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User's Guide
Digital Sound Level Meter
Model 407732
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
FAX 781.665.0780 - TestEquipmentDepot.com
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information. A Return Authorization (RA) number must be issued before any product is
returned to Extech. The sender is responsible for shipping charges, freight, insurance and
proper packaging to prevent damage in transit. This warranty does not apply to defects
resulting from action of the user such as misuse, improper wiring, operation outside of
Introduction
specification, improper maintenance or repair, or unauthorized modification. Extech
specifically disclaims any implied warranties or merchantability or fitness for a specific
Congratulations on your purchase of the Extech 407732 Digital Sound Level Meter. The
purpose and will not be liable for any direct, indirect, incidental or consequential damages.
407732 measures and displays sound pressure levels in dB from 35 to 130dB. The LCD
Extech's total liability is limited to repair or replacement of the product. The warranty set
is backlit for viewing readings in dimly lit areas. User selectable features include
forth above is inclusive and no other warranty, whether written or oral, is expressed or
Frequency Weighting (‘A’ and ‘C’), Response Time (Fast and Slow), Max Hold, and
implied.
Range (High and Low). Careful use of this meter will provide years of reliable service.
Safety
Warranty
Read the following safety information carefully before attempting to operate or
service the meter. Use the meter only as specified in this manual; otherwise, the
protection provided by the meter may be impaired.
Environmental Conditions
Altitude up to 2000 meters
Relative Humidity: 90% max.
Operating Temperature: 32 to 104
Maintenance and Cleaning
Repair or servicing not covered in this manual should only be performed by qualified
personnel.
Periodically wipe the case with a dry cloth. Do not use abrasives or solvents.
o
F (0 to 40oC)
Calibration and Repair Services
Extech offers repair and calibration services for the products we sell. Extech also
provides NIST certification for most products. Call the Customer Service Department for
information on calibration services available for this product. Extech recommends that
annual calibrations be performed to verify meter performance and accuracy.
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Model 407732 Version 1.4 June 2004
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Specifications
Display 4-digit (4000 count) backlit LCD
Display update rate 0.5 seconds
Microphone 0.5” Electret condensor
Measurement Bandwidth 31.5Hz to 8KHz
Dynamic range 65dB
Measurement Range 35 to 130dB (Low: 35 to 100; High: 65 to 130dB)
Frequency weighting ‘A’ and ‘C’ (selectable)
Accuracy / Resolution ± 1.5dB (under reference conditions) / 0.1dB
Standards Meets ANSI and IEC Type 2 SLM standards
Maximum Hold decay time <1dB / 3min
Response time Fast: 125 milliseconds / Slow: 1 second
Calibration source required 1KHz sine wave @ 94dB
Power 9V Battery
Battery life 50 hours (typical); low battery indicator alerts user
Automatic power off After approx. 15 minutes of inactivity
Operating temperature 32 to 104oF (0 to 40oC)
Operating humidity 10 to 90% RH
Storage temperature 14 to 140oF (-10 to 60oC)
Storage humidity 10 to 75% RH
Dimensions/weight 9.45 x 2.68 x 1” (240 x 68 x 25mm) / 6.75oz (210g)
Technical support: Extension 200; E-mail: support@extech.com
Repair & Returns: Extension 210; E-mail: repair@extech.com
Product specifications subject to change without notice
For the latest version of this User’s Guide, Software updates, and other
up-to-the-minute product information, visit our website: www.extech.com
Support line (781) 890-7440
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Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
FAX 781.665.0780 - TestEquipmentDepot.com
Model 407732 Version 1.4 June 2004
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Meter Description
1. Microphone
2. 4-digit LCD Display
3. ON-OFF button
4. LCD Backlight button
5. Frequency weighting selection button
6. Response time selection button
7. Range selector button
8. Max Hold / Data Hold selector button
9. Battery compartment on rear
10. Calibration pots in battery compartment
11. Windscreen
Measurement Considerations
1. Wind blowing across the microphone increases the noise measurement. Use the
supplied windscreen to cover the microphone when applicable.
2. Calibrate the instrument before each use if possible. Especially if the meter has not
been used for a long period of time.
3. Do not store or operate the instrument in areas of high temperature or humidity.
4. Keep meter and microphone dry.
5. Avoid severe vibration.
6. Remove the battery when the meter is to be stored for long periods of time.
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Model 407732 Version 1.4 June 2004
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Operation
1. Power the meter by pressing the power button. The meter will begin displaying
sound level readings. If the LCD does not switch on, check the 9V battery located in the
rear battery compartment.
2. Hold the meter in hand facing the microphone toward the source of the sound to be
measured.
3. View the measurement on the meter’s LCD. An indication of OVER means that the
measurement is out of range. Toggle the ‘Hi’ (65 to 130dB) and ‘Lo’ (35 to 100dB)
measurement ranges using the HI/LO button. For measurements in the 65 to 100dB
region either range can be used.
‘A’ and ‘C’ Frequency Weighting
Use the ‘A/C’ button to select ‘A’ or ‘C’ frequency weighting. With ‘A’ weighting selected,
the frequency response of the meter is similar to the response of the human ear. ‘A’
weighting is commonly used for environmental or hearing conservation programs such as
OSHA regulatory testing and noise ordinance law enforcement. ‘C’ weighting is a much
flatter response and is suitable for the sound level analysis of machines, engines, etc.
Most noise measurements are performed using 'A' Weighting and SLOW Response.
‘FAST’ and ‘SLOW’ Response Time
Use the ‘F/C’ button to select FAST (125 ms) or SLOW (1 second) response time. Select
FAST to capture noise peaks and noises that occur very quickly. Select the SLOW
response to monitor a sound source that has a consistent noise level or to average quickly
changing levels.
Select Slow response for most applications.
‘Hi’ and ‘Lo’ Range Selections
Use the ‘Hi/Lo’ button to select the appropriate range. If the measurement is in the range
of 35 to 100 dB, use the ‘Lo’ range. If the measurement is between 65 and 130dB, use the
‘Hi’ range. For measurements between 65 and 100dB, either range can be used. If the
display flashes the OVER icon, press the range button to toggle the range.
MAX HOLD
In this mode, the meter only updates the LCD when a higher reading than the one
presently on the display is detected. Select MAX HOLD by momentarily pressing the MAX
HOLD button. The meter displays the MAX icon when in the MAX HOLD mode. Press the
MAX HOLD button again to exit this mode (the MAX indicator will switch off).
DATA HOLD
To freeze a displayed reading, press and hold the MAX HOLD button until the MAX and
HOLD display icons appear. To release the display and return to the normal operating
mode, press and hold the MAX HOLD button until the MAX and HOLD icons switch off.
Backlight button
The LCD is equipped with backlighting for easier viewing, especially in dimly lit areas.
Press the backlight button to turn the backlight on. Press again to turn the backlight off.
The backlight does not have an automatic power down function; judicious use will
conserve battery life.
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Model 407732 Version 1.4 June 2004
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Calibration
To calibrate the 407732, an external calibrator such as the Extech 407744 or the Extech
407766 is required in addition to a small screw-driver.
1. Open the battery compartment and locate the two
calibration potentiometers behind the 9V battery (see
diagram)
2. Turn the meter ON
3. Put the meter in the ‘A’ weighting mode
4. Put the meter in the ‘SLOW’ response mode
5. Place the 407732 microphone into the calibrator. Set
the calibrator to output a 1kHz sine wave @ 94dB
6. Put the meter in the low range
7. Adjust the ‘A (Lo)’ potentiometer for a display of 94.0
dB
8. Put the meter in the high range
9. Adjust the ‘A (HI)’ potentiometer for a display of 94.0
dB
Battery Replacement
When the low battery icon BAT appears on the LCD replace the 9V battery as soon as
possible. The battery compartment cover is located on the rear of the meter. Remove the
Phillips screw to loosen the cover. Slide the battery compartment cover off, change the
battery, and replace the compartment cover.
Typical A-Weighted Sound Levels
dBA
50HP Siren (100')
Jet takeoff (200')
Riveting machine
Subway (20')
Pneum atic drill (5 0')
Vacuum cleaner (10')
Lar ge st o re
Small off ic e
Night residential area
Whispe r (5' 0)
Threshold of hear ing
140
130
120
110
Chain saw
100
90
Boile r room
80
Freight train (100' )
70
Speech (1')
60
Large Office
50
Resid e n ce
40
30
Sound studio
20
10
0
Copyright © 2004 Extech Instruments Corporation
All rights reserved including the right of reproduction in whole or in part in any form.
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Model 407732 Version 1.4 June 2004
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
FAX 781.665.0780 - TestEquipmentDepot.com
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