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Old 1st February 2003
  #4
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groundcontrol's Avatar
 

The problem is that your tracks are recorded close to digital full scale and thus bear no relation to the analog world of 0VU=+4dBu. The 192 i/o comes factory calibrated for 0VU=+4dBu=-18dBFs. That means that when a track meters at -1 on your PT peak level meter the analog signal sent to your outboard insert unit peaks at +17 over 0VU which is it's nominal reference level. Now if this is an uncompressed snare track or some other transient rich percussive sound and the analog unit has reasonably high headroom (likely in the +22db to +26db in pro gear) you're probably not too far off the ideal operating level of this analog box. However if the track is an instrument that has less "attack" and more "sustain", i.e. a sound that has a realtively low "peak-to-average" ratio (aka as "crest factor") like, say, fingered bass or a slow pad and that track is also recorded in PT peaking at -1, then you're feeding the analog unit with an "average" or RMS level that is clearly way over what it wants to get. (You're probably also overdriving the analog stages of the 192 i/o at the same time which is a less than ideal way of making it sound good.) Such a signal should modulate around 0VU on this analog box VU meter if it has one, so it would have to be attenuated by close to 16 dB before being fed to the analog box. The easiest way to do so would be to insert a trim plug-in right before the hardware insert.

If you want to be able to easily interface with the analog world while working with a DAW, you'll have to respect the analog level reference of 0VU. That means that our pad track from earlier would have been recorded reading around -18dB on PT's meter since it has no peaks so to speak. While our SD recorded reading the same 0VU level on the analog box VU meter (which is an RMS or "loudness" sort of meter) would peak a lot higher on PT's meter, probably just shy of 0dBFs (Full digital Scale) in fact.

It's a bit late over here but hopefully it should make sense...

Cheers!