by Bruce Graham » Tue Apr 08, 2014 2:23 pm
H Joe;
I will check it out (-15dbfs = +4dbu), and let you know, but, the rest of the headroom (from -15dbfs to 0dbfs), is used for transient peaks. As long as your levels do not go above 0dbfs you are good to go, and to reduce the analog and digital noise (yes thee is digital noise), the more signal you have the more the noise is "masked". Hence "fill the meter".
It is possible that -15dbfs is 0dbu, but the international standard for most audio is +4dbu.
At this point it is very difficult to say why the vocal sounds louder than the CD, other than, as I mentioned, apparent loudness.
I use Unity Gain as a reference as to how much more or how much less gain do I need to adjust the trim to have the signal be at unity. In other words, what comes in is what goes out.
The Line inputs of the d8b are a range from -20dbu to +22dbu with a nominal level of +4dbu at the unity setting. So, if a signal of +4dbu is input into the console, the Unity setting on the trim would give you +4dbu at the putput assuming all faders are at "0" (which means Unity. Neither adding nor reducing the gain).
Mackie wants you stay at -15dbfs, when recording, so that you do not run the risk of having your levels go over 0dbfs as any signal over that, in the digital world, is pure, 100% distortion (clipping). They want you to keep the 15db (-15dbfs to 0dbfs) as a protection area or headroom). With compression and proper mixer technique that headroom and be used to achieve a "louder signal during mixing.
I know this doesn't answer your question but hopefully it gives you the basic idea.
I'll get that info and be back here with what I find.
Regards
Bruce