Nagra IV-SJ User manual

• 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
o Main attenuator CHANNEL 2: in steps of 10 dB for channel 2,Iower track
• Vernier attenuator CHANNE L 2; in steps of 1 dB 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
CD
•Fll TERS: filter selector switch for channel 2. identical to II
Meter: indicates sound level and checking functions according to the position
of selector switch 12
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• PILOT: indicator which shows a white lone when frequency and amplitude
of the pilot signal are correct
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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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«I» 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
IS" = 38.1 cmls
7'/," = 19.05cm/s
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3% .• = 9.525 cm/s
1 'h" = 3.81 ·cm/s
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• BIAS: 5'position bias selector switch
• Pinch-wheel
6)Fast wind switch:
REW.
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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
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• 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
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 J.lN/m
2
or 20 J.lPa.
This level coincides in practice with the audibility
threshold of the human ear at 1kHz; at this fre-
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 accor-
dance 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 sub-
ject 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 1kHz
lasting 200 ms gives a reading 1dB lower than that
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
INSTRUCTION MANUAL
I
Measurements
the GEl standard 179 for precrsion sound level
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
only
5 ms. This very fast reading cannot be used
because it causes visual fatigue: in order to over-
come 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 mag-
netic tape and analyzed later in the laboratory.
While the two tracks used for direct recording are
in use, the third track
C'IO record F M signals for
synchronization, a commentary, or a measuring-
signal 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
par
ticular 2nd and 3rd harmonics), which falsify the
analysis of the signals.

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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 unwan-
ted signal from the other channel. Crosstalk
increases at high frequencies.
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The maximum peak level, which corresponds to a
tape flux of 32 mM/mm, is reached when the
measuring instrument shows +10 dB on the
RMS scale and +20 dB on the PEAK scale.
These two values are given in relation to the sound
·pressure reference level 0 dB
= 20 pPa or
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-
mum level is given at +
10 dB: the 10 dB lead avoids
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 fre-
quencies is limited to 25 Hz on playback only, it is
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 25 Hz if it is played back at 15 ips
(transposition
1: 1 0), and can be analyzed easily by
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 transposi-
tion does not alter the signals in any way, taking
into account the limitations of the frequency res-
ponse at the speeds used.
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Maximum frequency deviation t>fo
Frequency response at -3 dB
Signal-to-noise ratio for deviation
of ±20%
±45%
o to 4 kHz
44dB
Peak-to-peak input voltage for deviation of ±20 %
PILOT 2_8 V
CUE 2.0 V
I OPERATING CONDITIONS
Temperature
with manganese batteries
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with external power
- 4to+160°F
-20to+ 71°C
-67 to +160
0
F
-55 to
+ 71 °C
I The recorder functions correctly in any position.
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1

ht'
Wei21 In2 curve
A
dB Ffequency lEe Recommendation 179
N"GRAIV.sJ
Rt'I.tI~
Tolrnn~
Toler.nee
Respome
limitl
lImln
+10
H, dB dB dB
20 ·50.5
,.
3
25
-" •. 7
••
: :2.S
0
31,5 -39.4 oJ
.,
/
.•...•.
40
-34.6 oJ
. .,
./
'-..
SO
-30.2
oJ
.,
./
<,
63
-26.2
±3
t2
80 -22.5
12 11,5
-10
/
'00
-'9.1
11
t,
'25
-16.1
t'
11
V
'60
-13.4
.,
11
200 -10.9
.,
l'
-20
250
- •. 6
11 11
3'5
- 6.6
11
.,
.I
"""
- ".8
11
t,
/
500 - 3.2
±,
11
630
- 1.9
.,
11
-30
I
800
- O.S
.,
11
1000 0 ±1
11
/
1250
.•. 0.6
"
11
1600 + I
"
et
-40
2000 + 1.2
"
11
/
2500
.• 1.3
., .,
3150
+ 1.2
et
.,
/
4000 + 1 et 11
5000
-+ 0.5
.1.S
11
-50
6300
- 0.1 +1.5
-2
.,
J
8000 -1.1
+1.5
-3
%1.5
I
10000 - 2.5 +2
..
11.5
'2500 - 4.3 +3 -6
11.5
'6000 - 6.6 +3
_M
1:1.5
20000 - 9.3 +3
_M
t2
Hz
80 200 500 1000 3150 8000 12500
20 31,5 50 100 315 800 1200 5000 10000 20000
hti
Wet21 n2 curve
B
dB
frequency
tEe Aecommmdation 1N NAGAAIV·SJ
A.I.live Toleranoe
To~nlnce
Response
limits
limite
+10
H,
d8 dB dB
20
·242
••
12
0
25 -20.4
15 12
»>
~
-r---.
31.5
-17.1 13 12
.•...•.
40 -14.2
03 12
./
<,
SO
-u.s
03
t2
./
63 - 9.3
03 12
-10
eo
- 7.4
12
:1:1.6
/
100
- 5.e
., .,
120 - 42
.,
11
/
ISO
- 3
"
"
-20
200 - 2
.,
et
V
260
- 1.3 11
"
316 - D.e
.,
11
-30/
"""
- 0.5
11 11
600 - 0.3
., .,
830
- 0.1
.,
11
800 0
tI
11
, GOD
0
at
11
1260 0
., .,
-40
1e00 0
.,
.,
2000
- O.t
"
11
2500 - D.2
.,
11
3160
- 0."
"
11
4000
- 0.7
11 11
-50
6000 - 12
.11.5
11
8_
o 1.8
.1.5
-2
.,
8000
-a
1-t.fI
-3
.11.5
10000
- 4."
'2 -4
i1.6
12500 - 6.1 +3
-6
11.6
18000 - 8.4
+3
--
il,6
Hz
20000 -11.1
+3
--
"
80 200 500 1000 3150 8000 12500
20 31,5 50 100 315 800 1200 5000 10000 20000
_.-._--------_. ---
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2.4. Connection of Brliel & Kjaer Amplifiers fitted
with Brliel & Kjaer Microphone Cartridges
B&K
CARTRIDGE
~
B&K
PREAMPLIFIER
---1
QJ I
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~T-'
=-=1 I I
QSJA-BK
='iJJ
==[J
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The following types of cartridges
- 'h";4133,4134,4149and4163
- 1 ";4144,4145,4146and4161
- 1,4"; 4135 and 4136
- 1/8"; 4 138
can be fitted to the following types of preamplifiers:
- 1", 1/2", 1,4" : 261 5
- '12 ",1,4 ", 1/8" : 2614
- 1", '12", 1,4", 1/8" : 2619
- 1" : 2627, 2612 and 2613
- 1,4", %" : 2618
The cartridges can be fitted directly onto the pre-
amplifiers 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 37: selector
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,
Signals and Voltages
Chassis connector external side or plug soldering
side
+200Y
+120V
.J
r -
L_
,
-10G
,-----r-GND
+12,6V
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 impe-
dance output; microphone sensitivity is 2 mV IMbar.
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.
Signals and Voltages
Chassis connector external side or plug soldering
side
~--..,.-- GNO
-8Y------
SIGNAL
-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 4to TEST: the circuits are
then switched on and will stabilize after about 10
seconds.
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.
- 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 1second.
The measuring circuit of the recorder should be
selected in accordance with the criteria given in
Section 3.
3.3. Adjustment of the Monitoring Circuit
The signals can be monitored on the headphones
with switch
4 in any position and with the built-in
loudspeaker on PLAYBACK with Loudspeaker
(see 6.).
The mono headphones, impedance 50 to 600 n.
plug into jack 17. The required channel can be
selected with switch
18 and the loudness regulated
by potentiometer
19, which can be adjusted with a
screwdriver.
3.4. Choice of Sensitivity
3.4.1. High·level Signals on the Line Input
Set selector 10 on LINE, turn main attenuator 7
fully to the left, or on GND, set vernier attenuator
7A on 0dB (CAL.),
Switch on the signal source connected to the line
input. While watching meter 14, turn main attenua-
tor 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.
3.4.3. Low·level Signals on the Microphone Input
QSJA-BK AMPLIFIER
With selector
10 on MIKE, set vernier attenuator
7A on 0 dB
Turn the cartridge type selector 40 to the position
which corresponds to the diameter of the cartridge
used. On
1f.t •• the positions of gain selector 39
become +40. +60 and +90dB, values inscribed in a
circle.
Turn attenuator 7to +20 dB and watch meter 14.
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
3.6.3.
QSJA-MKH AMPLIFIER
This amplifier has no gain selector or cartridge type
selector. The sensitivity can be determined by main
attenuator
7 only.
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 fre-
quency response of the direct chain is linear at
:to.3 dB from 2.5 Hz to 35 kHz. Selector switch
11
should be set on one of the following positions
according to the kind of measurements being taken:
HP: high-pass filter, attenuation 3 dB at
20 Hz, 12 dB per octave
WEIGHTING A, B, C, D: weighting of the
frequency response as determined by
international standards, the exact value
of which is given at the end of the section
entitled Specifications.
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 car-
tridge 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).

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The arrowhead opposite the +40 dB position on
attenuator 7 is to remind the user that certain
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
3.3.). and if the operator is not
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 cir-
cuits; when the attenuator is at this limit, any sound
signal which makes the needle of meter
14 deviate
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 trans-
ducer and the preamplifier.
3.6.3.1. Limits and Corrections with theOJPA
Preamplifier and OSJA-BK Amplifier
/
Same as below
G (preamplifier gain) same as for Brtiel
& Kjaer
2619 preamplifier.
3.6.3.2. limits and Corrections with Brfiel &
Kjaer Preamplifiers and the QSJA-BK
Amplifier
When main attenuator
7 is opposite the reference
at +40 dB, there is no risk of saturation as long as
the needle of meter
14 does not move beyond
+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 corres-
ponding preamplifier.
With cartridge type selector
40 in the position
corresponding to the cartridge used, the sound level
is obtained by direct reading when the potentio-
meter of the QSJP adapter is adjusted to a correc-
tion value K, given in dB by the following relation:
I K = Ko - G - X I
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/m
1
reference value, in accor-
dance with the following table:
Type of
cartridge
X in dB
1"
'12 "
1,4 ••
'14 I/~"
4135 4136* 4138"
0+12 +22 +30 +34
*With the 1/4" cartridge 4 136, 8 dB must be added
to the calculated value to obtain the sound level
(X
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:
K = 12.2 + 0.4 - 12 = +O.6d8

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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%.
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
± 1dB
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 satura-
tion when the signal frequency is high, even if the
modulometer shows the recording level to be
correct (see 4.7.2. Restrictions).
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 correspond-
ing 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
:w:
••••
o •
Push lever 32 backwards to its fullest extent. Raise
the head shield.