QA-403 Distortion Tile

[Buckskin]

Sorry for the likely dumb question, but what is the Dist measurement tile telling me? The attached plot shows a preamp under test. As an be seen, the noise floor is in the neighborhood of -140 dBV. THD is low as well. So what, exactly are the two Dist Tiles telling me?

Thanks.

[Claudio]

Hi @Buckskin. “Dist” indicates the value expressed in dB of the numerator of the expression used to calculate THD. I think you will find some clarification in these posts (Dist = D):

QA403 feature request

Yes of course, but that is a value relative to the signal S. In other words : THD= D/S and using dB expressions THD = D - S. What I was asking for was a tile of just the value of D and not its value relative to S (THD). It is a little like THD+N and N+D. THD+N is the component relative to the S signal of N+D. Of course, this is just a requirement of mine that perhaps no one cares about!