MARTINDALE
E L E C T R I C
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INSTRUCTIONS
SOUND LEVEL METER
SP75
INTRODUCTION
This instrument is a portable easy use 3½ digit, compact-sized digital sound level
meter designed for simple one hand operation, and can be mounted on a tripod
for long-term measurement. This meter is equipped to measure A and C
frequency weighting of the RMS signal, with Fast and Slow time weighting and
maximum level indication.
SAFETY INFORMATION
It is recommended that you read the safety and operation instructions before
using this sound level meter.
1. The sound level meter must be protected from shocks and vibration as it is a
precision instrument.
2. The microphone in particular must be protected from exposure to water or dust.
The unit should also not be stored in locations with high temperatures or humidity.
3. Dust or contamination can alter the performance characteristics of the unit.
Always replace the unit in its carrying case when not in use.
4. The microphone cover at the tip of the unit is not designed to be removed. Do
not try to disengage the cover. Cleaning the microphone is not advisable.
SPECIFICATIONS
GENERAL
Display:
3½ digit liquid crystal display (LCD) with maximum reading of 1999
Low battery indication:
the symbol " " is displayed when the battery voltage
drops below the operating level
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Measurement rate:
once per second, nominal
Operating Environment:
-10°C to 50°C at < 90% relative humidity
Storage Temperature:
-20°C to 60°C, 0 to 80% R.H. with battery removed
Battery:
4 pcs 1.5V (AAA size) UM-4 R03
Battery Life:
50 hours
Dimensions:
217mm(H) x 44mm(W) x 40mm(D)
Weight:
168g including batteries
Accessories:
Windscreen x1, Battery x4, Plug x1,Tripod mounting screw-nut
x1,Carrying case x1
ELECTRICAL
Applicable Standard:
IEC 651-1979 Type 2
ANSI S1.4-1983 Type 2
JIS C 1502
Measurement Range:
Lo - range 35-90 dB
Hi - range 75-130 dB
Resolution:
0.1dB
Frequency Weighting:
A and C according to IEC 651 Type 2
Frequency Range:
31.5 Hz to 8000 Hz
Detector:
True-RMS with independent frequency weightings
Dynamic Range: 55dB
Maximum Hold decay time:
<1dB/3minute with Reset switch
Time Weighting:
S(SLOW) and F(FAST) according to IEC 651 Type 2
Microphone:
1/2" electret (prepolarized) condenser microphone
DC Output:
Output - 10 mV/dB Output Impedance - 50
Ω
approx
AC Output:
Output -1.0V RMS corresponding to the top of the selected
measurement range.
Output Impedance - 600
Ω
approx
Warm-up:
<5s
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Calibration Conditions:
Reference Frequency: 1000 Hz
Reference SPL: 94 dB
Reference Temperature: 20°C
Reference RH: 65%
Reference Range: 75-130dB
Reference Direction of incidence: Frontal
Environmental Effects
Effect of Temperature:
<0.5dB (-10°C to 50°C)
Effect of Humidity:
<0.5dB for 30%<RH<90%(at 40°C , 1KHz)
OPERATING INSTRUCTIONS
1.
Setting the Measurement Range :
Slide switch "O(power-off) / Lo(35-90dB) / Hi(75-130dB)".
The meter has 2 sound pressure level (SPL) measurement ranges each with
a dynamic range of 55dB. The sound pressure level indication is updated
every one second.
If OVER or UNDER is continuously shown, change the setting of the power
range slide switch to a suitable range.
2.
Setting the Time Weighting
Slide switch: S(SLOW) / F(FAST)
The time weightiness available are shown over:
S(SLOW): for normal measurements
F(FAST): for checking average levels of fluctuating noise.
3.
Setting the Frequency Weighting
Slide switch: A / C
The available frequency weightings of the RMS signal are shown below:
A: for general sound level measurement
C: for checking the low-frequency content of a noise (If the C-weighted level is
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