Waldorf Pulse User Manual page 71

Envelope
An envelope is used to modulate a sound-shaping component within a given time frame so
that the sound is changed in some manner. For instance, an envelope that modulates the
cutoff frequency of a low-pass filter opens and closes this filter so that some of the signal's
frequencies are filtered out. An envelope is started via a trigger, usually a fixed trigger.
Normally, the trigger is a MIDI Note. The classic envelope consists of four individually
variable phases: Attack, Decay, Sustain and Release. This sequence is called an ADSR
envelope. Attack, Decay and Release are time or slope values, and Sustain is a variable
volume level. Once an incoming trigger is received, the envelope runs through the Attack
and Decay phases until it reaches the programed Sustain level. This level remains constant
until the trigger is terminated. The envelope then initiates the Release phase until it reaches
the minimum value.
Gate
The term „Gate" has different meanings in a technical context. Like a real gate, it describes
something, that can be open or closed, or - to use a technical term - active or inactive. A
gate in sense of a device is a unit, that damps a throughpassing signal corressponding to
some specific conditions. E.g. in a noise gate a signal is cut off, when its level falls above a
predetermined threshold.
Gate stands also for a control signal of analog synthesizer systems. A keyboard generates an
active gate signal as long as a key is held down. When the key is released, the gate signal
becomes inactive again. An envelope generator can use this signal for its trigger purposes,
and as a result a VCA unit can be controlled.
LFO
LFO is an acronym for low-frequency generator. The LFO generates a periodic oscillation at
a low frequency and features variable waveshapes. Similar to an envelope, an LFO can be
used to modulate a sound-shaping component.
Low-pass Filter
Synthesizers are often equipped with a low-pass filter. A low-pass filter dampens all
frequencies above its cutoff frequency. Frequencies below the cutoff are not affected.
MIDI
The acronym MIDI stands for "musical instrument digital interface." It was developed in the
early '80s so that diverse types of electronic musical instruments by different manufacturers
could interact. At the time a communications standard for heterogeneous devices did not
exist, so MIDI was a significant advance. It made it possible to link all devices with one
another through simple, uniform connections.
Essentially, this is how MIDI works: One sender is connected to one or several receivers.
For instance, if you want to use a computer to play the Pulse, then the computer is the
sender and the Pulse acts as the receiver. With a few exceptions, the majority of MIDI
devices are equipped with two or three ports for this purpose: MIDI In, MIDI Out and in
some cases MIDI Thru. The sender transfers data to the receiver via the MIDI Out jack. Data
are sent via a cable to the receiver's MIDI In jack.
MIDI Thru has a special function. It allows the sender to transmit to several receivers. It
routes the incoming signal to the next device without modifying it. Another device is
simply connected to this jack, thus creating a chain through which the sender can address
a number of receivers. Of course it is desirable for the sender to be able to address each
device individually. Consequently, there is a rule which is applied to ensure each device
responds accordingly.
User's Manual Pulse • PulsePlus 71