User's Guide
Digital Sound Level Meter
Model 407730
Introduction
Congratulations on your purchase of the Extech 407730 Digital Sound Level Meter. The
407730 measures and displays sound pressure levels in dB from 40 to 130dB. User
selectable features include Frequency Weighting (‘A’ and ‘C’), Response Time (Fast and
Slow), Max Hold, and Max/Min recording. Careful use of this meter will provide years of
reliable service.
Meter Description
1. Microphone
2. LCD Display
3. ON-OFF button
4. A/C weighting selection button
5. Min/Max Record button
6. Range selector button
7. F/S response selection button
8. Max Hold selector button
9. Calibration adjustment
10. AC analog output jack
11. Windscreen
1. Record icon
2. Auto or Manual range
3. Range indicator
4. Bargraph
5. A or C weighting
6. Low bat icon
7. Max level indicator
8. Hold indicator
9. Min indicator
10. Fast or Slow weighting
11. dB display
11
1
2
9
3
6
10
4
5
8
7
9
7
8
10
1
FAS T
REC
2
3
4
AUTO
MANU
SPL
40
+0
MAX
HOLD
+10
MIN
SLOW
A
C
dB
+20 +30
6
5
11
Model 407730 Version 1.4 April 2006 2
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 away from the body.
3. View the measurement on the meter’s display. If the meter is in the autoranging mode,
the display may briefly indicate “HI” or “LO” if the noise level is above or below the
currently selected range. The meter will change the range as needed to display the dB
level.
‘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. “A” or “C” icons will appear in the display.
Most noise measurements are performed using 'A' Weighting and SLOW Response.
‘FAST’ and ‘SLOW’ Response Time
Use the ‘F/S’ 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. “FAST” or “SLOW” icons will appear in the display.
Select Slow response for most applications.
Auto or Manual Ranging
The meter will turn on in the auto-ranging mode and “AUTO” will be indicated on the
display. In this mode the meter will automatically select the best range for the noise level
being measured. If the measured dB level exceeds the range of the meter or the range of
a selected range, “HI” will appear in the display. If the measured dB level is lower than the
selected range, “LO” will appear in the display.
1. Press the RNG button to manually select the range, “MANU” will be indicated on the
display. The four ranges are: 40-70, 60-90, 80-110 and 100-130. Press the RNG button
to step through the ranges.
2. Press and Hold the RNG button for 2 seconds to exit the manual range mode.
MAX HOLD
In this mode the meter only updates the LCD when a higher reading than the one presently
on the display is detected.
1. Press the MAX HOLD button to enter the Max Hold mode.. The “MAX HOLD” icon will
appear in the display.
2. Press the MAX HOLD button again to exit this mode.
Model 407730 Version 1.4 April 2006 3
MAX/MIN Recording
In this mode the meter records the Maximum and Minimum readings and stores them into
memory.
1. Press the REC button to enter the RECORD mode. The “REC” icon will appear in the
display.
2. Press the REC button again to display the minimum value recorded since the mode was
entered. The “MIN” icon will appear in the display. The meter is not recording during this
time.
3. Press the REC button again to display the maximum value recorded since the mode
was entered. The “MAX” icon will appear in the display. The meter is not recording
during this time.
4. Press the REC button again to display the present dB level and continue recording.
5. Press and hold the REC button until the “REC” icon clears to exit the mode.
Auto-Power Off
The meter will automatically shut off after 20 minutes of operation. To disable this feature:
1. With the meter OFF, Press the and MAX HOLD buttons simultaneously.
2. will appear in the display
3. Release the button and then release the MAX HOLD button.
4. The meter will remain on until the power button is pressed.
Calibration
To calibrate the meter, an external calibrator such as the Extech 407744 or the Extech
407766 is required in addition to a small screw-driver.
1. Turn the meter ON
2. Select the 80 to 110dB range
3. Select ‘A’ weighting and ‘SLOW’ response
4. Place the microphone into the calibrator. Set the calibrator to output a 1kHz sine wave
@ 94dB
5. Adjust the calibration potentiometer for a display as close as possible to the calibrator’s
output
Battery Replacement
When the low battery icon appear replace the battery by removing the screw securing
the rear battery compartment and replacing the 4 AAA batteries.
Tripod Mount
A camera tripod mount is located on the rear of the meter for increased stability and
elimination of body reflections.
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.
Model 407730 Version 1.4 April 2006 4
Specifications
Display LCD with bargraph
Microphone 0.5” (10mm) Electret condensor
Measurement Bandwidth 300Hz to 8KHz
Measurement Range 40 to 130dB (A wtg), 45 to 130dB (C wtg)
Frequency weighting ‘A’ and ‘C’ (selectable)
Accuracy / Resolution ± 2dB @1kHz (under reference conditions) / 0.1dB
Response time Fast: 125 milliseconds / Slow: 1 second
Calibration source 1KHz sine wave @ 94 or 114dB
AC output 0.707Vrms full scale
Power 4 AAA Batteries
Battery life 30 hours (typical); low battery indicator alerts user
Automatic power off After approx. 20 minutes
Operating temperature 32 to 122oF (0 to 50oC)
Operating humidity 10 to 90% RH
Storage temperature -4 to 140oF (-20 to 60oC)
Dimensions/weight 9 x 2.3 x 1.7” (230 x 57 x 44mm) / 6oz (172g)
Warranty
EXTECH INSTRUMENTS CORPORATION warrants this instrument to be free of defects
in parts and workmanship for one year from date of shipment (a six month limited warranty
applies to sensors and cables). If it should become necessary to return the instrument for
service during or beyond the warranty period, contact the Customer Service Department at
(781) 890-7440 ext. 210 for authorization or visit our website www.extech.com for contact
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
specification, improper maintenance or repair, or unauthorized modification. Extech
specifically disclaims any implied warranties or merchantability or fitness for a specific
purpose and will not be liable for any direct, indirect, incidental or consequential damages.
Extech's total liability is limited to repair or replacement of the product. The warranty set
forth above is inclusive and no other warranty, whether written or oral, is expressed or
implied.
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.
Model 407730 Version 1.4 April 2006 5
Typical A-Weighted Sound Levels
dBA
50HP Siren (100')
Jet takeoff (200')
Riveting machine
Subway (20')
Pneumatic drill (50' )
Vacuum cleaner (10')
Lar ge sto re
Small offic e
Night residential area
Whispe r (5'0)
Threshold of hear ing
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
Copyright © 2004 Extech Instruments Corporation
All rights reserved including the right of reproduction in whole or in part in any form.
140
130
120
110
Chain saw
100
90
Boiler r oo m
80
Freight train (100' )
70
Speech (1')
60
Large Office
50
Resid ence
40
30
Sound studio
20
10
0
Model 407730 Version 1.4 April 2006 6
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