[LAU] master levels

[Harry van Haaren]

 On Mon, Feb 2, 2015 at 2:30 PM, Brent Busby <brent at keycorner.org> wrote:
> So, I could mix to -6db in Ardour and still use most of the headroom on
> a CD?  Is there any advantage to keeping your peak level that low on the
> master in the digital world?  Or, put another way, if I *could* get the
> whole track to behave itself and not go above -1db at loudest peak, is
> there a reason not to?

Throughout the digital signal flow (JACK, JACK clients) assuming a
"somewhat" normal signal level, there is no perceivable degradation of
the signal. Traditionally degradation of sound was caused by lack of
bits to represent sound: signal-noise-ratio is proportional to number
of bits used. Floating point removes this cause of degradation.

Soundcards play integer streams: not floating point, so the
floating-point samples are converted to integers. During DAC stage the
number of bits used is important: so a very low signal level will use
less bits, causing a worse SNR (signal-noise-ratio).

In short: mix with enough headroom in Ardour, ensure that the
master-output level in Ardour is happy - ideally somewhere between -20
and -6dB. When that signal arrives at the DAC, it will not
significantly impact on SNR. Then use an analog volume fader to change
the speaker-volume.

Do *not* do this:
-Good Ardour, analog dials on speakers turned up to max, and digitally
(Ardour master fader) regulate the volume (eg -60dB through DAC causes
much larger SNR).

Hope that helps, -Harry

-- 

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