Open Fruity Loops. Click "File" and select "Open New." This opens a blank session in the Fruity Loops interface.
Click "Channel Presets." Select the "3x Osc" folder and click the instrument folder named "Nasty." This preset bass synthesizer sound is particularly bass-heavy, creating a deep and low bass sound. Drag that folder onto a blank space on the Fruity Loops interface. This automatically opens a new channel.
Right-click on the "Nasty" channel and select "Piano Roll" from the drop-down menu. Piano Roll is a universal MIDI interface that lets you sequence beats and melodies using a grid interface. The vertical axis represents pitch and the horizontal axis represents time, measured in beats and bars.
Program a bass line. Plot the notes in the grid on the piano roll interface. For example, clicking in the first square on the bottom row gives you a low starting note. Hit the "Play" button on the piano roll interface so you can hear what you are programming in real-time. If you want to turn a note off, click it. The squares light up to indicate that a note is selected.
Open "Mixer View" by clicking the fifth button to the right of the tempo window, where it says "120 BPM." This enlarges the mixer parameter controls. Click on "Nasty" to assign subsequent actions to the master channel, drag "Compressor" and "Equalizer" into the "Nasty" channel.
Adjust the compressor's "Ratio" parameter control to around 80 percent. This makes for an intense compression effect that squashes the sound of the bass. It does this by cutting the volume peaks and boosting the dips.
Move the slider dials on the left of the equalizer up to around 70 percent. These control the volume of the bass frequencies in the audio. By boosting them, you are enhancing the low sounds of the bass line.