Nagra IV-SJ Manuel utilisateur

INSTRUCTION MANUAL

o

KUDELSKI

SA

NAGRA

Tape Recorders Manufacture

CH-1033

Cheseaux/Lausanne

Switzerland

Tel (021)

91

21

Telex

459

302

nagr

ch

code

no. 20.01.004.151

MEASUREMENTS

chapter 1

SPECIFICATIONS

chapter 2

DIRECTIONS

FOR USE

chapter

3

BATTERIES

AND

ACCUMULATORS

chapter

4

ACC

ESSO

RI

ES

chapter

5

Printed

in

Switzerland by

KUD

ELSKI S.A.

Edition

August 1985

NAGRA,

KUDELSKI,

NEOPI

LOT,

NEOPI

LOTTON,

NAGRASTATIC,

NAGRAFAX,

sont

des marques enregistrees, proprit'!te de

KUDE

LSKI

S.

A.

fabrique

d'enregistreurs

NAGRA.

25

23

24

26

21

35

20

27 28

29

30

31

22

34

32

33

18

1719

107

70 8 6

60

9

16 15 14 13

11

12

5

4

1

TAPE/DI

RECT,

LINE

&PHONES:

switching

ofthe

play-

back signal

or

of

the

direct

signal

on

the

line

outputs,

headphones and loudspeaker;

switch

inactive

on

TEST

2

TAPE/DIRECT,

METER:

switching

of

the

playback

signal

or

of

the

direct

signal

on

the

circuit

of

meter

14;

this

switch

cannot

be locked

on

TAPE

3 POWER:

power

selector

switch

i.e.

built-in

batteries

or

accumulators

or

external

power

supply

connected

to

plug

48

21 BIAS:

5-position

bias

selector

switch

22

Pinch-wheel

23

Fast

wind

switch:

3

3/4

ips =

9.525

cm/s

1

1/2

ips =

3.81

cm/s

rewind

with

main

switch

4

any

po-

sition

except

STOP,

lever

32

in

disengage

position

fast

wind

when

main

switch

4

on

PLAYBACK

with

Loudspeaker

REW·444

~~~~~~

17

PHONES:

connector

for

mono

headphones,

impedance

25

to

600[2

18

CHANNE

L,

PHONE

& L.S.:

channel

selector

for

listening

with

headphones

and

loudspeaker

19

LEVE

L,

PHON

ES:

adjustment

of

the

headphones

volume

20

Tape

speed

selector

s.witch

15

ips =

38.1

cm/s

7 1

/2

ips =

19.05

cm/s

13

FI

L

TERS:

filter

selector

switch

for

channel

2, identical

to

11

14

Meter:

indicates

sound

level

and checking

functions

ac-

cording

to

the

position

of

selector

switch

12

15

PI

LOT:

indicator

which

shows

a

white

zone

when

frequency

and

amplitude

of

the

pilot

signal

are

correct

16

SPEED

&

POWER:

indicator

which

shows

a

white

zone

when

the

following

three

conditions

are

fulfilled:

power

supply

voltage

higher

than

the

maximum

admis-

sible value

motor

regulation

within

the

correct

operating

range

tachometric

speed

fluctuations

not

exceeding

the

maximum

value

24

Supply

reel

25

Tension

roller

of

the

supply

reel

26

Erase

head

27

Stabilizer

roller

with

50

or

60

Hz

stroboscope

28

Recording

head

track

1

and

2

29

Recording

and

playback

head

track

3

30

Playback

head

tracks

1

and

2

31

Capstan

32

3-position

lever

controlling

the

pinch-wheel

and

tape

guides:

lever

pulled

to

the

left:

for

threading

the

tape

(rewind

possible

in

this

position)

lever

at

45°

tb

the

edge

of

the

tape-deck:

motor

running,

but

tape

not

moving

lever

pushed

backwards:

tape

running

33

Tension

roller

of

the

take-up

reel

34

Take-up

reel

35

RECORDING

EQUALIZATION

ADJUSTEMENT

4 Main

function

switch

STOP:

recorder

at

a

standstill

TEST:

power

supplied

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

01

RECT if

the

output

signal

is

reintroduced

into

the

direct

chain,

see

42)

PLAYBACK

with

Loudspeaker:

playback

of

tape

using

loudspeaker

5

LIGHT:

meter

14

lights

up

momentarily;

remains

illu-

minated

when

the

button

is

turned

to

the

right

6 Main

attenuator

CHANNEL

2:

in

steps

of

10

dB

for

channel

2,

lower

track

6a

Vernier

attenuator

CHANNEL

2:

in

steps

of

1

dB

for

channel

2

7 Main

attenuator

CHANNEL

1:

in

steps

of

10

dB

for

channel

1,

upper

track

7a

Vernier

attenuator

CHANNEL

1:

in

steps

of

1

dB

for

channel

1

NOTE: dB scale:

for

the

microphone

inputs,

in rela-

tion

to

the

sound

pressure

level

0.0002

J.Lbar

=0

dB

Voltage scale:

effective

voltage

applied

to

the

line

output,

which

gives a reading

of

0

dB

on

the

RMS scale

of

meter

14

8

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

9 L1NE/MI KE: line

or

microphone

input

selector,

channel

2

10

L1NE/MI KE: line

or

microphone

input

selector,

channel

1

11 FI L

TERS:

6-position

filter

selector

switch

for

channel

1

HP

=

high-pass

LIN. = linear

WEIGHTING

A,B,C,D =

weighting

curves

A,B,C,D

12

METER

FUNCTION:

six-position

selector

switch

for

meter

14

LEVEL,

RMS

FAST:

on

the

decibel

scale, RMS value

of

the

sound

level,

fast

characteristic,

red

needle

for

channel

1, green

needle

for

channel

2

LEVEL,

RMS SLOW:

the

same

as RMS

FAST,

but

slow

characteristic

LEVEL,

PEAK:

on

the

PEAK

decibel

scale,

peak

value

of

the

sound

level,

channels

as

above

BATT:

onthe

BATTERIESscale,

battery

or

accumulator

check,

reed

needle:

battery

voltage per cell

(VOL

TS/

CELL),

green

needle:

voltage

required

by

the

motor,

with

the

same

reduction

factor

as

battery

voltage

PI

LOT & 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

PI

LOT

+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

36

MICROPHONE

CHANNEL

2: channel 2

microphone

input

44

PILOT:

pilot

signal

input

for

the

3rd

track

EXTERNAL

VIEW

OF C

HAS

SIS

CONNECTOR

OR

PLUG FROM THE

SOLOERING SIDE

ground

Clapper: reference

oscillator

or

crystal

pilot

generator

control

terminal

3

Xtal:

50

or

60

Hz internal crystal

pilot

generator

output

4

PI

LOT

IN:

pilot

signal

input

LINE

OUTPUT

2:

channel 2 line

output

on

banana jacks

45

200V

voltage available

with

built-

120V

in

microphone

power

supply

voltage, varies according

to

the

type

of

amplifier

-lOG:

-10V

stabilized voltage,

maximum

current

350

mA

chassis

preamplifier

supply

voltage

signal

input

signal

input

ground

4

1

2

3

5

6

7

8

EXTERNAL

VIEW

OF

C

HAS

SIS

CONNECTOR

OR

PLUG FROM THE

SOLDERING SIDE

46

LINE

OUTPUT

1:

channell

line

output

on

banana jacks

37

MICROPHONE

CHANNEL

1:

channel 1

microphone

input

connector,

identical

to

36

47

CUE:

connector

fo

recording and playback

on

the

third

track

38

Gain selector

for

channel 2

microphone

amplifier,

3 posi-

tions,

+40,

+60

and

+80

dB

39

Gain selector

for

channel 1

microphone

amplifier,

identical

to

38

40

MICROPHONE

TYPES:

B & K cartridge

type

selector

EXTERNAL

VIEW

OF

C

HAS

SIS

CONNECTOR

OR

PLUG FROM THE

SOLDERING SlOE

1 CUE

IN:

modulation

signal

input

2

-lOG:

-10V

stabilized voltage

3

PI

LOT

OUT:

pilot

signal

output

4

-10V:

stabilized voltage available

only

during

recording

5

-10V

FM: voltage

terminal

to

activate

the

FM

modulator

6 CUE

OUT:

signal

output

(direct

or

recorded)

7

ground

EXTERNAL

VIEW

OF C

HAS

SIS

CONNECTOR OR

PLUG FROM THE

SOLDERING

SIDE

41

CHANNEL

2:

channel 2

multiple

connector

VAR.

LEVEL

IN: line

input

impedance

100kr2,

input

voltage

> 1

mV

2

-10

G: stabilized voltage

-10V

4 Playback

output:

output

voltage

10

mV

at

0

dB,

load>

47 kr2

7 ground

EXTERNAL

VIEW

OF

C

HAS

SIS

CONNECTOR

OR

PLUG FROM THE

SOLDERING SlOE

48

POWER

PACK:

connector

for

external

power

supply

1

-BATT.:

negative pole

of

the

bat-

tery

box

2

+BATT.:

positive pole

of

the

bat-

tery

box

and

ground

3 STOP:

motor

stop

control

terminal

(connect

to

-10V

to

stop)

4 SPEED

CORRECTION:

tape speed

correction

signal

input

5

EXTERNAL

-12V

to

-30V:

12

to

30V

external

power

input,

negative

pole

6

-lOG:

-10V

stabilized voltage

42

CHANNEL

1:

channell

connector,

identical

to

41,

shown

with

strap plug

to

reintroduce

the

playback signal

into

the

direct

chain (switch 10 must be on

LINE)

EoIITERNAL VIEW

OF

C

HAS

SIS

CONNECTOR

OR

PLUG FROM THE

SOLDERING SIDE

43

OUTPUTS:

line

output

connector

1

LINE

OUT

2:

line

output,

channel

2,

output

voltage

100

mV

at

0

dB

in a load greater

than

10

kr2

2

-lOG:

stabilized

output

voltage

-10V

3

LI

NE

OUT

1: line

output

channell,

output

voltage

100

mV

at

10

dB

in

a load greater than 10 kr2

4 unstabilized negative supply voltage

5

-lOR:

stabilized voltage

-10V

available

only

during

recording

6 STOP:

motor

stop

control

terminal

(connect

to

-1

OV

to

stop)

7 ground

INSTRUCTION MANUAL

I

Direct

analysis

of

sound signals

Used solely

as

an

amplifier

the

NAG

RA

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

Ilbar, i.e.

201lN/m

2

or

20

IlPa.

This level coincides in practice

with

the

audibility'

threshold

of

the human ear

at

1

kHz;

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

Ilbar

reference.

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,

C 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 1

kHz

lasting

200

ms

gives a reading 1 dB

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

Measurements

the

CE

I standard

179

for

precIsion 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

can record FM 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

cu

rve

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.

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.

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

,uPa

or

0.0002,ubar.

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

+10dB:

the

10dB

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

ti

mes

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.

INSTRUCTION MANUAL

R20

D and

L

90

120mA

205mA

260mA

465mA

305mA

DIMENSIONS

AND

WEIGHT

Dimensions

of

the

box

as

such

with

the

lid

closed,

without

knobs, feet, handle

or

handle

mounts

12.6 x 8.8 x

4.4"

-

318

x

222

x

110

mm

Overall dimensions

without

the

removable handle

13.2 x

9.6

x

4.5"

-

333

x

242

x

113

mm

Thickness

of

the

Anticorodal

sheet

used

for

the

box

.

080"

- 2

mm

Thickness

of

the tape deck

.120"

- 3

mm

Empty

weight,

without

batteries

or

tape

14 Ibs -

6.150

kg

Weight

with

ordinary

batteries,

5"

reels and tape

161bs -

7.300

kg

POWER SUPPLY

Supply

voltage,

direct

current,

positive

to

the

ground 12

to

30

V

Current

consumption

on Test

on Line Playback

on Record

direct

mic.

(1

BK

2619)

on Rapid Rewind

Type

of

batteries used (12 cells)

CE

I standard

ASA

standard

2

Specifications

MAGNETIC

TAPE

Nominal

width

1/

4

" -

6.25

mm

Admissible thickness

0.5

to

2

mils

- 12

to

50jlm

Maximum

reel

diameter

with

lid

open

7"

-178mm

Recording

time

at 7

1

/

2

ipswith35jlm

(1.5

mils)tape

45

min

.

Maximum

reel diameter

with

lid

closed

5"

- 127

mm

Recording

time

under

the same

conditions

22 min.

Rewind

time

with

5"

reel and

35

/-lm

(1.5 mils)

tape 2

min.

TAPE

TRANSPORT

Switchable

nominal

speeds:

15 ips 38.1

cm/s

7

1

/2

ips 19.05 cm/s

3%

ips

9.525

cm/s

1

12

ips 3.81 cm/s

Stability

of

the nominal

speed

in relation

to

the

temperature

(from

0°

to

50°C), the position

of

the recorder, the distribution

of

the tape between

the reels, and the supply voltage (except

for

1

1/2

ips). ±0.1%

Wow

and

flutter

weighted peak-to-peak value, in accordance

with

DIN

45 507 standard: (lEE

193-1972

1 ANSIS

4.03.1972)

26 hours

11~

hours

Approximate autonomy

with

Eveready E95 man-

ganese

dioxide alcaline batteries

Continuous

use,

recording

direct

with

mic.

and

2619 preamp.

15 ips

7 1/2 ips

3314 ips

1

1/2

ips

Starting time

±0.05% (0.07%)

±0.07% (0.11%)

±0.12% (0.15%)

±0.25% (0.3%)

3

seconds

DIRECT

RECORDING

TRACKS

Amplifier

chain

(without

microphone

amplifiers)

Input

impedance

100

kS1

Overall accuracy

of

the

attenuator

±0.1 dB (±0.2 dB)

Frequency response

from

2.5 Hz

to

35

kHz

±0.3 dB (±0.5 dB)

Record and Playback

Nominal

recording level, identical

to

Maximum

Peak Level (M.P. L.) =

320

nWb/m

for

NAB

405

nWb/m

for

CCIR

Bias

frequency

150

kHz

Bias

switchable per

10%

increments

Weighting curve accurac'{

better

than

CE

I

179

and

CEI

537

(for

exact curve

see

diagrams)

High

pass

filter

attenuation

- 3 dB

at

20

Hz, 12 dB per octave

± 1 dB

(2

dB)

3M

177

LPR

35 LH

82 dB (80 dB)

± 1.5 dB

(3

dB)

7

1/2

ips 25 Hz

to

20 kHz

33/4

ips 25 Hz

to

10 kHz

*1

1/2

ips 25 Hz

to

3.5 kHz

*recording possible

from

2.5 Hz

with

translation

to

15 ips in playback

for

NAB

Tape

used

for

testing

for

CCI

R

Erase

efficiency referred

to

M.P.L.

Frequency

response, recording at

20dB

below

M.P.L.

15 ips 25 Hz

to

35 kHz

66 dB (62 dB)

74

dB (70

dB)

80dB

(74dB)

at

Maximum

Peak

10

mV

RMS

1%

distortion

refer-

+8.5 dB (+8 dB)

Input

voltage

for

recording

Level,

maximum

sensitivity

Maximum admissible level

for

red

to

MPL

Signal-to-noise

ratio

linear

ASA

A weighted

Crosstalk

attenuation

at

1

kHz

METER

PEAK

indication

semi-logarithmic scale, usable

from

-10

to

+23dB

Third

harmonic

distortion

at

M.P. L.

1%

(2%)

Signal-to-noise

ratio

Linear

ASA

A

dB

15 ips - 38 cm/s

NAB

58 (53)

63

(60)

CCIR

58 (55)

66 (63)

7 1/2 ips - 19 cm/s

NAB

60

(56)

64 (62)

CCIR

57

(55)

63

(60)

Crosstalk

attenuation

at 1

kHz

(60 dB)

at

10kHz

(50 dB)

Phase

shift

between tracks

at

71/2

ips

(19cm/s)

and 10

kHz

±15°

(±20

o

)

+10 dB ±0.2 dB

frequency response

from

30

Hz

to

35 kHz ±0.5 dB

(1

dB)

integration

time

for

2

dB

below

reference

deviation

5 ms

±20

%

RMS

(sonometer) indication

normalised scale, usable

from

-10

to

+12dB

frequency response

from

10Hz

to

35 kHz ±0.5 dB

(1

dB)

from

20 Hz

to

20 kHz ±0.2 dB (0.5 dB)

Outputs

Output

voltage

at

M.P.L. on

10

kS1

Output

voltage

for

1% distorsion

at

1

kHz

Output

voltage

for

200

S1

headphones,

adjustable

Built-in

loudspeaker,

power

output

of

amplifier

Reference signal level

RMS

1 V

(2.5

V)

o

to

1 V

1W

FAST

integration

time,

200

ms

for

1 dB

below

reference

deviation

SLOW

integration

time,

500

ms

for

4 dB

below

reference

deviation

±0.5 dB

(1

dB)

±0.5 dB ( 1 dB)

FM

TRACK

Operating

speeds,

15 and 7

1/2

ips - 38 and 19 cm/s

Input

and

Ouptput

centered at OVDC

Reading accuracy below 0 dB

above 0 dB

Peak

factor

(±0.5 dB)

(±0.2 dB)

>5

Carrier freqency

Static linearity

17 kHz

±0.4% (±1%)

o

to

4

kHz

(0

to

3.5

kHz)

Maximum

frequency

deviation

.6.fo

Frequency response

at

-3

dB

Signal-to-noise ratio

for

a ±20% deviation

±45% (40)

44

dB (40 dB)

Peak-to-peak

input

voltage

for

a ±40% deviation

PILOT

CUE

OPERATING

CONDITIONS

± 2.8V ± 0.5 dB

±

2 V ± 0.5 dB

with

external

power

Temperature

with

manganese batteries

- 4

to

+160

0

F

-20

to

+

71

0

C

-67

to

+160

0

F

-55

to

+

71

0

C

The recorder

functions

correctly

in

any

position.

All

values given

are

typical;

exact values

for

each

machine

are

given on its final measurement

protocol

sheet.

A

ht"

W

eifl

In~

curve

Frequency

lEe

Recommendation

179

NAGRA

IV·SJ

Relative Tolerance

Tolerance

Response Limits Limits

Hz

dB

20

-50.5

±5

±3

25 -44.7

±5

±2.5

31.5

-39.4

±3

±2

~

-

.........

40 -34.6

±3

±2

./

I"-....

50 -30.2

±3

±2

/'

'"

63 -26.2

±3

±2

80

-22.5

±2

±1.5

/

100 -19.1

±1

125

-16.1

±1

160 -13.4

±1

V

200

-10.9

±1

250

-

B.6

±1

/

315 - 6.6

±1

/

400

- 4.8

±1

V

500 - 3.2

±1

630 -

1.9

±1

/

800

- 0.8

±1

1000

0

±1

1250

+ 0.6

±1

/

±1

1600

+ 1

2000

+

1.2

±1

/

2500

+

1.3

±1

3150

+

1.2

±1

/

4000

+ 1

±1

5000

+ 0.5

±1.5

±1

6300

-

0.1

+1.5

-2

±1

/

8000

-

1.1

+1.5

-3

±1.5

I

10

000

- 2.5

+2

-4

±1.5

12500

- 4.3

+3

-6

±1.5

16000

- 6.6

+3

-~

!1.5

20000

- 9.3

+3

-~

±2

Hz

80

200

500

1000

3150

8000

12500

-10

o

+10

-50

-20

-30

-40

dB

20

31,5

50

100

315

800

1200

5000

10000

20000

dB

Frequency

I

EC

Recommendation

179

NAGRA

IV·SJ

Relative Tolerance

Tolerance

Response

Limits

Hz

dB dB

dB

20 -24.2

±5

±2

25

-20.4

±5

±2

31.5

-17.1

±3

±2

40

-14.2

±3

±2

50

-11.6

±3

±2

63

- 9.3

±3

±2

80

7.4

±2

±1.S

100

-

5.6

±1

125

4.2

±1

160

-

3

±1

200

2

±1

250

-

1.3

±1

315

0.8

±1

400

- 0.5

±,

±1

500

0.3

±1

630

-

0.1

±1

800

±1

1000

±1

1 250

±1

1600

0

±1

2000

0.1

±1

2500

0.2

±1

3 150 -

0.4

±1

4000

0.7

±1

5000

-

1.2

±1.5

±1

6300

1.9

+1.5

-2

±1

8000

2.9

+1.5

-3

±1.5

10

000

4.4

+2

-4

±1.5

12500

6.1

+3

-6

±1.5

16000

8.4

+3

±1.5

20000

-11.1

+3

±2

B

ht"

elfl

In2

curve

~

r--

.........

/"

,/'

"'"

/

,

Hz

80

200

500

1000

3150

8000

12500

-10

o

+10

-20

-50

-30

-40

r-;::====W

20

31,5

50

100

315

800

1200

5000

10000

20000

c

ht

Wei21

in2

curve

dB

Frequency

lEe

Recommendation 179

NAGRA

IV·SJ

Relative

Tolerance

Response

Limits Limits

+10

Hz

dB

20

- 6.2 ±5

±1.5

0

25

- 4.4

±5

!1

.---

I-"

-

--.....

31.5

- 3

!3

!1

./

I"--..

40 - 2

!3

±1

/'

"~

50

- 1.3

±3

±1

63

-

O.B

±3

±1

-10

80

- 0.5

±2

±1

100

- 0.3

!1

125

- 0.2

±1

160 -

0.1

±1

-20

200 0

±1

250 0

±1

315

0

!1

±1

400

0

!1

±1

500 0

±1

-30

630

0

±1

800 0

±1

1000

0

±1

!1

1 250

0

!1

-40

1600

-

0.1

±1 ±1

2000

- 0.2

±1

2500

- 0.3

±1

!1

3 150 - 0.5

±1

4000

- 0.8

±1

-50

5000

- 1.3

±1.5

±1

6300

- 2 +1.5

-2

±1

8000

- 3

+1.5

-3

±1.5

10

000

- 4.3

+2

-4

±1.5

12500

- 6.2

+3

-6

±1.5

16000

- 8.5 +3

-~

!1.5

Hz

20000

-11.2

+3

-~

±2

80

200

500

1000

3150

8000

12500

20

31,5

50

100

315

800

1200

5000

10000

20000

SJ)

ht+

Wei21

In2

curve

D

Frequency

IEC

Recommandalion 537

--

Relative

Tolerance

""

"

Response

Limits (same

as

for

IV-

/'

Hz

dB

/

",

20

-20.6

±

3.0

25

-18.7

± 2.0

31.5

-16.7

± 1.5

..--""""

'"

40

-14.7

± 1.5

/"

50

-12.8

± 1.5

/"

\

63

-10.9

± 1.5

V

80 - 9.0

± 1.5

/'

100

- 7.2

± 1

./

125

- 5.5

± 1

V

160 - 4.0

± 1

/'

200 -

26

± 1

250 - 1.6

± 1

315

- 0.8

± 1

400

- 0.4

± 1

500

- 0.3

± 1

630

- 0.5

± 1

800 - 0.6

± 1

1000

0.0 ± 1

1250

2.0 ± 1

1600

4.9

± 1

2

000

7.9 ± I

2500

10.4 ± 1

3150

11.6 ± 1

4

000

11.1

± 1

5000

9.6 ± 1.5

6300

7.6 +1.5

-2.0

8000

5.5 + 1.5

-3.0

10

000

3.4

+2.0

-4.0

12500

1.4

+3.0

-6.0

16

000

- 0.7

+3.0

~

Hz

20000

- 2.7

+3.0

~

80

200

500

1000

3150

8000

12500

o

+10

-10

-20

-30

-50

-40

dB

20

31,5

50

100

315

800

1200

5000

10000

20000.

1.

BASIC

EQUIPMENT

1.1.

Installation

of

Batteries

or

Accumulators

Select

the

type

of

battery

or

accumulator

accor-

ding

to

the

expected

working

conditions

for

the

recorder

(see

Section

4j.

Turn

the

recorder over

so

that

it

is

resting

on

its

lid;

turn

the

screws marked

A and remove

the

cover

of

the

battery

compart-

ment. Insert the

12

cells in

the

position

shown,

u

+

/,

1r 1r

o fjJA

~

~A

0

\

0

H H

~

then replace the cover and secure

it

by

turning

the

screws marked A. Set POWE R

switch

3 on

Batt.

1.2.

Connection

of

an

External

D.C. Source

Connect

the

12-30 V voltage source

to

the

POWE R

PACK

connector

48,

with

the

negative pole

to

5.

Set POWE R

switch

3 on

External.

1.3.

Connection

of

Mains Power

Supply

Connect an

ATN

or

ATN

2 mains

power

supply

to

the

POWER

PACK

connector

48.

If

necessary, check

the

position

of

the

voltage selec-

tor.

Set POWE R

switch

3 on

External.

INSTRUCTION MANUAL

Directions for use

1.4.

To

Check

the

Power

Supply:

Turn

METER

FUNCTION

switch

12

to

BATT.

and main selector

switch

4

to

TEST:

the

red needle

of

meter

14

indicates on

the

lowest scale

the

un-

stabilized

battery

voltage expressed

for

one cell:

the

total

voltage

is

therefore

obtained

by

multiply-

ing

the

meter

reading

by

12. The

pointer

at

1.25 V

indicates

the

minimum

voltage

at

which

the

man-

ganese

dioxide

batteries should

be

recharged so

that

they

are able

to

go

through

the

discharge/charge

cycle several dozen

times

(see

Section

4).

Turn

main selector

switch

4 back

to

STOP.

2.

CONNECTION

OF

SIGNAL

SOURCES

Since

the

two

direct

recording channels are iden-

tical,

instructions

are given

for

channel 1

only,

but

they

are

also valid

for

channel 2.

2.1.

Connection

of

a High Level

Line

The recorder can

be

connected

to

an appliance

or

a

measuring

instrument,

the

output

voltage

of

which

is

equal

to

or

higher

than

1

mV

RMS:

input

is

direct

on

the

main

attenuator

and

input

impedance

is

100 kQ.

The

lower

the

output

impedance

of

the

signal

source,

the

better

the

signal

to

noise

ratio

is.

The external signal source

is

connected

to

connec-

tor

42:

the

wiring

of

the

corresponding plug

is

shown in General

View

lion

the inside cover.

Selector

10

will

then

be

on

LINE.

2.2.

Connection

of

a High Level

Microphone

or

Transducer

Input

identical

to

2.1.,

but

using

connector

37,

with

selector

10

on

MIKE.

The

wiring

of

the

plug

is

shown in General

View

II:

only

contacts

4, 5, 7

and 8 can be used;

contact

3 supplies a -10- V

stabilized voltage

which

can feed

an

external pre-

amplifier,

if

desired.

2.3. Connection

of

the OJPA Preamplifier

fitted

with

a Bruel & Kjaer Microphone Cartridge

~[]I

-------L..I~I

~

---.JI

\\

MECH.ANICAL

ADAPTORS

-;:=======-

======:::/

C

I .

QSJA-SK

=-=~-i

~d

~

--T---'

-1

I

QSJC0

~

I

I I I

L

-L

.l

-={T~

~

I

QSPB

B&

K

CARTRIDGES

~

M3x8

Signals and Voltages

Chassis

connector

external side

or

plug soldering

side.

"'---

+12,6

V

----=--SIGNAL

,-----~GND

F

A

::

..

:

.':.-;~

c:1+-:

_~!;_;.

_~

~::::r::::G~_~~~~~~~~

B

M2x6

-10G-----1

+200V------.

+

120V--

........

Bruel & Kjaer

V2"

4133,

4134,

4149

and

4163

microphone

cartridges screw

directly

onto

the

QJPA

preamplifier,

and

the

preamplifier

output

plug

fits

into

microphone

connector

37.

Other

cartridges

can be screwed

on

using a mechanical adapter, i.e.

-1

":

4144,4145,4146

and 4161

type

-

V4":

4135

and

4136

type

-

Ih":

4138

type.

The

25

m or 50

m.

QCPA extension cable

can

be

inserted between the

output

plug

of

the QJPA pre-

amplifier

and

the

microphone

connector.

Set selector

switch

10

on

MI

KE.

The recorder

must

be

fitted

with

the

QSJA-BK

microphone amplifier

and the QSJC universal

power

supply.

Installation

of

aSJA-BK

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 A.

Carefully

position

the

metal

ground

strap B and slip

it

under

the ground

comb

C.

The

two

switch

spindles 0

should be

passed

through

the

corresponding holes

in the

box,

then the

blocking

rings E threaded on.

Introduc~

the

spindle

into

the

switches, press the

rings against the ground strap and

tighten

them.

Place the shield in

position

and

fix

it

under

the

ground

comb

and

under

a

nut

screwed

onto

one

of

the

two

hinge

fixing

screws (this screw should

be

longer -

M3x8l.

Reinstall the level adapter

board

A.

Installation

of

OSJC Power

Supply

Plug in

the

power

supply

circuit

and

fix

it

with

screw G

to

the connector.

Pass

a

M2x6

flat

head

screw

through

from

the

inside

of

the

battery

box

and

through

the

bracket

of

the

metal

box,

and

fix

with

a

nut.

2.4. Connection

of

Bruel & Kjaer

Amplifiers

fitted

with

Bruel & Kjaer

Microphone

Cartridges

-,------l

OSJt

~

@ I

I I

L~

--....1....

~

B&

K

PREAMPLI

FI

ER

MECHANICAL

ADAPTOR

B&

K

CARTRIDGE

~======-..===::::::!J

The

following

types

of

cartridges

-

Ih":

4133,4134,4149

and

4163

- 1

":4144,4145,4146and4161

- Y4":

4135

and

4136

- 1/8": 4138

can

be

fitted

to

the

following

types

of

preamplifiers:

-

1",

Y2", Y4" :

2615

-

Y2",

Y4", Y8" :

2614

-

1",1/2",1/4",Y8"

:2619

-

1"

:

2627,2612

and

2613

-

1,4",

1/8" :

2618

The cartridges can

be

fitted

directly

onto

the pre"

amplifierswhen the diameters match;

if

they

do

not

match, a mechanical adapter can

be

used. The

output

plug

of

the

preamplifier

screws

into

the

QSJP

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 precedi

ng

paragraph.

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

/i.Lbar.

It

should

be

connected

to

microphone

connector

37

by

the QCJ-MKH cable; selector

10

should

be

on

MIKE.

The

r~corder

should be

fitted

with

the QSJA-MKH

microphone

amplifier,

which

also supplies the vol-

tage

for

the

microphone.

Installation

of

QSJA-M

KH

Amplifier

Lock

the

lid

of

the

recorder,

turn

screws 50 several

ti

mes

and open

the

case

to

its

fu

II

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

the

ground

comb

and

under a

nut

screwed

onto

one

of

the

two

hinge

fixing

screws (this screw should be longer -

M3x8l.

Reinstall the level adapter board.

Signals and Voltages

Chassis

connector external side

or

plug soldering

side

Signals and Voltages

Chassis

connector

external side

or

plug soldering

side

+200V

GND

+120V

SIGNAL

r-

L_

+12,6

V

-8V

-10G

2.6. Connection

of

General Radio 1560-P42

Preamplifier

fitted

with

a

Microphone

Cartridge

This preamplifier can

be

fitted

with

the

same

car-

tridges and mechanical adapters

as

the Bruel & Kiaer

2619 preamplifier. Its

output

plug

fits

into

the

input

connector

of

the QSJP-G R adapter;

the

out-

put

connector

of

this adapter must

be

plugged

into

microphone connector 37; selector

10

should

be

on

MIKE.

Preamplifier 1560-P42

can

also

be

fitted

with

GR

1"

and GR

V2"

ceramic microphone cartridges.

When Bruel

& Kjaer cartridges are being used the

recorder should

be

fitted

with

the QSJA-BK

amplifier

and QSJC-power supply, version 2

only,

which should

be

modified

to

supply the

+16

V

voltage required

for

the

GENERAL

RADIO

pre-

amplifier.

Version 2

of

the QSJC

power

supply

differs

from

version 1 (which

can

supply

only

+12 V) in the

value

of

certain components, e.g. resistances R24

and R25:

@

o

@

R26

R24

G

o

R27

R25

o

Version 1: R24 =

33

kn,

R25 = 27

kn

no

modification

possible

Version 2: R24

= 47

kn,

R25 =

33

kn

modification

possible

It

is

not

possible

to

transform

a version 1

circuit

into

version 2,

as

the osci IIator coiI

of

the converter

is

different

in

each

case.

Before

modifying

a version 2

circuit,

it

is

essential

to

measure the negative voltage available

at

terminal

6

of

connector CUE 47, in relation

to

the

ground

(terminal

7)

with

no

modulation.

Bridge terminals

5 and 2 and set main switch 4 on

TEST;

note

the

value

of

the negative voltage at

terminal

6

(see

para-

graph 7.6

for

the meaning

of

this value).

To

obtain a.+16 V voltage, remove resistance R26

(180

kn),

which

is

soldered

to

two

pins;

it

is

not

necessary

to

dismantle the

circuit.

After

this

modification

has

been made, the voltage

available

at

terminal 6

of

connector

CUE 47 shoulQ

be

adjusted

to

the value noted before the

modifica-

tion

was

made; this

can

be

done

by

adjusting

potentiometer

R83

of

circuit

A24

(THIRD

TRACK

CI

RCU ITS).

If

it

is

impossible

to

obtain

the

value

noted, replace resistance R82

of

this

circuit

by

a

10

kn

resistance and adjustable

potentiometer

R83

by

a 2.2

kn

model.

Signals and Voltages

Chassis

connector

external side

or

plug soldering

side

~-~-GND

-----=-SIGNAL

-------

+

16

V

-10G--------J

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.

3.2. Selection

of

Measuring

Circuit

Set the

METER

FUNCTION

switch on one

of

the

LEVEL

positions:

-

RMS

FAST : average value

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

1 second.

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 0 dB

(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

oli

the

Microphone

Input

Same

procedure

as

in the preceding paragraph,

but

with

selector 10 on

MI

KE.

3.4.3. Low-level Signals on

the

Microphone

Input

QSJA-BK

AMPLIFIER

With

selector

1"0

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

V4"

the

positions

of

gain selector 39

become +40,

+60

and

+90

dB, values inscribed in a

circle.

Turn

attenuator

7

to

+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

fi

Iter selector switch

11

is

on

LI

N,

the

fre-

quency response

of

the

direct

chain

is

linear at

±0.3 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).

3.6. Calculation

of

the

Value Measured

3.6.~.

Measurement

of

High-level Signals

by

the

Line

Input

A 1

mV

sine wave signal applied

to

the

line

input

gives

a reading

of

0

dB

on

the

PEAK

scale

or

on the

RMS

scale, when main

attenuator

7

is

on

0.001

V

or

0 dB.

Meter 14

is

graduated in decibels

only;

since the

value indicated

by

main

attenuator

7 corresponds

to

a reading

of

0 dB on the meter, the exact value

of

the signal - in decibels in relation

to

t!"Je

0 dB

reference level -

is

obtained

by

adding algebraically

the value shown on meter 14

to

the value shown on

main

at4!nuator

7 and, when necessary, on vernier

attenuator 7A. The

number

of

decibels obtained

should then

be

converted

into

a voltage ratio, and

the line

input

voltage deducted

from

the 1

mV

reference voltage.

It

is

a convention in electro-acoustics

to

express

measurements taken at peak value in terms

of

the

RMS value which

would

be

given

by

a sine wave

signal

with

the

same

peak value;

the

input

sensitivity

and the

output

voltage

of

the

recorder

are

therefore

expressed in terms

of

their

RMS value, assuming the

signals

are

sine wave.

On

RMS,

the measuring circuit

of

the recorder

responds

to

the

RMS

value

of

the signal

and

indicates,

after decibel/voltage conversion, the

RMS

value.

On

PEAK,

the measuring

circuit

of

the recorder

responds

to

the peak value

of

the signal and

indicates, after decibel/voltage conversion, a value

which

is

the RMS value

of

the

signal

only

if

it

is

a

pure sine wave; the actual peak value, whatever the

form

of

the signal,

is

obtained

by

multiplying

the

value indicated

by

1.414.

A 1

mV

RMS sine wave signal applied

to

the

line

input,

with

the attenuators on 0 dB, gives

an

iden-

tical reading on

PEAK

and on

RMS

,

which

is

equal

to

0 dB,

A signal

without

a well-defined

form,

applied

to

the line

input,

gives the

following

values

after

decibel/voltage conversion

of

the reading:

-

on

PEAK,

peak

value divided by 1.414

-

on

RMS,

RMS

value

The line

input

impedance

is

100

kn.

On

the

maxi-

mum sensitivity position

(9

dB) there

is

no

increase

in

input

noise

as

long

as

the

sound source impe-

dance remains

low

in relation

to

the

100

kn

input

impedance.

Select the attenuator

position

for

which the needle

of

the meter shows the closest possible value

to

+10 dB

RMS

or

+20 dB

PEAK,

without

exceeding this

limit.

The

attenuator

knob

then

indicates a decibel value

which,

when added

to

the

value shown

by

the needle, makes

it

possible

to

determine

the

voltage applied

to

the

input,

i.e.

for

xdB:

x

input

voltage in

millivolts

= 10

20

Basically, vernier

attenuator

7A remains on 0 dB

(CAL.).

With

this

attenuator

it

is

possible

to

make

afine adjustment,

if

necessary, in steps

of

1 dB: the

value shown

by

its switch should

be

added

to

that

of

main

attenuator

7.

The graduations

in

dB

of

attenuators7

and

7A

and

meter

14

are also usable

for

relative measurements

without

pinpointing

the

reference.

3.6.2. Measurement

of

High-level Signals

by

the

Microphone

Input

Proceed in

the

same

way

as

described in

the

pre-

ceding paragraph,

but

with

selector 10 on

MI

KE.

3.6.3. Measurement

of

Low-level Signals

by

the

Microphone

Input

The sound level, measured

in

decibels, in relation

to

the

2.10-

5

N/m

2

reference level,

is

equal

to

the

algebraic sum

of

the

values indicated

by

gain

selec-

tor

39, main

attenuator

7, vernier

attenuator

7

A,

the

reading on meter

14

and a specific correction

value given according

to

the

cartridge and

amplifier

circuits used.

The

correction

value includes, amongst

other

things,

a correction

factor

K

o

. This

is

the difference,

expressed in decibels, between the sensitivity

of

a

standard cartridge (50

mV

/N/m

2

)

and the actual

sensitivity measured in the

laboratory

by

the

manu-

facturer. The K

o

factor

is

given in

the

calibration

chart issued

with

each Bruel & Kjaer

microphone

cartridge.

To

facilitate

the

reading

of

meter

14

the

needle

should

be

as

n.ear

as

possible

to

the

+20

dB

PEAK

or

+10

dB

RMS

values,

without

exceeding

them.

If

the

signal

is

too

weak when

attenuator

7

is

on

+20

dB,

turn

the

knob

to

the

right;

if

the

readi

ng

is

sti

II

too

low

when the

attenuator

is

on

o

dB,

turn

gain selector 39

from

+60

dB

to

+40

dB.

If

necessary, readjust main

attenuator

7.

If

the

signal

is

too

strong when

attenuator

7

is

on

+20 dB,

turn

its

knob

to

the

left;

if

the

reading

is

sti

II

too

high when

the

attenuator

is

on

+40

dB

(marked

with

an

arrowhead), move gain selector 39

from

+60 dB

to

+80

dB.

IK = K

o

- G - X I

Same

as

below

The preamplifier gain

"G"

is

the

same

as

for

Bruel & Kjaer 2619 preamplifier.

K

o

=

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

2

reference value, in accor-

dance

with

the

following

table:

3.6.3.2.

Limits

and Corrections

with

Bruel &

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

+60

dB;

when

the

latter

is

on

+80

dB (+90 dB

for

a

1/

4

"

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:

Limits

and Corrections

with

the QJPA

Preamplifier and

OSJA-BK

Amplifier

3.6.3.1.

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.

Type

of

cartridge

X in dB

1"

Ih"

1/

4

"

1/

4

"

1/

8

"

4135

4136*

4138**

0

+12

+22

+30 +34

*With

the

1/

4

"

cartridge

4136,

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 1J4"; add 12 dB

to

the calculated value

to

obtain

the sound level.

Example

1J2" cartridge

4133

with

preamplifier

2619:

K

o

= +12.2 dB G =

0.4

dB X = +12 dB

Value

to

which

the

potentiometer

of

the

QSJP

adapter should

be

adjusted:

K

= 12.2 +

0.4

- 12 =

+0.6dB

3.6.3.3.

Limits

and Corrections

with

the

M

KH

110

Microphone

and

the

OSJA-MKH

Amplifier

TheOSJA-MKH

amplifier

does

not

in any way alter

the performance

of

the

microphone

and its elec-

tronic

circuit'; reference should

be

made

to

the

sound level

limits

indicated

by

the manufacturer

for

saturation

'and

background noise.

Correction: With the

MKH

110

microphone

add

60 decibels

to

the value set on main

attenuator

7

and

to

the value shown

by

meter 14.

With

the

MKH

110-1

microphoneadd80dB.

3.6.3.4.

Limits

and Corrections

with

the

1560-P42

GENERAL

RADIO

Amplifier

As

the

OSJA-BK

amplifier

is

being used, the

same

limits

and corrections

as

those given in paragraph

3.6.3.2.

are

valid.

The G value,

which

represents

preamplifier

gain in

relation

to

the

type

of

cartridge,

is

shown in the

following

table.

Type

of

cartridge

G in dB

IMPORTANT

-2.5

%"

-6

In all

cases

where there

is

uncertainty

about

the

sensitivity, the K correction

factor

of

the

cartridge,

or

the gain

of

the

input

circuits, we recommend the

use

of

a calibration device. This device

is

applied

to

the cartridge and produces a calibrated sound level

of

a precisely

known

value. The BrLiel & Kjaer

pistonphone and the acoustic

calibrator

produce a

fixed frequency signal;

with

calibration

equipment

using

an

electrostatic

actuator

for

condenser

micro-

phones

it

is

possible

to

calibrate at

different

frequencies.

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

re-

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"/s

(3.8

cm/s):

25

Hz

to

3.5

kHz

±1

dB

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

:.:

••••

.

~

•••

~

Push lever

32

backwards

to

its

fu

lIest

extent.

Ra

ise

the

head shield.

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