Nagra IV-SJ Service Manual

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• TAPE/DIRECT, LINE&PHONES: switching of the playback signal o~ of
the direct signal on the line outputs, headphones and loudspeaker; switch
inactive on TEST

• TAPE/DIRECT, METER: switching of the playback signal or of the direct

signal on the circuit of rIleter 14; this switch cannot be locked on TAPE

• POWER: power selector switch i.e. built-in batteries or accumulators or

external power supply connected to plug 48

• Main function switch

STOP: recorder at • standstill
TEST: power sopplied to all circuits, except record and erase

RECORD: power supplied to all circuits and the motor; record and erase on

the 3 tracks
PLAYBACK: the recorded signal can be heard on the headphones and is fed
to the line outputs of connectors 41, 42,43,45 and 46 when switch 1 is on
TAPE (or on DIRECT if the output signal is reintroduced into the direct
chain. see 42)
PLA YBACK with Loudspeaker: playback of tape using loudspeaker

LIGHT; meter 14 lights up momentarily: remains illuminated when the

button is turned to the right

•

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Main attenuator CHANNEL 2: in steps of 10 dB for channel 2,Iower track

• Vernier attenuator CHANNE L 2; in steps of 1dB for channel 1

• Main attenuator CHANN.E L 1: in steps of 10 dB for channel I, upper track

• Vernier attenuator CHANNE L 1: in steps of 1 dB for channel 1

dB scale: for the microphone inputs, in relation to the sound pressure

level 0.OOO2pbar=0 dB
voltage scale; effective voltage applied to the line input, which gives a reading
of OdB on the AVERAGE scale of meter 14

REF. OSCILLATOR: switched on when the button is depressed, the
reference oscillator supplies a +10 dB signal to the direct amplifier on each

channel, after the attenuator

•

LINE/MIKE: line or microphone input selector, channel 2

LINE/MIKE: line or microphone input selector, channell

•

FI LTERS: 6-position filter selector switch for channell:

•

HP high·pass
L1N. linear

•

WE IGHTING A, B, C, D weighting curves A, B, C and D

METER FUNCTION: six-position selector switch for meter 14
lEVEL. AVERAGE FAST: on the AVERAGE decibel scale, average value

of the sound level, fast characteristic, red needle for channel I, green needle

for channel 2
lEVEL. AVERAGE SLOW; the same as AVERAGE FAST, but slow

characteristic

LEVEL, PEAK: on the PEAK decibel scale, peak value of the sound level,

channels as above
BATT.: on the BATTERIES scale, battery or accumulator check

Red needle: battery voltage per cell (VOLTS/CELL)

Green needle: voltage required by the motor, with the same reduction factor
as battery voltage
PILOT8o CUE:
Green needle: on the PILOT 0 to 100% scale, overall frequency deviation
caused by the pilot and CUE signals, 100% on the scale corresponding to a

deviation of ±40%

Red needle: on the PILOT +4 to -4% scale, frequency shift, as determined by
the built-in OFMS frequency meter, between a signal recorded or played back

on the third track and an internal reference

Position M:

Green needle: same as PILOT&CUE
Red needle: on the 0 to 100% scale, current through the motor, 100% on the
scale corresponding to 250 mA

Fll TERS: filter selector switch for channel 2. identical to II

CD

Meter: indicates sound level and checking functions according to the position

of selector switch 12

•

• PILOT: indicator which shows a white lone when frequency and amplitude

of the pilot signal are correct

SPEED&POWER: indicator which shows a white lone when the following
three conditions are fulfilled:

- power supply voltage higher than the maximum admissible value

- motor regulation within the correct operating range
tachometric speed fluctuations not exceedinq the maximum value

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PHONES: connector for mono headphones, impedance 25 to 600n

• CHANNEL, PHONES&L.S.: channel selector for listening with headphones
and loudspeaker

• LEVEL, PHONES: adjustment of the headphones volume

• Tape speed selector switch

• BIAS: 5'position bias selector switch

• Pinch-wheel

IS"=38.1 cmls

7'/,"

=

19.05cm/s

6)Fast wind switch:

REW.

• Supply reel

• Tension roller of the supplV reel

• Erase head

•• Stabilizer roller with 50 or 60 Hz stroboscope

• Recording head tracks 1 and 2

e.

Recording and playback head track 3

•• Playback head tracks 1 and 2

CD

Capstan

• 3'position lever controlling the pinch-wheel and tape guicles:

. - lever pulled to the left: for threading the tape (rewind possible in this

position)

- lever at 45° to the edge of the tape-deck: motor running, but tape not

moving

- lever pushed backwards: tape running

•• Tension roller of the take-up reel

• Take·up reel

3% .•=9.525 cm/s
1

'h"

=

3.81 ·cm/s

rewind with main switch 4 in any position
except STOP, lever 32 in disengage position

fast wind when main switch 4 on

PLAYBACK with Loudspeaker

6)RECORDING EOUALIZA TION ADJUSTMENT

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Direct analysis of sound signals
Used solely as an amplifier the NAGRA IV-SJ is a

precision sound level meter, which operates with
any calibrated microphone cartridge. The sound
pressure measurements must be taken in relation to

the

0

dB reference level, which corresponds to a

pressure of 0.0002 ubar, i.e. 20
This level coincides in practice with the audibility
threshold of the human ear at
quency, the sound level can be expressed in phones,
the phones value being equal to the dB value read
in relation to the 0.0002 /-Ibarreference.

'.The frequency response of the human ear is not

linear and depends very much on the sound level; a
sound level meter must therefore include weighting
filters which modify the values measured in accor­dance with certain criteria, so that they can be

interpreted in relation to the subjective impression
felt by the human ear. There are three standard
weighting curves, A, Band C. Curve A is used for

low and medium sound levels, which are the sub­ject of most analyses; curves Band C relate to

higher levels. Curve D relates to contour-lines of·

perceived noisiness, in particular with noise pro-

duced by aviation: this weighting is used for the

measurement of sounds which cause annoyance

in general. Curves A, B, G and D are shown after

the specifications.

The sound level measured is shown on a dual

galvanometer. with one needle per channel. Its

measuring circuit determines the average value of

the signal on RMS and its peak value on

PEAK, with different dynamic characteristics in
relation to the integration time. On RMS
FAST integration time is 200 ms: a signal at
lasting 200 ms gives a reading

which would correspond to the steady signal. On

RMS SLOW, integration time is 500 ms and
a signal lasting 500 ms gives a reading 4 dB below

that which would correspond to the steady signal.

These two integration times are in accordance with

J.lN/m2or 20 J.lPa.

1 kHz; at this fre-

1 kHz

1 dB lower than that

INSTRUCTION MANUAL

I

the GEl standard 179 for
meters. Naturally, any signal which is shorter than
the integration time will be shown below its real
value. For analysis of pulse signals or strong
transients a more useful reading is obtained on
PEAK, i.e. peak value with an integration time of

5

only
because it causes visual fatigue: in order to over­come this disadvantage the measuring circuit holds
the signal for about one second, thereby increasing
the fall time of the needle.

Recording and playback of the sound signals

In all cases where direct. measurement is not
sufficient for studying the signals picked up by the
microphone, these signals can be recorded on mag­netic tape and analyzed later in the laboratory.
While the two tracks used for direct recording are
in use, the third track

synchronization, a commentary, or a measuring­signal from D.C. up to 4 kHz. The three tracks
thus store signals in fully-synchronized form, which
is an important factor for analysis.

However, this storage is restricted to some extent

due to the limitations of present magnetic tapes.

These limitations concern the following charac-

teristics in particular:
the response curve

Attenuation at the upper and lower extremes of
the spectrum depends on the speed used. Very low
frequency signals, which are difficult to play back
with a small reproduce head, should be analyzed
by frequency transposition.

distortion

This increases very rapidly as soon as the maximum

recording level is exceeded, and tape saturation

occurs, generating harmonic frequencies (in

ticular 2nd and 3rd harmonics), which falsify the

analysis of the signals.

ms. This very fast reading cannot be used

Measurements

precrsion

C'IO

record F M signals for

sound level

par

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crosstalk
The juxtaposition of the two channels inside the
recording head and the playback head produces
crosstalk. This is the ratio, at a playback amplifier
output. between the wanted signal and the unwan­ted signal from the other channel. Crosstalk
increases at high frequencies.

The maximum peak level, which corresponds to a
tape flux of 32 mM/mm, is reached when the

measuring instrument shows

RMS scale and +20 dB on the PEAK scale.

These two values are given in relation to the sound

·pressure reference level 0 dB

0.0002J.1bar.
On RMS the integration time of the

measuring circuit is long enough not to indicate
short pulses at their exact value and risk exceeding
the maximum recording level, thereby saturating
the tape. That is why, on RMS , the maxi-

+

10

mum level is given at
the signals with strong pulse content saturating the
tape too Quickly.

In all cases where the nature of a signal is not
obvious it should be recorded with the measuring
circuit on PEAK, which is the only way to make
the peak value of very short pulses visible and to
avoid their exceeding the maximum recording level.

Frequency transposition
Playback speed may be different from recording

speed: this produces a frequency transposition of
the signals recorded within the ratio of these two
speeds. Since the response curve in the low fre­quencies is limited to
possible, if the tape transport speed is ten times
faster on playback than on recording, to play back
frequencies which are ten times. lower. Thus, a

2.5 Hz signal recorded at 1.5 ips will have a fre·

quency of

(transposition
conventional equipment. In the same way, the
time needed to analyze signals which vary very
slowly is reduced in the same ratio by this process.
Conversely. it is possible to analyze in more detail
a signal which varies rapidly by playing it back

more slowly than it was recorded. However, in
both cases, care must be taken that the transposi­tion does not alter the signals in any way, taking

into account the limitations of the frequency res-

ponse at the speeds used.

25 Hz if it is played back at 15 ips

1: 1

0), and can be analyzed easily by

dB: the10dB lead avoids

25 Hz on playback only, it is

+10 dB on the

=

20 pPa or

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Maximum frequency deviation t>fo
Frequency response at

Signal-to-noise ratio for deviation
of ±20%

Peak-to-peak input voltage for deviation of ±20

PILOT

CUE 2.0 V

-3 dB

o

to 4 kHz

±45%

44dB

2_8 V

%

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OPERATING CONDITIONS
Temperature

with manganese batteries

with external power

The recorder functions correctly in any position.

- 4to+160°F

-20to+ 71°C

-67 to +160

-55 to

+

0

71 °C

F

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]

1

dB

+10

-10

-20

-30

-40

-50

Wei21

ht'

0

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V

curve

/

A

Ffequency lEe Recommendation 179

/

./

./

.•...•.

!'-..

<,

10000
'2500

'6000 - 6.6 +3
20000

Rt'I.tI~

Respome

H,

20
25

31,5

40

SO

63

80

'00
'25
'60

200
250
3'5

"""

500
630

800
1000
1250

1600 + I
2000
2500

3150
4000 + 1

5000
6300

8000

dB

·50.5

-" •. 7

-39.4

-34.6

-30.2

-26.2

-22.5

-'9.1

-16.1

-13.4

-10.9

- •. 6

- 6.6

- ".8

- 3.2

- 1.9

- O.S

.•. 0.6

+ 1.2
.• 1.3

+ 1.2

-+

- 0.1

-1.1

- 2.5

- 4.3

- 9.3

0

0.5

Tolrnn~

limitl

dB dB

,.

••

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oJ

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±3

12

11

t'

.,

.,

11 11
11

11

±,

.,

.,

±1

"

"

.,

"

et
et

!.1.S
+1.5

+1.5
+2

+3 -6

+3

N"GRAIV.sJ

-2

-3

..

_M

_M

Toler.nee

lImln

!3
:!:2.S

.,

.

.,
.,

t2
11,5

t,

11
11

l'

.,

t,

11

11
11

11

11

et

11

.,
.,

11

11

.,

%1.5

11.5

11.5
1:1.5
t2

Hz

20

80

50 100 315

31,5

200

500

1000 3150 8000 12500

800

1200

5000 10000

20000

dB

+10

-10

-20

-30/

-40

-50

Wet21 n2

hti

0

./

/

/

V

20

Hz

31,5 50

80

./

100

»>

curve

~

200

B

500 1000

315

800

-r---.

.•...•.

8000

3150

12500

1200 5000 10000

<,

20000

frequency

H,

20
25

31.5
40 -14.2

SO

63

eo

100
120

ISO

200
260
316

"""

600
830

800

, GOD

1260

1e00
2000
2500

3160

4000
6000

8_
8000

10000
12500

18000

20000

tEe Aecommmdation 1N

A.I.live

Response

Toleranoe

limits

d8

·242

-20.4

-17.1

-u.s

- 9.3

- 7.4

- 5.e

- 42

- 3

- 2

- 1.3

- D.e

- 0.5

- 0.3

- 0.1

- O.t

- D.2

- 0."

- 0.7

- 12

o

-a

- 4."

- 6.1

- 8.4

-11.1

_.-._--------_.

0
0
0

0

1.8

dB dB

••

15
13 12

03
03

03

12

., .,

.,

"

.,

11

.,

11 11

.,

.,

tI

at

.,

.,

"

.,

11 11

"

.11.5
.1.5

1-t.fI

'2
+3
+3
+3

NAGAAIV·SJ

-2

-3

-4

-6

--

--

To~nlnce

limite

12
12

12
t2

12
:1:1.6

11

"

et

"

11

.,

11
11

11

.,

.,

11
11

11

11

.,

.11.5
i1.6

11.6

il,6

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---

r

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2.4. Connection of Brliel&Kjaer Amplifiers fitted
with Brliel

&

Kjaer Microphone Cartridges

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B&K

CARTRIDGE

~

The following types of cartridges

- 'h";4133,4134,4149and4163

- 1 ";4144,4145,4146and4161

- 1,4";

- 1/8";

can be fitted to the following types of preamplifiers:

- 1",

- '12

- 1",

- 1" : 2627, 2612 and 2613

- 1,4",

The cartridges can be fitted directly onto the pre­amplifiers when the diameters match; if they do not
match, a mechanical adapter can be used. The
output plug of the preamplifier screws into the
OSJP adapter and the plug of the preamplifier
adapter fits into microphone connector

10 should be on MI KE.

The recorder should be fitted with the QSJA-BK
microphone amplifier and the QSJC universal power
supply. These circuits can be installed as described
in the preceding paragraph,

4135 and 4136

4 138

1/2",

1,4" :

",1,4 ",

1/8" :

'12",

1,4",

1/8" :

%" : 2618

B&K

PREAMPLIFIER

261 5
2614
2619

37:

selector

---1

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=-=1

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2.5. Connection of Sennheiser MKH 110 Measuring

Microphone

The MKH 110 microphone consists of a capacitor
cartridge and an electronic circuit with a low impe­dance output; microphone sensitivity is 2 mV

It should be connected to microphone connector

37

by the QCJ-MKH cable; selector 10 should be on

MIKE_

The recorder should be fitted with the QSJA-MKH
microphone amplifier, which also supplies the vol-·
tage for the microphone.

Installation of aSJA-MKH Amplifier
Lock the lid of the recorder, turn screws 50 several

times and open the case to its full extent. Unscrew
the connector between the microphone input wiring
and the case interconnection board. Plug in and fix
this connector to the microphone amplifier and
secure the latter to the case interconnection board.
Unscrew the level adapter board. Place the shield
in position and fix it under tile ground comb and
under a nut screwed onto one of the two hinge
fixing screws (this screw should be longer - M3x8).

Reinstall the level adapter board.

IMbar.

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Signals and Voltages
Chassis connector external side or plug soldering

side

+200Y

+120V

r -

L_

-10G

,-----r-GND

+12,6V

Signals and Voltages
Chassis connector external side or plug soldering

side

~--..,.-- GNO

SIGNAL

-8Y------

-10G----~

,

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3. DIRECT MEASUREMENT OF SIGNALS

3.1.

Position of the Controls

Set switch 1 on DIRECT: switch 2, which cannot
be locked in position, remains on DIRECT. Turn
main selector switch 4 to TEST: the circuits are
then switched on and will stabilize after about 10
seconds.

3.4.3. Low·level Signals on the Microphone Input
QSJA-BK AMPLIFIER
With selector

7A

on0dB

Turn the cartridge type selector 40 to the position
which corresponds to the diameter of the cartridge
used. On
become +40. +60 and +90dB, values inscribed in a

circle.

10

on MIKE, set vernier attenuator

1f.t ••

the positions of gain selector 39

3.2. Selection of Measuring Circuit
Set the METER FUNCTION switch on one of the

LEVEL positions:

- RMS FAST : average valu~ of the sig·
nal on the RMS' scale of meter 14,
integration time 200 ms.

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- RMS SLOW : average value of the
signal on the same scale, but integration
time 500 ms.

- PEAK: peak value of the signal, on the
PEAK scale of meter 14, integration time
5 ms, with a memory circuit holding the

signal for about

The measuring circuit of the recorder should be

selected in accordance with the criteria given in

Section

3.3. Adjustment of the Monitoring Circuit
The signals can be monitored on the headphones

with switch

loudspeaker on PLAYBACK with Loudspeaker
(see 6.).

The mono headphones, impedance 50 to 600

plug into jack 17. The required channel can be
selected with switch
by potentiometer
screwdriver.

3.

4

in any position and with the built-in

1 second.

18

and the loudness regulated

19,

which can be adjusted with a

n.

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3.4.

Choice of Sensitivity

3.4.1.

I

Set selector 10 on LINE, turn main attenuator 7
fully to the left, or on GND, set vernier attenuator

7A on 0 dB (CAL.),

High·level Signals on the Line Input

I

Switch on the signal source connected to the line
input. While watching meter 14, turn main attenua­tor 7 to the right until the red needle makes a
visible movement. Calculate the value measured as
described in paragraph 3.6.1.

3.4.2. High-level Signals on the Microphone Input

Same procedure as in the preceding paragraph, but

with selector

10

on MIKE.

Turn attenuator
If the needle moves noticeably beyond +20 dB
PEAK or +10 dB RMS , turn switch 39 to
+80 dB. If the needle is clearly below 0 dB, turn
switch 39 to +40 dB. Calculate the value measured

and take into account the restrictions described in

paragraph

QSJA-MKH AMPLIFIER

This amplifier has no gain selector or cartridge type
selector. The sensitivity can be determined by main
attenuator

AMPLIFIER FOR GENERAL
RADIO MICROPHONE

The amplifier for use with the GENERAL RADIO
microphone is the QSJA-BK; please refer to the
above instructions for using this amplifier.

3.5. Choice of Filter
When filter selector switch 11 is on LlN, the

quency response of the direct chainislinear at
:to.3 dB from 2.5 Hz to 35 kHz. Selector switch
should be set on one of the following positions
according to the kind of measurements being taken:

HP: high-pass filter, attenuation

WEIGHTING A, B, C, D: weighting of the

The HP position should be used systematically when
the measurement of signals is not extended to very
low frequencies: in fact, since these are inaudible,
they are likely to falsify results and, in some cases,
saturate the amplifiers. Furthermore, this position
eliminates very low frequency noise from the car­tridge itself.

The weighting positions A, B, C and D are used, in
the case of noise measurement, to obtain a value
corresponding to the subjective impression felt by

the human ear (see Section 1).

7 to +20 dB and watch meter 14.

3.6.3.

7

only.

fre-

3

dB at

20 Hz, 12 dB per octave

frequency response as determined by
international standards, the exact value
of which is given at the end of the section
entitled Specifications.

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The arrowhead opposite the +40 dB position on
attenuator
restrictions must be observed in order to avoid
saturation of the input circuits, when measurements
are taken by microphone, preamplifier and ampli-

fier.
The performance of the microphone cartridges and

input amplifier circuits is restricted by the occur-

rence of saturation phenomena which are produced
when the sound level measured becomes very high.
These phenomena may be detected by a trained ear

if measurements are being taken and monitored
simultaneously (see
exposed acoustically to the sound source. If the
phenomena pass unnoticed the measurement will
be incorrect. The only sure way to avoid saturation
and its consequences is to impose a limit on the

attenuator which directly follows the input cir­cuits; when the attenuator is at this limit, any sound
signal which makes the needle of meter
to the right to its fullest extent, saturates the input
circuits and cannot be measured. In this case, the
amplifier gain must be reduced by turning its selec-

tor from +40 dB to +60 dB or from +60 dB to

+80 dB; if saturation still occurs on this position it

means that the output level of the transducer used

is too high. A less sensitive transducer should then
be used or an attenuator inserted between the trans­ducer and the preamplifier.

7

is to remind the user that certain

3.3.).

and if the operator is not

14

deviate

3.6.3.1. Limits and Corrections with theOJPA
Preamplifier and

Same as below

G (preamplifier gain) same as for Brtiel
2619 preamplifier.

3.6.3.2.

When main attenuator
at +40 dB, there is no risk of saturation as long as
the needle of meter
+20 dB PEAK, with gain selector 39 on +40 or
+GOdB; when the latter is on +80dB (+90 dB fora
~" cartridge), the main attenuator may be set
beyond the +40 dB position as saturation then
depends only on the cartridge used and the corres­ponding preamplifier.

With cartridge type selector
corresponding to the cartridge used, the sound level
is obtained by direct reading when the potentio­meter of the QSJP adapter is adjusted to a correc­tion value K, given in dB by the following relation:

limits and Corrections with Brfiel
Kjaer Preamplifiers and the QSJA-BK

Amplifier

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K=Ko - G - X

Ko==open circuit correction factor given by

the manufacturer

G

==

preamplifier gain in relation to the

type of cartridge and its mechanical

adapter given by the manufacturer

X difference between the typical sen-

sitivity of the cartridge and the

50 mV/N/m1reference value, in accor-

dance with the following table:

OSJA-BK Amplifier

7

is opposite the reference

14

does not move beyond

40

in the position

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Kjaer

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Type of
cartridge

X

in dB

*With the 1/4" cartridge 4136, 8 dB must be added

to the calculated value to obtain the sound level

takes into account the adjustment range limits of

the QSJP adapter).

**

Cartridge type selector 40 on 1/4 ": add 12 dB to

the calculated value to obtain the sound level.

Example

Ih"

cartridge 4133 with preamplifier 2619:
Ko=+12.2dB G=-O,4dB X=+12dB
Value to which the potentiometer of the QSJP

adapter shou Id be adjusted:

1"

K

=

'12 "

+12

0

12.2+0.4 - 12=+O.6d8

1,4 ••

4135 4136*

+22

'14"

+30

I/~"

4138"

+34

(X

t

p"-

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4. RECORDING OF SIGNALS

4.1. Choice of Tape
It is essential to use the type of magnetic tape for

which the recorder was adjusted at the factory; it is
only in this way that the values indicated in the
technical specifications {Section 2) can be obtained.

It is possible to use another type of tape by reo

adjusting the bias, equalization and recording level

. The performance obtained may

differ from the values shown in the test report

issued with each recorder; it is necessary to check

the results obtained with a new tape before using
the recorder for taking accurate measurements.

The positions of bias selector switch 21 correspond
to steps of 10%.

The length of the recording to be made is also a
determining factor in choosing the tape speed.
Place speed selector 20 on the position correspond­ing to the wanted speed; the speed can be switched
while the tape is running without damaging the
recorder.

4.3. Threading the Tape
Pull lever 32 forward to its fullest extent. Place a

full reel on the left-hand spindle (24) and fix it in
position with the knurled nut; place an empty reel
on the right-hand spindle (34) and fix it in position.

Lower the head shield. Unwind the tape slowly

from the supply reel arid thread it across the two

tension rollers 25 and 33 to wind it onto the take-up

reel; turn this reel a few times to that the tape is
pulled taut

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4.2. Speed Selection
The tape speed should be selected in relation to the

upper and lower limits of the frequency response:

at 15"/s (38 cm/s) : 25 Hz to 35 kHz ±1 dB
at 7.5"/s (19 cm/s) : 25 Hz to 20 kHz ±1 dB
at 3.75"/s (9.5 cm/s): 25 Hz to 10kHz ±1 dB

±

at 1.5"/5 (3.8 crn/sl: 25 Hz to 3.5 kHz

At 1.5"/s recording is possible from 2.5 Hz, with
playback by transposition (see 4.8).

When the tape speed is being selected recording

equalization should also be taken into account; this
is higher for low speeds and may cause tape satura­tion when the signal frequency is high, even if the
modulometer shows the recording level to be
correct (see 4.7.2. Restrictions).

1dB

:w:

••••

o •

Push lever 32 backwards to its fullest extent. Raise
the head shield.

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which is similar to the distribution spectrum of the
spoken word and of music - was used as the basis
for an inverted curve which determi nes the possible
pre-emphasis. For the three higher speeds, emphasis
and de-emphasis conform to the recorder standard
(mentioned in the test report and marked on plate

51).

For the

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ticular for recording very low frequency signals to
be played back by transposition at
emphasis has been calculated in relation to compati­bility for playback at

The emphasizing of signals during recording in
accordance with the standards has the advantage of
making it possible to play back the tapes on any
conventional recorder. On the other hand, this
process has one disadvantage: the frequencies
affected by emphasis are likely to cause tape
saturation, even if the recording level indicated on
meter 14 is correct. In fact, emphasis occurs in the
recording amplifier, i.e. after the measuring circuit,
which cannot under any circumstances indicate it.

Pre-emphasis depends on the tape speed: the lower
the speed the higher the treble emphasis will be.

Furthermore, the NAB standard also requires bass
pre-emphasis which, however, should not exceed
6

dB at the lower limit of the recording frequency
response. Treble pre-emphasis therefore pre­dominates and, to avoid saturating the tape, high
frequency signals must be recorded below the
maximum recording level (+20 dB PEAK). Taking
into account the difference between the NAB and
cel R standards, ifarecording is made at 6 dB
below the maximum level, i.e. at +14 dB PEAK,
there is no risk of saturation, as long as the signal
frequency is not higher than:

20

kHz for the

14 kHz for the 7.5" speed

5 kHz for the 3.75" speed

2.5

kHz for the

Since the pre-emphasis curve shows a rise of about

6 dB per octave. it is possible to calculate the pre-
emphasis value at a different frequency and deduct
the recording level reduction in relation to the

+20 dB maximum peak level.

1.5"

speed, which is used in par-

15"/5.

15"

speed

1.5"

speed.

15"

Is,

the

which means that noise inherent to the recording is
60 dB below the maximum recording level: this
level is reached when meter 14 indicates +20 dB
PEAK and, as gain selector 39 is on +40 dB, the

60

dB difference brings the noise level produced

during recording to 0 dB, i.e. to the 2.10- 5 Nlm
reference level. For the 40 dB signal the signal-to­noise ratio would also be 40 dB, therefore clearly
higher than the 10 dB signal-to-noise ratio obtained
with the cartridge and the input circuits used.

I

n practice, whi Ie the signal . of the
transducer and input circuits is below
noise level does not increase when the signal is
recorded. On the other hand, as soon as the sound
level reaches 100 dB, the signal must be kept as near
as possible to the maximum recording level in order

to obtain the highest possible signal·to-noise ratio.

To record, set main selector switch4on TEST;
allow the circuits to stabilize for about t~n seconds,
then

switch to RECORD: the tape begins to run.

4.7.4. Tape Monitoring during Recording

When main selector4is on TEST, the di rect signal

is present at the line outputs 43 and headphones

output

selector

When selector
DIRECT, it is again the direct signal which is
present at the outputs; but, if switch 1 is on TAPE,
the recorded signal is immediately played back and
will be present at the line and phones outputs.

Switch 2 fulfils the same function for meter 14,
which indicates the direct signal on DIRECT and
the playback signal on TAPE; this switch springs
back automatically to DIRECT.

TAPE/D IR ECT switches 1 and 2 make it possible
to check the quality of the signal during recording;
any audible or visible deterioration of the signal
indicates a false manoeuvre or defect.

17

according to the position of track

18.

4

is on RECORD and switch1on

60

dB, the

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4.7.3.

When gain selector 39 is on +40 dB and attenuator

7 on 0, maximum amplification can be obtained.

It

meter 14 then shows -10 dB, which is the limit of
readability. These signals are very weak, but can
nevertheless be recorded as such without decreasing
the signal·to-noise ratio of the cartridge and input
circuits. Thus, by using a BrLiel&Kjaer 4133

cartridge with its preamplifier and QSJP adapter,

the weighted noise level is 30 dB; with a 40 dB
signal the signal-to-noise ratio is 1OdB.

signal-to-noise ratio is always higher than 60 dB,

Signal·to·noise Ratio

is possible to measure signals at about +30 dB;

In the record/playback mode, the weighted

4.8. Frequency Transposition

Playback of signals recorded at a very low frequency
is difficult because of the smallness of the

NAG RA
of the frequency response of the amplifiers. To
analyse signals withafrequency between
and 35 Hz, set the speed selector 20 on

1.5"=3.81

meter function selector 12 on RMS SLOW
this position gives a more accurate reading than

RMS FAST and PEAK, which have too

rapid a characteristic.

Playback is at

(see 6.).

IV -SJ

playback head and the lower limit

crn/s, the filter selector

15"=38.1

em/s

in the usual way

11

on LI N. and

2.5

Hz

6.3. Interpretation of the Recorded Signals
It is necessary to fix a reference during recording

so that, when the recorded signals are analysed,
the exact value of the sound level can be
determined.

I

6.3.1. Written or Recorded Reference

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Before recording is begun, the position of the micro­phone amplifier gain selector
attenuator
or7A) should be noted on the recording data sheet,
or dictated on the third track using the QSCM
microphone. On playback, with METER switch 2
and LINE
will indicate the same value as during recording
and the output voltage will be in proportion to the
meter reading. If the tape is analysed on the recor­der itself, it is sufficient to add, in the usual way,
the value shown by the meter to the attenuator
and gain selector readings, which were taken during
recording. If analysis is done with the recorder
connected to exter.nal analysing equipment, the out·
put voltage can be compared with the 0 dB
references given in paragraph 6.1., thus making it
possible to determine the fraction of the sound
level given by the meter reading and to calibrate
the equipment. Finally, if analysis is done on a
recorder other than the NAGRA IV-SJ, the same
fraction of the sound level will be deducted from
the tape flux, the 0 dB meter reading corresponding
to 32 nWb/m on the tape.

In all cases, the position of the attenuators and that
of the microphone amplifier gain selector must be
known in order to determine the sound level at the
time of recording.

The accuracy of the meter reading on playback
depends on the quality of the tape used; even if it
is the kind of tape for which the recorder was
adjusted, the difference between the reading on
TAPE and on DIRECT may reach 2dB.

6.3.2. Recorded Internal Reference Signal

This method is more rapid and more accurate, but

still requires written notes or commentary on the

third track; it can be used to eliminate the playback

level inaccuracy due to the dispersion of the charac-

teristics of a tape of the same type. The reference

·generator built into the recorder applies a calibra­tion signal to the output of the direct amplifier,
without passing through the attenuators. When the
microphone amplifier gain selector and the
attenuators are adjusted to obtain a correct record­ing, the reference signal must be recorded at the
beginning of the tape and note taken of the sound

level to which it corresponds. This signal will be
used on playback for finding the sound level again
by conversion.

(6 or 7) and the vernier attenuator (6A

&

PHONES switch 1 on TAPE, meter 14

(38 or 39), the main

Example: the gain selector of the microphone
amplifier is on +60 dB, the main attenuator on
+30 dB and the vernier attenuator on 0 dB; record

the reference signal: the meter shows +10 dB; the

reference signal therefore corresponds to a sound

=

level of 60 + 30 + 10

the equipment will be calibrated at +100 dB when

the reference signal is played back.

6.3.3. Recorded External Signal Reference

An acoustic signal with a known sound level can be

used as a reference during recording. The B

pistonphone supplies a 250 Hz signal at 124 dB

±O.2

dB, and the B &Kcalibrator a 1 kHz signal at

94 dB ±0.3 dB.

Insert the microphone into the sound source and
check the calibration of the recorder by trying to

obtain a deviation on the meter between 0 and

+10 dB, then record this signal noting the position
of the microphone amplifier gain selector and that

of the attenuators. On playback this signal will

rep resent a reference at +124 or +94 dB.

If the signal to be analysed is at a very different

sound level, after calibration has been checked, the
gain selector and the attenuators must be reset in a

position which allows correct recording, and the

positions noted again. On playback the level of the

recorded reference signal no longer corresponds to
+124 or +94 dB; it should be calculated by adding

the difference in decibels between the first and

second reading to these values.

Example: the gain selector is on +80 dB, the main
attenuator on +40 dB and the vernier attenuator
on 0 dB; using the pistonphone, the reference signal

will be indicated at +4 dB (80 + 40 + 0 + 4

+124 dB) and recorded. The signal to be ana lysed

must be recorded with the gain selector on +60 dB,
the main attenuator on +30 dB, the vernier
attenuator on 0 dB, and it gives a reading of +10 dB;

its level is therefore 60 + 30 + 0 + 10=+100dB.
Attenuation indication for the reference signal:

80 + 40 + 0=120 dB

Attenuation indication for the signal to be analysed:

60 + 30 + 0
Difference: 90 - 120=-30 dB
Apparent level of the reference signal on playback:

124 - 30=+94 dB

=

+100 dB. During analysis

&

90 dB

K

=

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INSTRUCTION MANUAL

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Batteries and Accumulators

I

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The NAGRA IV-SJ or IV-SJS has space for .12

1.5 V cells (nominal voltage). Batteries conforming

I

to CE I (e.g. R20 type) or ASA (e.q. D or L90 type)
standards are suitable; their diameter should not
exceed 1
ween 21

The central electrode is positive and the can
negative, with a few exceptions; polarity is generally
shown byEBandesigns. If the batteries do not fit
securely in the box, the cells can be packed with
cotton wool, which will prevent them from pro­ducing unwanted noise while the recorder is in use.
If the batteries are too short and do not produce
the required contact, nickel or bronze (not alu­minium) coins can be inserted between the cells. A
mechanical adapter is available for use with NAGRA

recorders; this can be fixed to the contacts when
cells shorter than the minimum length are used
consistently.

1. Power Supply Voltage

New carbon-zinc batteries supply a total voltage of

18 V. The recorder will still function correctly
with 12 V at 15 ips (38 cm/s) and 11 V at the three

low speeds, when it is in perfect condition and wor-

king at a normal temperature. The built-in voltage
stabil izer means that the functioning of the recorder
does not depend on the unstabilized supply voltage,
except during fast wind which is at a speed in
direct proportion to the supply voltage.

2. Danger of Polarity Inversion

A diode connected in parallel on the power supply
will short circuit it if polarity inversion occurs.
The discharge current may overheat the wiring

insulation, which disintegrates and produces cor-

rosive agents. 2,5A fuses inserted in the battery box

5

/

" (33.5 mm) and they should be bet-

16

\132"

(59.5 mm) and 2

breaks the circuit; this fuse should be replaced

j

5/

" (62.5 mm) long.

32

if the recorder still does not work after the cells
have been replaced in the correct order.

3. Check on Supply Voltage and Condition of
the Batteries or Accumulators

Set meter function switch 12 on BATT. and main
switch 4 on RECORD. The red needle of meter 14
shows the unstabilized voltage expressed for one
cell (VOLTS/CELL); the total voltage is obtained
by multiplying this reading by 12. Simultaneously
the green needle indicates the voltage required by

the motor, with the same reduction factor; the
wider the angle between the two needles, the greater
the voltage reserve.

The index at 1.25 V on the scale marks the mini-

mum voltage at which manganese dioxide batteries
should be recharged so that the discharge/recharge

cycle can be repeated several dozen times.

SPEED

signal when the recorder is in operation: it shows a
white segment when voltage and speed are correct,
but turns black as soon as the supply voltage falls

below the minimum admissible value.

4. Operating Conditions

The following data have been extracted from docu-

mentation obtained from various suppliers. The list

of makes quoted here is not exclusive; the manu-

facturers mentioned are those which provide the

most accurate and readily-available information.

KUDELSKI S.A. does not accept any responsibility

for the degree of accuracy of the values indicated.

In general, thr, performance of a battery cell or

accumulator depends largely on the conditions and

length of storage before use. Care should therefore

be taken when suppliers are selected

&

POWER indicator 16 gives a warning

•

L

5. Leclanche Standard Batteries (carbon-zinc)
These batteries are light, inexpensive and sold every-

where. Their capacity varies considerably, depend-

ing on how they are used: it is high with low current,
but low with high current and acceptable with an
average current of about 350 mA, if periods of use
are interspersed with rest periods during which the

cells can depolarize (e.g. 4 hours use every 24 hours).

Normally the batteries can be used at temperatures

from 32° F (0° C) to 122

special types can be used at a lower temperature.

If batteries are stored at or below 68
their shelf life should be more than 12 months,
with remaining energy content 75 to 90%. This is
reduced to three months when the storage tem­perature is "04° F (+40° C). Above 122
batteries deteriorate rapidly. Cold storage produces
excellent results and certain cells retain their full
capacity if deep-frozen.

A carbon-zinc battery is considered to be com­pletely discharged when the voltage at its terminals
falls to 0.9 V with normal current flow.

6. Manganese Dioxide Alkaline Batteries

Of more recent design, these batteries have a higher

capacity, with the same current, than carbon-zinc

batteries. They can be used between 4

and 158

24 months at 68° F (+20° C) and even for more

than 12 months at 113° F (+45° C) according to

MALLORY. The discharge current is constant and
does not require rest periods as there is no need to
depolarize. However, these batteries are about 50%

heavier and cost more than the standard type. They

are suitable for use when:

0

F (+710C) and stored for more than

- the temperature is unfavourable for carbon­zinc batteries

- a long storage period is required

- the ratio of weight or volume to recording
hour must be as low as possible (ease of trans-

port and forwarding)

- the recorder is used for long uninterrupted

periods
there is high power consumption using
measurement microphones and preamplifiers
with a heating circuit.

0

F (+50°

CI,

and certain

0

F (+20° C)

0

F (+50° C)

0

f

(_20° C)

charging the cells beyond this limit, thus shortening
their life. A completely discharged cell can also be
recharged, but only once or twice.

Warning
WONDE R recommend recharging their battery
cells: MALLORY forbid it and warn the user of the
danger of explosion. EVEREADY produce a
special cell which can be recharged.

Before recharging manganese batteries it is absolu­tely essential to consult the manufacturer or supplier
to make sure that the type used lends itself to this
procedure.

7. Mercury Cells

The capacity and shelf life of these cells are greater
than for manganese batteries. However, they are
heavier and more expensive and they do not per­form so well at low temperatures, their lower limit
being 50
types.

In the majority of cases polarity is inverted - the
can is the positive pole - and a mechanical adapter
is required for using the batteries with a NAGRA
recorder; the only known exception is WONDE R
Pilat which has conventional polarity. As there is a
high risk of inversion, the polarity of mercury
batteries should be determined very carefully.

The voltage at the terminals of mercury cells
remains almost constant at 1.2 V during discharge;

it istherefore impossible to estimate their remaining

capacity by measuring their voltage.

8. Danger of Leakage

Electrical energy is liberated through a chemical re­action which fundamentally alters the constituants
of the battery cell and, in particular, attacks the
can. When the cell is completely discharged, it may

leak a corrosive liquid which can cause serious
damage to the inside of the recorder. The batteries
should therefore be checked frequently; if the

recorder is not going to be used for several weeks,

the batteries should be removed.

Leak-proof batteries are available which almost

completely eliminate the risk of leakage.

0

F (+100C]. except for certain special

[

r

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Some manufacturers indicate that it is possible to
recharge their manganese batteries under certain
conditions; WONDE R sanctions recharging their
manganese batteries when their charge falls to 80%
of their total capacity. Voltage per cell is then

1.25 V and this value is indicated by an arrow on

the VOL TS/CELL scale of meter 14.

Recharging can be done with a maximum current
equivalent to one fifteenth of the nominal capacity,
i.e. 0.5 A fora 7.5 A cell; charging should be stopped
when the voltage at the cell terminals reaches

1 fiR to 1.7 V. It is important not to continue

9. Nickel-cadmium Accumulators
The information below is again based on docurnen-

tation obtained from manufacturers and is an

indication only, as the evaluation criteria used are

different in each case.

Length of Life
The essential advantage of accumulators is that they
have a long life. Even if only 100 charge/discharge
cycles can be obtained, the cost per hour of opera­tion is approximately one-tenth that of battery

12. Conclusion

Generally, since battery or accumulator cells are
chosen according to the power consumption of a
given recorder, the following uses are possible:

- NAG RA IV S-J plus accessories, with .accumu­lators or with mercury or dioxyde manganese batteries

- NAGRA IV S-J without accessories or
NAGRA IV S-JS, possibility of using carbon­zinc battery cells.

Leak-proof battery cells are preferable. A PAR
charger is recommended for recharging accumula­tors as they do not have to be removed from the

if

recorder

this accessory is used.

m

Average
Current

240mA

310mA

400mA

460mA 100% RECORD

620mA 100% RECORD

765mA

Recorder

Setting in

Relation to

Length of

Use

50% TEST; Line input (without microphone)
50% RECORD

100% RECORD line input

lor Fast Wind

or 50% TEST! Microphone inputs with 1 OSJA-B K amplifier
50% RECORD 2 QJPA preamplifiers with heating

100% RECORD

or Fast Wind

or Fast Wind

or Fast Wind

100% RECORD

or Fast Wind

TOTAL LENGTH OF

OPERATING CONDITIONS

Inputs and Accessories

4 Hours

every

24 Hours

Eveready 1150IEveready E95 Accumulators

Carbon· zinc : Manganese·

Batteries dioxide Capacity

10 h 25 h

6h 22 h

-

Microphone inputs with 1 QSJA-BK amplifier
2 QJPA preamplifiers with heating

Microphone input with 1 B & K 2619 or 2618
preamplifier with heating, QSJP adapter and 3h 11 h
QSJA·BK microphone amplifier

Microphone inputs with 2 B & K 26 19 or 261 B
preamplifiers with heatinq, QSJP adapters and
QSJA·BK amplifier

Microphone inputs with 2 B&K 2615 pre­amplifiers, QSJP adapters and OSJA·BK
amplifier

4.5h 5h

-

-

use

Continuous Use

Nickel·cadmium

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Batteries 2-2.5 Ah

9h

6.5 h

14,5h

4.5 h

5.5 h

3h

3h

2h

Capacity

4Ah

17 h

13 h

10h

9h

6.5 h

5h

NAGRAIY.SJ

configurator

L
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[

[

[

Synchronization

SlO 13400

SlO-3

GClS 16300

OSV-2

OSlS 16350

Automatic speed synchronizer

Synchroniseur automatique de vitesse

13419

Crystal pilot generator for SlO
Generateur piloteaquartz pour SlO

Adapter for connecting SlO to NAGRA IV-SJ

Adaotateur

14600

Manual speedvariator

Variateur manuel de vitesse

Synchronizer for NAG RA IV-SJ
Synchroniseur pour NAGRA IV-SJ

pour

la connection SlO NAGRA IV-SJ

f

Internal electro accessories

OFMS 06780 Frequency meter for 50 Hz pilot signal

QSGX

QSJC 01128 Universal power supply for measuring microphones

QSJA­SK Amplificateura2 canaux pour prearnpliticateur QSPB

OSJA
BK Amplificateura2 canaux pour preamplificateur BK

OSJA­MKH

Frequence-rnetre pour signal pilote 50 Hz
Frequency meter for 60 Hz pilot signal

06781

Frequence-rnetre pour signal pitote 60 Hz

06698 Crystal pilot generator for 50 Hz

Generateur piloteaquartz 50 Hz

Crystal pilot generator for 60 Hz

06699

Generateur oitoteaquartz 60 Hz

Alimentation universelle pour microphones de mesure
2-channel amplifier for QSPB preamplifier

01165

2-channel amplifier for BK preamplifier

01170

01175 2-channel amplifier for MKH 110 microphones

Amplificateurs il2 canaux pour microphone MKH 110

Modulation

OSPB 11001

QSJP 11025

QSJP- 11050
GR

QJPA

11075

QCJ-

11902

MKH

16450

QSSF

OCJE 11900

QCJC

11901

16001

QSCM

16475

OSSC

Preamplifier for BK microphone cartridges
Preamplificateur pour microphoneacapsule BK

Adapter for connecting BK preamplifiers to NAGRA IV-SJ
Adaptateur pour connecter les preamptlficateurs Bk

Adapter for connecting GR preamplifiers to NAGRA IV-SJ
Adaotateur pour connecter les prearnplificateurs GR au NAGRA IV-SJ

Preamplifier for BK measuring cartridges
Preamplificateur pour capsulesde mesure BK

Cable for connecting MKH 110 microphone to NAGRA IV-SJ

Cable pour connecter les microphones MKH 110 au NAGRA IV-SJ
Amplifier with balanced outputs

Amplificateur avec sorties tlottantes
Line input cable with banana plugs

Cable d'entres ligne avec fiches banane
CUE input/output cable

Cable d'entree/sortie CUE
Commentary microphone with AlC

Microphone de commentaire avec RAS
Synchronizer for slide projector

Synchroniseur pour projecteur de diapositives

iau

NAGRA IV-SJ

[

[

[

[
[
(

I

NAGRAI\l..SJ

configurator

[
[

Power supply

ATN-2

OCAS 98001

OCAW

PAR

PPO

PO

PA-R 98251

PA-4 98254

AST

Carrying eases

OHP 14120

OHC 14125

OHTP 99009 Standard carrying casewith pocket

OHTRC 99220 Leather cover for OSET

Mains power supply 110-250 V with pilot signal output

14350

Alimentation secteur 110-250 V avecsortie signal pilote
Mains cable with Swissplug

Cable d'alimentation secteur avec fiche suisse

98003 Mains cable without mains plug

Cable d'alimentation secteur sansfiche secteur

13200

Charger for PA type rechargeable cells
Chargeur pour accumulateurs du type PA

14150 Multiple connection box

Bolte de derivation

98202 Set of 12 standard cells

Jeu de 12 piles standard
Set of 15 rechargeablecells withextension 2,5 Ah

Jeu de 15 accumulateurs avec rallonge 2,5 Ah

Set of 12
Jeu de 12 accumulateurs 4 Ah

Stabilized power supply for measurements

90400

Alimentation stabilisee de laborataire

Carrying handle
Poignee

Spare carrying strap for NAGRA IV-SJ
Courraie de rechange pour porter Ie NAGRA IV-SJ

Saooche standard avec poche

Cauvercle de sacachepour OSET

4 Ah rechargeable cells

E)(ternal electro accessories

OGB 14001 10 1/2" reel adapter

OCA

OGBC 14005

OGBN 14006

OGBA 14007 AEG-type hub holder

OSM 14700

IACC 17910

OCAS 98001 Mains cable with Swiss-type plug

OCAW 98003 Mains cable without mains plug

Mechanical accessories

OTIM 14650 Tape driven timer

OLEN

OAAC 06260 Tape cleaning blade

MAG

OSH

Adaotateur grande bobine 267 mm

Start-stop cable for remote controt

14102

Cable start-stop pour commandeadistance

Normal 8 mm cinespool holder
Parte-bobine cinema (standard I

NAB-type hub holder
Porte noyau type NAB

Porte noyau type AEG

Field monitor and amplifier

Maniteur-amplificateur de reportage

Removable cell compartment for OSM and IS
Magasin arnovible d'accumulateurs pour OSM et IS

Cable d'alimentatian secteur avec fiche suisse

Cable d'alimentatian secteur sansfiche secteur

Compteur temps eruralne par la bande

14655 Tape driven metrical counter

Compteur rnetrique entralne par la bande

A.deur de bande

9OBOI

90802 Electronically-controlled degausser 110 - 117 V

14130 Lid when using 7" reels

,

Electranically-contralled degausser220 - 240 V
Demagnetiseur Acommande electronique 220 - 240 V

Demagnetiseuracommande electronique 110 - 117 V

Couvercle pour I'emploi de babines 178 mm

[
[
[

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