Join Rick Schmunk for an in-depth discussion in this video Filter module, part of Learning Serum.
- [Presenter] Oscillators often get a lot of attention when discussing the merits of one synth versus another, but the component that often has the biggest impact on sound is the filter. Serum's filter has all of the typical options that you would expect and more. Let's start by taking a look at the more basic parameters. So let's start by reinitializing Serum. Let's go up to menu and choose Init Present, and then let's enable the filter by clicking on the on-off button. Now the signal from Serum's four oscillators, oscillator A, oscillator B, and the sub and noise oscillators are routed through the filter when the related buttons here in the routing matrix are enabled.
So A for for oscillator A, B for B, N for noise, and S for sub. So currently only oscillators active, and it's the only one that's being routed through the filter. So the filtered sound sounds like this. (electronic beeping) If I disable the routing button here, we'll get this. (electronic beeping) Now, the same thing would have happened if I turned the filter off. (electronic beeping) Now let's check out what happens when I enable the sub.
So we'll turn that on, and let's put it on a saw wave, and let's take it down an octave so that we can hear the two different pitches. Now, at this point I'm not routing the sub through the filter, so we should hear the more rounded off sound of the higher tone and then the more buzzy sound of the sub tone here. (electronic buzzing) And if I click the button here next to the sub, we'll actually route that through the filter and it will shape both of the signals from both oscillators.
Alright, let's turn the sub off, and let's take a look at the different filter types we have. And we can do that by clicking on the little hidden popup menu here. So there's four different sub-folders, and if we look in each one, there's about 10 or 15 different presents. Let's start off in normal. So here if you want to choose something, we just go on the list to the one you want to go to and choose it. Now, once you get there, if you want to go back and forth through the other similar filter types, we can do that using these two arrow buttons.
That one will take you through the list further into the list and the other one will take you backwards through the list. Now while there you'll notice that we've got the typical filter types. We've got low pass, high pass, band, peak and notch filters. And it looks like we also have a second type of low pass. So the ones that start with MG are emulations of Moog ladder filters, and the number on the right-hand side of all these indicates the filter's slope.
So if I choose, for example, the MG low 6, I'm going to get a low pass filter, and it's going to have a 6 DB per octave slope here. This is what that sounds like. (electronic beeping) So it's a little bit shallower. Now if I click the button to go further into the list, I'll get the 12db pro octave slope, and we can see it's steeper, taking away a little bit more of the high frequencies. 18, even more. And the 24db pro octave slope is quite dramatic.
Now the difference between this Moog type of low pass and the more normal low pass variations found here are that the Moog is said to be a little bit more warmer and darker, fuller sounding, and these other ones here have a little bit more of a modern, brighter sound to them. But let's check it out. I'm going to leave it on the low 24. Let me move the cutoff frequency up just a little bit. And then let's check out that versus the normal low 24.
(electronic beeping) It's subtle but there is a little bit more of a bump here around the cutoff frequency, and it sounds a little brighter to my ears. Let's go back to the Moog. And I'm going to use the 18 db per octave slope here. So the point at which we start to attenuate frequencies here is called the cutoff frequency, and that is this frequency that's about right here where my mouse is pointing.
And you'll notice that, as I move the cutoff frequency around, that's the point at which it starts to attenuate anything above the cutoff frequency. Now, with a low pass filter, the area here in black are the frequencies that are going to be allowed to pass through the filter. And then over here above the cutoff frequency in the blue are the frequencies that are going to get attenuated. Now, next to the cutoff option here, we have resonance, and resonance adds a little bit of gain and a narrow band of frequencies right around the cutoff frequency.
So if I push that up, we start to see a little bump appear right here. (electronic beeping) And that's particularly noticeable when we sweep the cutoff frequency. (electronic whirring) I call that the character switch. Now you'll notice with this particular filter shape that as we add resonance, and we get this little bump, it also looks like it's pulling down the low end a little bit.
Now one thing you can do to counteract that is you can use the fat knob. And what fat does is add post-filter gain, so I can add that, and you'll notice that it's raising the whole filter shape up a little bit. But now I can get this resonance without losing that low frequency area. Now the opposite of that post-filter gain is the drive control, and this one actually adds pre-filter gain or saturation. And to demonstrate this, I'm going to turn the resonance down a little bit.
So there's our tone. And now, as I add drive, it's adding gain pre the filter. Now as I do this, it might get a little bit loud, so we can actually use the mix knob, but not actually the mix knob. There's a hidden knob here. And if I click on the word mix, you'll notice that this turns to level. So I can add this filter drive pre-filter, but I can control the output gain here with the level and I can use that to turn it down. So we can actually gain this up quite a ways and not let it get any louder but get the benefit of that pre-drive saturation.
(electronic beeping and humming) So it's a little fuller sounding, and it's got just a little bit of grit to it versus if I take the drive all the way down and put the level all the way back up. (electronic beeping) A little thinner. (electronic beeping) A little fuller sounding. Alright, let's reinitialize this. And I'm going to turn the filter on, and we'll go back to that Moog low pass filter with the 18 db pro octave slope.
So another control we have here is the mix knob, and this is going to mix our filtered signal versus an unfiltered signal. And it's got a little bit of an interesting result to it. Notice that, as I pull this up (electronic humming) it actually looks like it's turning into a little bit of a shelving filter, and we're just rolling off the highs a little bit. So this is really handy if you like the cutoff frequency but you feel like you're losing a little bit more high end than you want.
You can adjust that to bring back just a little bit of the higher frequencies to round out your sound. Now the last thing I'll mention is we've got a pan knob on the filter here. If you've got headphones on, you could hear that moving back and forth. But I just wanted to mention that what's actually happening here is that when you pull the pan knob one way, it's actually lowering the cutoff frequency on one side and raising it on the other side. And then vice-versa if you move it back and forth.
So you might want to experiment with this and just hold a key down as you move it back and forth. And notice that the level is not changing, but instead you are actually hearing the tone change differently in the two speakers or ears. (electronic humming) So as you can see, there's a lot you can do with the basic filter parameters that Serum offers. Let's move on to Serum's more unusual filter options and in the next video we'll look at some of the more advanced filter presets.
- Wavetable warping
- Oscillator tuning
- Shaping sound
- Assigning and adjusting LFOs
- Advanced filter presets
- Adding effects
- Creating and editing sounds