dBFS and VU

BGTD,
-18db on the logic meter is ~ the same as 0VU on an analog desk.
there is more than one standard, and they vary by 3db or so.
some use -14db on logics meter.
that's a bit too hot for me.
PSP's free vintage meter is good for this.
the old EA plugs, now Roger Nichols, have excellent meter plugs.
even sonalksis' Free G will do.
the main issue is, when you back-off the output, you'll have to boost your monitor level.
this will be difficult if you're using a small system.
you'll run out of usable headroom.
DR9.

BGTD,
Pursuant to my response I left you on LogicProHelp for this question, it would help if you told us what medium you're producing for. This is really where the reference takes on any actual meaning. Note also that "volume units" have no absolute physical or electrical reference. They are more a function of meter ballistics and the meters integration over time. How they are "steady state" calibrated to a hard reference like 0dBfs, is specific to your application.

Hi

It is COMPLETELY DEPENDENT on the target medium that you are going to mix for.

TV in the US is one standard, Radio is another, while Cable TV is another, and CD Masters are another....etc...etc...etc...etc...

If you know the target medium, then you can know what to deliver, level-wise.

Cheers

Hi.

Since you mention a CD as the target medium, then you can understand:

0DBFS is equal to hitting the MAXIMUM digital level on a CD. Not going over, mind you, but -0-.

This is what is called an ABSOLUTE level reference. There is no going OVER that 0, above that 0 is digital distortion. BAD.

Now, DBu and DBm and DBv are three different methods of measuring volume, in audio applications.

ALL of these are called RELATIVE level references.

Relative to what, you might ask? Relative to something else. This "somthering else" is your target medium. In this case, a digital medium (the CD).

So now the question really is, "how can I CALIBRATE my equipment that has RELATIVE level references, to my ABSOLUTE level reference?"

You do this by running pink noise, a 1000Hz sine tone, and checking your levels going out of your DBu/v/m device and going into your DBFS device.

When your relative device hits -0- in your absolute device. check where the level is on your relative device. It should be pretty loud.

Usualy, engineers use levels like -18dBu or -14DBu, which will give HEADROOM of either 18DBu or 14DBu BEFORE hitting that DBFS -0- clipping level.

So, when you playback your relative level device, and IT says it is playgin back at ITS -0- level, you should see in the absolute digital device, either -14DBFS or 18DBFS, dependgin on what level YOU want to use.

The headrom is VERY important, because things like analog tape machines that have very sloooooooow ballistic meters, and cannot reproduce al the transients in those slooooooow ballistic meters, will have enough headroom going into your absolute digital DBFS device, so as to NOT cause and digital cliping (distortion) when you record into your computer.

Is this clear?

Cheers

I feel it is vital to appreciate that a VU is completely unrelated to digital FS meter. The VU meter was designed for analogue gear and NOT for digital. For this reason it makes absolutely no sense whatsoever to use a VU meter for digital measurement.

The VU meter was designed to give the user an idea of sound volume as our ears would perceive. This results in the musical peaks not being shown and in the digital world this is essential - less so for analogue where distortion is less noticeable, even acceptable for short peaks. It is true that 0dB on the VU scale typically equates to -18dBFS but this is only true for constant amplitude sinusoidal test tones. For music, it is entirely possible for the VU meter to be showing a maximum level of 0dBVU while your digital meter will show peaks of say -6dBFS. Then change the tune and you may well see peaks of 0dBFS with the VU meter hardly going above -10dBVU. It is entirely dependent on the "energy" of the music.

My advice is to turn your back on VU. its old technology and has no place whatsoever in the digital world. Truly.

When delivering music to the mastering house, the broadcaster, whoever, the important thing to know is what the maximum peak level they work to or want. The next important thing is the perceived loudness required which can be adjusted with compression, limiting etc and that is a whole other subject.


What level you track at is entirely up to you and has no relevance to the mastering house etc. Record your vocalist or instrument at a level you find convenient to work with. I'd allow a vocal to peak around -12dB at most, for eg. If you are working in 24 bit you can allow very large headroom without compromising on sonic quality (peak at -20dB for eg)

When the track is done and mixed, I would bounce the lot to a single audio file, at a level depending on where it is going. If its going to a mastering house I'd allow at least 6 to 10 dB of headroom to provide some "breathing space" for the mastering engineer. If its going straight to CD/CD duplicator (and is therefor in 16 bit too) I'd normalize the track so that my peaks reached a shade below 0dBFS - say about -0.5dB.

It is COMPLETELY DEPENDENT on the target medium that
you are going to mix for.

TV in the US is one standard, Radio is another, while
Cable TV is another, and CD Masters are
another....etc...etc...etc...etc...

If you know the target medium, then you can know what
to deliver, level-wise.

What is a good way to find a summary of expected levels for these media?

Hi,

The National Association of Broadcasters

http://www.nab.org/AM/Template.cfm?Section=Home

They have a standards settgin comittee, and white papers:

http://www.nab.org/AM/Template.cfm?Section=Standards_Setting&Template=/TaggedPag e/TaggedPageDisplay.cfm&TPLID=50&ContentID=3512

Here is their store:

http://www.nab.org/AM/Template.cfm?Section=Books&Template=/TaggedPage/TaggedPage Display.cfm&TPLID=2&ContentID=490

If you are living in another country, you should locate the appropriate Broadcast Standards Institution for your Country. They all have one, or use one from a close by Country.

BBC (England) hold the standards for a lot of Countries that were, or still are colonies of the British Empire. Their standards are different than US ones.

Cheers

Ask the folk you are delivering to?

And...

You can always ASK the client. Maybe they know what they want, maybe they don't...

Cheers

Yeah... the writers, directors and producers didn't know that stuff at all. They count on the people they hire to know what to do. Thanks for the great help and links!

You're welcome!

<Yeah... the writers, directors and producers didn't know that stuff at all. They count on the people they hire to know what to do.>

True, but the director or producer should be able to tell you who to ask. If its for tv for eg you need to speak to the dubbing mixer.

I appreciate there are some areas of the media that just want a "CD that works" (for eg)

If this is the case then they can't really blame you if things aren't quite right. I feel if you use your intuition/own judgement in these cases you can't go far wrong. If they want an audio CD for eg just master it like you would any CD - ie with peaks close to 0dBFS