Amprobe SM-20A Sound Meter User Manual

1. Introduction

The Amprobe SM-20A Sound Level Meter is designed for precise sound level measurements, meeting the requirements of safety engineers, health and industrial safety offices, and quality control departments across various environments. This device offers both A-weighting and C-weighting measurement capabilities.

The A-weighting is suitable for general noise sound level measurements, while the C-weighting is used for measuring the sound level of acoustic materials, such as a 94dB at 1 kHz reference. The SM-20A conforms to IEC651 Type 2, ANSI S1.4 Type 2, and JISC1502 requirements for Sound Level Meters, ensuring accurate and reliable performance.

Figure 1: The Amprobe SM-20A Sound Meter, a compact device for accurate sound level measurements.

2. Safety Information

To ensure safe operation and service of the meter, follow these instructions:

• Read this manual thoroughly before use.
• Do not operate the meter if it appears damaged or is not functioning properly.
• Avoid exposing the meter to extreme temperatures, humidity, or direct sunlight.
• Do not attempt to open or modify the meter. Refer all servicing to qualified personnel.
• Keep the meter away from strong electromagnetic fields.
• Dispose of batteries according to local regulations.

3. Setup

3.1 Unpacking and Inspection

Carefully unpack the meter and check for any signs of damage. Ensure all components are present:

• Amprobe SM-20A Sound Level Meter
• Carrying Case
• USB Cable (for PC connection)
• Software CD (for data download)
• User Manual

Figure 2: The Amprobe SM-20A Sound Meter shown with its included carrying case, USB cable, software CD, and user manual.

3.2 Battery Installation

The SM-20A requires a 9V battery (not included). To install:

1. Locate the battery compartment cover on the back of the meter.
2. Slide the cover open.
3. Connect a 9V battery to the battery clip, observing polarity.
4. Place the battery into the compartment and close the cover securely.

4. Operating Instructions

4.1 Power On/Off

Press the POWER button to turn the meter on or off.

4.2 Display Overview

Figure 3: A close-up view of the Amprobe SM-20A's LCD display, showing measurement readings and various indicators.

The LCD displays the sound level in 0.1dB steps. Indicators for A/C weighting, Fast/Slow response, MAX/MIN, HOLD, and REC will also be visible.

4.3 Weighting Selection (A/C)

Press the A/C button to toggle between A-weighting and C-weighting. The selected weighting will be indicated on the display.

• A-weighting: Simulates the human ear's response to sound, suitable for general noise measurements.
• C-weighting: Provides a flatter response, useful for measuring the true sound pressure level of machinery or acoustic materials.

4.4 Response Time Selection (Fast/Slow)

Press the FAST/SLOW button to select the desired response time:

• FAST (125ms): For capturing peak and rapidly changing noise levels.
• SLOW (1 sec): For measuring average noise levels and stable sounds.

4.5 MAX/MIN Recording

Press the MAX/MIN button to activate the maximum and minimum value recording function. The display will show the highest (MAX) or lowest (MIN) sound level recorded since the function was activated. Press again to cycle through MAX, MIN, and current readings.

4.6 Data Hold

Press the HOLD button to freeze the current reading on the digital display. Press again to release the hold function.

4.7 Data Recording (REC)

The SM-20A features an internal memory capable of storing up to 14,000 records. To initiate data recording:

1. Press the REC button to start recording. The "REC" indicator will appear on the display.
2. To stop recording, press the REC button again.
3. Recording intervals can be set from 1 second to 8 hours using the included PC software.

For data download and analysis, connect the meter to a PC using the provided USB cable and software.

Figure 4: An individual using the Amprobe SM-20A Sound Meter to measure noise levels in an industrial environment, demonstrating its practical application.

5. Maintenance

5.1 Cleaning

Wipe the meter's casing with a soft, dry cloth. Do not use abrasive cleaners or solvents. Keep the microphone clean and free of dust.

5.2 Battery Replacement

Replace the 9V battery when the low battery indicator appears on the display. Refer to Section 3.2 for battery installation instructions.

5.3 Storage

When not in use for extended periods, remove the battery to prevent leakage. Store the meter in its carrying case in a cool, dry place, away from direct sunlight and extreme temperatures.

6. Troubleshooting

7. Specifications

8. Warranty and Support

Amprobe products are designed for reliability and performance. For specific warranty information, please refer to the warranty card included with your product or visit the official Amprobe website. Keep your purchase receipt as proof of purchase.

For technical support, troubleshooting assistance, or service inquiries, please contact Amprobe customer service. Contact details can typically be found on the Amprobe website or in the product packaging.

Online Resources: For additional resources, software updates, and FAQs, please visit the official Amprobe support page.