Tag: Synthesizer

Synthesizer Secrets – ADSR Tutorial – What Is An ADSR Envelope and How Is It Used?

ADSR Envelopes are very commonly used in synthesiser designs – in fact you’d be hard pressed to find a synthesiser that didn’t feature an ADSR Envelope generator.

But what are they and how are they used?

What is an ADSR Envelope?

ADSR is an acronym which means Attack, Decay, Sustain and Release.

In an ADSR envelope these four elements are given values. Generally these will be time-based values for Attack, Decay and Release (such as seconds). Sustain will generally be a percentage (of maximum volume).

An ADSR envelope is generally used to control the intensity, or volume, of a particular signal but may also be used for other things such as managing the frequency cut-off of filters. For demonstration purposes we will focus on using ADSR envelopes for controlling volume as that is probably the easiest to visualise.

The diagram below is a pictorial description of the ADSR envelope over time.

Imagine that the envelope is applied to the volume on a sound at the moment the sound starts. Using a synthesiser example, that would be at the moment a note was triggered.

Starting in the Attack phase, the volume would start at 0 and then move up towards peak amplitude. The time taken for the note to reach the peak amplitude from the zero point is the Attack setting – i.e. 2 seconds. As a result the note will fade in over this time.

Once the note reached peak amplitude the envelope would then transition to the Decay phase. In this phase the note volume reduces from the peak amplitude to the Sustain level. The time taken for the note to reach the sustain level from the peak is the Decay setting – i.e. 2 seconds. The note will therefore fade to the sustain level during this phase.

Once the note has reached the sustain level then the Sustain phase is entered and the amplitude will remain constant at the defined level. The envelope will remain in the sustain phase at a constant level until the note was released.

At the point the note is released the Release phase will be immediately entered. The release phase will then transition from the sustain level to zero, taking the length of time defined for the release, i.e. 2 seconds. The note will therefore fade to zero during this time.

If the note were released at any point before the sustain phase then the Release phase would immediately be entered and the note would fade away to zero amplitude in line with the release settings.

Why would you use an ADSR Envelope?

As described above, ADSR envelopes can serve a multitude of purposes.

Let us consider here the application of an ADSR envelope settings operating on the volume of a note.

Here are some example settings and the effect they would have.

1. 0s Attack, 0s Decay, 100% Sustain, 0% Release

In this case the attack, decay and release settings are set to 0s so these phases will execute immediately. This would result in a note that reached maximum volume immediately, sustained during the Sustain phase at this volume level and returned to zero volume as soon as the note was release.

Using these settings the ADSR envelop would open as a simple gate, triggered by note on and off.

2. 1s Attack, 0s Decay, 100% Sustain, 1s Release

Here a note would have a 1 second fade in and out time, making the note sound softer than the above gate. There would also be a slight fade out, giving a little extra depth on note off.

3. 5s Attack, 0s Decay, 100% Sustain, 5s Release

This would have the effect of a very long fade in and fade out, giving a distinctive ethereal sounds. Very atmospheric and ‘floaty’.

4. 3s Attack, 5s Decay, 0% Sustain, 0s Release

In this case, due to the sustain being set at 0%, the note will be reduced to a zero volume once the decay step was complete, regardless of whether the note was still active or not. As a result, these settings would result in a note that faded in and out to zero while the note was still being held.

This type of envelope would be useful for controlling filters etc..

Hopefully that has given you a quick overview of what ADSR envelopes are and how they can be used to create some basic effects.

To get a full appreciation download the RedLion VST/AU FM Synth and experiment!

There are also several video tutorials available in our blogs that could assist your understanding:

> FM Synthesis – Intensity and ADSR Envelopes with the RedLion FM Synth Tutorial

> FM Synthesis – Low Pass Filters with the RedLion FM Synth Tutorial

FM Synth Tutorial – Selecting and Using Algorithms with the RedLion FM Synth

Algorithms form the basis of any FM synth patch. They define the arrangement of signals and define signals as either carriers or modulators.

The origins of the sound of your patch are determined by the choice of algorithm.

The RedLion FM synth features a number of different algorithms which can be used depending on your sound goals. These range from those with a majority of carriers and only a few modulators to those featuring only one carrier and the remaining signals as modulators.

This breadth of algorithms enables you to select the best algorithm for your needs.

Don’t worry – this video explains all!

FM Synth Tutorial – Low Pass Filters with the RedLion FM Synth

Every good synth has a fantastic low pass filter that can be used in a variety of ways to create an array of interesting sounds and to add ‘movement’ to your patches.

The RedLion FM synth is no exception. It features a fully resonant low pass filter with additional ADSR envelope control.

This video is a complete guide to using the low pass filter within the RedLion FM synth..

FM Synth Tutorial – Intensity and ADSR Envelopes Tutorial with the RedLion FM Synth

Intensity plays a key role in creating the kinds of sounds we want from our FM synthesisers. Whether this is carrier intensity or modulator intensity, it can help sculpt the sound and type of sound that we are looking to create.

The RedLion FM Synth enables us to manage the intensity of our signals in a variety of interesting ways, including the use of a per-signal ADSR envelope. If you aren’t familiar with envelopes and ADSR then check out our post explaining ADSR envelopes in detail.

This video takes you through all of the ways of manipulating intensity in RedLion that you can use when creating your own amazing sounds..

FM Synth Tutorial – Ratios and Tuning Concepts with the RedLion FM Synth

The concepts of ratios and tuning are of fundamental importance in FM synthesis.

Ratios determine the relationship between the incoming note(s) frequency and the frequency of a signal, be it carrier or modulator. Using this technique we can change the pitch of carrier signals on either a constrained (octave) or unconstrained (free select) basis.

The ratio of a modulating signal to the incoming note frequency determines the effect created by the frequency modulating – the best way to understand this is to download a copy of RedLion and try for yourself!

The fine tuning knob in RedLion can be used in conjunction with the ratio knob to tune to particular intervals or can be used to move two (or more) signals slightly out of tune and produce a range of beating and phasing effects.

This video demonstrates all of these concepts using the RedLion FM synth VST/AU plug-in. Enjoy!