OPPERATION MANUAL
SOUND LEVEL METER
Your purchase of this DIGITAL SOUND LEVEL METER marks a step forward for you into the field of precision measurement.Although this SOUND LEVEL METER is a complex and delicate instrument,its ruggedness will allow many years of use if proper operating techniques are developed.Please read the following instructions carefully and always keep this manual within easy reach.
TABLE OF CONTENTS
1.FEATURES.........................................................………………………………1
2.SPECIFICATIONS………………………...................................................…..1
3.FRONT PANEL DESCRIPTION.............………………...........................……4 3-1 Electric condenser microphone………………………………………….….4 3-2 Display …………………………………………………………………….4 3-3 Power switch & Output type selector………………………………………4 3-4 A/C weighting & Calibration selector……………………………………..4 3-5 Time Weighting (Fast/Slow)/Max.hold selector……………………………4 3-6 Range selector……………………………………………………………...4 3-7 Signal output terminal……………………………………………………...4 3-8 Battery Compartment/Cover ……………………………………………….4 3-9 Range upper/lower indicator……………………………………………….4 3-10 Calibration VR (Accuracy adjust VR)…………………………………....4
4.MEASURING PROCEDURE ………………………………………………….5
5.MEASURING CONSIDERATION ………………………………………….6 .
6.SIGNAL OUTPUT………………………………………………………………6
7.REPLACEMENT of BATTERY……………………………………………… 7
8.CALIBRATION…………………………………………………………………7
9.FREQUENCY WEIGHTING CHARACTERISTICS OF A&C NETWORKS...9
10.TIME WEIGHTING (FAST & SLOW) CHARACTERISTICS……………….9
1. FEATURES
* Large LCD display,easy to read.
* Frequency weighting networks are designed to meet the IEC 651 type 2. * A&C weighting networks are conformity to standards.
* Time weighting(FAST&SLOW)dynamic characteristic modes. * AC/DC output for system expansion.
* Build in CALIBRATION VR on front panel.
* Condenser microphone for high accuracy & long-term stability. * Max.Hold function for stored the maximum value on display. * Warning indicator for over and under load.
* LCD display for low power consumption & clear read-out even in bright ambient light condition.
* Used the durable, long-lasting components, including a strong, light weight ABS-plastic housing case. * Small and light weight design allow one hand operation. * Low battery indicator.
2. SPECIFICATIONS
Display 18mm(0.7″)LCD(liquid Crystal Display), 3 1/2 digits. Function dB (A&C frequency weighting), Time weighting(Fast,Slow), Max. hold, AC & DC output. Measurement 35 to 130 dB, input signal only, Range 3 ranges. Resolution 0.1 dB
Accuracy Frequency weighting meet IEC 651 type 2, calibrating input signal on 94 (23±5°C) dB (31.5 Hz to 8 kHz), then the accuracy of A weighting is specified as
followwing: 31.5 Hz-±3dB, 63Hz-±2 dB, 125Hz- ±1.5dB 250 Hz-±1.5DB, 500Hz-±1.5dB, 1kHz-±1.5dB, 2kHz-±2dB, 4kHz- ±3dB, 8kHz-±5dB Frequency Characteristics of A & C Weighting A weighting：
Network The characteristic is simulated as ―Human Ear Lighting‖ response. Typical, if making
the environmental sound level measurement,always select to A weighting.
C weighting
The charscteristic is near the ―FLAT‖ response. Typical, it is suitable for checking the
noise of machinery(Q.C.check) & knowing the sound pressure level of the tested equipment.
Frequency 31.5 Hz to 8,000 hz. Calibrator B&k (Bruel & Kjaer):
Multi-fuction acoustic calibrator, Model:4226.
Microphone Electric condenser mircrophone. Size of 1/2 inch standard size. microphone
Range selector 30 to 80 dB, 50 to 80 dB, 80 to 130 dB, 50 dB on each step,with over & under range
indicating.
*30 to 80 dB range are operated from 35 80 dB offically.
Time weighting (Fast & Slow) Fast – t =200ms *‖Fast‖ range is simulated the human ear
response time weighting.
Calibration *Build in external calibration VR on front panel *Calibrated via external SOUND CALIBRATOR. *Calibrated via internal 94 dB/1 KHz generator. Output Signal AC output :
AC 0.5Vrms corresponding to each range step. DC output:
DC 0.3 to 1.3 VDC, 10 mV per dB. Out put impedance- 600 ohm.
Output terminal 3.5 mm Dia. Phone output terminal is provided for
connection with analyzer, level recorder, tape recorder.
Operating Temperature 0°C to 50°C ( 32 °to 122° F ) Operating Humidity Max. 90% RH (0°to35°C).
Power Supply 006P DC 9V battery (heavy duty type). Power Consumption Approx. DC 6 mA.
Dimension 245×80×35mm (9.6×3.2×1.4 inch). Weight 300g/0.66 LB (including battery). Standard Accessories Instruction Manual ………… 1 PC Calibration screw driver …… 1 PC.
Optional 94 dB Sound Calibrator, model: SC – 941 Calibrator 94 dB Sound Calibrator, model: SC – 940A
3. FRONT PANEL DESCRIPTION
3-1 Electric condenser microphone 3-2 Display
3-3 Power switch & Output type selector 3-4 A/C weighting & Calibration selector
3-5 Time Weighting (Fast / Slow) / Max . hold selector 3-6 Range selector
3-7 Signal output terminal
3-8 Battery Compartment / Cover 3-9 Range upper / lower indicator
3-10 Calibration VR (Accuracy adjust VR)
4. MEASURING PROCEDURE
1) Slide the ―A/C weighting selector‘‘ (3-4,Fig. 1) to ‗A‘ or ‗C‘ position for sound level measuring. NOTE:
a. the characteristic table of A , C weighting ,please ref . page 9.
b. The characteristic of A weighting is simulated as the “Human Ear Listening’’ response .Typically ,if making the environmental sound level measurement , always select the A weighting typically.
c. The C weighting characteristic is near the “FLAT’’ response. Typically , it is suitable for checking the noise of machinery (Q.C. check ) & knowing the real sound of the tested equipment
2) Determine proper measuring range by selecting the ―Range selector‖ (3-6,Fig.1) to minimize the tolerance of readout. When left corner of LCD show ``▲`` indicator, (3-9,Fig.1),it shows the dB range selection is upper or lower setting . Slide range selector to other range for measuring.
3) According on various measuring sound source, select the ― Time Weighting selector‖ (3-5,Fig.1) to ―Fast‘ or ―Slow‖ position .
4) Hold the instrument in hand and point the microphone at measured noise source, the sound level will be displayed on ‗dB‘ (decibel) unit.
5) Max hold— During the sound level measurement, if intend to store the maximum (peak) value on display, please slide the ‗Time weighting/Max. hold selector‘ (3-5,Fig.1) to the
― Max . hold‖ position. NOTE:
a. When measure long-term stability under slowly varying noise environment please use the Max. hold function to read the maximum values.
b Slide the selector to “Fast” or “slow” position will cancel the max. hold values.
5.MEASURING CONSIDERATION
1) Please should select the proper weighting selector(A weighting or C weighting ). The A weighting selector will be engaged normally.
2) Please select proper measurements range to minimize the tolerance of readout.
3) Please don‘t keep or operate the instrument at high temperature & humidity environment for a long period.
4) Keep microphone dry & avoid serious vibration .
6. SIGANL OUTPUT
The instrument is provided an‘‘3.5mmDia. phone output‘‘ (3-7,Fig.1) terminal for connection with analyzer, level recorder, tape recorder, controller…etc. Slide‖ Power switch & Output type selector ―(3-3,Fig.1) to AC output or DC output according the user requirement.
7. REPLACEMENT OF BATTERY
1) When the left corner of LCD display show ―BAT‖,it indicate a normal battery output of less than 6.5 V-7.5V. It is necessary to replace the battery. However,in-spec.measurement may still be made for several hours after LOW BATTERY INDICATOR appears before the instrument become inaccurate. 2) Slide the ―Battery Cover‖(3-8,Fig.1)& take the battery away from the battery compartment. 3) Replace with 9V battery (heavy duty type) and reinstate the cover.
8.CALIBRATION
The sound level meter is built in the ―Internal calibration VR/Accuracy Calibration VR‖(3-10.Fig.1) on the front panel. Please according the following procedures to calibrate the instrument accurately, if it is necessary.
8-1 Calibrated via external SOUND CALIBRATOR
1)Prepare the ―SOUND CALIBRATOR‖, model:SC-941 (optional) or model:SC-940A(optional).Power on the Sound Calibrator& plug calibrator output into the Electric condenser micro-phone(3-1,Fig.1) of the Sound Level Meter.
2)Slide the Range selector (3-6,Fig.1) to ―50-100 dB”position. 3)Slide ―Time Weighting selector‖(3-5,Fig.1) to ―SLOW‖ position.
4)Slide the ―A/C weighting & Calibration selector ‖(3-4,Fig.1)to ―A weighting ‖position.
5)Carefully adjust the ―Calibration VR‖(3-10,Fig.1) with ―- ‖ screw driver,until the display read within ―94.0±0.2‖dB.
8-2 Calibrated via internal 94 dB generator
The sound level meter is built in the internal standard 94dB/ 1 KHz square wave generator for the purpose to calibrate some certain amplifier circuit. Please according the following procedures to calibrate the instrument before making operation, if the instrucment not in use for a long time.
1)Slide ―Range selector‖(3-7,Fig.1) to ―50-100‖ position. 2)Slide ―Fast/Slow selector‖(3-6,Fig.1) to ―SLOW‖ position.
3)Slide ―A/C weighting & Calibration selector‖(3-4,Fig.1) to ―94 dB CAL ‖ position.
4)Carefully adjust the ―Calibration VR‖(3-10,Fig.1) with ―-‖ screw driver, until the display read within ―94.0±0.2‖ dB.
NOTE:
If intend to make calibration accurately,it is recommended to use calibrating procedures of above 8-1 “Calibrated via extrnal SOUND CALIBRATOR”
▲ 3—1
3—9 3—2
3—3 3—4 3—10 3—5 3—6 3—7
3—8
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