Digital signal question

[Bertrand Allaume]

When using PRO|MON and a digital AES output:
Is the AES Output Level control applied in the 28-bit floating-point PRO|MON engine before the final 24-bit AES quantization, or is it applied after the PRO|MON summing stage?

Are different dithering or word-length reduction processes used depending on whether attenuation is performed in PRO|MON or in the Digital Output Level control?

I get slightly different results when listening if I keep my AES output at 0 dB FS and attenuate my “Sources” signal in DADman, or, conversely, if I attenuate my AES output but keep the “Sources” signal at 0 dB FS in DADman.

I’m using a Dynaudio CONNECT 02.

Thanks for your feedback.

[Jon Schumann]

Hi Bertrand,

Thanks for reaching out.

The reply is going to be less “bits and bytes” than you would perhaps want, but a lot of this technology is our IP, so I’m afraid you’re going to have to bear with us:

In short: The order of the factors is not completely irrelevant in the very fundamental math, however in practical use it will not make any difference to any well-structured session. Only when we start to add up sources with crazy amounts of attenuation, will the math start “math’ing” to create a product that is slightly different on the other side of the equals-sign.

We recommend that you keep a good input gain structure in your monitor profile and allow our summing structure to do the work that it was created to do so very accurately, with low noise and a high dynamic range.

If you truly feel like the results are different in your speaker setup, I would invite you to record both output versions in parallel and email the WAV files to our support@ntp.dk for analysis.

On a personal note:
It’s a bit like Laurent Fignon’s 8-second heartbreaking loss to Greg Lemond in the 1989 Tour de France : The ponytail theoretically lost him the Tour in pure wind resistance, but overall it is clear that it did not matter. (He should have worn that helmet.)

At DAD we eat lunch and design our hardware with our helmets on. 🙂

Kind regards and with much respect,

Jon
NTP

[Author]

Posts