Some electronic musical instruments can invert the ADSR envelope, reversing the behavior of the normal ADSR envelope. During the attack phase, the modulated sound parameter fades from the maximum to zero then, during the decay phase, rises to the value specified by the sustain parameter. After the key has been released the sound parameter rises from sustain amplitude back to maximum amplitude.
There is one surprising aspect of the parallel FM equation. Since we can fiddle with the initial phases of the modulating signal's components,we can get very different spectra from modulating signals with the same magnitude spectrum. In the next two graphs, both cases involve amodulating signal made up of 6 equal amplitude harmonically related sinusoids, but the first uses all cosines, and the second uses aset of initial phases that minimizes the modulating signal's peak amplitude:
In the realm of "anything" as the modulating signal, consider
One implementation of an instrument featuring wavefolder~ and wavestretcher~ objects is detailed in the next-but-one panel. It is clear that subtle offsets away from aninteger CMR result in rhythmic effects, and so an obvious thing to do is tosynchronise these effects to a pulse. Commonly used formulae for establishinga frequency based on tempo are used to add a linear offset to the modulatorfrequency such that, for the example of a single-note pulse:
DX7 | Frequency Modulation | Synthesizer
Let's add an LFO to our synthesizer that causes the pitch of our oscillator to wiggle up and down a little bit, like a violinist moves their hand to create vibrato. We're also going to use the envelope generator to modulate the frequency of our filter, so we get a cool sweeping effect automatically on every note, especially if we turn up the filter's resonance. Using a control signal to change the frequency of another module is called , or , as indicated in the diagram below:
FM Synthesis Frequency Modulation
Another type of module frequently used to control other modules is the , or . An LFO is just like a normal oscillator, it can have any waveform and amplitude we specify, but it has a very low, sub-audio frequency, producing a very slowly oscillating signal generally used to control other modules within a synthesizer. For example, an LFO might move the volume level of a VCA up and down, creating a tremolo effect. LFOs are like little robots that turn knobs back and forth for you.
Amplitude Modulation; Frequency Modulation; Re-Synthesis; ..
builds sounds by adding together waveforms into a composite sound. Instrument sounds are simulated by matching their natural harmonic overtone structure. Early analog examples of additive synthesizers are the , Hammond organ, and Synclavier.
Frequency modulation - MATLAB fmmod - MathWorks
ADSR envelopes are often used to control the volume of a sound, although they can be used to control almost anything inside a modular synthesizer. For example, the same envelope could control a resonant low pass filter, making a cool sweeping and wooshing effect evolve as we play each note.