Envelope Generator - Yamaha CS-50 Servicing Manual

ENVELOPE GENERATOR
e BASIC CONSTRUCTION OF ENVELOPE GENERATOR
A time-dependent DC voltage generator. In this circuit, the sound parameters such as rising rate following key-ON,
peak level, decaying rate, sustain level for steady key-ON, time from release to die-away are substituted by voltage
level, time course of voltage change or slope, which are combined to form a voltage envelope.
There are two envelope generators, for VCF and for VCA.
~~6
e~
81'
~
Time
vo
~
KEY-ON signa!L__ J---
ON OFF
-"'~
::lOl)
0."'
~.:=:
o!i?--- ___ ov
Time
KEY -ON
L________l
signal
+ 15
IC
s-5oK
r-· _ _.__ _ _
42
::.::
0
~
"'
§;,r
-15
+15~-15
B-JOOK
VRJS
Test point
l
ov+8.5V
- 65V
KEY-ON signal
The output of VCF-EG circuit is used as the control voltage for VCF cut-off frequency, and that of VCA-EG
circuit as the volume control voltage for VCA circuit.