise fades

Click the waveform button to reveal a zoomable wave. Drag anywhere on it to scrub, you'll hear a real tape-jog in your headphones, then drop fade points exactly where you want them.

1. A
   Zoom, Fit / 2× / 4× / 8× / 16× around the playhead; the visible range (e.g. 1:05 – 2:30) shows at the right.
2. B
   The waveform, drag to scrub (tape-jog on your headphones); it reshapes live as you move EQ bands. The bright bar + white line is the playhead.

Load / Fade in / Fade out are saved on the song and follow it everywhere. Mix fade in / out belong to a single DJ-Mix slot only (§4.5).

Section 2.2

The main (Live) deck

The transport bar at the bottom of the window, marked LIVE. Load a track by dragging a row (or a whole playlist) onto it, it loads paused, then you press Play. (Double-clicking a row cues to preview, not here.)

1. 1
   Lock, protects a playing deck (green = locked): blocks pause / next / tempo on a live tanda. Cortinas & mixes stay free.
2. 2
   Previous track.
3. 3
   Play / pause (the big button).
4. 4
   Next track.
5. 5
   LIVE badge + track, red when Live mode is on, grey when off (§5.1).
6. 6
   Timeline + markers, drag to seek; Load (green) / Fade-out (orange) pins.
7. 7
   Time readout, current · −remaining · total.
8. 8
   Ends, the wall-clock time the set finishes if the rest plays out.
9. 9
   Tempo, −/+ in 0.5% steps (70–130%) with pitch unchanged; the gauge menu sets when it snaps back; the arrow resets to 100%.
10. 10
    Playback variant, save/recall an EQ + tempo + reverb preset for this track.
11. 11
    Fade out (⌘F), ramp a cortina or DJ mix into the next track.
12. 12
    Equalizer, open the main-deck EQ (or press q while it plays).

Section 2.3

EQ, key, BPM & even gaps

El Eje shapes sound per track and analyses each recording for you, locally, offline. Open the equalizer from the slider button on either deck (or press q while a deck plays).

1. 1
   Flat, reset every band to 0 dB.
2. 2
   Lock, the bands are locked by default; click to unlock, then drag them.
3. 3
   Close (Esc).
4. 4
   The 10-band curve, drag a band (32 Hz → 16 kHz, labelled Sub … Air) to boost or cut. On the main deck this auto-saves to the playing song; on the preview deck it's a sandbox until you press Save to song.
5. 5
   Extra toggles, Reduce noise (low-pass) for hiss on old transfers, Normalize loudness, and Milonga Mode reverb.

Key & BPM

Right-click a track → Detect Key / Detect BPM to (re)measure one track. To fill missing values in bulk, select tracks → Update metadata (it fills blanks only). Keys are shown in Open Key notation and imported keys are never overwritten.

Part 3

The library

Everything you own lives in the right-side panel, organised the way you program a night.

Section 3.1

The library panel & its tabs

Open the panel (the Playlists button, or Space over the right edge). It has four tabs, only one open at a time:

• Music, a Finder-style browser of everything you've added, with breadcrumbs, sort chips (Year / Name / Color), genre & singer filters, and a quick-find.
• Cortinas, your cortina tracks.
• Tandas, reusable tandas you've saved, filed by orchestra and genre (§4.7).
• Playlists, the DJ sets you build for an event (§4.8).

1. 1
   Colour dot, the Traktor-style colour you can tag a track with.
2. 2
   Best-version star, the transfer your saved tandas use for this recording.
3. 3
   BPM.
4. 4
   Year.
5. 5
   Lyrics, pop the lyrics, translation & contributors.
6. 6
   Edit info, open the metadata editor (§1.3).
7. 7
   Cue in headphones, load it on the preview deck.

Select rows with click / ⌘-click / ⇧-click, right-click for actions, and use the ＋ button to add a playlist or folder to the open tab.

Section 3.2

Search

The search box sits at the very top of the library panel.

1. Type 2+ characters. Results are grouped by recording, accent- and case-insensitive, so darienzo finds “D'Arienzo”.
2. Toggle the Title / Orchestra / Lyrics / Credits chips to choose what's searched (Lyrics and Credits are off by default).
3. Add a 2+ digit number to filter by year, e.g. di sarli 1944.
4. Mix an orchestra with a rhythm. calo milonga returns Caló's milongas and any Caló track with the word “milonga” in it, same for vals and tango.
5. Results group by rhythm: Tango, Vals, Milonga, unless you typed milonga (milongas first) or vals (valses first).
6. Flip on the Tandas chip (beside the field chips) to search your saved tandas instead, by orchestra (pugliese) or a track they contain (gallo ciego); append or play-next straight from the result.
7. Misspelled it? Tap a “Did you mean” suggestion. Searching a person or orchestra name also surfaces a Learning jump-link.

This box searches your whole library. To search inside the folder you're browsing, use the per-folder box in the Music tab, see §3.3.

◐ Good to know, every track row shows a small rhythm tag at the end (T tango · V vals · M milonga); a saved tanda shows the combined tag of its tracks (e.g. TV). Double-click any row to cue it to the preview deck, and press ⌘⇧L to see the selected track's lyrics & credits.

Section 3.3

Browse & filter your folders

Inside the Music tab, each folder has its own tools for finding and narrowing what's in front of you, separate from the library-wide search in §3.2.

• Search this folder…, the box just under the breadcrumb. Type 2+ characters and the listing is replaced by matches grouped by sub-folder; click a sub-folder heading to drill in. (It clears when you navigate away.)
• Sort, the Year / Name / Color chips. Each click cycles off → ascending → descending → back to your manual drag order.
• Genre chips, Tango / Vals / Milonga / Other (only the ones present in this folder appear) narrow by rhythm.
• Singers, opens a popover to tick one or more singers (or Instrumental), reorder them, and Select all / Clear. The × clears every filter at once.

Section 3.4

Smart Playlists

A Smart Playlist fills itself: instead of dragging tracks in, you set a few filters and El Eje keeps it in sync with every matching track in your library, automatically, as you import and tag.

1. Open the Music tab, click the shared ＋ button, and choose New Smart Playlist.
2. Name it, then stack filter rows with Add filter, each row is one of Orchestra, Singer, Genre, Year, Contributor or Lyrics, with an is / is not (or has / has no) operator. Rows are combined with AND.
3. Watch the live count at the bottom, “N tracks match these filters”, then click Create. (Save stays disabled until there's a name, a filter, and at least one match.)

It appears in the Music tab with a filter icon. Right-click it → Edit filters… to change the rules later; it re-matches whenever your library changes.

Part 4

Building a set

A set is a playlist made of sections: tandas, cortinas, performances and DJ mixes. This part builds one from scratch.

Section 4.1

Start a set & add sections

1. In the Playlists tab, click ＋ → New Playlist and name it.
2. The empty set shows “Add a tanda, cortina, performance, or DJ Mix to start.”
3. Use the add bar under the playlist name, Tanda, Cortina, Performance, DJ Mix (shown in §4.4). Each adds an empty, auto-named section; names come from the music later.
4. Reorder sections by dragging the grip handle , or right-click → Move up / Move down.

Section 4.2

Build a tanda

1. Add a Tanda section (it should be unlocked, open padlock, showing “drop audio here”).
2. Drag tracks onto the section header, four for tango, three for vals/milonga, from the Music tab or Finder.
3. The tanda auto-names itself from the music, e.g. “Di Sarli, Rufino (1939–1941)”. Double-click the name to override it.

Section 4.3

Add cortinas

A cortina is the short break between tandas. In El Eje a cortina holds exactly one song.

1. Click Cortina in the add bar to place one between two tandas (or let Live mode add it for you, §4.4).
2. Drag a single cortina track onto it. Dropping a new song replaces the one that's there.
3. Tune its fade length with the −/+ control in the cortina's header.

Section 4.4

The built-in guardrails

El Eje quietly watches your set so a slip never reaches the floor. The guardrails are advisories, nothing is blocked.

1. 1
   Mixed genres!, a red warning when a section's tracks are all tagged but don't share one genre.
2. 2
   Gap / fade, the −/+ time between tracks (or a cortina's fade), 1–20 s.
3. 3
   Lock, make a finished tanda read-only (it auto-locks in Live mode once it's full / starts playing).
4. 4
   Cortina missing, in Live mode, an empty cortina is enforced between back-to-back tandas; drop a track on it to clear the warning.
5. 5
   Add-section bar, append a Tanda, Cortina, Performance, or DJ Mix.

There's also a tanda-size warning in Live mode: an orange 3/4 marker when a tanda is short of the convention (tango 4, vals/milonga 3).

Section 4.5

DJ Mix (crossfades)

A DJ Mix is a section where consecutive tracks crossfade into one another instead of playing with a gap, for an opening set, a cumbia bracket, or a seamless blend.

1. Add a DJ Mix section and drag in two or more tracks.
2. Set the crossfade length with the −/+ stepper in the section header (default 5s, 1–20s).
3. Cue each track to the preview deck and use Add cue → Add Mix fade in / Mix fade out here (the teal / pink markers from §2.1) to author exactly where each track enters and leaves. These points live on the mix only.
4. Play it: a live transition bar appears above the main deck. Let it auto-crossfade, or drive it by hand, on a middle track the Fade Out button crossfades to the next; on the last track it fades out to finish.

Section 4.6

Performance sections & video

A Performance section is for a show piece or demo: it plays, then stops instead of rolling into the next section, so you stay in control.

1. Add a Performance section and drag in the track(s).
2. Optional, open its settings to Repeat the ending: after the song finishes, a short tail replays quietly (length, pause and volume are adjustable) so a couple can close the floor.

Performance video sync experimental

Lock a performance video to the music so you can study how a recording actually moves dancers:

1. Load the track, open the Performance Video section in the panel, and click Assign Video… (or drag a video onto the black surface).
2. Click Auto-align (by audio). If it can't match, use Align by ear: find the same moment in the track and the video and click Set A, then a second moment for Set B, then Done.
3. Play, the video now stretches to stay locked to the music. Use Follow and the mute toggle as needed.

Project it on a second screen

Expand the Performance Video section in the panel and click the small Open in window link (top-right) to pop the video into its own clean, chrome-free window, drag that to a projector or second display and fullscreen it. It stays frame-synced to the deck; closing the window just tucks it back, with the sidebar panel still running. The inline Video switch turns the video off entirely to save power (the window then reads “Performance video is off”).

Section 4.7

Save & reuse tandas

Turn the tandas you've built into a reusable library.

1. Click Save tandas (top-right of the playlist header; it reads “Save tandas & mixes” when the set has a DJ Mix).
2. Each tanda is auto-titled and filed in the Tandas tab, into a per-orchestra playlist under Tango, or into Vals / Milonga / Others / DJ Mix. Subsets of existing tandas are skipped as duplicates.
3. Reuse one later: from the Tandas tab, drag it into a set, or use its … menu, Append to end of set, Play next, Rename…, Remove saved tanda.

Section 4.8

Playlists vs the Tandas tab

Two tabs that are easy to mix up:

• Playlists = the editable DJ sets you build for an event.
• Tandas = reusable saved tandas & mixes, filed by orchestra/genre.

Build a set in a playlist, drop saved tandas into it from the Tandas tab, and rearrange freely. To change which transfer plays, right-click a track → Show all versions…, then Use here (this slot), Make best (everywhere), or Degroup to split a mislabeled copy out safely.

Tip: in the Playlists tab, right-click a playlist or folder → Add label… to tag it with a coloured chip; the set currently loaded shows a coral Playing chip.

Group versions by hand

El Eje groups copies of the same recording automatically, but you can correct it. Right-click a track in the Music tab and you'll see one of these (whichever fits the track):

• Group with…, for a lone track the app thinks is unique. Search for the song it's really a copy of and click it; the track joins that group and adopts its title / artist / year. Reverse it any time with Ungroup.
• Degroup / Regroup, split a wrongly-grouped copy off into its own island so its edits don't touch the others (it shows a “detached” badge), or rejoin it later. The same buttons appear per-row inside Show all versions…

Part 5

Performing & learning

The last two pieces: running the actual night, and going deeper into the music.

Section 5.1

The Live button

The LIVE pill sits next to the playlist name. Gray = practice (everything unlocked); red = Live. Click it, or press ⌘L.

While Live, El Eje protects the night:

• Tandas lock as they play, so you can't disturb a set that's on the floor.
• A cortina is enforced between back-to-back tandas (§4.4).
• The main EQ locks; cortinas and DJ mixes stay free so you can fade by hand.
• If enabled, macOS alert sounds are silenced for the duration (§1.5).

Switch back to gray any time to rearrange freely.

Section 5.2

The Learning suite

El Eje is also where you study the music. In the panel, expand Learning and Lyrics:

• Encyclopedia, browse Orchestras, Singers, Poets & Composers, Instrumentalists, Dancers, Movies, Archetypes, a year-by-year timeline and numbered Music Theory lessons (with playable audio examples). Click a name anywhere in the app to jump to its entry, and drag a cited recording straight into a set.
• Thesaurus flashcards, spaced-repetition cards for tango/lunfardo vocabulary; rate each word I know it / Sometimes / Hard.
• Synced lyrics + translation, open the Lyrics section and play a track: each Spanish line scrolls with its English line beneath it; toggle Lyrics / Sung. Click Open in window at the top of the section to put the lyrics on a second screen or projector, it stays synced to the deck.

Section 5.3

Control El Eje from your phone coming soon

El Eje can be driven from an iPhone, play/pause, skip, fade, cue the next tanda, over Wi-Fi, your phone's hotspot, Bluetooth, a USB cable, or (later) the internet. The Mac side is built in; the companion iPhone app is on the way.

On the Mac it lives in Settings → Phone remote…:

1. Turn on Let a phone control this Mac, El Eje becomes discoverable by name.
2. Click Pair a phone… to show a one-time PIN; you enter that on the phone.
3. Approve the phone when it appears under “Waiting for approval”, a phone can't control anything until you approve it here, even if it knows the PIN.
4. Manage trusted phones under Paired devices, each has a Remove that revokes it instantly.

Section 5.4

Keyboard shortcuts

Everything you reach for most, without the mouse.

Playing & cueing

• Double-click any track row, cue it to the preview (headphone) deck.
• Space, over the main area, show/hide the preview waveform; over the right edge, toggle the panel. (Not play/pause.)
• q, open/close the equalizer for the deck that's playing.
• ⌘F, fade the current track out (a cortina, a DJ Mix, or a tanda in practice).
• ⌘L, toggle Live mode on/off.

Library & lyrics

• ⌘⇧L, show lyrics & credits for the track selected in the sidebar.
• Type any letters with the pointer over the library, Finder-style jump to the first match.
• Esc, leave the search box.

Editing the set

• ⌘- or ⇧-click rows, multi-select.
• ⌘A, select every track in the set.
• ⌫ Delete, remove the selected cue, otherwise the selected tracks.
• ⌘Z, undo.
• ⌘Q, quit (blocked while the Live deck is playing, stop it first).

More

Under the hood

Curious how El Eje works underneath, the design principles, the community feedback loop that turns your fixes into everyone's updates, sound identity, privacy, and the research ahead (recovering lost music, singer voice transfer)? It's all laid out on the El Eje Player page → “The design”.