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Old 17th August 2009 | Show parent
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gwailoh's Avatar

I'm not PF. Very definitely. But I'm brave and foolhardy, and I've been putting a lot of work in over the last couple of months to implement PF's specific suggestions, going back and re-mixing completed mixes for instance following his guidelines. So I'll take a stab.

Caveat: I'm not a digital audio expert. My education re these issues is from reading and re-reading PF's posts. My answers here attempt to paraphrase some of PF's own answers on PSW and here on GS.

Suppose I have a track with material that has adjacent sample points at 0dbfs, and would (for the sake of argument) create an inter-sample peak of +2. But, this track is going into a mix buss whose fader is down -2.

Problem solved?
If you're mixing to a digital format (internal bounce, Masterlink, etc.) without going through your DAC, the problem is probably not solved. The mastering engineer will bring the level back up to near 0, and with it the hot signals which will clip the listener's DAC downstream. (Unless you tell him or her not to, I suppose!)

If you're mixing through your DAC to analog tape or a DSD recorder or etc., the problem may or may not be solved. You can't really know unless you monitor through meters which will show you the reconstructed signal level, rather than the DAW's sample levels. You're probably safe if you pull the master fader down far enough. But, maybe not.

Or further, what if I have an EQ (pre-fader) across the buss? Assume I haven't trimmed the input, so it's seeing the two 0dbfs samples.

Is it even conceivable that this EQ could clip at +2 since the EQ, being ITB, is only working within the context of a sample rate?
It might not clip the bus, if I understand the question. But the mix bus isn't where the problem lies. The problem is downstream at the DAC, where signals which are legal within the DAW's arithmetic can still turn out to be too hot for unclipped reconstruction during D/A.

Are inter-sample peaks even "visible" to most ITB processes since ITB, nothing is technically "inter-sample"?
I dunno that one. But "inter-sample peaks" aren't really the issue which PF has tried to explain to us all, especially in the wonderful PSW thread where he discusses a number of interrelated issues at length. The crux of the problem is the disparity between DAW headroom (big) and DAC headroom (small), exacerbated by the fact that default DAW meters display sample values, rather than reconstructed signal values.

Are inter-sample peaks really only important at the mastering stage, when preparing audio to be converted by a playback system?
No, because overly hot digital levels will impact monitoring of your track through your own DAC in your studio. In PF's view, the "too hot for the DAC" syndrome is what's responsible for many people's dissatisfaction with the sound of their DAWs, including complaints about narrowing of the stereo image, harshness, lack of depth, etc., compared to analog summing. All of those problems will exist in your own environment if the levels are too hot.

Paul: if you're monitoring GS these days, please correct me if I've misrepresented you!