10. DJing With Mixxx

Mixxx was designed to be easy to learn for both novice and experienced DJs.

This part of the manual provides you with directions for using Mixxx’s features to create your own mixes.

10.1. Setting Your Levels Properly (Gain Staging)

A level meter in Mixxx with the gain set properly for the loudest part of a track

Setting your levels properly, also known as gain staging, is essential for getting the best sound quality out of the equipment you are using. At every link in your signal chain, from Mixxx’s channel gains to the power amplifier, the level should be well above the noise floor, but lower than the maximum level before the signal clips. The level meters should mostly be around the top of their green region. The level meter pictured to the left shows where Mixxx’s level meters should average at the loudest parts of tracks. The average level should not be in the yellow region. Use the yellow region to leave headroom, or available level above the average before the signal clips. The loudest parts of the music (the transients) should briefly go into the yellow region.

A waveform at a good level

A waveform at a good level. Note that the example waveforms in this section were made by adjusting the visual gain of the waveform display in Mixxx to illustrate the concepts. Adjusting the visual gain of the waveform display does not change the level of the audio.

A level meter in Mixxx indicating clipping. The gain should be turned down!

If a level meter is in its red region, the signal is clipping and the gain should be turned down. Some equipment doesn’t have a level meter and only has an LED that turns on when the signal clips. Clipping means that the peaks of the waveform are flattened because the equipment has reached the maximum level that it can amplify the signal to. This distorts sound in an unpleasant way and can damage equipment by driving it with more power than it is designed to handle. Increasing the gain past the point where clipping begins (further into the red on a meter) will distort the signal more. If you want to make the sound louder when every part of the signal chain is at its maximum without clipping, use more speakers or use speakers that are more sensitive and convert electrical energy into acoustic energy more efficiently.

A clipping waveform

A clipping waveform

A level meter in Mixxx with the gain set too low

On the other hand, the signal should not be too low. This is because every audio device generates a little noise at a level referred to as its noise floor. Additionally, analog signals pick up noise as they travel along wires. The signal measured by the meter on the left is relatively close to the noise floor. When a device is turned up, the noise floor does not go up; only the signal does. However, every time the signal is amplified by the gain of another piece of equipment, both the noise and the signal from previous devices in the signal chain are amplified. For example, if your sound card is turned down and you turn the gain up on your mixer to compensate, the signal-to-noise ratio (SNR) of the sound card output will be low and the mixer’s gain will amplify the signal and the noise from the sound card, plus the noise picked up along the wire. The end result will have more noise than if the output of the sound card was turned up before the signal reached the mixer and the mixer’s gain did not have to be turned up.

A waveform at too low of a level

A waveform that is too close to the noise floor

Note

To adjust the output volume of a sound system while maintaining a high signal-to-noise ratio, the gain should be adjusted as close to the speakers as possible. Refer to the Gain Knob section for details.

10.2. Beatmatching and Mixing

Beatmatching is the process of adjusting the playback rate of a track so that it matches the tempo of another track. Beatmatching also involves adjusting the phase of the beats in a track so that they are aligned with the beats in the other track. Matching the tempo and aligning the beats are the two things a DJ must do to beatmatch.

Mixxx can match the tempo and align the beats for you but this requires an accurately detected BPM value and a correct beat grid for both tracks. To enable this feature, tap the SYNC button. To beatmatch manually, the tempo of the two tracks must be synchronized by adjusting the playback rate sliders. You can adjust the phase of the beats by right-clicking and dragging on either waveform display to temporarily speed up or slow down one of the tracks until the beats are aligned. The temporary pitch bend buttons can also be used to momentarily adjust the playback rate, allowing you to “shuffle” the beats in a track forwards or backwards, so they can be aligned with another track. See the chapter Sync and Rate Controls.

Two tracks are beatmatched once their tempos are matched and their beats are aligned. A “perfect” beatmatch is nearly impossible - there will always be a tiny difference in the playback rates. A keen DJ will keep his or her ears open and listen for the beats drifting out of alignment. This has a distinct “double bass kick” sound which is often preceded by the kick weakening in intensity as the two kicks drift out of phase. When this happens, the beats can be realigned by simply tapping one of the temporary pitch bend buttons a few times in the appropriate direction.

10.3. Master Sync

New in version 2.0.

Master Sync is an intelligent assistant that allows you to leave the beatmatching to Mixxx so you can focus on track selection, effects manipulation, looping, 4 deck mixing, and other advanced DJing techniques.

To activate Master Sync on a deck, push and hold (or click and hold) the SYNC button. You’ll know Master Sync is on because the sync button will remain lit. Changing the rate of any deck that has Sync lit will change the rates of all other decks that also have the Sync button lit. There is no need to set specific decks to be a master or followers. You can play, stop, eject, load, and queue any track with master sync and it won’t interrupt the playback of the other decks. However, changing the rate of a stopped deck will change the rate of playing decks.

Master Sync will also notice if one of your tracks is double the BPM of another track and match them correctly. So if you want to mix a 140 BPM drum & bass track with a 70 bpm dubstep track, Master Sync will make sure they are lined up properly.

Hint

Usually, Master Sync will only make sure the rate sliders are set correctly. If you also want to make sure your beats are perfectly in sync, turn on the QUANTIZE button. When activated, Quantize will ensure that the beats are perfectly lined up as well.

10.4. Harmonic Mixing

Harmonic mixing is a technique to mix songs with matching melodies and harmonies. To learn more about harmonic mixing you might want to check out the mixshare site.

Mixxx has two features to help you with harmonic mixing. The first is a key lock. When it is active changing the speed of a track won’t affect the key. To enable key lock, click the key lock button in the Deck Options Button Grid. The second is that Mixxx can automatically detect the key of a track and will display it in the library and the decks. The notation which is used to display a key can be changed in Key Detection Preferences.

10.5. Using Effects

New in version 2.0.

Mixxx comes with a set of native effects.

10.5.1. Flanger

The Flanger is simple modulation effect, created by taking the input signal and mixing it with a delayed, pitch modulated copy of itself.

Depth
Controls the intensity of the effect.
Delay
Sets the value for the delay length.
Period
Controls the speed of the effect.

10.5.2. BitCrusher

The BitCrusher is an effect that adds quantization noise to the signal by the reduction of the resolution or bandwidth of the samples.

Bit Depth
Adjusts the bit depth of the samples.
Downsampling
Adjusts the sample rate to which the signal is downsampled.

10.5.3. Filter

The filter changes the tone of the music by allowing only high or low frequencies to pass through.

LPF
Corner frequency ratio of the low pass filter.
Q
Resonance of the filters, default = Flat top.
HPF
Corner frequency ratio of the high pass filter.

10.5.4. Reverb

This is a port of the GPL’ed CAPS Reverb plugin, which has the following description: This is based on some of the famous Stanford CCRMA reverbs (NRev, KipRev) all based on the Chowning/Moorer/Schroeder reverberators, which use networks of simple allpass and comb delay filters.

Bandwidth
Higher bandwidth values cause more bright (high-frequency) tones to be included.
Damping
Higher damping values cause reverberations to die out more quickly.

Note

This effect is not available in the Mac App Store version of Mixxx.

10.5.5. Echo

Simple Echo with pingpong

Send
How much of the signal to send into the delay buffer.
Delay
Delay time in seconds.
Feedback
Amount the echo fades each time it loops.
PingPong
As the ping-pong amount increases, increasing amounts of the echoed signal is bounced between the left and right speakers.

10.6. Recording Your Mix

With the integrated recording feature you can record your mix as an audio file and listen to it later, distribute it as a Podcast or burn it to CD. Mixxx records the master output - the audio you hear from the speakers including the microphone.

Mixxx library - Recordings view

Mixxx library - Recordings view

Mixxx can record your mix in various audio formats and quality settings. You can split your recordings, generate cue files, choose a custom recording directory and even set your own metadata. By default, Mixxx saves your recordings as lossless wav files to a Mixxx/Recordings sub-folder in the Mixxx music directory. Before you start recording, we recommend that you adjust the settings in Preferences ‣ Recording.

If you click on the Recordings icon in the sidebar of the Mixxx library, the track table to the right displays the content of your recordings directory. New recordings are automatically saved to this directory as well as CUE files if you choose to create them in the preferences.

Hint

Recording your mixes and listening to them later to critique yourself is a great tool for improving your DJing skills. Sending your mixes to other DJs for feedback can also be helpful.

10.6.1. Record your mix to disk

New in version 2.0: Displays the duration of the recording.

  • Click on the Recordings icon in the sidebar to switch to the Recordings view
  • Click the Start Recording button or click Options ‣ Record Mix in the menu on top of the Mixxx application window.
  • The display above the track table shows how much data has already been recorded, as well as the duration of the recording.
  • Perform your mix
  • Click the Stop Recording button to stop the recording when the mix has finished.

Hint

You can instantly play your recording as a track in Mixxx. Simply drag-and-drop the track to a deck.

10.7. Using Auto DJ For Automatic Mixing

Mixxx library - Auto DJ view

Mixxx library - Auto DJ view

New in version 2.0: Add random tracks from Auto DJ track sources

Auto DJ allows you to automatically load tracks from the Auto DJ playlist when the current track is nearly finished, and crossfade into it. See Auto DJ - Automate your mix.

10.7.1. Loading tracks into Auto DJ

To play tracks automatically, they must first be loaded into the Auto DJ playlist. The Auto DJ playlist is empty by default.

Mixxx library - Adding a playlist to Auto DJ

Mixxx library - Adding a playlist to Auto DJ

There are several ways to load tracks into the Auto DJ playlist:

  • Select single or multiple tracks from the library, a regular playlist or crate and drag them to the Auto DJ icon on the left.
  • Select a regular playlist or crate, right-click with the mouse and select Add to Auto DJ from the mouse menu. This adds all tracks to Auto DJ.
  • While in the Auto DJ view of the library, drag tracks from external file managers to the Auto DJ icon in the sidebar or to the Auto DJ track table on the right.

10.7.2. Using Auto DJ crates

Instead of inserting the contents of the crates directly into the Auto DJ playlist, Auto DJ crates are associated crates that become a source of random track selections.

  • Add a crate to the Auto DJ track sources: Expand the Auto DJ item in the sidebar, and right-click on the Crates sub-item. Select one of the existing crates from the list. This makes the content of the crate available for random selection into the Auto DJ queue for automatic mixing. The name of the crate is now listed as sub-item below.

    If you do not have any crates available for selection in the list, go and create a crate first and add some tracks, see Crates - Organizing tracks into collections.

  • Manually add tracks from track sources to Auto DJ: Click the Auto DJ item in the sidebar and switch to the Auto DJ view of the library. Click the Add random button to add one track at the time from Auto DJ track sources to the bottom of the Auto DJ playlist.

    Note

    If you did not set any crates as an Auto DJ track source, clicking the Add Random button will add a randomly selected track from the whole library instead.

  • Automatically add tracks from track sources to Auto DJ: Mixxx can randomly add tracks to the Auto DJ playlist from track sources as soon as a specified minimum number of tracks remain. Select Preferences ‣ Auto DJ ‣ Enable random track addition to queue ‣ On. Set Minimum allowed tracks before addition to change the minimum number of tracks after which random tracks may be added.

    Note

    If you did not set any crates as an Auto DJ track source, tracks are selected from the whole library instead.

  • Remove a crate from the Auto DJ track sources: Expand the Auto DJ item in the sidebar, and right-click on one of the crates listed below the Crates sub-item. Select Remove Crate as Track Source to remove the crate from the Auto DJ track sources.

10.7.3. Playing tracks in Auto DJ

Now that you have loaded tracks into the Auto DJ playlist, you can activate Auto DJ as follows:

  • Click on the Auto DJ icon in the sidebar to switch to the Auto DJ view of the library.
  • Click the Enable Auto DJ button.
  • The first tracks from your list are loaded into the decks and the playback starts.
  • Mixxx will continue to automatically mix until the Auto DJ playlist is empty.
  • Click the Disable Auto DJ button to stop the automatic mixing

Hint

You can add a track to the end of the Auto DJ playlist once it is played instead of removing it. Set Preferences ‣ Auto DJ ‣ Re-queue tracks after playback ‣ On.