User's Guide Digital Sound Level Meter Model 407732 Introduction Congratulations on your purchase of the Extech 407732 Digital Sound Level Meter. The 407732 measures and displays sound pressure levels in dB from 35 to 130dB. The LCD is backlit for viewing readings in dimly lit areas. User selectable features include Frequency Weighting (‘A’ and ‘C’), Response Time (Fast and Slow), Max Hold, and Range (High and Low). Careful use of this meter will provide years of reliable service. 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. Safety 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. o o Operating Temperature: 32 to 104 F (0 to 40 C) 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. 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. 2 Model 407732 Version 1.4 June 2004 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 104 F (0 to 40 C) Operating humidity 10 to 90% RH Storage temperature 14 to 140 F (-10 to 60 C) Storage humidity 10 to 75% RH Dimensions/weight 9.45 x 2.68 x 1” (240 x 68 x 25mm) / 6.75oz (210g) o o o o Support line (781) 890-7440 Technical support: Extension 200; E-mail: [email protected] Repair & Returns: Extension 210; E-mail: [email protected] 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 3 Model 407732 Version 1.4 June 2004 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. 4 Model 407732 Version 1.4 June 2004 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. 5 Model 407732 Version 1.4 June 2004 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 140 50HP Siren (100') Jet takeoff (200') Riveting machine 130 120 110 Chain saw 100 Subway (20') 90 Pneumatic drill (50') 80 Vacuum cleaner (10') 70 Large store 60 Small office 50 Night residential area 40 Whisper (5'0) 30 Boiler room Freight train (100') Speech (1') Large Office Residence Sound studio 20 10 Threshold of hearing 0 Copyright © 2004 Extech Instruments Corporation All rights reserved including the right of reproduction in whole or in part in any form. 6 Model 407732 Version 1.4 June 2004