AD-Envelope

A simpler form of envelope has Attack and Decay parameters only, and is therefore called an AD-envelope. In effect, the AD-envelope behaves like an ADSR-envelope with Sustain set to 0 (see the picture at the top of this page). This type of envelope, often with amount and inversion controls, is suitable when you want to affect the start of the sound only.

On the Nord Lead 2X, the Modulation Envelope is of AD-type. Typically, it can be made to modulate the FM amplitude or the pitch of Oscillator 2, to create a different timbre during the attack part of the sounds.

LFOs

An LFO is an oscillator, just like the ones that produce the sound in a synthesizer, but with two main differences:

• The LFO produces very low frequencies, most often below the hearing range (up to 20Hz).

• The LFO is not used to produce sound, instead it is connected to other modules to provide modulation of parameters. If you for example route an LFO to pitch, you get a vibrato. If you route it to the filter’s cutoff frequency you get a wah-wah type of effect. And if you route it to the amplifier of an instrument you get a tremolo.

The three basic parameters for an LFO are Waveform, Rate (frequency) and Amount:

• The waveform determines the type of vibrato, for example “regular” (triangle or sine), ramp (sawtooth) or random.

• The Rate determines the speed of the vibrato.

• The Amount controls to what degree the LFO affects its destination.

• Если Вы отпустите клавишу до того как огибающая достигнет сустейна, она сразу же "прыгнет" в затухание. Этот эффект можно изучить на рисунке ниже:

Уровни огибающей могут изменяться в зависимости от силы нажатия клавиш. Это используется, для изменения звука в зависимости от вашего стиля игры, например, чтобы сделать звук ярче (огибающая фильтра) или громче (огибающая усилителя).

Дата добавления: 2015-08-20