Resource for ADC quality? Recording interfaces

[Blumlein 88]

The THD + N measurement itself, does it at least provide a worst case scenario when both noise and distortion are measured together. So not one or the other can be higher on their own when compared against the THD + N measurement itself?

You could say that.

Normally one or the other is predominant. For instance let us say noise is -80 db, and THD is -95 db. Combined they are -78.6 db. So it is pretty much noise setting the SINAD number (inverse of THD+N). You'll notice the level vs THD+N curves all slope just about exactly the same because usually at lower levels it is noise well above any THD. Where they flatten out THD and noise are roughly equal in level and when the curves rises with level THD has become predominant a good 15 db or so higher than noise. There are some exceptions of course like Scott Wurcer mentioning some class AB amps having more real THD at low levels.

And that is why Amir chose to use SINAD for charts. You can have low THD and high noise or low noise and high THD, but you have to have low THD, and low noise to get the better SINAD numbers.

 

[amirm]

And that is why Amir chose to use SINAD for charts. You can have low THD and high noise or low noise and high THD, but you have to have low THD, and low noise to get the lower SINAD numbers.

This is why SINAD is useful. To get excellent marks, the device has to have both low distortion and low noise. It is a single number that represents two variables, both of which we want to be low.

 

[restorer-john]

but you have to have low THD, and low noise to get the lower SINAD numbers.

Higher...

 

[Blumlein 88]

Higher...

Okay I'll change to better. It is a larger number representing a lower level.