-18db digital is 0db analog?? Please explain

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kats

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Was reading an artical by one of the guys in 9" Nails and this is what he says:

0db's in your analog equipment is atually -18db's in Protools. So when you run a line out from PT into one of your analog pre's you should reduce the PT trak to -18db's.


alright, I understand what he's saying...but is this true?
 
kats said:
Was reading an artical by one of the guys in 9" Nails and this is what he says:

0db's in your analog equipment is atually -18db's in Protools. So when you run a line out from PT into one of your analog pre's you should reduce the PT trak to -18db's.


alright, I understand what he's saying...but is this true?
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In a roundabout way maybe. Why would you run an output into a pre? Reducing the output -18dB is effectively a pad, so the signal going into the pre won't clip it. But that isn't because 0dBu=-18dBFS on a particular converter, it's because most pres have a minimum gain that would clip the preamp if you fed it a signal with a +18dBu peak.
 
Why would you run an output into a pre
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Well in this artical (and common practice I guess for us guys) is recording to PT dry and running that track through a channel strip onto a new track in PT to get "that sound". IE using your channel strip kind of like a tone box.

HE's insisting that you should be running the PT source track at -18db. I'll try and find the artical BRB

Ahh here it is http://emusician.com/tutorials/emusic_groove/

Heres the thrust:

If you set it up right, yes. In Pro Tools, -18 is analog zero. But a lot of people don't know that — I didn't know that. And you're always told to print digital as hot as you can to get the best dynamic range. So everybody's printing every track clipping red.

But when you go to mix and you strap all your analog outboard gear over, if you use a zero digital signal you'll blow up your compressor, or your Neve channel, or whatever. So you've got to take all your analog gear and gain it way down, where it doesn't sound as good and it isn't in its efficient range. Suddenly, you've got the pad in, and the [good old gear] you're using sounds like shit. To interface with analog properly, you've got to print digital at lower levels.

I worked with [engineer-producer] Joe Ciccarelli, who brings his own little VU meters everywhere. He prints everything at 0 VU analog, and into Pro Tools at -18. When you look at his Pro Tools levels, they're barely hitting, but it works properly with the analog gear. You do lose a little dynamic range; your noise floor goes up a little. But as Joe says, “I'll take a little more noise to allow the analog gear to do its job in its optimal range.”
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Yeah that all makes sense, except for the part about the pads killing the analog sound. I don't get it, a few resistors (of presumably good quality, being in high end gear) shouldn't kill tone. Also a line-level signal shouldn't blow up a compressor. That I don't understand at all.
 
He's refering to DBFS (Decibels Full Scale) which is what digital gear looks at and a VU meter. To further complicate things you can have the same meter deflection on two consoles, one operating at a -10dBm level and another at +4dBu.
 
None of this would be an issue if they weren't tracking into Protools too hot in the first place. Normally 0dbvu is more like -12dbfs, I don't know about the convertors they were using.
 
:rolleyes: Assuming you have decent 24-bit converters, you DO NOT want to track everything as hot as possible. Maybe he needs to say "as hot as possible without clipping" But as Murphy's Law would have it, if you try to get your peaks to -.0001 when setting levels, it WILL clip when you're actually doing the take. In my experience (now I'm no Nine Inch Nails, but I do know a bit about this stuff) you're generally fine keeping things peaking around -6. Also, I think he meant to say you'd get the best signal-noise ratio, instead of dynamic range. If your tracking is stuck right around 0, you'll have NO dynamic range.

And you're always told to print digital as hot as you can to get the best dynamic range. So everybody's printing every track clipping red.
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kinda off topic....but has anybody noticed that the db meters on software programs is always different?,....I mean half the time i ever get a beat from a producer it clips in CEP ....but when i ask them whats the deal they'll say it wasnt clipping in Fruity Loops,..or Reason.....I have the same problem with my own beats...something that isnt clipping in fruity will be clipping everywhere i else
 
gordone said:
If your tracking is stuck right around 0, you'll have NO dynamic range.
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I'm reading that article thinking he mean tracking clipping red on the preamp, which wouldn't necessarily be clipping ProTools (presuming +18dBu = 0dBFS). Now +18dBu shouldn't clip a pre, but I'm assuming that was artistic license.

I think he is saying to track peaks at 0dBu, or -18dBFS, so that when the tracks are "repre-ed", the inherent gain in the pres doesn't clip going back in. Whereas most of us are tracking average levels near 0dBu, or -15dBFS (for me), and peaks at +9dBu/-6dBFS.

Seems strange to me, but I guess it works.
 
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