Discrepancy in my dB SPL calculations
Forget decibels for a moment. There is 1 Pa sound. Microphone output for 1 Pa sound is 50mVrms. Since the preamp does not have gain, and oscilloscope output is about 5Vrms, so there must be about 100x gain somewhere in the systen, so this must happen in the signal conditioner. I don't know what 100mV/unit means in this case so my assumption is that is it means 100x, or +40dB. If you work this backwards, from 16.2Vpp you get 5.7Vrms, so without 100x gain this is 57mVrms from mic. This is within the given tolerance for a 1 Pa sound, which nominally is 50mVrms. So 50mVrms is 1 Pa and thus 94dB SPL, and 57mVrms is 1.14 Pa and thus 95dB SPL.