Specifications
CH.l
LOW
LEVEL
INPUTS
FIG.2g
MONOPHONIC
PHONO
CH.2
LOW
LEVEL
INPUTS
CH.l
HIGH
LEVEL
INPUTS
CH.2
HIGH
LEVEL
INPUTS
CH.l
TAPE
OUT
CH.2
TAPE
OUT
SPEAKER
CH.l
f---
SPEAKER
CH.2
c) INPUTS: There are identical pairs of MAG. PHONO,
TAPE
HEAD,
MICROPHONE,
AUXILIARY
A, and AUX-
ILIARY
Binputs
-one
of
each
pair in
channell
and
chan-
nel 2 - and
each
is identified accordingly by the suffix
1 or 2. The MAG. PHONO,
TAPE
HEAD,
and MICRO-
PHONE pairs of inputs are all "low level" inputs,
mean-
ing
that
they all feed through a preamplifier/equalizer
stage in
either
channel 1 or 2. The
AUXILIARY
A and
AUXILIARY
Bpairsofinputs are "high level" inputs,
mean-
ing that they enter
either
channel 1 or 2 at a point after
the preampl
ifier/equalizer
stages. The AM, FM and FM-
FM Multiplex inputs are also "high level inputs", which
nr", intArnnllv
~"'IA...,t",rl
in
nnir~
- nn", fnr
",n...,h
...,hnnn"'l
are
Interne
y se
ectea
In
pal rs - one for
each
channe
- by the INPUT
SEL.
switch. At the MONAURAL posi-
tion of the FUNCTION SEL., AM only is
selected
at the
AM-FMposition of the INPUT SEL., and FMonlyis
select-
ed at the FM- FM
MULTI.
position of the INPUT
SEL.
l) MAG. PHONO 1, MAG.
PHONO
2: These inputs
are intended for the two outputs
ofa
stereo magnetic
car-
tridge, or for a stereo ceramic cartridge with adaptors.
The correct method for wiring a three terminal cartridge
is shown in Fig. 3. If the cartridge is a four terminal
type, short the two inside terminals of the cartridge
to-
gether and
treat
it
exactly
as if it were the single center
terminal shown in Fig. 3. The loading presented to
each
output of the cartridge by
each
MAG.
PHONO
input is
100,000 ohms. If a lower loading resistance is required
by the particular cartridge used, connect a shunt resistor
of appropriate value from
each
outside terminal of the
car-
tridge to the center (common) terminal. This can be done
actually
by mounting a 3-post terminal strip on the
under-
side of the phonograph mounting board
at
a point near the
lead break-out from the pickup arm. These shunt resistors
are then wired to this terminal strip as shown in Fig. 3.
The value of
each
of the two shunt resistors (R
s)
can
be
determined fromthe desired loading resistance (RI) by this
formula
Rs
= 100,000 x
RI
ohms
100,000 -
RI
or this tabl e; for
RI
= 50KQ, use
Rs
= 1
OOKQ;
for
RI
::33KQ,
use R
s
= 50KQ; for
RI
= 25KQ, use
Rs
= 33KQ.
7
* NOTE: All ceramic cartridge manufacturers have
devel-
oped simple networks which when connected the outputs
of their cartridges result in a characteristic identical to
that of magnetic cartridges. By interposing the recom-
mended adaptor for the particular ceramic cartridge
be-
tween the cartridge outputs and the MAG. PHONO
in-
puts of the amplifier, it is possible to use the MAG. PHONO
inputs for the ceramic cartridge with
excellent
results.
Adaptor networks are given in the literature for the
par-
ticular
ceramic cartridge and can be built on a terminal
strip mounted on the underside of the phonograph base, or
may be
available
in convenient component form from the
cartridge manufacturer. Stereol;lhonic crystal cartridges
ccrrrrcge
mcnurccrurer,
orereopnoruc
crysTal
carrnages
(Ronette "Binofluid"
OV
and
BF40)
can be connected
di-
rectly to auxiliary high level inputs.
2}
TAPE
HEAD
1,
TAPE
HEAD
2: These inputs are
in-
tended for
direct
connection to the two outputs of a stereo
tape playback head. A front panel slide switch permits
choice of
NARTB
tape head equalization
either
for71/2
(& 15) ips
or3
3/4
ips tape speeds. The loading resistance
presented by
each
tape head input is 100,000 ohms.
3} MICROPHONE 1, MICROPHONE 2: These inputs are
intended for
rec~~:ving
the output signals directly from
two separate microphones. It ispreferable that the micro-
phones used be of the high impedance type.
4)
AUXILIARY
A1,
AUXILIARY
A2: These inputs are
intended for
either
a stereophonic or monophonic high
level source. A stereophonic high level source might be
a stereo tape deck with
built-in
playback equal ization
for both tracks. A monophonic high level source might
be a monophonic crystal cartridge or tv sound. Plug a
monophonic source intoAUXJLlARYA1, leaving theAUX-
ILIARY
A2 input unused.
Note
that
the input impedance
at all these high level inputs is
0.5
megohm,which is too
low for ceramic cartridges requiring 2 to 3
megohms
in-
put impedance. For ceramic cartridges, use the MAG.
PHONO
inputs with the simple adaptor networks recom-
mended by the manufacturers. For stereophonic crystal
cartridges (Ronette "Binofluid" OVturnover and
BF40
sin-
gle needle), the
0.5
megohm load provided at the high
level inputs is
exactly
the loading impedance required.