Norsonic nor1256 User manual

INSTRUCTION
MANUAL
nor1256
Class 1 sound calibrator
Complies with IEC 60942 class 1

Nor1256 - May 2017
IM1256_Ed2R3En
Norsonic is a registered trademark of Norsonic AS. All other brand
or product names are trademarks or registered trademarks of their
respective companies.
Every effort has been made to supply complete and accurate in-
formation. However, Norsonic AS assumes no responsibility for the
use of – nor for the consequential damages of the use of – this
information and/or the instrumentation described herein. Further-
more Norsonic AS assumes no responsibility for any infringement
of the intellectual property rights of third parties, wherever applica-
ble, which would result from such use.
Norsonic AS reserves the right to amend any of the information
given in this manual in order to take account of new developments.
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Norsonic AS, P.O. Box 24, N-3421 Lierskogen, Norway
Find us on the web: www.norsonic.com
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nor1256
Class 1 Sound Calibrator

1
Nor1256
Instruction Manual
Introduction
The Sound Calibrator Nor1256 is a small, battery
operated sound source for the calibration and check
of sound measuring instruments. The specifications
conform to the requirements in IEC 60942 for a class
1 sound calibrator. The combination of two different
levels and two different frequencies allows both level
linearity and frequency linearity to be verified. In addi-
tion the Sound calibrator measures the environmental
conditions: air pressure, temperature and humidity.
The sound calibrator may be used for calibration
and check of most laboratory and working standard
microphones with diameter not larger than 1” (LS1/
WS1).
The microphone of the sound level meter shall
be placed in the acoustic coupler of the calibrator
before the calibrator is switched ON. After start up the
calibrator will produces a regulated sinusoidal sound
pressure signal at 1 kHz with a sound pressure level
of 94,0 dB. The sound is generated by a small loud-
speaker integrated in the acoustic coupler. The level is
measured with an internal reference microphone and
is automatically adjusted until the level is correct. This
is indicated by the LED on the front turning from red
to green. The feedback ensures that the sound level is
nearly independent of the acoustic load volume of the
microphone.
By pressing the dB button, the sound pressure level
may be switched between 94 dB 114 dB.
By pressing the Hz button, the frequency of the
sound may be switched between 1 kHz and 250 Hz.
Due to the principle of operation, the calibration level
is virtually independent of ambient conditions like tem-
perature, atmospheric pressure and humidity within
the specified range of operation.
The calibrator has been designed to serve one-
inch and smaller microphones and sound level
meters equipped with such microphones. One-inch
microphones fit directly in the calibrator coupler, while
half-inch and smaller microphones are served by
application of a suitable adaptor. Adaptor for half-inch
microphones is included, while adaptors for other
microphone sizes must be ordered separately.
The calibrator is powered from two type LR03
alkaline batteries (AAA-size, also classified as 24A by
ANSI/NEDA). If the voltage is too low to ensure proper
operation, the calibrator will switch off or not switch on.
Remove the batteries as soon as they are discharged
or if the sound calibrator is stored for a prolonged
period of time. Leakage from the battery may other-
wise destroy the electronic components.

2Nor1256
Sound Calibrator
Using the sound calibrator
• Switch on the sound level meter to be calibrated
and let the meter stabilize before calibration. A
typical sound level meter needs at least 3 minutes
to stabilise.
• Place the microphone of the sound level meter
to be calibrated in the coupler of the calibrator.
Use a suitable adaptor, if necessary. Use a slow
movement, since a fast movement may create an
excessive pressure which temporarily may change
the sensitivity of the microphone.
• Press ON/OFF button. Wait for the LED above
the “dB-button” to change from red to green. The
level and frequency is indicated in the display of
the calibrator. After powering the sound calibrator,
the first combination of frequncy level is 94 dB re.
20µPa and 1 kHz. Select the appropriate level and
frequency for your calibration by pressing the dB or
Hz button, respectively.
• Normally the background level should be more
than 20 dB lower than the level from the calibrator
in order to not influence the reading. Therefore it is
good practice to notice the indicated sound level
before the sound calibrator is switched on.
Display
LED
Change level
ON/OFF
Environmental
Acoustic coupler
Battery compartment
Adapter
Calibration button
Change frequency

3
Nor1256
Instruction Manual
• Press Hz to select a new frequency. Press dB to
select a different levels.
• Press the °C/°F to display the environmental
conditions: air pressure, temperature and humidity.
The temperature and humidity is measured in-
side the calibrator. Note that due to the power
consumption of the calibrator the temperature
may rise above the ambient condition after long-
er time of operation affecting both the tempera-
ture and the humidity indication (Typically 3°C
after 30 minutes). It is therefore a good practice
to measure the conditions shortly after powering
the unit. The temperature may be displayed in
centigrade (Celsius) or in degree Fahrenheit.
• Press the °C/°F again for returning to the sound
calibrator mode.
• Press ON/OFF for switching the calibrator off.
The calibrator shuts off by itself after ten minutes.
However, if a microphone has not been inserted or the
level has not otherwise reached stability, the unit will
switch off after 20 seconds. The automatic power off,
may be deactivated by keeping the power on button
depressed for more than 3 seconds when the unit is
switched on (Keep the ON button depressed until the
red LED turns on).
Acclimatisation
Is always a good practice to let the calibrator and the
sound measuring equipment reach the prevailing en-
vironmental conditions (mainly temperature) before
using a sound calibrator. If the sound calibrator and
the microphone to be calibrated have different temper-
atures, an unstable conditions exits and the calibration
will not be reliable.
Unit for temperature
The temperature may be displayed in either degree
Celcius (°C) or degree Fahrenheit (°F). In order to
change the unit, keep the button °C/°F depressed
during power on.
Sound pressure levels
The sound pressure in the coupler of the calibrator
is produced by a small loudspeaker. The level is
monitored by a reference microphone and adjusted to
obtain the specified levels at the different frequencies.
All sound level meters should display at least the
A-weighted sound pressure level. The A-weighting is a
standardized, frequency dependent weighting which
originally was developed to mimic our auditory organ
and is specified in the standards for a sound level
meter. The stated levels for calibrator Nor1256 are all
un-weighted levels for both frequencies.
Power off!
The automatic power off, may be deac-
tivated by keeping the power on button
depressed for more than 3 seconds when the unit
is switched on (until the LED lights).

4Nor1256
Sound Calibrator
Recalibration
At regular intervals – at least once per year – proper
operation of the sound calibrator should be verified,
preferably by an accredited acoustic calibration labo-
ratory or the Norsonic factory. The calibration should
be performed as specified for periodic verification
in the International standard for sound calibrators
IEC 60942 (2003), Annex B.
The level should preferably be measured with a labo-
ratory standard microphone type LS2, according to
IEC 61094-1, where the pressure sensitivities at the
different frequencies are known with a sufficiently high
accuracy.
Various types and makes of microphones may have
different effective load volume. Due to its working
principle, the Nor1256 has a large effective coupler
volume. The variations in sound pressure level due
to variations in effective load volume among micro-
phones are therefore for most applications insignifi-
cant. An equivalent microphone volume of 250 mm³ is
used as reference load volume for ½” microphones.
This corresponds to most ½” measuring microphones
with protecting grid mounted like the Norsonic types
1220, 1225, 1226, 1227 and 1230. If no adaptor ring is
used, the nominal reference front volume is 1333 mm³.
This corresponds to most 1” measuring microphones
with the protection grid mounted.
The sound pressure levels generated by the calibrator
may be adjusted by the following procedure (NOTE: it
will not be possible to switch the calibrator OFF during
calibration mode):
The nominal attenuation of the A-weighting is 0 dB
at 1 kHz (reference frequency) and 8,6 dB at 250 Hz.
The nominal A-weighted sound pressure levels for
the calibrator will therefore at 250 Hz be 85,4 dB
and 105,4 dB, respectively. The attenuations of the
C-weighting are for both frequencies 0,0 dB and C-
weighted levels correspond therefore with the un-
weighted levels.
Most sound level meters are designed to show the
correct free-field sound pressure level. This means
that the indication shall correspond to the level in a
free, progressive field before the sound level meter
was placed in the field. The size of the microphone
– and eventually the sound level meter body – will
modify the pressure just in front of the microphone –
especially at higher frequencies. For a ½”microphone
(type WS2F) the pressure increase will typically be
0,1 dB at 1 kHz. It is therefore a common recom-
mendation to adjust the sound level meters applying
such microphones to display 93,9 dB and 113,9 dB,
respectively at 1 kHz.
If microphones other than WS2P are used, the read-
ing from the sound level meter should be corrected
accordingly. See the list below for some microphones
in common use

5
Nor1256
Instruction Manual
Correction for different Microphones
Supplier Type of microphone
Adjustment level/dB
250 Hz
Adjustment level/dB
1000 Hz
Brüel & Kjaer 4144, 4134, 4166, 4192 94,0 bzw. 114,0 94,0 bzw. 114,0
Brüel & Kjaer 4145 94,0 bzw. 114,0 93,7 bzw. 113,7
Brüel & Kjaer 4149, 4165, 94,0 bzw. 114,0 93,9 bzw. 113,9
Brüel & Kjaer 4176, 4188, 4189, 4190, 4191 94,0 bzw. 114,0 93,9 bzw. 113,9
Brüel & Kjaer 4180 94,0 bzw. 114,0 94,0 bzw. 114,0
CEL 186/3F, 192/2, 192/2F 94,0 bzw. 114,0 93,9 bzw. 113,9
GRAS 40 AE, 40 AF 94,0 bzw. 114,0 93,9 bzw. 113,9
GRAS Low Noise 40 HL 94,0 93,9
GRAS 40 AU, 40 AIR, 40 AQ 94,0 bzw. 114,0 94,0 bzw. 114,0
GRAS 40 AG, 40 AK, 40 GK 94,0 bzw. 114,0 94,0 bzw. 114,0
Larson Davis 2540, 2541 94,0 bzw. 114,0 93,9 bzw. 113,9
Mikrotech Gefell MK 102.1 94,0 bzw. 114,0 93,7 bzw. 113,7
Mikrotech Gefell MK 221, MK222, MK223 94,0 bzw. 114,0 93,9 bzw. 113,9
Norsonic 1220, 1222, 1225, 1227, 1228 94,0 bzw. 114,0 93,9 bzw. 113,9
Norsonic 1230 94,0 bzw. 114,0 94,0 bzw. 114,0
NTI M2010 94,0 bzw. 114,0 93,9 bzw. 113,9
RION UC-52, UC-53, UC-53N 94,0 bzw. 114,0 93,9 bzw. 113,9

6Nor1256
Sound Calibrator
• Place the reference microphone in the coupler and
select the appropriate frequency.
• Press the calibrator button for about one second
until the display starts blinking and the LED turns
red. The calibrator button is accessible through a
small hole in the left-hand side of the enclosure.
Use a small rod with a diameter of about 1 mm.
• While the display is blinking, press Hz to increase
the level or dB to reduce the sound pressure level.
The level is changed in step of about 0,02 dB.
Warning!
Never enter the calibration mode without
access to reliable references.
• While the display is blinking, press Hz to increase
the reading or dB to reduce the reading.
• When the correct value is displayed, press °C/°F
and the value for air pressure start to blink.
• While the display is blinking, press Hz to increase
the reading or dB to reduce the reading.
• When the correct value is displayed, press °C/°F
and the value for humidity start to blink.
• While the display is blinking, press Hz to increase
the reading or dB to reduce the reading.
• When the correct value for humidity is displayed,
press °C/°F and the calibration mode is terminated
and the instrument returns to normal mode of
operation.
• When the correct level is obtained, press the
calibrator button once more for returning to normal
operation.
The displayed temperature, air pressure and humidity
may be adjusted in a similar way:
• Place a microphone in the coupler and select any
frequency.
• Press the calibrator button for about one second
until the display starts blinking and the LED turns
red. The calibrator button is accessible through a
small hole in the left-hand side of the cabinet. Use
a small rod with a diameter of about 1 mm.
• Press °C/°F and the temperature value starts
blinking.

7
Nor1256
Instruction Manual
Main specification:
Sound calibrator class 1 according to IEC 60942 Ed. 3 (2003) and ANSI/ASA S1.40-2006 (R2011).
In addition, the calibrator displays: Temperature, Air
pressure and Humidity. The temperature and humidity
is measured in the enclosure where the temperature will
be higher and humidity lower after some time of opera-
tion.
Temperature range: -10ºC to +50ºC; Resolution 0,1ºC; Ac-
curacy ±2ºC,
Atmospheric pressure: 65 kPa to 108 kPa; Resolution 0,1
kPa; Accuracy ±0,4 kPa, (for temperature above 0ºC)
Relative humidity: 0% to 100%; Resolution 1%; Accuracy
±4%, (for temperature above 0ºC and humidity in the range
25% to 85%)
Level and frequencies at reference conditions
(23,0°C/101,325 kPa/50% RH) – levels in decibel relative
to 20µPa:
250 Hz (251,19±0,30)Hz : (114,0±0,2)dB; 94,0±0,2)dB
1 kHz (1000,00±1,00)Hz : (114,0±0,2)dB; (94,0±0,2)dB
Distortion: Max 2,0%
Stabilizing time: 20 seconds.
Sensitivity to environmental conditions: As specified for
IEC 60942 class 1.
Microphone size: 1/1” and below. Adapter for 1/2” micro-
phone Nor4583 (included)
Power supply:
Battery operated: two LR03 alkaline batteries (AAA-size,
also classified as 24A by ANSI/NEDA).
Voltage for specified operation: 2 V – 3.4 V. Automatic
switch off if the voltage is too low for operation according to
the specifications.
Battery life:> 10 hours
Display: Mono-colour OLED graphical display with resolu-
tion 128 x 64 (W x H) and a dual colour LED.
Principal sound pressure level (IEC 60942 point 6.3):
114,0 dB,
Principal frequency (IEC 60942 point 6.3): 250 Hz.
Environmental range for specified operation:
Temperature: -10 °C to +50 °C (14 °F to 122 °F)
Relative humidity: 25% to 90%.
Air pressure: 65 kPa to 108 kPa.
Reference orientation for testing the effects of exposure
to/radiation of radiofrequency fields: Display in direction
of antenna.
Weight: 125 g (0,28 lb)
Size: 97x51,5x41 mm (3,8x2,0x1,6”)

Declaration of Conformity
We, Norsonic AS, Gunnersbråtan 2, Tranby, Norway, declare under our sole responsibility that the product:
Sound Calibrator Nor1256
to which this declaration relates, is in conformity with the following standards or other normative documents:
Product Standard IEC 60942 ed. 3.0 – 2003 Class 1
ANSI/ASA S1.40-2006 (R2011) Class 1
Safety: EN61010–1 ed. 3.0 – 2010 for portable equipment and pollution category 2.
EMC: IEC 60942 ed. 3.0 – 2003
following the provisions of the LVD- and EMC-Directive. The direction of maximum sensitivity/emission is with
the display facing the antenna.
This product has been manufactured in compliance with the provisions of the relevant internal Norsonic production
standards. All our products are tested individually before they leave the factory. Calibrated equipment—traceable
to national and international standards—has been used to carry out these tests.
This Declaration of Conformity does not aect our warranty obligations.
Tranby, September 2015
Dagnn Jahr
Quality Manager
The declaration of conformity is given according to EN 45014 and ISO/IEC Guide 22.
Norsonic AS, P.O. Box 24, N-3421 Lierskogen, Norway

P.O. Box 24
N-3421 Lierskogen
Norway
Tel: [phone]
Fax: [phone]
[email protected]
www.norsonic.com
Norsonic AS supplies a complete range of instrumentation for acoustics – from sound calibrators, micro-
phones & preamplifers; via small handheld sound level meters to advanced, yet portable, real time analysers,
but also building acoustics analysers and complete community, industry and airport noise monitoring systems.
Contact your local representative or the factory for information on our complete range of instrumentation.