Join Rick Schmunk for an in-depth discussion in this video Wavetable oscillators, part of Learning Serum.
- [Instructor] One of the first things you typically do when starting to build or modify a sound is to choose a waveform. Because Serum is a wavetable synth, selecting a waveform can be a bit more complicated. So let's start with an explanation of what that means. So analog synth oscillators output a repeating waveform, but where early synthesizers output analog waveforms, virtual synths like Serum instead use recordings or samples of waveforms. And like early digital synths, which didn't have a lot of memory, the samples used are single cycles of waveforms, which are looped to generate a continuous signal.
Because the waveforms were stored and accessed through a table, the term wavetable synthesis came into use. So Serum has four oscillators. The sub and noise oscillators, we'll discuss in an upcoming video. So the two main oscillators are oscillator A and oscillator B, and these are our wavetable oscillators. Now, you'll notice that oscillator B is currently disabled. You can turn it on by clicking on the On/Off button that you find in the upper left-hand corner of each of the four oscillators.
And before we get started, I'll point out that at any point you want to get back to the default settings, you can go to the menu over here, and you can choose Init, or initial preset, and that will reset things back to the default sawtooth waveform that we see here. So to choose a wavetable, all we need to do is click on the popup menu that you find just below the title bar of oscillator A and oscillator B. Here where it says Default, I'll click, and that takes us into some subfolders, which each have a couple dozen wavetables.
Let's go into the first one, Analog, and I'm just going to choose something. And I'll point out that if you want to go through that particular folder now, you can use the right and left arrows, and those will take you forward through the list of wavetables or backwards. And let's back up until we get to the basic shapes option. So within a wavetable there can be as many as 256 separate waveforms, which are referred to as frames.
And you can move between those frames or those different waveforms by using the WT Position knob that you find in the lower left-hand corner of the oscillator. Now, with this one, there's only seven different frames, so as I move this, we're going to go from, right now it looks like a sine wave, or something close to a sine wave. (beeping) And if I move that once, I see more of a sawtooth wave shape. (beeping) And then a triangle shape.
(beeping) Square. (beeping) Then we have a couple pulse wave variants. (beeping) And an even thinner one. (beeping) And over on the end here, on the last frame, we've got something that looks a bit like a sawtooth wave shape, but when I play it, (beeping) it sounds a little bit more like a square wave. So if I pull back to the first one, (beeping) that sounds a little bit sharper.
(beeping) Sounds a little bit more rounded off, but still like a square wave. So I mentioned that the wavetable contained single-cycle waveforms, and we can actually see that. So if you go to the menu here, and you go to Show Serum Presets Folder, it'll take you into this subfolder and you'll also see that there's a Table subfolder. So if we go there, we see the same subfolders that we saw in Serum, and with each one of those, we see the different wavetables, and they're simply .wav files.
Now, I've already taken the Basic Shapes .wav file, and I've put that on a track here in Ableton. So you can drag this into your own DA if you want to do the same thing. So let's go back over here. Going to hide Serum for just a second, and I'll double-click on that clip, and we'll see that, yeah, there's a sine wave and then there's a sawtooth, the triangle, square. Here we can see the pulse wave variants, and over on the end, we can see that hybrid waveform.
Now, let's check out another one. So let's go back over here to Serum, and let's go back into the wavetable chooser, and let me grab the, let's see, let's go to Basic MG, or basic Moog. Now, when I dial the wavetable position, we don't get those drastically different wave shapes. In fact, it looks like we're kind of crawling between variants of the same thing. Now, right now the rendering that we're seeing here in the display is 2D, but we can also see a 3D view of that, and you can do that by just clicking on the display.
And that's a toggle. You can go back and forth between those two. So now when I move the wavetable position, the currently selected position is identified by the yellow line. And we can see that those are all very close together. Now, if I hold down a note and do that, you can hear how it kind of gradually morphs the one frame to the next. (electronic tone buzzes) We can even modulate that using an LFO, and I'm just going to grab one here and drag and drop that on the wavetable position, and then I'll go to this little arc here in the upper left-hand corner to kind of set the range that I want to work with.
And so now, when I dial the wavetable position, that sets the starting point, and then this blue little arc here shows the range that this is going to move in. (electronic tone buzzes) Now, that's moving pretty fast, so I'm going to slow that down by using the Rate knob here. (electronic tone buzzes) So when you're creating a patch, you can actually add movement by having it switch back and forth between the different frames within a wavetable. And I'll also show you that if you want to modify this wavetable or even create your own, you can click the little pencil button here in the upper right-hand corner of the display, and that takes you into an editor, and again, we'll talk about this in an upcoming video.
So let me close that. So when you first start using a virtual synth like Serum, the number of wavetables and waveforms can be quite intimidating. So go through and listen to the different wavetable presets, and you'll find a few that you think are particularly useful or interesting. Use those wavetables to start building sounds. Later you can explore further when you're tired of those presets and looking for something new or different.
- Wavetable warping
- Oscillator tuning
- Shaping sound
- Assigning and adjusting LFOs
- Advanced filter presets
- Adding effects
- Creating and editing sounds