How to Calibrate Smaart RTA Pro

The default calibration offset value does not guarantee scientifically accurate SPL in accordance with applicable standards. It is an approximation based on an average of tested devices. For increased accuracy, calibration is recommended using SPL capable external hardware.

Smaart RTA Pro supports the calibration of both internal and external microphones. Calibration is not supported in the base feature set of Smaart RTA. The default calibration offset for internal microphones in Smaart RTA is 120 dB. Regardless, the ability to accurately calibrate for SPL is not strictly guaranteed due to the variance in hardware capabilities - especially when using a device's internal microphone(s), which are susceptible to variance caused by age, cleanliness, or external factors such as cases or screen protectors.

Internal Microphone Calibration

Calibrating the device's internal microphone requires using a known-accurate reference SPL meter. (handheld SPL Meter, calibrated Smaart Desktop system, etc)*

• Physically place the device you wish to calibrate (perhaps the one you are holding in your hand right now) as close as possible to the microphone of the reference calibrator, in a way that allows you to see the display of the reference calibrator. 

• Set the display of the reference calibrator to dB A Slow, matching it to the SPL display of Smaart RTA during calibration. 

• Play a pink noise signal from a system that excites the reference meter to a range of 70-85 dB. It is not necessary to reach 94 dB or higher, but you may if that is acceptable to do in your environment. If you are using subwoofers, turn them off and/or high pass filter the system to remove the low-mid range so that you are comparing mostly mid-high frequencies. 

• Go to Settings > Microphone Settings, select the desired input from the Microphone drop-down menu and then select "Set Calibration". 

• Use the scrolling wheel encoder to adjust the Calibration Offset of the selected microphone until its display matches the reference calibrator. 

• Select "OK" and the calibration offset value will be applied to that input. 

• Repeat this process for any additional inputs.

External Microphone Calibration

Calibrating with an External Microphone is best achieved with a dedicated external SPL calibration device. Such a device will emit a 1 kHz tone at a specifically known dB level. 

• Affix your SPL calibrator to the external microphone connected to Smaart RTA. 

• Go to Settings > Microphone Settings and select the external microphone from the Microphones drop-down menu and select "Set Calibration".

• Using the scrolling wheel encoder, set the Calibrator Level to match that of your SPL calibration device.

• Select "Calibrate". The calibration routine will take a moment to complete. Once finished, the required Calibration Offset will be automatically applied. The SPL dB A Slow value should also match the output of the external calibration device. 

• Select "OK" to apply the Calibration Offset to that microphone input.

• Repeat this process for any additional inputs.

*It is possible to calibrate an external microphone without an external SPL calibrator, but not recommended . You can follow the steps for calibrating an internal microphone, with the addition that after you calibrate, adjust the Calibrator Level to match the display of your reference calibrator, and then adjust the Offset Applied value until they match.