EFM1: Basic frequency modulation - Logic Pro Tutorial

- [Instructor] Okay the next instrument we have to talk about is EFM, and I really like working with this one because it uses a synthesis method, known as frequency modulation, or FM. This is a synthesis method that was developed by John Chowning, back in the day, in the 70's, and was popularized by the Yamaha DX7, which was a huge success in the synthesizer market, because it had such a cool, new sound. So let's go through some of these presets, we'll talk about the nuts and bolts of frequency modulation in a second, but I would like to take a look at some of these presets, so let's start out with bass, because some of the bass is a lot of fun. We can get these cool rubbery sounds. (bass notes) as you can hear, frequency modulation is great for creating things that are very, very expressive, and also have a lot of texture to them. (bass notes) let's go through, a stereo bass. Let's check out some of the pads as well. (synthesizer) A lot of texture there, a lot of stuff to work with. Let's check out some of these FM leads or keyboards or things like that, actually let's check out the bells, because one of the things that we can do very nicely, (bell chimes) is create metallic sounds using frequency modulation. So, one of the things that you might be noticing, I'm just going to go back to the default sound here, one of the things you might be noticing here, is that there aren't too many new characters here. You might also be noticing, that there isn't a filter. Frequency modulation is sort of the opposite of subtractive synthesis, in the sense that, instead of taking a band wave, like a Sawtooth or a square, we're actually creating a sound, we're building it from the ground up, so in the past, what we've done is we've taken our Sawtooths, our square waves, and we've chipped away at them over time, using envelopes and using filters and things like that, and what we wind up being able to do with our frequency modulating synthesizer, is kind of grow a sound, it's a really cool approach, so (notes) right off the bat we have a little bit of FM going, and essentially what we're doing here, is we're taking two oscillators, one is known as the carrier, that's the audio signal, and then one is known as the modulator, that's the control signal here. And, we're just using the modulator to modulate the pitch of the carrier, or the frequency. So, think of the carrier as being the one that's plugged into the audio chain, that's the one we're listening to, but, think of making a vibrato with an LFO, as we've done in the past. Making that vibrato you're using an LFO to move the pitch of the audio oscillator up and down, kind of slowly, slowly enough that we can actually hear it. Now here's the thing about frequency modulation, is that we're doing it so fast, we can't hear the individual movements anymore, what we wind up is actually creating these side bands and these tones and these textures because it's moving at audio rate. And so, we have a specific set of controls that we generally use when we're talking about frequency modulation. So, first of all let's talk about the carrier. It's over here on the right, and we can find it, (notes) now, I've turned FM all the way down. (notes) okay, and the first thing I'm going to do is just move my harmonic motion over here. I'll have the ability now, to change the pitch of my carrier over here. The carrier pitch and the modulator pitch are using what's called a ratio, so we have a C:M ratio of six to one, it means that the carrier is at a ratio of six and the modulator is at a ratio of one, and what this actually refers to, are these numbers that we're using here, which represent different degrees of the harmonic series. So when we were talking about the harmonic series before, building a Sawtooth wave or a square wave, we have these harmonics that make up a sort of chord, that create a pitch that we can hear, that has some texture to it, some tambour. We use the harmonic series as a tuning tool for our different oscillators in frequency modulation. So I can move the carrier up and down, (notes) and you notice that it is changing the pitch and then we can also turn the modulator up and down. (notes) okay, now we said before we don't actually have a filter in here, what we're using to create that brightness, those sidebands, is the modulator here, so we have an envelope for the modulator, I'm just going to turn the volume envelope up to full sustain. So that we can really hear what the modulator is doing here. So if I turn all the modulator stuff down, and we're not using it, here we don't have much going on, let me turn the harmonic up to one. There we go, we can hear that this is actually a sign wave that we're using. Or something very close to it. Okay, we have an FM depth knob over here, which is actually controlling the extent to which the modulation envelope is controlling the FM amount. So, the FM amount is essentially how wide that modulation is, if we're modulating pitch and we're doing it very slowly with a vibrato, it tends to be very subtle, like a third of a step or something like that. That's a nice vibrato area, if we're using an LFO to control the frequency of an oscillator. In this case, with frequency modulation, we call the amplitude of the modulator the index of modulation. Now you don't have to worry about that here, this is a pretty basic frequency modulating synthesizer, and they just have the term FM put here, and so we turn this knob up if we want to hear more FM. And this is a very simple setup right now, essentially what we've got, is a carrier and a modulator, both the same pitch, you see we have a one on both sides, and so what that does, is it just creates some very simple side bands as we up the amount of modulation. (notes) Now I can also change the ratio of the modulator. (notes) okay, this is kind of cool, we can also change the wave of the modulator over here. (very synthesized notes) now you can hear, as I push this up, we're getting buzzier and buzzier, so I would imagine that over to the far left we have a sign wave, or something very similar. So we get different flavors as we move that wave around.