Head Alignment And Track Control With Tandberg Test Tapes; Sound On Sound; Preferred Instruction For Sound On Sound Recording - TANDBERG 12 Service Manual

m a s t e r t r a c k i s t h e n r e p r o d u c e d f r o m o n e c h a n n e l ,
a n d t h e s l u d e n t ' s t r a c k f r o m t h e o t h e r . T h e p l a y b a c k
c a n b e h e a r d i n t w o l o u d s p e a k e r s o r m i x e d t h r o u g h
t h e c e n t e r c h a n n e l i n t h e e a r p h o n e s . T h e s i u d e n t i s
a b l e t o r e c o r d a n d e r a s e h i s o w n e x e r c i s e a t w i l l ,
with no inlerference to the master track.
Procedure
We presume that the pre-recorded master programme
is recorded on ch. I (upper track). Set the funclion
selector switch ch. I to <PLAYBACK)) position, and
the speaker selecior swifch fo <EXT>. The master's
voice will be heard in the earphones, which are con-
nected lo the center channel output, when the tape
recorder is started. The level is adiusted wilh the up-
per volur:re control knob. The recording of ihe stu-
dent's voice is made on ch. 2 (lower track). Set the
funciion selector switch ch.2 to (RECORD> position
s i m u l t a n e o u s l y w i t h f h e o p e r a t i n g l e v e r b e i n g m o v e d
to normal forward drive position. The level of the re-
cording is adiusted with the lower volume control
knob. The student will monitor his own voice in ihe
earphones with the volume determined by the record-
i n g l e v e l .
Rewind the recorded tape and play it back with both
function selector levers in pos. <PLAYBACK> (stereo
playback). The levels from the two channels can be
s e t i n d i v i d u a l l y w i t h t h e v o l u m e c o n f r o l k n o b s .
T h e o p e r a t i o n w i l l b e a n a l o g i c a l i f t h e m a s t e r p r o -
gramme is recorded on ch. 2 (lower track). lt is also
p o s s i b l e t o u s e t h e i n t e r n a l l o u d s p e a k e r s , a t a l i m i t e d
level, for language studing groups. The feedback be-
t w e e n t h e i n t e r n a l l o u d s p e a k e r s a n d t h e m i c r o p h o n e
w i l l d e c i d e t h e m a x i m u m l e v e l a p p l i c a b l e .
5.2.10 Sound on sound
R e f . b l o c k d i a g r a m f i g . 3 9 .
Sound on sound recording is a technique where a pro-
g r a m m e i s p l a y e d b a c k f r o m o n e t r a c k a n d s i m u l -
taneously a second programme is added, lhe two pro-
g r a m m e s b e i n g r e c o r d e d c o m b i n e d o n a n o t h e r t r a c k .
(One superimposed on the other.) Consequently fhe
p l a y b a c k o f t h e c o m b i n e d p r o g r a m m e m u s t b e i n
mono. ln <add a track> where two programmes are
on two separate tracks the playback must be in stereo.
I n < < s o u n d o n s o u n d r > o n e h a s t h e p o s s i b i l i t y o f b u i l d -
ing up a complete programme from separate sources,
however the sound quality may be slightly reduced
by many re-recordings.
T h e s e r i e s 1 2 h a s l i m i t e d p o s s i b i l i t i e s f o r s o u n d o n
s o u n d r e c o r d i n g s . T h e s e t a p e r e c o r d e r s a r e e q u i p p e d
w i t h c o m b i n e d r e c o r d a n d p l a y b a c k h e a d s , a n d t h e r e
w i l l a l w a y s b e s o m e m a g n e t i c c o u p l i n g b e t w e e n t h e
h e a d w h i c h i s r e c o r d i n g a n d t h e h e a d p l a y i n g b a c k .
W h e n t h e s o u n d o n s o u n d r e c o r d i n g i s m a d e , t h e
o u t p u t f r o m t h e p l a y b a c k c h a n n e l i s c o n n e c t e d t o t h e
i n p u f o f i h e r e c o r d i n g c h a n n e l . l f t h e l o o p a m p l i f i c a -
t i o n f r o m t h e p l a y b a c k h e a d t o t h e r e c o r d i n g h e a d
is too great the feedback between the two heads
w i l l c a u s e i n s t a b i l i t y a n d o s c i l l a t i o n s . T h e t a p e s p e e d
7 1 / z i . p . s . i s r e c o m m e n d e d f o r t h i s p u r p o s e . S o u n d o n
sound recordings can only be completely satisfactory
on a taperecorder with separate record and playback
h e a d s , i . e . T a n d b e r g T a p e R e c o r d e r M o d e l s 6 4 a n d
6 2 . l f i n s p i i e o f t h i s , y o u w i s h i o r e c o r d s o u n d o n
s o u n d o n t h e s e r i e s 1 2 , y o u m u s t f i r s t f i n d o u t w h e r e
t h e o s c i l l a t i o n l i m i t i s a n d k e e p y o u r v o l u m e c o n t r o l s
b e l o w t h i s l i m i t .
Preferred instruction for sound on sound recording
We presume that the pre-recorded programme is re-
c o r d e d o n c h . l . T h e p o w e r o u t p u t t e r m i n a l s c h . I i s
c o n n e c t e d t o t h e l i n e i n p u t c h . I b y a s t r a p . T h e
speaker selector switch is set to EXT position. The
function selector switch ch. 2 is set lo RECORD posi-
t i o n a n d t h e o p e r a t i n g l e v e r i s m o v e d t o n o r m a l f o r -
w a r d d r i v e . T h e f u n c t i o n s e l e c t o r s w i t c h c h . I i s s e t
to PLAYBACK position.
T h e v o l u m e c o n t r o l c h . 2 ( l o w e r k n o b ) i s a d j u s t e d i o
m a x i m u m r e c o r d i n g l e v e l f r o m t h e m i c r o p h o n e w i t h
fhe sfart-slop lever in STOP position and with lhe vo-
l u m e c o n t r o l c h . I s e t t o m i n i m u m . T h e i s a l e s f r e -
c o r d i n g a n d t h e t a p e i s n o t m o v i n g . T h e r e c o r d -
i n g l e v e l f o r c h . 2 i s n o w p r e - s e t a n d s h o u l d n o t b e
t o u c h e d d u r i n g t h e a c t u a l r e c o r d i n g . M o v e t h e s t a r t -
s t o p l e v e r t o l e f t p o s i t i o n a n d s t a r t t h e r e c o r d i n g . I n -
c r e a s e t h e s e t t i n g o f t h e v o l u m e c o n f r o l c h . I ( u p p e r
k n o b ) u p t o a p o i n t i u s t b e l o w c o m p l e t e c l o s i n g o f t h e
r e c o r d l e v e l i n d i c a t o r c h . 2 ( t h e p o i n t o f i n s t a b i l i t y ) .
T h e p r e - r e c o r d e d p r o g r a m m e o n c h . I i s p l a y e d b a c k
t h r o u g h t h e p l a y b a c k p r e - a m p l i f i e r a n d i h e p l a y b a c k
e q u a l i z i n g a m p l i f i e r a n d t o t h e p o w e r o u l p u t a m p l i -
f i e r . T h e s i g n a l i s f e d t o i h e l i n e i n p u t c h . 2 b y r h e
strap. The two outputs from the record pre-amplifiers
are interconnecfed. The pre-recorded programme and
t h e p r o g r a m m e f r o m t h e r e c o r d p r e - a m p l i f i e r c h . 2
are bolh fed to the input of the record equalizing
a m p l i f i e r a n d t h e r e c o r d h e a d c h . 2 . R e w i n d t h e t a p e
w h e n t h e r e c o r d i n g i s c o m p l e i e d , a n d p l a y b a c k f h e
sound on sound recording with fhe function selector
s w i t c h c h . 2 i n P L A Y B A C K p o s i t i o n ( m o n a u r a l p l a y -
b a c k c h . 2 ) .
(
,n
(
5.3 HEAD AI.IGNMENT AND TRACK CONTROL
W I T H T A N D B E R G I E S T T A P E S
5.3.1 The models l2-4 and l2-2
'I
. Demagnetize the heads and ihe adiacent paris be-
f o r e a l i g n i n g t h e h e a d s .
2 . M o v e t h e o p e r a f i n g l e v e r t o n o r m a l f o r w a r d d r i v e
with a tight tape inserted. Align the vertical posi-
t i o n o f t h e a d i u s t a b l e t a p e g u i d e ( 7 9 . 3 i ) u n t i l t h e
tape runs equidistant from the f langes of the tape
g u i d e . R e f . f i g . l l .
34
P l a y b a c k t h e t e s t t a p e N o . 1 . T h i s i s a f u l l t r a c k
pre-recorded tape with 1000 c/s recorded at 7Vz
i.p.s. tape speed. The record level of ihe exact area
c o r r e s p o n d i n g t o t r a c k 3 i s r e d u c e d 3 0 d B . A d i u s t
t h e h e i g h t o f t h e c o m b i n e d r e c o r d / p l a y b a c k h e a d
u n t i l m i n i m u m o u t p u t i s o b t a i n e d o n a V T V M
from track 3.
P l a y b a c k t h e t e s t t a p e N o . 2 . T h i s i s a f u l l t r a c k
pre-recorded tape with I 0 000 c ls at 7th i.p.s. tape
speed. Adiust the azimuth position of the com-
4 .