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CH.
l HIGH
LEVEL INPUTS
CH.
T APE OUT
CH. 1 LOW
LEVEL INPUTS
FIG.
MONOPHONIC PHONO
SPEAKER
CH.
CH. 2 LOW
LEVEL INPUTS
COM
CH. 2 HIGH
LEVEL INPUTS
CH.
T APE OUT
c) INPUTS: There
are identical pairs of MAG. PHONO,
TAPE HEAD
MICROPHONE, AUXILIARY A, and AUX-
ILIARY B inputs
-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 II
low level" inputs, mean-
ing that they all feed through a preamplifier/equalizer
stage in either channel
l or 2.
The AUXILIARY A and
AUXILIARY Bpairsofinputs are
high level" inputs, mean-
ing that they enter either channel
l 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
are internally selected in pairs
- one for each channel
- 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 of a stereo magneti c 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 (Rs
) can be
determined from the desired loading resistance (RI) by
this
formula
Rs =
100,
000 x RI
ohms
00)'
- RI
or th is tabl e; for RI = 50KQ, use
Rs = 1 OOKQ; for RI
:: 33KQ,
use Rs = 50KQ; for
RI = 25KQ, use Rs = 33KQ.
SPEAKER
CH.
* 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 ampl ifjer, 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. Stereophonic
crystal cartridges
(Ronette "
Binofluid II 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
314
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 is preferable that the micro-
phones used be of the high impedance type.
4) AUXILIARY AI, 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 intoAUXJLlARY A 1, 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 pro
vided at the high
level inputs is exactly the loading impedance required.
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