Technical Outline - Pioneer RG-9 Operating Instructions Manual

TECHNICAL OUTLINE
T h e b a s i c f u n c t i o n o f t h e R G - 9 i s t o e x p a n d t h e l e v e l
v a r i a t i o n s o f t h e i n p u t s i g n a l ( s e e F i g . 5 : i n p u t - o u t p u t
transfer characteristics). Due to the expander circuit com_
position, the input and output circuits are not necessarily
l i n e a r .
The block diagram is shown below. The circuit consists
m a i n l y o f a f l a t f r e q u e n c y r e s p o n s e g a i n c o n t r o l a m p l i f i e r
( G C A ) a n d a s e n s o r s e c t i o n w h i c h p r o d u c e s t h e s i g n a l t o
c o n t r o l t h e g a i n o f t h e g a i n c o n t r o l a m p l i f i e r . A f t e r p a s s i n g
t h r o u g h t h e i n p u t l e v e l c o n t r o l a n d b u f f e r a m p l i f i e r , a
p o r t i o n o f t h e i n p u t s i g n a l g o e s t o t h e s e n s o r s e c t i o n . A t
the sensor section, the signal first passes through an energy
distribution filter, which possesses a slope of -6dB/octave
above and below a 2.5kHz center frequency. This effec_
t i v e l y r e d u c e s n o i s e c o m p o n e n t s , s u c h a s m o t o r r u m b l e ,
h u m a n d t a p e h i s s , y i e l d i n g o n l y t h e c e n t e r f r e q u e n c y
c o m p o n e n t . A t t h e R G d e t e c t o r . a p e a k d e t e c t o r ( r i p p l e
c a n c e l l i n g t y p e ) p r o d u c e s a D C o u t p u t p r o p o r t i o n a l t o t h e
p e a k v a l u e s o f t h e A C i n p u t s i g n a l . T h e o u t p u t f r o m t h i s
R G d e t e c t o r b e c o m e s t h e g a i n c o n t r o l s i g n a l f o r t h e G C A .
Current from the sensor section determines the open-
l o o p g a i n o f t h e g a i n c o n t r o l a m p l i f i e r . T h e g a i n t h e r e f o r e
increases as the control current increases in accordance
w i t h t h e i n p u t s i g n a l . T h e c h a r a c t e r i s t i c s
o f t h i s s i g n a l
u n d e r g o c h a n g e s s u c h a s t h o s e i n F i g . 6 : i n p u t - g a i n c h a r a c -
t e r i s t i c s . T o p r o v i d e t h i s c h a r a c t e r i s t i c s ,
a n N F B ( n e g a t i v e
feedback) circuit returns a portion of the GCA output to
t h e i n p u t , a n d t h e d y n a m i c e x p a n s i o n s e l e c t o r s e l e c t s t h e
N F B e l e m e n t s t o c o n t r o l t h e f e e d b a c k r a t i o , t h e r e b v
d e t e r m i n i n g t h e t o t a l g a i n ( F i g . 6 ) .
L e f t a n d r i g h t c h a n n e l s a r e m i x e d b y a b l e n d i n g r e s i s t o r
a t t h e s e n s o r s e c t i o n i n p u t , t o p r e v e n t e x c e s s i v e g a i n
d i f f e r e n c e b e t w e e n t h e c h a n n e l s f r o m p r o d u c i n g a n u n -
n a t u r a l e f f e c t d u r i n g s t e r e o p l a y b a c k .
P R O C E S S O R
SWITCH - Bulter Amp
I n p u t t e v s l l m V )
F i g . 5 : R G p r o c e s s o r i n p u t - o u t p u t t r a n s f e r
characteristics
1 0
100 1,ooo
Inp!i tevet (mv)
F i g . 6 : R G p r o c e s s o r i n p u t - g a i n c h a r a c t e r i s t i c s
Sensor S€ilion
D Y N A N l I C
o
a
4 , 1 . 1 0
Dynamic Expansion Merer
F i g . 7
M,J,l
i l ,
' l - - l - - l - l
I
t:::::______:lEqll
E
r 3,16
( 0 m o t h e r c h a n n e l