In my previous measurements, I was peaking around 122dB SINAD measurement, with a direct ADC connection

Using

I was finally able to achieve a more relevant SINAD measurement of the D90LE

Measurement is done with

Output of the DAC goes into

ADC is

The RME is also used to send the test signal to the D90LE through AES.

Software is

Now, there are some tricks to know to achieve such a measurement !

First, we need, of course, to calibrate the chain to compensate for the notch.

Then you need to adapt the way the measurement software is computing the fundamental:

Indeed, you'll realize soon that the "foot" of the 1kHz peak in the spectrum anlyzer is wider than if you connect the ADC directly, like in the following picture.

This has a direct consequence:

SINAD is typically computed by comparing the Fundamental to the total signal level.

This is usually done by taking into account the width of the FFT window that is used to compute the levels for each frequency.

Unfortunately, this doesn't work here, since the fundamental "spreads" over a much wider area.

This results in a much higher Noise level, including a good part of the 1kHz signal in the noise.

Then comes AES-17 (2015), which, for practical reason, I guess, introduced a "workaround":

To measure THD+N (or SINAD), measure the fundamental over 1/2 octave below the fundamental frequency and 1/2 octave above.

For a signal at 1kHz, that means, from 707Hz and 1414Hz.

Noise is computed on the remaining frequencies only (from 20-707Hz and from 1414-20000Hz)

(The very last release of REW, v5.20.9, even allows to display the frequency range taken into account for the fundamental. That's genious !)

The selected region for the fundamental is the greyed frequency range.

where the selected region spreads from 707Hz to 1414Hz:

This last way should be more compliant to AES-17 2015 standard

And to Audio Precision @amirm is using.

Virtins Multi-Instrument doesn't support this "AES-17 Notch" workaround natively.

But it is very flexible, so I was able, with the kind author's help, to measure and display SINAD and SNR, computed from the RMS levels in the different bands.

We then reach the exact same SINAD value than with REW.

Using

**E1DA Cosmos APU Notch**, (and some lessons learned from last REW editions),I was finally able to achieve a more relevant SINAD measurement of the D90LE

Measurement is done with

**Topping D90LE**AES input, 48kHz, right Channel, 5V modeOutput of the DAC goes into

**E1DA Cosmos APU**, 1kHz Notch, +6dB (pre-notch)ADC is

**RME ADI-2 Pro fs R**, 19dBu range, Mono modeThe RME is also used to send the test signal to the D90LE through AES.

Software is

**Virtins Multi Instrument 3.9.6.1**Now, there are some tricks to know to achieve such a measurement !

First, we need, of course, to calibrate the chain to compensate for the notch.

Then you need to adapt the way the measurement software is computing the fundamental:

Indeed, you'll realize soon that the "foot" of the 1kHz peak in the spectrum anlyzer is wider than if you connect the ADC directly, like in the following picture.

This has a direct consequence:

SINAD is typically computed by comparing the Fundamental to the total signal level.

This is usually done by taking into account the width of the FFT window that is used to compute the levels for each frequency.

Unfortunately, this doesn't work here, since the fundamental "spreads" over a much wider area.

This results in a much higher Noise level, including a good part of the 1kHz signal in the noise.

Then comes AES-17 (2015), which, for practical reason, I guess, introduced a "workaround":

To measure THD+N (or SINAD), measure the fundamental over 1/2 octave below the fundamental frequency and 1/2 octave above.

For a signal at 1kHz, that means, from 707Hz and 1414Hz.

Noise is computed on the remaining frequencies only (from 20-707Hz and from 1414-20000Hz)

**This is what REW is implementing with its new "AES-17 standard notch" option :**(The very last release of REW, v5.20.9, even allows to display the frequency range taken into account for the fundamental. That's genious !)

**The "standard" way :**The selected region for the fundamental is the greyed frequency range.

**And then the "AES-17 notch" way,**where the selected region spreads from 707Hz to 1414Hz:

This last way should be more compliant to AES-17 2015 standard

And to Audio Precision @amirm is using.

Virtins Multi-Instrument doesn't support this "AES-17 Notch" workaround natively.

But it is very flexible, so I was able, with the kind author's help, to measure and display SINAD and SNR, computed from the RMS levels in the different bands.

We then reach the exact same SINAD value than with REW.

**So we have a 126.4dB SINAD measurement**
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