LFO stands for Low Frequency Oscillator. A typical oscillator in a synth outputs sound in the shape of a waveform through the rapid cycling of an electrical signal. If you can imagine unwinding a toy yoyo and spinning it in big circles as fast as you can (oscillation), you would start to hear a sound through the air in the form of a sine wave.
However, LFOs don’t create sound. Imagine spinning that same yoyo at a very slow rate (low frequency). If you spun it slow enough, you wouldn’t hear any sound at all because the cycle (oscillation) is too slow. Still, this frequency creates an electrical signal that can be used to modulate parameters of other signals. For instance, volume and panning. If you assign an LFO to either of those parameters, the signal levels will follow the LFO settings in terms of shape, speed, etc. This is useful for imitating someone turning a knob up and down over and over again at whatever rate you set the LFO to, without physically needing an actual person to do it.
In FL Studio, many of the stock virtual synths like 3xOsc and Sytrus have LFOs built into them. You can also access LFOs in sampler channels, piano roll, playlist and even through FX plugins like Fruity Peak Controller. First, let’s go over the LFO located in the sampler channels.
This is located in the second tab of the sampler channel that is labeled with the automation icon. There is an LFO automatically assigned to each of the envelope types and filter controls. The blue LFO pictured above controls the volume envelope. At the top, you have 3 different LFO shapes including sine, triangle and square from left to right. The delay knob will postpone when the LFO becomes active. Increasing the ATT knob will fade in the attack, or start of the LFO. The AMT knob controls the range of the LFO. The SPEED knob controls the rate of the selected waveform in the LFO. If you select TEMPO, it will match the LFO rates to the project tempo. Selecting GLOBAL will allow the LFO to continue its cycle as you play new notes. Without it, the LFO will start over with each new note. These settings apply to the LFOs for each envelope including pan, volume, mod x, mod y and pitch. Mod x and y control the filter.
Mod x is the cutoff knob, which determines at what frequency the sound will be filtered out. Mod y controls the resonance, which will create a boost or dip at the cutoff point. You can select the filter type from the drop-down menu below. Utilizing the LFO to control mod x will help you to achieve the infamous dubstep wobble you hear in a lot of their synths and basses.
The piano roll also has its own LFO, which is accessed by pressing ALT+O.
Unlike the channel LFO, you can manipulate the beginning in addition to the end of the LFO signal. The value knob will control the overall levels of each midi note. The range will increase or decrease the difference between the highest and lowest values of the LFO. The speed controls the LFO rate. You still have the same waveform shapes from the channel LFO (sine, triangle, square).
The phase knob will manipulate where in the LFO waveform to start the LFO signal. This is also the same LFO window that will pop up in the Event Editor when your right-click any knob or fader in FL Studio and select Edit Events. Press ALT+O to access the LFO there.
Another option you have when you right-click a knob or fader is to create an automation clip.
Once you’ve created the automation clip, it will show up in the playlist. By left clicking the automation icon in the top left corner of the clip, you can select channel settings, which has options to use an LFO to draw in your automation for that clip.
The SPEED knob, once again, controls the LFO rate. TNS controls the tension of the wave shape. SKEW will shift the wave shape to the left or the right. PW stands for pulse width, which controls how narrow or wide the wave shape is. AMT controls the lowest and highest values of the LFO in terms of depth (volume).
Another great way to use LFOs in FL Studio is with Fruity Peak Controller.
After you add Peak Controller to a mixer insert, you can assign this controller’s LFO to any parameter in FL Studio or any plugin by right-clicking and selecting link to controller and choosing Peak CTRL – LFO from the Internal Control drop-down menu. The special thing about Peak Controller is the added wave shapes including saw and random. It’s especially nice to have the ability to randomize any parameter in FL Studio or your plugins.
A common use for this is to use subtle fine-tune pitch randomization for synths to create a more analog feel to the oscillators. By now, you should be familiar with all of the knobs in the LFO section. Base controls the starting level of the knob or slider you’re manipulating. Volume is the amount of LFO you’re adding to the signal. Tension controls the shape of the selected waveform. Speed is the rate of the LFO. Phase will determine where in the waveform the LFO will start its cycle.
Hopefully, this allows you to explore modulation options within FL Studio and even in your synths and plugins. LFOs create movement in your sounds that can bring life to your mixes. It’s the perfect tool for automation and gives you both precision and accuracy for adding modulation to any of your tracks.