User Manual

16
TIME
KEY "ON" KEY "OFF"
VOLUME
ATTAC K DECAY RELEASE
SUSTAIN
TIME
KEY "ON" KEY "OFF"
VOLUME
TIME
KEY "ON" KEY "OFF"
VOLUME
TIME
KEY "ON" KEY "OFF"
VOLUME
ATTAC K DECAY
RELEASE
SUSTAIN
SUSTAIN
RATE
TIME
KEY "ON" KEY "OFF"
VOLUME
ATTAC K DECAY
RELEASE
SUSTAIN
SUSTAIN TIME
TIME
KEY "ON" KEY "OFF"
VOLUME
ATTAC K DECAY RELEASE
SUSTAIN
TIME
KEY "ON" KEY "OFF"
VOLUME
ATTAC K DECAY RELEASE
SUSTAIN
TIME
KEY "ON" KEY "OFF"
FILTER
CUT-OFF
Attack Time
Adjusts the time it takes after a key is pressed for the volume to climb from zero to full
volume. It can be used to create a sound with a slow fade-in.
Decay Time
Adjusts the time it takes for the volume to fall from its initial full volume to the level set by the
Sustain control while a key is held down.
Sustain Level
This is unlike the other Envelope controls in that it sets a level rather than a period of time.
It sets the volume level that the envelope remains at while the key is held down, after the
Decay Time has expired.
Release Time
Adjusts the time it takes for the volume to fall from the Sustain level to zero once the key is
released. It can be used to create sounds that have a “fade-out” quality.
Most synthesisers can generate multiple envelopes. Peak has three Envelope Generators:
Amp Env has a dedicated set of ADSR controls, and is always applied to the amplifier to
shape the volume of each note played, as detailed above. The two Modulation Envelopes
(Mod Env 1 and Mod Env 2) share an identical set of controls, with an assignment switch
selecting the envelope being controlled. Modulation envelopes can be used to dynamically
alter other sections of the synthesiser during the lifetime of each note. Peak’s Mod Env
Generators can be used to modify the filter cut-off frequency, or the pulse width of the
Oscillators’ Square Wave outputs, for example.
ATTAC K DECAY RELEASE
SUSTAIN
TIME
KEY "ON" KEY "OFF"
FILTER
CUT-OFF
FREQUENCY
LFOs
Like the Envelope Generators, the LFO (Low Frequency Oscillator) section of a synthesiser
is a Modulator. Thus instead of being a part of the sound synthesis itself, it is used to
change (or modulate) other sections of the synthesiser. In Peak, for example, the LFOs can
be used to alter Oscillator pitch, or Filter cutoff frequency.
Most musical instruments produce sounds that vary over time both in volume and in pitch
and timbre. Sometimes these variations can be quite subtle, but still contribute greatly
towards characterising the final sound.
Whereas an Envelope is used to control a one-off modulation over the lifetime of a single
note, LFOs modulate by using a repeating cyclic waveform or pattern. As discussed
earlier, Oscillators produce a constant waveform, which can take the shape of a repeating
sine wave, triangle wave etc. LFOs produce waveforms in a similar way, but normally at a
frequency which is too low to produce a sound that the human ear could perceive directly.
As with an Envelope, the waveforms generated by the LFOs may be fed to other parts of
the synthesiser to create the desired changes over time – or ‘movements’ - to the sound.
Peak has two independent LFOs, which may be used to modulate different synthesiser
sections and can run at different speeds.
Imagine this very low frequency wave being applied to an Oscillator’s pitch. The result
is that the pitch of the Oscillator slowly rises and falls above and below its original pitch.
This would simulate, for example, a violinist moving a finger up and down the string of the
instrument whilst it is being bowed. This subtle up and down movement of pitch is referred
to as the ‘Vibrato’ effect.
A waveshape often used for an LFO is a Triangle wave.
TIME
PITCH
PITCH WITHOUT MODULATION
Alternatively, if the same LFO signal were to modulate the Filter cut-off frequency instead of
the Oscillator pitch, a familiar wobbling effect known as ‘wah-wah’ would be the result.
Summary
A synthesiser can be broken down into five main sound generating or sound modifying
(modulating) blocks:
1. Oscillators that generate waveforms at a various pitches.
2. A Mixer that mixes the outputs from the Oscillators together (and add Noise and
other signals).
3. Filters that remove certain harmonics, changing the character or timbre of the sound.
4. An Amplifier controlled by an Envelope generator, which alters the volume of a
sound over time when a note is played.
5. LFOs and Envelopes that can be used to modulate any of the above.
Much of the enjoyment to be had with a synthesiser is with experimenting with the factory
preset sounds (Patches) and creating new ones. There is no substitute for ‘hands on‘
experience. Experiments with adjusting Peak’s various controls will eventually lead to a
fuller understanding of how the various synth sections alter and help shape new sounds.
Armed with the knowledge in this chapter, and an understanding of what is actually
happening in the synth when tweaks to the knobs and switches are made, the process of
creating new and exciting sounds will become easy. Have fun!