Calibration file(s) when using a separate mic preamp

[dlr]

I am testing several microphone setups. One has a separate stand-alone mic preamp (unbalanced) with a calibrated Panasonic electret mic capsule. The mic output will feed a sound card unabalanced input. REW has options for sound card and mic calibration files, but nothing for a separate mic preamp. The latter has three attenuation settings, but I will likely use only one, although a calibration could be made for each gain setting.

My problem is that there is no option for an additional mic preamp in the circuit. I've run a calibration of the mic preamp.But the magnitude is related to a the voltage. It could be output in dbV or dBu, but I don't see how to incorporate that into the REW scheme.

I thought about trying to find a way combine the preamp and mic cal files, but they are not the same scale and the sample points don't overlap.

I don't see the way to do this.

Edit: It just occurred to me that I'm looking at from the wrong end. Maybe I can combine the sound card input cal with the mic preamp since both are or could be in dBv (I assume).

 

[John Mulcahy]

Cal results are generally in dB, offset to be zero at 1kHz. They are ratios in effect so the unit doesn't matter. If you have individual cal file results you could drag them into REW and use trace arithmetic to sum them.

 

[dlr]

Thanks.