The Kontrol S4 MK2 is a 4 deck all-in-one controller with a sturdy build quality and integrated sound card. The MK2 has substantial improvements over the S4 MK1, including large multicolor buttons. The MK1 is not supported and cannot be supported because it uses a proprietary communication protocol exclusive to Traktor. The MK2 uses the standard HID protocol (also used by keyboards & mice) to send and receive signals from a computer, so it can work with Mixxx. The easiest way to tell the MK1 apart from the MK2 is the appearance of the jog wheel. On the MK1, the top of the jog wheel is black plastic; on the MK2, the top of the jog wheel is shiny aluminum.
The mapping for the Kontrol S4 Mk2 is included in Mixxx 2.0, although it is incomplete.
The Kontrol S4 Mk2 can run from USB bus power. Using the separate power supply increases the brightness of the LEDs, which is helpful for using it in daylight, and increases the volume of the headphone output.
The Kontrol S4 MK2 is a USB class compliant audio, HID, and MIDI device, so it is compatible with Mixxx without any proprietary drivers on GNU/Linux and Mac OS X. On Windows, it is recommended to install the driver from Native Instruments and select the ASIO sound API in the Sound Hardware section of Mixxx's Preferences. There is currently a bug in the mapping preventing it from working on Windows.
With the S4 plugged in, a MIDI device is listed as an available controller in Mixxx's Preferences. That is the MIDI input/output ports on the back of the S4 for connecting external MIDI gear; no mapping for the S4 will appear in the menu for the MIDI device. The controller uses HID for the knobs, buttons, and other components on the device, so the mapping can only be loaded when you select the HID device on the left side of Mixxx's Preferences.
The phono inputs on the S4 can be used with turntables for timecode vinyl control of Mixxx. Unlike Traktor, there is no additional software to install to use timecode with the S4; the free version of Mixxx is the full version. However, note that Mixxx is not compatible with Traktor Scratch Mk2 timecode; refer to the Mixxx manual for a list of supported types of timecode.
Note that Mixxx doesn't have the concept of a single “master” deck for sync. Instead, push and hold the sync button to “lock” sync on for all decks you want to remain in sync. Or you can push Shift + Sync to lock sync on. Refer to the Mixxx manual for details.
Mixxx does not have remix decks, so the four remix slot buttons control the samplers. There are some more bonus actions that can be accessed by holding shift and pressing certain buttons.
The Master Volume knob on the S4 controls the volume of the S4's master output in hardware, so it does not affect the software master gain knob in Mixxx. Peak display is only generated from software, however. So if you see or hear clipping, lower the gain of the playing decks; adjusting the master volume knob on the S4 will not help.
The knob on the left of each effect unit controls the mix (dry/wet) knob for all 3 effects in the unit. The other knobs control the metaknobs of the effects. The buttons below the metaknobs control the effect enable buttons. When pressed with shift, they cycle through the available effects. The button below the mix knob toggles whether the effect parameters are showing on screen. This will be expanded in a future update to implement the Standard Effects Mapping.
The buttons at the top of each mixer column control which decks are routed to which effects units.
If you choose, you can edit the controller script and change the Remix Slot buttons to perform loop rolls instead. Also by default, Shift + CUE rewinds the track to the beginning but you can change this to a Reverse Roll (or “Censor”) effect instead.
Making these changes is still a little awkward and we will be making controller preferences easier to change in the future. For now you'll have to make a small change to the mapping script file. Don't worry, the actual edit only involves replacing a single word in a text file.