Double-click the Atomix desktop icon to launch the program. It may take a few seconds for the program to fully launch.
Search for the audio file you want to use to make an acapella, in the browser box at the the left of the Atomix interface. Once you identify the file, click it. Wait while it loads into the Atomix mixer interface.
Click on the "Effects" tab, located just below the cross-fader dial in the Atomix DJ deck interface.
Select "Equalizer." This opens a new window, where the frequency curve of the imported audio appears, superimposed on a grid interface. The horizontal axis of the grid represents frequency, and the vertical axis represents amplitude. The frequency curve show the most prominent frequency and its current amplitude.
Hit "Play" so you can hear your mix modifications in real-time.
Click on and drag the curve to the top-left of the grid. This alters the frequency profile of the audio file. Move it horizontally until you hit an unwanted frequency. As you move the curve, listen for the vocals in the song disappearing. The aim of moving the curve is to identify frequencies where there are no vocals, before removing them.
Hit the "Kill" button, when you identify a frequency without vocals. The "Kill" function is designed for removing unwanted sounds. It mutes the selected frequency, making it inaudible. Because MP3 files are typically master recordings, there is no option to mute or remove individual instruments. The next-best solution is to filter out as much as possible of the backing, so the only remaining audible part is the vocal.
Move the curve again, and repeat the frequency. Once you've "killed" the first frequency, quieter frequencies become more prominent. Repeat this process as many times as required, to get a mix where the vocals are the dominant feature. As you start off, the non-vocal frequencies are obvious. For example, sub-bass and drum sounds rarely share frequency bands with vocals.
Click "Save." There may be traces of backing music at low levels in the remaining audio, but these will be inaudible or very quiet. When you add the acapella mix to a backing track of your own, it will be very difficult to hear the original backing, effectively rendering the original file as an acapella only.