GRAS 42AG Multifunction Sound Calibrator, Class 1

Developed as an improved replacement for the successful 42AB Sound Calibrator, the 42AG Multifunction Sound Calibrator is specifically designed for fast verification of microphones and sound level meters in the field. It represents new and improved functionalities and is easy to use. There is a real need for a portable and intuitive calibrator that can be used for testing in multiple situations.

42AG meets that challenge as it has a user-friendly interface, automatic compensation for ambient environmental conditions such as ambient air pressure, temperature and humidity as well as two calibration frequencies and levels.

The calibration level, frequency and environmental parameters are displayed on an OLED display. A push on the dB button toggles between 94 and 114 dB. Likewise, a push on the Hz button toggles between 1,000 and 250 Hz. The °C/°F button displays the ambient pressure, temperature and humidity.

The 42AG conforms to standard IEC 60942 for Class 1 sound calibrators, is battery operated and supplied with a protection case, which makes it ideal for in-field verification across industries.

Calibration is an essential step in every precision noise measurement in order to achieve reliable and repeatable test results. So if it is important to you to ensure repeatable measurements, make sure to add the 42AG calibrator from GRAS to your solution.

Sound pressure level: 94 dB or 114 dB
Frequency: 250 Hz or 1 kHz
ANSI: S1.40
IEC: 60942 class 1

The GRAS 42AG Multifunction Sound Calibrator is a portable, battery-operated precision microphone calibrator. The calibrator can be used directly on 1" microphones. Adapters for calibrating 1/2" (factory mounted), 1/4" and 1/8" microphones are included.


The GRAS 42AG Multifunction Sound Calibrator is a portable, battery-operated sound source for calibration and check of microphones and sound level meters. It is designed for field use and comes with a protective casing. It conforms to the requirements in IEC 60942 for a class 1 sound calibrator.

It can produce a sinusoidal signal of 250 Hz or 1 kHz at 94 dB or 114 dB. For documentation purposes, 42AG provides display of the environmental conditions: ambient air pressure, temperature.

The sound is generated by a small loudspeaker integrated into the acoustic coupler. An internal reference microphone measures the level in the coupler and a feedback circuit automatically adjusts the level. Therefore, the calibration level is virtually independent of ambient conditions like temperature, atmospheric pressure, and humidity within the specified range of operation.

The calibrator has been designed to serve 1” and smaller microphones and sound level meters equipped with such microphones. 1” microphones fit directly in the calibrator coupler, while 1/2”, 1/4” and 1/8” microphones are served by application of adapters that are part of the delivery.

The calibrator is powered from two type LR03 alkaline batteries (AAA-size). If the voltage supplied by the batteries is too low to ensure proper operation, the calibrator will automatically switch off or not switch on.


42AG is designed to fulfill the need for a portable and versatile calibrator for field use. Also, it is designed to be the logical replacement or upgrade from existing calibrators.

42AG represents improved functionality and user-friendliness. Its combination of portability, automatic level adjustment, and two calibration frequencies and levels makes it a complete and self-sufficient solution that can be used to perform a complete field-verification without the need for other instrumentation, e.g. for recording ambient calibration conditions.

With two calibration frequencies, 250 Hz and 1 kHz it is well suited for calibration of microphones that normally are calibrated at 250 Hz as well as sound level meters which normally are calibrated at 1 kHz.

42AG can calibrate at two different levels, 94dB, and 114 dB. The 114  dB is a level that suits microphones with medium sensitivity, while the low level of 94 dB makes it possible to calibrate microphones with high sensitivity without overloading the microphone.


The warranty for 42AG is 5 years and covers defective materials and workmanship





250 (251.19 ± 0.30 Hz) or 1 kHz (1000 ± 1 Hz)
Sound pressure level
94 (± 0.2 dB) or 114 (± 0.2 dB)
ANSI standard
S1.40 (2006)
IEC standard
60942 (2017)
Temperature range, operation
°C / °F
-10 to +50/14 to 122
Battery type
LR03 (AAA)
CE/RoHS compliant/WEEE registered
g / oz

Level and frequencies at reference conditions (23,0°C/101,325 kPa/50% Relative Humidity) - levels in decibel relative to 20 µPa.
GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.


Ordering info

Included items


Adapter for ½" microphones.


Adapter for ¼" microphones


Adapter for 1/8" microphones


Four LR6-AA alkaline cells

 GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.