Ableton/Live/UG/17 Routing and IO
- Track inputs and outputs: monitoring, external audio and MIDI, resampling and routing between tracks.
- Routing sets each track's signal source and destination. Most of it happens in the mixer's In/Out section, Live's patchbay.
- Show or hide In/Out from the mixer's view control menu at the bottom right, from View → Mixer Controls → In/Out, or with
Ctrl+Option+I (Mac) / Ctrl+Alt+I (Windows). - Every clip-playing track has the same layout:
- Audio/MIDI From — the input. Return tracks take their input from their sends.
- Monitor — when the input is heard through the track.
- Audio/MIDI To — the output. Every track outputs audio except MIDI tracks with no instrument.
- In each chooser pair, the upper Type chooser picks a category (such as Ext. for an audio or MIDI interface) and the lower Channel chooser picks a specific input, output or channel within it.
- Monitoring passes a track's input to its output through the device chain, so you hear what you play, with effects and interface latency.
- Each audio and MIDI track has three monitor modes:
- Auto (Ableton/Track/IO/Monitor/Auto) — monitors while the track is armed, but not while it plays clips. Suits most recording.
- In — always monitors the input and silences the track's clips, turning it into an aux-style input. The track's Activator switch turns blue to show it.
- Off (Ableton/Track/IO/Monitor/Off) — never monitors. For acoustic instruments heard in the room, an external mixer, or an interface's direct monitoring. Set Overall Latency in the Audio Settings when recording this way.
- With In or Auto, Keep Monitoring Latency in Recorded Audio is on by default, lining the recording up with what you heard. Leave it on for software instruments and effects; turn it off for acoustic instruments or external monitoring. Right-click the In or Auto button to switch it.
- Clicking a Monitor button applies to all selected tracks. With In/Out shown,
Delete or Edit → Return to Default resets it: Off for audio tracks, Auto for MIDI tracks.
- Choose Ext. In as an audio track's Input Type to use the interface's inputs; the Input Channel chooser lists them with level meters that flash red on overload. Outputs work the same way. Changes apply to all selected tracks.
- The Configure… entry opens the Audio Settings, whose Channel Configuration dialogs choose which interface inputs and outputs Live uses and whether they are mono or stereo pairs.
- Channels can be renamed in those dialogs (
Tab moves between them); the names show in the choosers and belong to that audio device.
- A MIDI track's Input Type chooser picks one MIDI port or All Ins, the merge of every port. Input Channel picks one channel or All Channels, with activity meters on each entry. Changes apply to all selected MIDI tracks.
- Settings → Link, Tempo & MIDI lists every MIDI input and output port. Each can be used by any number of tracks.
17.3.1.1 Track
- Sends or receives notes and CC messages.
- Turn it on for an input to play or record notes, or to record CC from a hardware synth into clips.
- Turn it on for an output to play external hardware, send notes to another app through a virtual MIDI bus, or send CC automation out.
- A controller's output port needs Track only if the controller makes its own sound.
17.3.1.2 Sync
- Sends or receives MIDI Clock, or receives MIDI Timecode. A controller needs it only if it has a sequencer or arpeggiator.
- Input: to follow an external sequencer, drum machine, groovebox or another DAW. Output: to drive those from Live, or to sync an external synth's LFO and arpeggiator.
- Expanding an output port with Sync on shows more options:
- MIDI Clock Sync Delay — delays outgoing sync in milliseconds to fix timing offsets.
- MIDI Clock Type — Song sends Song Position Pointer and Continue whenever the play position changes; Pattern sends only Start, at the next bar, for devices that ignore SPP.
- Hardware Resync — what the Control Bar's Resync External Hardware button sends to bring synced gear that has fallen out of time back in line: Stop and Start (default), Start Only, or Don't Resync.
17.3.1.3 Remote
- Lets a controller map to Live's parameters, and sends feedback back to it.
- Input: for custom MIDI mappings, or to launch clips from a keyboard. Launchpad/Custom/Mode/1 Arrangement needs Remote on for the Launchpad's input.
- Output: for controllers whose LEDs or motorised faders show the state of mapped parameters.
- Turn on the computer MIDI keyboard with the Control Bar button, Options → Computer MIDI Keyboard, or
M. - The middle letter row plays the white keys starting at C3; the row above plays the black keys.
Z and X shift the octave; C and V change velocity in steps of 20.- Between C3 and C4 the middle row lines up with Impulse's sample slots, for playing drum patterns.
- While on, it takes over keys used for other shortcuts. Add
Shift to reach single-letter shortcuts, such as Shift+S for solo.
- To play an external synth, set the track's Output Type to the synth's MIDI port and Output Channel to its channel.
- The External Instrument device does the same from inside the device chain, and also brings the synth's audio back into the same track. See Ableton/How To/Record MIDI and Audio from external device.
- When one keyboard synth is both your controller and a sound source, turn on its Local Off so Live becomes the hub that passes keyboard and clip MIDI to it.
- The Control Bar has three pairs of MIDI lights. In each pair the top flashes on incoming MIDI and the bottom on outgoing.
- From left to right: MIDI Clock and Timecode (shown only when a port has sync enabled); remote control of Live's interface; MIDI to and from MIDI tracks.
- MIDI used by a remote mapping doesn't reach the tracks. The lights show when that is why a track hears nothing.
- Choosing Resampling as an audio track's Input Type records Live's Main output into that track.
- Uses: turn the current mix into a new sample, print processor-heavy tracks so their devices can be removed, or preview a mix before rendering.
- Keep the Main meter as high as possible without hitting red, arm the track and record into an empty slot. The recording track's own output is left out.
- Recordings go to the Project's Samples/Recorded folder, or the Temporary Folder until the Set is saved.
- Tracks can feed each other in two ways:
- Track A sends to B through A's Output Type. Suits many-to-one setups such as submixes or several MIDI tracks sharing an instrument. Soloing B still plays everything feeding it.
- Track B takes from A through B's Input Type. Suits one-to-many setups such as layering, where several tracks tap one source.
- When a track's Audio From is another track, the Input Channel chooser picks where the signal is tapped:
- Pre FX — straight from the track, before its devices and mixer.
- Post FX — after the devices, before the mixer.
- Post Mixer — the track's final output after volume and pan.
- Soloing the tapping track lets you hear the tapped track at Pre FX and Post FX, but not at Post Mixer.
17.5.1.1 Routing Points in Racks
- Every chain of an Instrument or Effect Rack, and every return chain of a Drum Rack, offers the same three tap points, listed as
Rack | Chain | Pre FX, Post FX or Post Mixer. Post Mixer is the chain's output just before the chains are summed. 
- Soloing a track that taps a chain still lets you hear that point.
17.5.2.1 Post-Effects Recording
- To record a guitar already processed by a gate or amp model, put the effects on a "Guitar" track with Monitor set to In, and record on other tracks whose input is the Guitar track at Post FX (or Post Mixer to include its level and pan). Set those tracks' Monitor to Off.
17.5.2.2 Recording MIDI as Audio
- When a complex instrument turns one note into something closer to a passage, record its audio: one MIDI track hosts the instrument, and an audio track taking input from it records the result.
17.5.2.3 Creating Submixes
- Route several drum tracks to one submix audio track that goes to Main, so one fader controls the whole kit.
- A Group Track sets up the same routing automatically and can fold its tracks away.
- Or set each track's Output Type to Sends Only and use a send, so a return track acts as the submix.
17.5.2.4 Several MIDI Tracks Playing the Same Instrument
- Point a second MIDI track's Output Type at the instrument track, and choose the instrument itself (not Track In) as Output Channel. Both tracks then play one instrument, so sound changes affect both.
- To mute each part separately, move the original clips to a third track and leave the instrument alone on its track, with Input Type set to No Input so it has no Arm button.
17.5.2.5 Tapping Individual Outs From an Instrument
- Impulse offers each of its eight sample slots as a source for other tracks. An audio track whose input is the Impulse track can choose one slot, which takes that slot out of Impulse's own mix for separate effects. Most plug-ins don't remove the tapped output this way.
17.5.2.6 Using Multi-Timbral Plug-In Instruments
- A multi-timbral instrument plays a different part on each MIDI channel. Extra MIDI tracks feed its parts by pointing Output Type at the instrument's track and Output Channel at each part's channel; audio tracks tap its individual outputs.
- External Instrument devices on other MIDI tracks can do both at once: set MIDI To to the instrument's track and channel, and Audio From to one of its auxiliary outputs. Several can share one track inside a Rack. The instrument's main outputs stay on its own track.
17.5.2.7 Feeding Sidechain Inputs
- A vocoder on a strings track needs a speech signal at its sidechain input: create a "Speech" track whose Output Type is the strings track and whose Output Channel is the vocoder's sidechain. Vocoder plug-ins with their own carrier synth go on a MIDI track and are fed the same way.
- Many of Live's built-in devices have their own sidechain choosers, so they don't need this.
17.5.2.8 Layering Instruments
- To double a strings part with brass, add a MIDI track with a brass instrument whose Input Type taps the strings track at Post FX. MIDI from another track is tapped after its MIDI effects and just before its instrument, so the brass gets the same notes.
