Rion NC-74 User manual

3-20-41 Higashimotomachi, Kokubunji, Tokyo 185-8533, Japan
http://www.rion.co.jp/english/
INSTRUCTION MANUAL
Sound Calibrator
NC-74

i
Organization of this manual
This manual describes the features and operation principles of the sound calibrator NC-74.
The contents of this instruction manual is based on IEC60942:2003.
The manual contains the following sections.
Outline
Gives basic information on the unit.
Controls and Features
Briey identies and explains all parts of the unit.
Preparations
Describes how to insert batteries and use the adapter.
Measurement
Describes the basic steps and procedures for measurement.
Reference
Describes the calibration values for sound level meter and sound calibrator. Also describes
effects of exposure to radiofrequency elds.
Specications
Lists the technical specications of the unit.

ii
* Company names and product names mentioned in this manual are usually trade-
marks or registered trademarks of their respective owners.
To conform to the EU requirement of the Directive on Waste Electri-
cal and Electronic Equipment, the symbol mark on the right is shown
on the instrument.

iii
FOR SAFETY
In this manual, important instructions are specially marked as shown below. To prevent the risk of
damage to the unit or peripheral equipment, make sure that all instructions are fully understood
and observed.
Important Disregarding instructions printed
here incurs the risk of damage to the
product.
Mentioned about the tips to use this
unit properly. (This messages do not
have to do with safety.)
Note

iv

v
Precautions
Operate the unit only as described in this manual.
Do not use or store the unit in locations which may be
- subject to splashes of water
- subject to high levels of dust
- subject to direct sunlight
- subject to vibrations or shock
- subject to air with high salt or sulphur content, or to gases, or are in the vicinity
of stored chemicals
- outside of the specied temperature and humidity range
- subject to drastic temperature changes and to condensation
Store the unit in the desiccator in locations subject to high temperatures and high hu-
midity.
Do not use the unit for any purpose other than calibrating sound level meters or mi-
crophones.

vi
Do not hold the active coupler to the ear for a long time.
Be sure to use only the specied batteries.
Remove the batteries from the unit when not using it.
Do not try to disassemble or alter the unit.
Never insert any foreign object into the coupler.
The NC-74 is a precision product. Always handle it carefully and do not subject it to
shocks.
When not using the unit, always store it in its soft case for protection.
In case of malfunction, do not attempt any repairs. Note the condition of the unit clearly
and contact the supplier.
Dispose of the unit and of used batteries in accordance with local laws and regulations.
The unit does not contain any substances harmful to the environment. Treat the unit
as non-combustible waste.
In order to maintain continued precision, have the unit checked and serviced once per
year. Contact the supplier.

vii
To clean the unit, use only a dry cloth or a cloth lightly moistened with lukewarm water.
Do not use solvents or alcohol-based cleaners.
When mounting and dismounting the microphone and sound calibrator, do not rotate the
sound level meter or sound calibrator. Otherwise the protective grid of the microphone
may become loose or detached, causing damage to the microphone diaphragm.

viii

ix
Contents
FOR SAFETY.............................................................................................iii
Outline ......................................................................................................... 1
Controls and Features................................................................................... 2
Preparations ................................................................................................. 4
Inserting the Batteries............................................................................. 4
Using the 1/2-inch Microphone Adapter NC-74-002............................... 6
Measurement................................................................................................ 7
Reference ................................................................................................... 11
Sound level meter and sound measurement system calibration value .... 11
Electromagnetic Compatibility ............................................................ 16
Specications ............................................................................................. 19

x

1
Outline
The NC-74 is a compact, lightweight, easy-to-use sound calibrator. It conforms to IEC 60942:2003
Class 1 specications and can be used to calibrate class 1 and class 2 sound level meters.

2
Controls and Features
Coupler
The microphone of the sound level meter to be calibrated is inserted here.
Case top
Separate from the case bottom by simultaneously pressing the two sections marked
PUSH. (See illustration on page 4.)
Coupler
1/2-inch microphone adapter
NC-74-002
Case top
Case bottom
LED
Power switch
MADE INJAPAN
RIONCO.,LTD.
SER.No.
MODEL:NC-74
****

3
Controls and Features
Case bottom
Two IEC LR6 (size AA) alkaline batteries are inserted here.
LED
Lights up when the power switch is set to ON.
Power switch
Serves to turn the unit on and off.
1/2-inch microphone adapter NC-74-002
Use this adapter when the outer diameter of the microphone is 1/2 inch.

4
Preparations
Inserting the Batteries
1. Open the case by pressing the
sections marked PUSH and pull-
ing the case top off the case
bottom.
2. Insert two IEC LR6 (size AA)
alkaline batteries with correct
polarity.
3. Snap the case top onto the case
bottom again.
PUSH
Press the PUSH sections on
both sides and open the case.
IEC60942:2003
IEC60942:2003
IEC 60942:2003

5
Preparations
Note
-
Before inserting the batteries, check the correct + and - orientation
as shown on the preceding page. The polarity is also marked inside
the battery wells.
- Do not mix old and new batteries.
- Do not mix different types of batteries.
- Always remove the batteries when not using the unit.
- Dispose of used batteries in accordance with local laws and
regulations.

6
Preparations
Using the 1/2-inch Microphone Adapter NC-74-002
If the outer diameter of the microphone is 1 inch, remove
the 1/2-inch microphone adapter NC-74-002.
When the microphone diameter is 1/2 inches, the adapter
must be in place.
Important
Insert the 1/2-inch microphone adapter NC-74-002 fully into
the coupler. Otherwise correct calibration is not possible.
1/2-inch microphone adapter
NC-74-002
MADE INJAP
AN
RION CO.,LTD.
SER.No.
MODEL:NC-74
****

7
Measurement
To make the measurement, place the units in a perpendicular position, as
shown in the illustration at left.
1. Make sure that the power switch of the NC-74 is OFF.
2. Carefully insert the microphone of the sound level meter all the
way into the coupler of the sound calibrator.
Important
The microphone of the sound level meter must always be
inserted or removed slowly and carefully, to avoid the pos-
sibility of damage to the microphone diaphragm caused by
abrupt changes in air pressure.
When mounting and dismounting the microphone and sound
calibrator, do not rotate the sound level meter or sound
calibrator. Otherwise the protective grid of the microphone
may become loose or detached, causing damage to the
microphone diaphragm.
ON OFF
PUSH

8
Measurement
3. After inserting the microphone, wait at least 30 seconds before reading the level
indication on the sound level meter. Make a note of the reading, because this will
be used in step 6.
Note
Immediately after inserting the microphone, the change in air
pressure inside the sound calibrator will lead to false readings,
thereby preventing correct calibration. The time required until the
air pressure inside the sound calibrator stabilizes is 30 seconds
or less.
The time required until the air pressure inside the microphone
itself stabilizes depends on the microphone type. Check the docu-
mentation of the microphone or the sound level meter.
4. Select the measurement range of the sound level meter so that 94 dB can be mea-
sured.