DirectOut Technologies ANDIAMO.MC - Appendix C: Sensitivity vs. Gain; Explanation of Sensitivity and Gain

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ANDIAMO.MC Hardware Guide - Version 2.0
Appendix C - Sensitivity <> Gain
Appendix C - Sensitivity <> Gain
Explanation
So what is the difference between ‘gain’ and ‘sensitivity’?
In the old days, it was easy to specify the amount of gain for a microphone
amplifier from input to its output. The gain is measured as a relative value in dB.
When the output was connected to an AD converter, there was a reference level at
which the converter would deliver 0dB full scale (dBFS) at its digital output.
With a combined microphone amplifier / AD converter, these numbers are not
really valid anymore - the internal level diagram can be quite different, as there
doesn’t have to be a standardized interconnect level. The reference level for digital
full scale is a virtual value now.
For the ANDIAMO.MC, we have therefore decided to specify the ‘sensitivity’ of
the input setting rather than the ‘gain’.
With a sensitivity of 0dBu, an input signal with 0dBu analog level will lead to a
digital output level of 0dBFS.
We can still calculate a gain value, if we decide for our virtual reference level.
If we set it to, say +18 dBu, a sensitivity of 0 dBu would translate to a gain of
18dB.
If we set our virtual reference at +24 dBu, the same sensitivity of 0 dBu would
translate to a gain of 24dB.
The following examples illustrate the correlation between ‘input sensitivity’, ‘input
level’ and ‘gain’, based on a virtual reference level of 18 dBu.
Formula
<gain> = - <sensitivity> + <reference level>