This document describes the use of the Larson Davis CAL250 calibrator, including basic operations, calibration process, calibration results recording, etc.
The Larson Davis CAL250 is a battery-operated precision microphone calibrator used for calibrating sound level meters. It delivers a 114.0 dB tone at 251.2 Hz and is designed for field or lab use with NIST-traceable accuracy. The manual covers installation, calibration procedures, environmental precautions, and technical specifications including frequency, distortion, and temperature/humidity ranges.
The device includes a 9-volt alkaline battery, storage case, and adapters for 1/4”, 1/2”, and 1” microphones. Calibration is automatic and lasts up to 60 seconds on a fresh battery. The manual also includes guidelines for recalibration frequency and environmental stability requirements. This manual is written in Chinese.
| Calibration Sound Pressure Level (Factory Specification) | 114.0 ± 0.1 dB re: 20 μPa @ 101.3 kPa, 23 ºC and 50% RH |
|---|---|
| Frequency | 251.2 Hz ± 0.7% |
| Total Harmonic Distortion | < 2% |
| Effective Volume | > 100 cm³ (6.1 in.³) |
| Battery | 9 V NEDA 1604A or IEC 6LR61 |
| Dimensions | Length 124 mm (4.9 in.), Diameter 44.5 mm (1.75 in.) |
| Weight | 249 gm. (8.8 oz.) |
The CAL250 runs for approximately 100 hours on one 9-volt battery, providing nearly 4,200 calibrations.
The CAL250 provides a nominal tone of 250 Hz at 114 dB.
The CAL250 operates accurately from -10 ºC to 50 ºC with SPL variation < ± 0.3 dB and frequency variation < ± 2 Hz.