After you've mastered the oscillators and filters (which are covered in Synth 101) it's time to add some life, motion and dynamics to your patches.
In this tutorial Fab explains everything you need to know about:
- What is modulation and why it's essential to sound design
- Envelopes (Attack, Decay, Sustain, Release) and how to visualize what they're doing to the sound
- LFOs (Low Frequency Oscillators) to add expression and motion
- Portamento (aka Glide) to smooth the transitions between notes
- How to route and combine modulations to create complex and unique synth sounds
Once logged in, you will be able to click on those chapter titles and jump around in the video.
- 00:00 - Start
- 00:24 - Modulation
- 02:22 - Envelopes (ADSR)
- 05:34 - Modulation Comparison
- 06:36 - Applying Modulation
- 08:37 - Envelope Comparisons
- 10:19 - LFOs
- 12:39 - LFO Comparisons
- 13:42 - Portamento (Glide)
- 14:12 - Pulse Width Modulation
Good morning children.
Today, we're going to modulate.
I am not talking about that moment in a boring song where the composer is forced to take the whole song a whole tone, to prevent you from falling asleep.
I'm talking about modulation in synthesizers.
Much more interesting. Check it out.
The question that's on your mind and everybody's mind, worldwide on the daily basis, is: How do you get from this...
to a usable sound for your song? The answer is modulation.
Let's not forget that originally synthesizers were kind of design to replace real instruments.
They actually kind of thought that this sort of sounds like a bassoon and so they've spent a lot of time to analyze what a bassoon sounds like and why and apply those parameters to the synthesizers.
Let's take a concrete example of modulation and apply it to our purpose.
Here's the accessory I need.
This is a semi-modular synth so it's perfect to explain to you what I'm talking about.
Every modulation has to have a source and a destination.
Something is being modulating by something.
So, you know this guy. It's a wheel.
On this synthesizer, it does nothing because it's not connected.
On modern synths, everything's been chewed up for you and everything is pre-connected, but not here.
Which is great to explain my principle.
So, this wheel here actually has an output. It generates voltage.
It has an output, it's right here. It says out.
Must be an output.
And there's a little cute little logo to "wheel" right here.
I think I'm in the right territory.
I'm gonna take my cable and take the output of the wheel and then I'm gonna modulate something.
So a lot of people know this wheel for pitch, right? So, why don't I connect the output of the wheel to the input of the VCO, which is what generates my pitch? What happens...
The first thing that the Founding Fathers came up with is to try to imitate with synthesizers the kind of shapes of sound over time that real instruments have.
For example, the piano will go: "diiing".
Or if you let it go: "ding".
So they tried to do that.
Violins or big sections will go on slowly with a slow attack time that stay for a while and then decay or not decay.
So, what they did is they gave us control for that to happen. It is modulation.
It is a modulation generator that is modulating the envelope, or the amplitude, or the volume of the sound.
Let me show you.
This one is hard-wired.
No matter what you do, the envelope generator goes to the volume control.
The controls are: attack, decay, sustain, release.
Korg calls it envelope generator, Moog calls it contour, Roland calls it something else. I don't know.
It doesn't matter, it's all the same thing. ADSR You'll see it everywhere. It all does one thing: shape the sound over time, like so.
The attack time decides how long is gonna take for the sound to raise.
With a short attack time it goes like this.
With a longer attack time it goes like this.
Decay is a little more tricky to understand.
Decay decides how long it takes for the sound to go for the peak of the attack to the sustain level. (Because every sound has a sustain) In my sound right now, my sustain is on stun because I wanted to sustain for a long time.
So, I'm gonna lower the sustain like this, so that my sustain is lower in level than the peak that the attack was, and the decay time is how long is gonna take to go from here to there.
With a longer decay time it goes like this.
Alright, so what happens if I have no sustain level? Well, it just dies.
As long as I have the key pressed.
So we've seen the attack, we've seen decay.
By the way, attack plus decay does something like this.
Obviously if your sustain level is on stun, all the way up it's at the same level as the peak of the attack.
Consequently, decay serves no purpose.
Yeah? Think about it.
OK, now, what happens when you release the key? Well, right now since there's no release time, very little.
The sound stops. But if I increase the release time, takes a while.
What the difference between release time and decay time might you ask.
They sound similar. Well, release time only happens when you lift your fingers of the keyboard.
Decay time, your finger has to be down on the key and it's traveling between the attack and the sustain.
It's a lot simpler than it seems or sounds, you just have to try it for yourself.
The reason why this may be confusing is because there's a certain mixing of metaphors here.
Sustain is a level and it hangs out together with attack which is a time.
Decay, which is a time, and release, which is a time.
As long as you remember that, you're good.
Some twisted synth designers might try and sneak a few extra controls by it but the reality is as such.
The sound starts from zero then you press the key and it raises to a certain point at certain speed then decays to the sustain level at a certain speed and then, once you release the key, fades down to nothing at another speed and that's it.
Let's compare the Korg envelope generator to the Moog loudness contour.
The Moog is a lot more basic.
It's got an attack, it's got a shared button for decay and release and a sustain.
Right now is there.
The fun thing here is there's a switch here for release.
The release is either on or off.
And the time is shared with the decay.
When I press a key you'll hear it shoot straight up to the top because the attack time is the shortest, then decay at a certain speed, all the way to the sustain.
And then when I leave the key release all the way to nothing at the same speed that it decayed from the attack to the sustain.
The difference between this two is I have a special dedicated decay time here.
Here the time is shared. So this is actually more basic than this guy.
So this envelope generator or contour is a modulation source.
In this particular case is hard-wired to the volume but I can use it for something else.
It's a modulation source just like the wheel was.
What could I use it for? Well, that's the fun part. Anything you'd like So, I can take this envelope generator, which is automatically applied to the volume in this synth, and then apply it to something else, like for example the filter. So...
then I say use this and apply it to the filter and it sounds like this.
Pretty cool, right? And you can go crazy with it.
What I just did is raise the peak or the resonance to dramatize the effect of the filter.
Without, as a reminder.
So, what's going on is the MS-10 is slowing the attack for the volume but it's also slowing the attack for the filter, so the filter doesn't sit where it's at. It moves, it changes frequencies according to the modulation.
Source is envelope-generated and the target is both the volume and the filter.
As you can see on the control panel, the envelope generator is automatically applied to the VCA, that is the volume. (Voltage control amplifier) The volume of the sound.
You can see here is a direct thing.
But I can also decide to assign it to anything else and so, because this is hard-wired in this synth in addition to it modulating the VCA (the volume), I can force it to modulate other stuff, like for example the filter, which is down here.
See, it says cut-off frequency, which is filter modulation.
You could decide what modulates that.
In this case EG, envelope generator.
Turn it on and yoo-hoo! As opposed to..
And of course it's not all or nothing.
This is a lot.
The modulation's on stun.
But I can make a half way point.
So, what's happening to the filter here is that the cut-off frequency of the filter is being modulated by the envelope generator, meaning it's gonna start at one point, use the attack time parameter to decide how long is gonna take for it to get to the cut-off frequency that you decided on the front panel.
Then decay back to whatever the sustain level is and then release down to zero.
Meaning the filter cut-off frequency will go back onto zero at that rate.
As opposed to just being there at the setting you've set is now animated following the parameters of the envelope generator which by the way, as a reminder, are also assigned to the volume at the same time, because in this synth it's hard-wired.
On newest synth, you can probably dissociate the two of them.
In contrast over there with Bob (Bob Moog) you have separate filter and envelope contour.
Meaning that you have two ADSR modulation generator that are assigned separately, one to the amplitude on the volume and one to the filter as opposed to the Korg which is stuck with one envelope generator, that you have to use for everybody.
So for example I can build a sound that it's fast because the attack time on the volume is short.
No decay time, full sustain.
And here because it's a Moog I can open the contour amount on the filter, meaning I'm gonna apply this to this by this amount.
And I'm gonna slow the attack down, just on the filter.
Right now is very fast, northing's changed.
And then, if I slow the attack down, you can hear it raise over time.
So, I have a fast attack for the volume but a slow attack for the filter.
That's not possible on the Korg, it's possible here.
Also, if you've been paying attention, this synth, when you modulate the filter, goes from all the way closed to wherever you are on the panel for the open frequency.
This guy, when you modulate the filter goes from the panel frequency all the way to wide open.
Fun, right? There're a couple more things that I'd like to touch on.
Most synth have another oscillator on top of their oscillator.
For example, this is a one oscillator synth, but not really. It's a two oscillator synth.
Only, one it's use to make some sound and one is used for modulation.
It's a modulation oscillator.
Also know as a modulation generator or a LFO or mod, or whatever.
They all do the same thing.
It's a low-frequency oscillator that you use to screw things up on a different oscillator.
For example here, on this synth it lives here, it has two settings.
A frequency setting, which is the speed at which is gonna operate and then a wave form setting, so you can have different shapes to modulate your other shape.
If we wanna use it on a frequency we have to use the modulation generator MG on the cut-off frequency. It sounds like this.
What is doing is it's supplying this wave form to the filter, starting from here and going all the way down. I can do this by hand.
Or you can have it be automated.
Speed it up.
Or I can change the wave form.
If you use less of it, you can make a nice vibrato for it.
So, what's going on is this oscillator is going like this.
And that wave form is being applied to the filters so the filter is going like this.
So, you're hearing the "wah-wah" thing is going.
You can also apply it to pitch.
Modulation generator at this speed with this wave form.
This is the modulation generator for the frequency modulation. I'm applying this oscillator to this oscillator like this.
Great for ambulances.
So the MS-10 has a pretty advanced system with multiple wave forms and everything.
The Moog doesn't.
First, the modulation generator is called Mod.
Second, I only have speed and two different wave forms.
But it's subjected to the level of the Mod-wheel.
So, if I have modulation on like this and no mod-wheel nothing happens.
If I add some mod-wheel then I can decide how much of the modulation goes to my destination.
And to keep it tricky I can decide for the modulation to effect the oscillator or the filter or both.
But the amount is fixed, by this.
So, again same principle, different spirits.
You're gonna find that on all synths.
That's why is cool to have different kinds of synths for different kinds of sound.
Modern synths are trying to do everything for everybody, all the way across.
And that's what makes them more complicated to understand.
One more source of modulation you'll see in just about any keyboard is called Portamento.
It decides how long is gonna take between notes.
How long is gonna take for the VCO to reach one note to the other.
It sounds like this. No Portamento.
Simple. Over here is called glide.
Of course, not Portamento.
but we will not hold that against them.
In the spirit of anything can modulate anything and because I love this sound and I'd like to share, who said that we can't use the modulation generator to modulate the pulse width? Let me translate.
Modulation generator is just an oscillator that does it's thing on its own and then the pulse width is the shape of the square wave.
when you select the square wave as your sound source.
So, I wanna take the output of the modulation generator, which happens to be here on this patchbay, (cush) and feed it to the pulse width modulation input.
It sounds like this.
So, I can confirm the nagging feeling you've had inside your belly since you've been watching this video series.
Synthesizers are wonderful and they're also the biggest time-suck in the history of the universe.
A parting thought...
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- Korg MS-10
- Moog Prodigy
Fab Dupont is a Grammy winning NYC based record producer, mixing/mastering engineer and co-founder of pureMix.net.
Fab has been playing, writing, producing and mixing music both live and in studios all over the world. He's worked in cities like Paris, Boston, Brussels, Stockholm, London and New York just to name a few.
He has his own studio called FLUX Studios in the East Village of New York City.
Fab has been nominated for Grammys 6 times, including two Latin Grammys and has received many other accolades around the world, including Victoires de la Musique, South African Music awards, Pan African Music Awards and US independent music awards.
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