PreSonus Blog

Studio One’s FM Synthesizer

On the surface, Mai Tai is an easy-to-program, fine-sounding virtual analog subtractive synthesizer. But let’s dig deeper—and unlock its unique FM synthesis talents (fig. 1).

Figure 1: Check out the sound of this 2-operator FM synthesis patch and the end of the post, and download the preset.

Mai Tai FM synthesis is possible because the LFOs go up to 8 kHz, and can also track the keyboard. So, using an LFO in the audible range to modulate oscillator pitch provides the basics of FM synthesis. What’s more, LFO 2 can modulate LFO 1’s frequency, which allows for 2-operator FM synthesis. However, note that you’ll probably want to use either the 80s or Normal quality setting. Oversampling with the High or Supreme settings can add more unpredictability because of the higher bandwidth…but then again, it can also add interesting variables.

For basic FM synthesis , try this: set Osc 1 to a sine wave. Set LFO 1’s waveform to sine, and enable its Key button. Assign LFO 1 to modulate Osc 1, and turn up modulation all the way. Vary the LFO frequency control in the audio range, and you’ll be greeted with a huge variety of bell and chime-like effects. Then, throw some delay and reverb on it—instant ambient sounds.

Basic FM Synthesis

You can also try other LFO waveforms, but let’s take this further. Turn up Osc 1’s Spread control past 80%, and you start to enter a world of tremolo and psycho-acoustic panning. Note that the following audio example uses no effects—just a long release time on the amplitude envelope. Changing the modulation depth gives wildly different sounds; for the next audio example it’s up about halfway.

Spread Control Turned Up

Let’s do one more “nice” sound before we get nasty. This uses the LFO to modulate Osc 1’s Pan instead of pitch, which creates a stereo image from Osc 1’s output.

FM Panning

Okay, it’s time for some sci-fi sound design. Here’s what happens when you modulate both Osc 1 Pitch and Pan, choose Sawtooth for Osc 1 and LFO, turn up Spread, and bend pitch up. Again, there are no effects.

Sci-Fi Sound Design

How about a nasty bass? The previous presets are all simple, but this one brings in another oscillator, adds envelopes for both the filter and VCA, and overlays a hint of distortion. Rather than take up the space to describe the parameters, you can just download the CA Nasty Bass.preset.

Nasty Bass

Note that for “pitched” sounds, the LFO setting is quite critical. Sometimes, offsetting the pitch for the Osc the LFO is driving can fine-tune the preset.

Finally, here’s a 2-Operator FM preset, where LFO 1 is modulating Osc 1, and LFO 2 is modulating LFO 1. Feel free to download the preset, I think it’s a pretty cool sound.

2-Op Big Sound

However, tuning is extremely tricky when one LFO is modulating another. This preset plays back 1 semitone sharp compared to concert pitch—sorry. Of course, there are plenty of ways to transpose it, either by shifting your controller down a semitone, or transposing the rendered audio. Like most FM synth presets, when you find something you like, save it! You may never find it again, and changing just one parameter might bring the whole house of cards falling down.

Now go have fun with your shiny new FM synth…that’s been around since Studio One 3 😊

Download the CA Nasty Bass preset here!

Download the CA 2-Op Big Sound here!