Calibration Process for Soundcards with Multichannel input AND Analog Mic Calibration Files

[tannerupthegrove]

When calibrating a soundcard with a multichannel input:

1. Should each input have a separate calibration file or does the calibration for an input get applied to all input channels?
2. If each channel gets an individual calibration file, where is that applied? Is there a way to sequentially add them in either the Soundcard or Cal Files in the Preferences menu?
3. I also have Mic calibration files which are applied to individual channels Preferences > Cal Files

Soundcard Calibration Procedure with macOS 48kHz 24 bit and Dante Virtual Soundcard as the interface:

1. [Gain Staging] Class 1 Calibrator 1kHz @ 94dB with adapter > Earthworks M23 Microphone > RME Mic12-D Preamp with output over Dante > REW SPL Meter dbA SPL Fast > adjust RME Preamp until SPL Meter reads ~94 dbA F
2. Remove Microphone for REW Calibrate Soundcard... -12dbFS 1kHz sine wave > RME Mic12-D Line Level Balanced Output 1/4" M Balanced Cable > XLRM on RME Mic12-D Input 1 > Adjusted the line output to match the -12dbFS test tone within +/- 1dB then run the sweep
3. Make Cal File... from measurement
4. Calibration applied (to only channel 1 of the soundcard or all?)
5. Preferences > Cal Files > Check Yes for Separate Cal for Each Input > Select appropriate Earthworks Calibration File for each input
6. Reconnect Microphone and calibrator and validate the 94dbA F in SPL Meter, repeat if needed

Does this make sense, especially the Gain Staging step?

 

[John Mulcahy]

The soundcard cal is linked to the output device, it is applied in combination with any mic cal files. Process looks good. To calibrate SPL for each input select each input in turn as the measurement input and go through the SPL calibration, the result is saved for the selected input.

 

[tannerupthegrove]

The soundcard cal is linked to the output device, it is applied in combination with any mic cal files. Process looks good. To calibrate SPL for each input select each input in turn as the measurement input and go through the SPL calibration, the result is saved for the selected input.

Thank you, John! To clarify, the SPL calibration in the documentation is very good. If I use gain at the preamp to get the microphone to measure 94dB SPL A at the SPL Meter, is this an acceptable equivalent to the dbFS offset method?

 

[John Mulcahy]

That's probably not ideal. Adjust gain so that you have sufficient headroom for your measurements, so make sure the input dBFS at 94 dB provides the headroom required. Then enter 94 dB as the input SPL so REW knows that's what's coming in and REW will manage the offset.