Understanding your audio: outputs, channels, routing and track types

The different audio channels of playback have to go to different places at once:

  • Playback tracks to front of house sound.
  • Click to the band's headphones.
  • LTC (Linear Timecode) to other technical departments.

Output routing is to get each stream to the right destination, and the more of those streams you keep separate, the more control the sound team has over the final mix.

Below are three possible setups, and the rest of the article explains the concepts behind them: what an audio device is, what an "output" and a "channel" are, how routing connects them, and what the channels in a KTPlayer show file actually carry.

Three possible setups


1. Laptop only, no audio device (viable low-budget option)

  • One stereo headphone output, used as two independent mono feeds.
  • Route Playback to one side of the headphone output and Click to the other, hard-separated, then split the single headphone jack into two mono cables: one to front of house, one to the headphone amp.
  • Front of house is mono and there's no timecode, but it runs a show on gear you already own.
  • A viable low-budget option when using a multi-output audio interface isn't possible

2. Four-output audio device

  • Playback as a stereo pair (outputs 1 | 2) to front of house, Click (output 3), and LTC (output 4) to the lighting desk.
  • Stereo FOH, a clean isolated click, and timecode, each on its own output.

3. Eight outputs or more

  • For productions where the sound designer wants specific control of the playback's tracks
  • Instead of a single stereo Playback feed, the show file's individual stems (vocals, strings, brass, SFX, and so on) each go to their own output, so the engineer can balance them in the room rather than taking your mix as-is.
  • Click and LTC each run separately as well
  • As a rule: the more individual FOH channels the sound team can control separately, the better the mix they can build.

What is an "output"?

An "output" is one physical connection on the back of the device, capable of carrying one stream of audio. KTPlayer numbers them (output 1, output 2, output 3, and so on) in the same order the device does.

Each output carries one stream of audio. Two outputs grouped together (1 and 2, or 3 and 4) form a stereo pair: one carries the left side of the signal, the other the right. Four separate outputs can carry four separate mono streams, or two stereo pairs, or any combination the show needs.

What is an "audio device"?

An audio device connects to your Mac (usually by USB) and gives you additional audio outputs. It's a bridge between channels of audio on your computer and physical outputs. Without an external audio device, the audio output can only come from the headphone output.

What is a "channel" inside KTPlayer?

A "channel" inside KTPlayer is a single stream of audio coming out of the show file, listed in the mixer. The show file KeyboardTEK ships you is not one stereo mix; it's has several separate channels so you can mix internally and end each wherever it needs to go.

Each channel appears as a vertical strip in KTPlayer's Mixer with a fader, a meter, and an output assignment at the top. Think of these as each carrying a different piece of the show's playback (for example, click, percussion, vocals, etc).

What "routing" is

Routing is how KTPlayer knows which channel goes to which output on your audio device.

This is done in the mixer. Each channel strip has an output assignment at the top: click it, and you see a list of every physical output on your audio device: 1 , 2 , 1+2  for a stereo pair, and so on. KTPlayer groups the choices into Stereo output and Mono output, and shows the assignment with two symbols:

  • | : a stereo pair (e.g. 1 | 2 ): the left channel feeds the first output, the right channel feeds the second.
  • & : both outputs fed the same signal (e.g. 1 & 2 ): used to send a mono channel across a pair.
  • A single number (e.g. 1 ): feeds one physical output.

Output assignments are global: once you set them they hold across every cue.

A typical pit routing could look like:

Channel in KTPlayer Output on the device Where the cable goes
Playback 1 | 2 (stereo) Front-of-house desk
Click 3 (mono) Musicians' headphone amp
LTC 4 (mono) Lighting console

See how to set up your audio routing.

How the three layers connect

  1. The show file holds several channels: different pieces of the show, kept separate on purpose.
  2. The Mixer is where you see those channels, level them, and assign each one to a physical output.
  3. The audio device receives those assignments and sends each channel out of its corresponding socket on the back, where a cable carries it to its destination in the room.

KTPlayer doesn't make a sound on its own. It hands streams of audio to the device, the device puts them out into the world, and the cables you've plugged in carry them to the people who need to hear them.

Every audio question in the rest of the documentation lives somewhere on that chain: show file → mixer channel → physical output → cable → destination.

Track types: what the channels in a show file are

A KTPlayer show file is built from a handful of distinct track types. Each type routes to a different place and gets its level set at a different time.

Track type Sounds like In the KTPlayer mixer Routing in performance
Click A metronome. Digital clicks that the band play along to. May include count-ins, often notated in the score. Typically the first channel after the master, labeled Click . Mono. To the band's in-ear monitor mix only. Never to FOH.
Playback tracks (stems) Tracks of playback that adds to the show's orchestration Usually labeled by stem group, e.g. Percussion , Synths  , Loops   Stereo, to the FOH. Mixed alongside the live band.
Pre-recorded vocals Vocals that use processing effects that can't be achieved live, or support for live vocals. Labeled Vocals , or similar Stereo, to FOH. Mixed alongside the live vocals.
LTC (Linear Timecode) Digital noise. A clock signal encoded as audio, used to sync lighting, video walls, or automation. Typically channel 2, labeled LTC . Mono, to its own physical output, patched directly to the destination system (lighting console, video server). Never to FOH.

How to identify what each track contains

KeyboardTEK labels every channel in the mixer.

  • Bring up one channel at a time and listen.
  • Check the show's player notes PDF

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