User Manual

22
The Mixer Section
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20
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MIXER
OSC 1
TO ENVELOPES
SECTION
RING MOD
OSC 2
OSC 3
NOISE
The outputs of the various sound sources can be mixed together in any proportion to
produce the overall synth sound, using what is essentially a standard 5-into-1 mono mixer.
The three Oscillators, the Noise source and the Ring Modulator output each have level
controls, Osc 1
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, Osc 2
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, Osc 3
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, Noise
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and Ring 1*2
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respectively.
There is also a “master” level control, VCA Gain
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, which sets the output level of the
mixer. As the mixer section precedes the Envelopes section, this control scales the ADSR
envelope.
Peak is capable of producing levels in the mixer section that can clip if all
sources are turned up to maximum. It may be necessary to balance the
levels either by turning the sources down or by reducing the VCA Gain
control
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to ensure that audible clipping does not occur.
The Envelopes Section
Peak generates three envelopes each time a key is pressed, which can be used to modify
the synth sound in many ways. The envelope controls are based on the familiar ADSR
concept.
ATTAC K DECAY RELEASE
SUSTAIN
TIME
KEY "ON" KEY "OFF"
VOLUME
The ADSR envelope can be most easily visualised by considering the amplitude (volume)
of a note over time. The envelope describing the “lifetime” of a note can be split into four
distinct phases:
• Attack – the time it takes for the note to increase from zero (e.g., when the key is
pressed) to its maximum level. A long attack time produces a “fade-in” effect.
• Decay – the time it takes for the note to drop in level from the maximum value
reached at the end of the attack phase to a new level, defined by the Sustain
parameter.
• Sustain – this is an amplitude value, and represents the volume of the note after
the initial attack and decay phases – i.e., while holding the key down. Setting a low
value of Sustain can give a very short, percussive effect (providing the attack and
decay times are short).
• Release – This is the time it takes for the note’s volume to drop back to zero after
the key is released. A high value of Release will cause the sound to remain audible
(though diminishing in volume) after the key is released.
Although the above discusses ADSR in terms of volume, note that Peak is equipped
with three separate envelope generators, referred to as Amp Envelope, Mod Envelope 1
and Mod Envelope 2.
• Amp Env is the envelope that controls the amplitude of the synth signal, and
is always routed to the VCA in the output stage (see “PEAK: Simplified Block
Diagram” on page 17). Peak also allows Amp Env to modulate the frequency of
the Filter section.
• Mod Env 1 & 2 – the two modulation envelopes - are routed to various other
sections of Peak, where it can be used to alter other synth parameters over the
duration of the note. They are:
• Mod Env 1 can modulate the waveform shape of any of the three Oscillators,
at a degree set by the Shape Amount controls
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when the associated
Source button
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is set to Mod Env 1.
• Mod Env 1 may also modulate the filter frequency, at a degree set by the Env
Depth control
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when the Source button
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is set to Mod Env 1.
• Mod Env 2 can modulate the pitch of any of the three Oscillators, at a degree
set by the Mod Env Depth 2 controls
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.
It should be noted that the above routings are only those available directly using Peak’s top
panel controls: many more routing options are available using the Modulation Matrix (see
“The Modulation Matrix” on page 26).