# Interpretation of ND9A Sound Level Meter Calibrator Specifications
## I. Summary of Key Specifications
Table
| Item | Specification Details |
| --- | --- |
| Product Model | ND9A |
| Accuracy Class | Class 2 |
| Compatible Microphone Sizes | 12.7 mm (1/2 inch), 23.77 mm (1 inch) |
| Compliance Standards | IEC 942, GB/T 15173 |
| Nominal Sound Level Output | Two settings: 94 dB and 114 dB |
| Sound Level Accuracy | ±0.5 dB |
| Output Frequency | 1000 Hz, frequency deviation ±0.1 Hz |
| Calibration Compatibility | Can calibrate sound level meters with A, B, C, and D weighting, as well as linear frequency weighting |
| Dimensions | 142 × 47 × 47 mm |
| Weight | 275 g |
# ND9B Class 1 Sound Level Meter Calibrator Parameter Analysis + ND9A/ND9B Comparison
## I. Complete Parameter Table for the ND9B
Table
| Parameter | Specification Details |
| --- | --- |
| Product Model | ND9B Sound Level Meter Calibrator |
| Accuracy Class | **Class 1 Accuracy** (Higher metrological class) |
| Compatible Microphone Sizes | Two standard sound level meter microphones: 12.7 mm (1/2 inch) and 23.77 mm (1 inch) |
| Compliance Standards | IEC 942, GB/T 15173 (Universal standards for sound level meter calibrators both domestically and internationally) |
| Output Sound Pressure Levels | Dual-level output: 94 dB and 114 dB |
| Sound Level Accuracy | ±0.3 dB |
| Output Frequency | 1000 Hz, frequency deviation ±0.1% Hz, supports A/B/C/D and linear full-weighting calibration |
| Dimensions | 142 × 47 × 47 mm |
| Weight | 275 g |
# Analysis of the ND9B Digital Sound Level Meter Calibrator Specifications & Comparison with the Standard ND9B
## I. Detailed Specifications of the Digital ND9B
Table
| Parameter | Specification Details |
| --- | --- |
| Product Type | Class 1 precision digital sound level meter calibrator |
| Compatible Microphones | 12.7 mm (1/2 inch), 23.77 mm (1 inch) |
| Compliance Standards | IEC 942, GB/T 15173 |
| Output Sound Level Settings | Two adjustable settings: 94 dB and 114 dB |
| Measurement Accuracy | ±0.3 dB (Class 1 accuracy) |
| Output Frequency | 1000 Hz, frequency deviation ±0.1% Hz, supports A/B/C/D and linear weighting modes for calibration |
| Dimensions | 137 × 51 × 51 mm |
| Weight | 200 g |
| Key Features | Equipped with a digital display that shows the current output sound level in real time; the panel features mode selection buttons and a power switch |
