The first module in our synthesizer is our oscillator, and this is the sound creator. It generates sound based on a geometric wave form. And we have wave forms like sawtooth, square wave, triangle wave, sine, and noise. And most of them get their name just by their shape. If you look at a square wave it is very squarish. If you look at a sawtooth wave form it does look kind of like a saw blade. The oscillator is always just putting out sound. Later in the signal flow, that sound will be turned on and off, and we tend to use very, very bright sounds in the very beginning. The sawtooth and square waveforms are really brilliant, harsh, kind of obnoxious, truthfully; which is why we use the filter after the fact. But another name for this oscillator is a VCO, a voltage control oscillator, and that's the important thing about synthesis. because we do have just general oscillators, like built into mixing boards, for test tones. But they don't change over time and that's the key to the synthesizer oscillator is that it can be modulated. It can change over time, and all these modules have one specific thing that changes over time. And in the oscillator, it's the pitch or frequency, which makes sense, because if you think about a synthesizer, one of the most important things is that you play up and down the keyboard. And it changes to be the correct note. Well that instance, that idea, the playing of it on the keyboard is changing the note. That's an example of modulation. That's key position modulating the pitch of the oscillator. So we can see that this, this idea of modulation is that time dimension. How is the oscillator going to change over time, and there are many things that can modulate the oscillator. I modulate the pitch of the oscillator and the key position is one of the most important ones. Now I think it's important that when you start getting into synthesis, to appreciate the sound of the different wave forms, and we tend to associate the square wave with kind of a hollow sound, and the sawtooth waveform with kind of a bright brilliant sound, and there's a good reason for that. If we look at the harmonic structure of a square wave, it's missing the even partials. Kind of jump we have, one, three and five. But if we look at a sawtooth waveform, it has them all, and it starts to sound more full. Now this is interesting because when you start listening to real instruments, you can start to picture, is that more saw wavish or square wavish. And actually the shape of the wave form is related to how the sound is actually initially created. So, if we think of a clarinet, we usually associate a clarinet sound with more of a square wave shape. And a clarinet does have like a hollow kind of sound to it. And if you think of how a clarinet makes its sound, it kind of makes sense that it would be square waveish. You'll over reed right, the players mouth, and that reed goes up, let's the air through, closes down, opens up, closes down, opens up, closes down, very fast right vibrating on and off. But it's like a switch, turning on, turning off, turning on, turning off, and that creates a square wave-ish shape, and if we're trying to emulate a clarinet we actually start with a square-wave waveform. If we're trying to emulate say, a string sound, like a violin, a bow on a violin, we have a horsehair bow with sticky rosin on the bow, and it's pulling against that string. And as it does so, that string goes to the right, right? It pulls away from it, and then eventually the tension on the string is so strong it snaps back. We call this motion a slip and stick kind of motion. And it's related to the wave shape, cause you can see as it pulls along that string, the string moves up in one direction, eventually just snaps back to zero and starts over again. So we get this saw wave-ish kind of shape. So for emulating a string instrument, we usually start with a saw wave type shape. So you see, we start getting a language and a way to think about these timbres and these sounds in a really nice way. So let's look at the oscillator section of my simple synthesizer, and then we'll move onto the filter next. In this video we're going to move into studying synthesis. And I'd like you to have a synthesizer of your own open so you can work along with this tutorial. Now the challenge for you, is going to be taking the knowledge we gain here, and applying it in your synthesizer. It'll take some exploration and some figuring out, but you will find these sections in your synth. To have the most success, I'd like you to choose a subtractive synthesizer, avoid synths that are based on frequency modulation, so if you see FM in the title, probably not what you want to use here. So this is built on a basic subtractive synthesis model, and I think you can find a subtractive sin in your DAW or in your collection of plug-ins. The main five sections we have here again are oscillator, filter, amplifier, envelope and LFO. I'd like you now to find the oscillator section of your synthesizer. It might be labled OSC or oscillator, and it will most likely have options to change the wave shape between a variety of common wave shapes like sine, saw, triangle, square and noise. Now, I'd like to look at the different wave shapes that are really common in the traditional subtractive synthesizer. The first one is sine wave, and a sine wave is a, what we would consider a pure tone. It's energy at a single frequency. Let's hear it. [NOISE] So we have energy at a single frequency. And a sine wave is the purest, simplest of tones. We also have options if we want to get a brighter timbre to switch to saw wave. And we are going to see that that's going to bring in a series of upper partials or upper harmonics. If I choose square we're going to see a different arrangement of the upper partials. Its a more hollow sound like we described earlier. Saw too. [SOUND] Is going to include all partials. And a square wave will include only the odd. With a square wave, you see it's an open sound, because it's missing every other harmonic. So a square wave is only the odd harmonics, and the saw wave is all harmonics. If you have the option for a triangle wave, you'll find that it sounds like a filtered square wave. And that only includes the odd harmonics, but they fall off faster as you go up the frequency spectrum. You might also find a Noise section in your oscillator, or a specific noise oscillator that will give you general broadband noise. White noise is energy across the frequency spectrum, and it's even across the frequency spectrum. So that's what we can expect to find in the oscillator section. Synth designers want you to understand their software. So they usually make it very clear where the different sections of the synth are. It will be obvious where the oscillator section is, where the filter section is, where the LFO is and where the envelope is. Id like you to go to your synth and try some of these things out now. Can you find the oscillator? Can you change the wave shape? Can you find the filter section? Can you find the envelopes? Just get a feel for the overall layout of one or two synthesizers, and then we'll move on to filters.
