(how-it-sounds)= # How A³ sounds You play a set as usual: tracks, EQ, faders, a filter, an echo. The difference is the room. The hi-hats of the break circle the crowd. The vocal lifts over the floor and drops back on the one. The kick and the bass stay put, so the floor never loses its ground. This page shows what happens to your sound on the way from the deck to the speakers, and what you touch to make it move. ## A³ in three sentences A³ is a DJ setup for a room with speakers **all around** the crowd, not just in front of it. You mix on a four-channel desk as on any club mixer, and **A³ Motion** or **StemDeck** decides where each part of the music is in the room, in time with the beat. A computer, **A³ Core**, runs **a3-core**: it takes everything you play, places it in the room, and feeds every speaker exactly its share. ## Two ways to play: stereo and stems Each of the four desk channels plays one of two kinds of source. You choose it with the channel's **INPUT** knob on the desk: **ST** is the stereo input, **A** to **D** are the StemDecks. You can mix both on one evening, for example a turntable on channel 1 and a StemDeck on channel 2. | | **Stereo mode** (ST) | **Stem mode** (deck A to D) | | :--- | :--- | :--- | | **You plug in** | a CDJ, turntable or laptop | nothing: StemDeck is software | | **A track is** | one stereo signal | four stems: drums, bass, other, vocals | | **What moves** | one band you pick (FREQ, Q) | one stem, while its action runs | | **What stays** | the rest of the track | the other stems | | **Who steers** | A³ Motion: its clip and 3d | StemDeck: ORBIT, PING, RISE, SCAT | | **You touch** | the desk, and 3d, FREQ, Q | the desk, the pads, GAIN, WIDTH, AUX-Send | (how-it-sounds-stereo)= ### Stereo mode: one band moves, the rest stays A whole track that flies around the room smears: the kick wanders off the floor and the crowd loses the beat. So A³ never moves the whole channel. It cuts **one band** out of it and moves only that band. - **FREQ** picks where the band sits, from the bass up to the hi-hats. - **Q** sets how wide the band is: narrow takes a single sound, wide takes a lot of the track. - **3d** sets how much of that band leaves the rest. At **0** nothing moves: the channel is plain stereo, spread around the room. Turn it up and the band comes loose and follows A³ Motion's path. - Everything outside the band stays where it is, so the kick holds the floor. **Try it:** play a track with a clear hi-hat. On A³ Motion, start a clip on its channel, turn FREQ high and Q narrow, then turn 3d up. The hats start to circle; the kick does not. See [A³ Motion](a3motion.md) for clips, paths and actions. (how-it-sounds-stems)= ### Stem mode: every stem has its own path StemDeck plays a track that is split into four stems. Each stem is placed in the room by StemDeck itself, before the sound reaches the desk. - **At rest every stem sits all around the room**, like the steady part of a stereo channel. You hear the track as one piece. - **An action lifts one stem out and moves it**: **ORBIT** circles, **PING** jumps from side to side, **RISE** goes up, **SCAT** scatters. It starts on the next bar and lasts ½ to 8 bars (the length keys under the pads). Then the stem goes back to its place and sinks into the rest again. - **WIDTH** sets how wide a moving stem is: a narrow point or a broad wall. - **GAIN** is the stem's level; a push on its knob mutes it. - **AUX** is the stem's AUX-Send to the beat delay (see [The extras](#how-it-sounds-extras)). - On the A³ Motion panel, the four pots are the AUX of the four stems, the upper encoders GAIN, the lower ones WIDTH. **Try it:** load a track on deck A and press PLAY. On the desk, turn channel 1's INPUT knob to **A**, push it, and bring the fader up. Tap **RISE** on the vocal stem: on the next bar the vocal lifts over the crowd and comes back down after the bars you chose. There are up to **four decks, A to D**. Deck A runs on A³ Core itself. Decks B to D can run on other computers next to the desk and send their sound to the Core over the network (**AES67**, see the glossary). A deck sounds the same either way. See [StemDeck](stemdeck.md). A³ Motion does not move a deck: on a deck channel its screen says **DECK A** (or B, C, D), and the stems follow StemDeck's actions. (how-it-sounds-flow)= ## From the deck to the speakers ```{figure} pics_user/a3-signal-flow.svg :alt: The A³ signal flow in six rows. 1, what plays: players into the audio interface, StemDeck deck A on the Core, decks B to D over the network. 2, the desk: four channels, INPUT picks ST or a deck. 3, into 3D: a stereo channel moves one band, a deck channel moves its stems with actions. 4, a3-core mixes: everything into one room mix; the AUX-Sends go to the delay, whose echoes come back through FX RETURN. 5, outputs: MASTER, BOOTH, REC and PHONES. 6, where it is heard: PA speakers, booth speakers, the recording, the headphones. The way of the sound, top to bottom. ``` 1. **What plays.** Players go into the audio interface of A³ Core, in stereo. StemDecks are already on the computer, or reach it over the network. 2. **The desk.** Each channel picks its source with **INPUT**, then works like any DJ mixer: **TRIM**, **EQ**, the **FX** filter, the **fader**. The desk makes no sound itself; it tells A³ Core what to do. 3. **Into 3D.** Each sound gets its direction: the moving band of a stereo channel from A³ Motion, the stems from StemDeck. Everything else stays spread around. 4. **The room mix.** The engine adds all channels into one mix that knows *where* every sound is, but not yet *which speaker* plays it (that is **B-format**, see the glossary). The echoes of the delay join this mix through **FX RETURN**. 5. **Four ways out.** The same room mix leaves four times: - **MASTER** for the PA. A **decoder** works out what each PA speaker plays. - **BOOTH** for the speakers around the DJ, with its own decoder. - **REC** for the recording: the whole room folded into headphone stereo. It does not follow MASTER, so a set is recorded even with the PA down. - **PHONES** for your headphones: what you cue, and the mix. 6. **The speakers.** The PA plays the room; the booth plays the same around you; StemDeck's **REC** key records the REC mix to a USB stick or the disk. When A³ Core starts, its outputs stay **silent** until every device has told the engine its settings. Then they fade in over one second. A restart never blasts the room with a wrong level. (how-it-sounds-extras)= ## The extras: cue, delay, recording **Cue (pre-listening).** Press **CUE** on a channel to hear it in your headphones before the crowd does, even with its fader down. **CUE/MIX** blends between what you cue and what the room hears; **PHONES** is the level. A StemDeck stem has its own **CUE** key, so you can check the vocal of the next track alone. The headphones get the same 3D sound, folded to two ears. **Delay (echo).** A³ has one beat-synced delay, a tape-style echo whose time follows the tempo. - A channel's **AUX-Send** on the desk sends that channel into it, from where the channel sits in the room, so the echo comes from the same side. - A stem's AUX-Send (its **AUX** knob in StemDeck) sends just that stem, for example only the vocal. - **FX RETURN** on the desk sets how loud the echoes are in the room. At zero the delay is silent on the PA. - A pulled fader sends nothing: an echo only starts from a channel that plays. **Recording.** StemDeck's **REC** key records the REC mix: everything that the room hears, echoes included, folded to stereo. On a USB stick if one is in, otherwise on the disk. (how-it-sounds-glossary)= ## Words used here One name per thing: every page uses these. | Word | In plain words | | :--- | :--- | | **3d** | how much of a channel's sound moves through the room. 0: none, it stays spread around. Printed **3D** on A³ Motion's screen | | **AES67** | a standard way to send many audio channels over an ordinary network cable. A StemDeck on another computer reaches A³ Core this way | | **A³ Core** | the hardware: the computer with its audio interface that everything plugs into | | **AUX-Send** | a second way out of a channel or a stem, into the delay. The normal way out (the fader) stays as it is. Printed **AUX SEND** on the A³ Mixer, **SEND** on the virtual desk and A³ Motion, **AUX** on a StemDeck stem | | **B-format** | sound stored as "what comes from which direction", not as "what plays on which speaker". It fits any speaker setup; a decoder turns it into speaker signals | | **bus** | a mix that several sources go into, like the room mix or the headphone mix | | **cue** | pre-listening in the headphones, before the crowd hears it | | **decoder** | the step that turns B-format into one signal for each speaker of a room. The PA and the booth each have their own | | **desk** | the four-channel mixer you play on: the **A³ Mixer** is the hardware panel, the **virtual desk** the same mixer in software, on a screen | | **ST** | a desk channel's stereo input, for a CDJ, a turntable or a laptop. (**A** to **D** are the StemDeck decks) | | **stem** | one part of a track: drums, bass, other or vocals. StemDeck plays four of them together | | **a3-core** | the program on A³ Core, audio backend included, that places every sound in the room and feeds the speakers. Its settings are in the a3-core window | | **zone** | one set of speakers with its own decoder: **MAIN** (the PA) and **BOOTH** | ## Where to go next - **A³ Motion**, to make stereo channels move: [first ten minutes](#motion-get-started). - **StemDeck**, to play stems: [StemDeck](stemdeck.md). - **The desk**: [A³ Mixer](a3mix.md). - **What you need**, speakers or headphones: [What you need](what-you-need.md). - **Setting up the room**, speakers and levels: [Setting up a room](audio-engine.md). - **Your first set**: [First set](first-set.md).