How does modulation work?

[Juljan]

Hey guys,

I am trying to make some sounds on my own but I don't understand how simple modulation works.
When I modulate Cutoff or Volume with a simple ADSR envelope, I can here the changes, of course. But I don't understand the theory behind it-so what I am exactly doing!

Could you tell me what the modulation, for instance Cutoff or Pitch does?

Best regards
Juljan

[tehlord]

Modulation just means change over time.

[MOK19]

As tehlord says.

Another way to think of it: When you route an envelope, or an LFO, etc, to the filter cutoff or volume(etc), you're giving an instruction. "Computer! Wiggle the cutoff knob like this so that I don't have to." That's modulation. To control, or change something, usually in a systemic, repeating fashion.

Here's what I consider the go-to tutorial for synthesizer basics. Watch the whole series, and you will likely have a good idea what's going on, and be able to better use your tools.
https://www.youtube.com/watch?v=MzN89Rc_06M

[Juljan]

Hey, thanks for your answers!
I guess, I know in which directions it goes.

But my problem is the following: Let's say, I want to modulate the Cutoff with a modulation ADSR envelope-which effects do attack, decay, sustain and release have in this case?

[MOK19]

Those words denote a 'stage' in the envelope process, which happens in sequence, like a numbered instruction set.

As soon as you bang on your keyboard, the attack stage begins. It's a period of time that ends where you set your attack knob, and also denotes the beginning of the next stage. During the attack stage, the volume(or the magnitude if you're modulating the filter, etc) typically starts at zero, and ends at full(or the magnitude/depth of the whole envelope).

Next the Decay stage begins. It ends within an amount of time, dictated by where you set your decay knob. So like attack, the decay stage knob controls a period of time. When decay starts, the envelope's magnitude is where it left off, possibly at full magnitude. When decay ends, the modulation magnitude will likely have been reduced. Reduced to what? The level dictated by the SUSTAIN stage.

Unlike Attack, and Decay, the Sustain stage does not control an amount of time. Instead, it determines a level of magnitude that A) your decay stage ends at, and B) the patch volume/fx magnitude will stay at for as long as you hold down your MIDI/piano key.

When you finally release your keyboard key, the Release stage begins. It functions just like decay - like it's decay #2. The volume/magnitude level begins where we left off, at whatever Sustain has dictated. By the time the stage ends, the modulation/volume magnitude or depth has reached zero. How long it takes to get there is determined by your Release knob.

In summary, Attack, Decay, and Release are measures of TIME. But Sustain is a measure of MAGNITUDE, which both Decay and Release need in order to know what magnitude they end and begin at, respectively. This process is generally repeated with every key press, when you're talking about Envelopes.

An extra bit of terminology - When you hear people talking about 'a stab,' this usually denotes a rough envelope setup, such that the decay time is fairly short, and the sustain is set to zero(therefore making the release irrelevant, since it starts at 0 magnitude and ends at 0 magnitude). The resultant sound will probably be very brief and sort of plucky. That's a stab. This envelope might commonly be applied to the filter(a lowpass filter stab), or the volume.

[fluffy_little_something]

Release also plays a role when sustain is set to zero.

[RunBeerRun]

You can always here the changes to. Trust your eayer, it tells you.

[fluffy_little_something]

I suppose it is obvious, but just in case it is not: the ADSR envelope applied to the filter cutoff frequency of a lowpass filter means, how fast the sound becomes brighter (A), how fast it becomes less bright (D), how bright it continues to sound as long as you keep the key pressed (S), and how fast it becomes muted completely after releasing the key (R).

All of that goes for a a positive value for the envelope amount/depth.

[Nielzie]

Here's another basic tutorial that might help a bit to understand the concepts
http://www.youtube.com/watch?v=se31yZHNLLI