[Ardour-Users] Overdrive artifacts after export

Don Fredricks ardour at handsfull.net
Wed Sep 2 12:03:11 PDT 2009

Carlo Capocasa wrote:
> I have created a short track on 24bit/96kHz that sports some rather
> heavy synthesized sounds and vocals. There is a hard limiter set to 0db
> on master out.
> On export to 16bit/44.1kHz, there are very audible overdrive artifacts.
> They disappear when the consumer media player is set to a low volume.
> Obviously the mixed down track is mixed too loud-- but how can that be?
> Pre-export the track sounded great at any volume.


It's possible that you're overdriving the analog electronics of the
player. Do commercially mastered CD's cause audible artifacts under the
same conditions on the same player?

Another possibility is that there are inter-sample peaks above 0dBFS. I
almost always set my hard limiter to -0.1dBFS or lower, depending on the
material. (This would also tend to reduce the likelihood of overdriving
the player's analog stages.)

Did you use dither to get from 24/96 to 16/44.1? (Oh, there's another
possible source of peaks over 0dBFS -- it may be that your samples were
just hitting the limit, and dither pushed them over the edge. Not likely,
but possible.)

Finally -- does your product really need to be that loud? Are you
competing with commercial mixes? If so, I think the deck is stacked
against you. There's simply no way for a small-time operator (I'm making
assumptions here!) to compete with a commercial mastering facility that
has millions of dollars worth of top-quality gear at their disposal. I
urge you to consider whether "pretty close" is close enough. "Pretty
close" is quite achievable.


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