33-2050.fm Page 1 Monday, April 17, 2000 2:04 PM Please read before using this equipment.
33-2050.fm Page 2 Monday, April 17, 2000 2:04 PM ˆ Contents Introduction ......................................... 3 Specifications ...................................... 5 Installing a Battery .............................. 7 Controls ................................................ 9 Range ............................................ 9 Output .......................................... 10 Response ..................................... 10 Weighting ..................................... 11 Microphone ......
3-2050.fm Page 3 Monday, April 17, 2000 2:04 PM ˆ Introduction Your RadioShack Sound Level Meter is an extremely versatile device for measuring sound intensity in just about any acoustic environment — loud or soft; highpitched, low-pitched, or broad-band; intermittent or continuous. You can use it to measure noise levels in factories, schools, offices, and airports, or to check acoustics of studios, auditoriums, and home theater installations.
33-2050.fm Page 4 Monday, April 17, 2000 2:04 PM Built-in Battery Condition Indicator — lets you check the battery condition. Phono-type Output Jack — for connection to home theater or test equipment. Threaded Insert — lets you attach the meter to a camera tripod for increased accuracy.
33-2050.fm Page 5 Monday, April 17, 2000 2:04 PM ˆ Specifications Range: Switch Setting Range of Measurement 60 dB 50–66 dB 70 dB 60–76 dB 80 dB 70–86 dB 90 dB 80–96 dB 100 dB 90–106 dB 110 dB 100–116 dB 120 dB 110–126 dB Accuracy ............................... ± 2 dB @ 114 dB Standard ........................... 0 dB = 0.0002 µbar Weighting ........................................... A and C Response ................................... Fast and Slow Signal Output .........................
33-2050.fm Page 6 Monday, April 17, 2000 2:04 PM Battery ................................................. One 9V Battery Check ................ Tests “good” from 7.0 to 10.5V Expected Battery Life ......... 110 working hours (alkaline battery) Size (HWD) .............. 5 /16 × 2 7/16 × 13/4 Inches (160 × 62 × 44 mm) Weight ................................................... 6.6 oz (185 g) Specifications are typical; individual units might vary.
33-2050.fm Page 7 Monday, April 17, 2000 2:04 PM ˆ Installing a Battery Your meter requires one 9V battery (not supplied) for power. For the best performance and longest life, we recommend a RadioShack alkaline battery. Caution: Use only a fresh battery of the required size and recommended type. Follow these steps to install the battery. 1. Press both sides of the battery compartment cover and lift it. Press both sides Note: The battery compartment cover cannot be removed. 2.
33-2050.fm Page 8 Monday, April 17, 2000 2:04 PM To test the battery, set RANGE to BATT. If the meter shows a reading in the red BATT TEST region, the battery is still good. Replace the batteries when the reading is in any other region or the meter stops operating. Warning: Dispose of old batteries promptly and properly. Do not burn or bury them. Caution: If you do not plan to use the meter for a week or more, remove the batteries. Batteries can leak chemicals that can destroy electronic parts.
33-2050.fm Page 9 Monday, April 17, 2000 2:04 PM ˆ Controls RANGE SLOW FAST RESPONSE Level Indicator CAL OUTPUT AC WEIGHTING RANGE The RANGE selector lets you select one of seven sound level ranges, each spanning 16 dB. The RANGE numbers refer to the center points of the seven ranges. The needle level indicator shows the actual sound level as a displacement from the center point. For example, if RANGE is set to 80 and the meter scale reads –3, the actual sound level is 77 dB (80–3).
33-2050.fm Page 10 Monday, April 17, 2000 2:04 PM OUTPUT The phono-type OUTPUT jack lets you connect the meter to recording or other measurement equipment. For example, you might use an audio patch cord to connect the meter to the AUX or high-level input of a recorder. Note: The meter response will not be flat, due to the A- and C-weighting networks. Set RANGE so the maximum needle deflection is never greater than +4, to prevent the built-in amplifier from clipping.
33-2050.fm Page 11 Monday, April 17, 2000 2:04 PM The effect of brief sound peaks is minimized in the SLOW position. WEIGHTING Set WEIGHTING to weight the sound measurement for a particular frequency range. When set to A, the meter primarily measures frequencies in the 500–10,000 Hz range, which is the area of greatest sensitivity to the human ear. When set to C, the meter measures uniformly over the frequency range from 32–10,000 Hz, giving an indication of the overall sound level.
33-2050.fm Page 12 Monday, April 17, 2000 2:04 PM MICROPHONE The meter’s built-in microphone works best when you point it directly at a sound source. TRIPOD ADAPTER You can mount the meter on a camera tripod (standard 1/4–20 thread) to eliminate hand noise and minimize the effects of sound reflected from your body. This makes it easy to use the meter with auxiliary recording or test equipment.
33-2050.fm Page 13 Monday, April 17, 2000 2:04 PM CAL (CALIBRATION) Your meter has been accurately calibrated and normally will not require further adjustment. If adjustment is necessary, take the sound meter to an audio professional who can calibrate the meter by connecting special equipment, such as a sound generator, to the CAL jack.
33-2050.fm Page 14 Monday, April 17, 2000 2:04 PM Follow these steps to select the desired response, weighting, and range. 1. Set RESPONSE to FAST if the sound source you want to measure consists of short bursts or if you want to measure only peak values. Or, set RESPONSE to SLOW if you want to measure average sound levels. 2. Set WEIGHTING to A if you want to measure noise level or C if you want to measure sound levels of musical material. 3.
33-2050.fm Page 15 Monday, April 17, 2000 2:04 PM While taking measurements, minimize the effect of your body’s presence. When the sound is coming mainly from one direction, the level reading might be significantly affected by reflections from your body. For the most accurate readings and the best polar response, point the meter’s microphone toward the sound source when possible.
33-2050.fm Page 16 Monday, April 17, 2000 2:04 PM CHECKING NOISE LEVELS This chart, gathered from Federal, State, and local agencies, shows standards for acceptable noise levels. Sound Level (dB) (A-weighting, SLOW response) Maximum Duration per Day (hours) 90 8 92 6 95 4 97 3 100 2 102 1 1/2 105 1 110 1/2 1/2 115 or less Permissible noise exposures. Extracted from U.S. Department of Labor Noise Regulations. Noise is inevitable in almost any environment.
33-2050.fm Page 17 Monday, April 17, 2000 2:04 PM To use your meter to check noise levels, set WEIGHTING to A and RESPONSE to SLOW. Take measurements at several points in the test area, with the meter positioned properly. Average dB levels of some common activities. CHECKING ROOM ACOUSTICS The size, shape, and furnishings of a room can have a tremendous effect on a home theater system’s performance.
33-2050.fm Page 18 Monday, April 17, 2000 2:04 PM Depending on the speaker placement, standing waves might also develop in the room, giving your system a “peaky”, eccentric response. To determine a room’s acoustics, analyze the acoustics with your meter and a suitable test recording. The test recording should produce pure tones, one at a time, at intervals spanning the audio spectrum. Make a graph or table showing the sound levels generated by the individual tones.
33-2050.fm Page 19 Monday, April 17, 2000 2:04 PM Note: When checking the frequency response, if WEIGHTING is set to C, the meter’s frequency response is flat from 32 –10,000 Hz (± 3 dB). Above 10 kHz, the frequency response of the meter drops off rapidly. Be sure to consider this when you use a test recording that includes tones at the extreme high end of the audio spectrum.
33-2050.fm Page 20 Monday, April 17, 2000 2:04 PM Limited Ninety-Day Warranty This product is warranted by RadioShack against manufacturing defects in material and workmanship under normal use for ninety (90) days from the date of purchase from RadioShack companyowned stores and authorized RadioShack franchisees and dealers.
