Review on High-Precision Sound Decibel Calibrator for Accurate Calibration Measurements by Gary Duncan

I recently purchased an Extech SL510 Class 2 Sound Level Meter and wanted to make sure the factory pre-calibration was correct. This Class 2 calibrator is one of the cheapest and works well - it fits a 1/2" mic and appears to be accurate: the SL510 delivered just 0.1dBA of the 94dBA sound produced by the calibrator. I have corrected the difference and will probably recalibrate the sound level meter (if necessary) every 3-6 months. Given that most calibrators are quite expensive ($300+), this one is both very affordable and accurate (judging by the fact that the factory pre-calibrated Extech meter reads the test signal at 94 dBA, 1 kHz so accurately corresponded to).