Envelopes and ADSR
Envelopes and ADSR
This week I'm going to talk about envelopes and what Attack, Decay, Sustain, and Release are in Logic's ES2.
First lets go back to basics and remind ourselve what synthesizers such as the ES2 actually do. They are called subtractive becuase they remove something from the signal, with the most reduce signal being the sine wave that has had all the harmonics removed. The following diagram shows the flow of sound through a subtractive synthesizer such as the ES2. It consists of various signal generating and processing modules—and these are coupled with a number of modulation and control modules.
The Oscillators Generate the basic signal, by way of a waveform that is rich in harmonics. The ES2 has three oscillators. These were covered in an earlier blog.
The Filter section is used to change the basic signal by filtering out bits of the frequency spectrum. ES2 has two filters that can be applied discretely to the oscillator signals. The Amplifier section is used to control the level of the signal over time and the amplifier uses a module known as an envelope.
An Envelopes is a time signal and there are 3 available in ES2: Env 1, 2 and 3. The envelope allows the signal to be broken down into several elements that will provide level control for the beginning, middle, and end portions of the signal. The Envelope controls amplitude, the rise and fall of the filter cutoff frequency and modulation sources. The Envelope has been likened to a “remote control” for a given parameter.
With the ES2, we are attempting to copy the Attack, Delay, Release and Sustain that would be characteristic of a real musical instrument, such as a snare drum that has a fast peak level with no sustain and the sound decaying rapidly, compared with say that of a violin where the sound slowly builds up to a peak as the bow is drawn across the strings and is sustained for a while as the bow pressure on the string reduces, then stops when the bow is lifted. A piano keyboard could have a fast attack and decay and sustain, but holding down the key and using a pedal will prolong the sustain. As you can see, these three sounds have very different characteristics over time, and whilst you may not want your sound to mimic a snare drum or grand piano, it is necessary to have a concept of the sound you would like to produce and how to create its qualities using these ES2 settings.
To summarise, the attack, decay, sustain and release (ADSR) are as follows:
Attack: Is the time taken from zero amplitude to 100%, full amplitude. Low attack will make the sound plucky, whilst a long attack may sound like a glide, handy though for a gradually rsing and falling sound effect.
Decay: Is the time it takes to fall from 100% amplitude to the sustain level.
Sustain: Is the steady amplitude level produced when a key is held down.
Release: Is the time taken for the sound to decay from the sustain level to zero amplitude when the key is released.
A sustain level of zero would be similar to a piano played without holding the key down and without a pedal; percussive with no continuous steady level, even when a key is held. With pianos and plucked string instruments, high notes decay quicker than low notes.
ENV 1 can be used with Attack time and Decay time parameter. Clicking on the D will change the parameter from Decay to Release.
ENV 1 can be used to simulate an early analog polysynths similar to Moog Polymoog, Yamaha SK20, and Korg Poly-800. The Poly mode will give a fast attack and decay whereas mono or retrigger give a slower attack and decay.
ENV 2 and ENV 3 are velocity sensitive, so no point in setting via to Velo in the modulation routing; just leave via off. ENV 3's task is to define the dynamic stage of each note.
https://www.soundonsound.com/sos/jun07/articles/logictech_0607.htm
https://help.apple.com/logicpro/mac/9.1.6/en/logicpro/instruments/ - chapter=5%26section=0