I'm about the start mixing my first song and I've been reading about gain-staging levels and the cumulative effect all the tracks' sonic energy build up as signals move through effects buses etc., on their way to the master bus. I'm using a VU emulation plug-in on my Master Bus. The plug-in has a Nominal Level knob so I can set my 0 VU reference level.
 
I came across this: "-15dB, which is the equivalent (the reference level) of "0 VU" in Pro Tools."
 
Can someone tell me what 0 VU is equivalent to in Sonar's dBfs meters?
 
Thanks you.

I believe, a 0 VU in sonar will be the same.
you might very well be confusing Peak with RMS.
I have found there to be a difference of 3db in the master bus while using plug ins during Mixdown and mastering.
Thus I create a whole new master bus for analyzing plug ins only. This can be done by sending your master to another bus before it hits your hardware.

chuckebaby
I believe, a 0 VU in sonar will be the same.
you might very well be confusing Peak with RMS.
I have found there to be a difference of 3db in the master bus while using plug ins during Mixdown and mastering.
Thus I create a whole new master bus for analyzing plug ins only. This can be done by sending your master to another bus before it hits your hardware.

Thanks. Curious... how/why do you create a separate bus for plug-ins (assuming you have various plug-ins spread out in fx bins on various tracks, as well as tracks sending to fx buses), and what do you do with the information you glean from that? I

Caa2
Volume Units are measured in decibels, but a decibel is a meaningless factor unless it is referenced to something.
 
So, you can say something like +3VU is 3dBVU ouder than 0VU and that may be a helpful descriptor in a limited context.
 
Historically Volume Units have been referenced to power transfer or voltage potential. You will see specifications such as 0VU = +4dBm or +4dBu respectively.
 
With the advent of digital systems a Digital Full Scale meter was adopted.
 
It is common to intergrate digital equipment into analog systems by calibrating the output of the digital to analog gear so that -12dBFS, -18dBFS, or even -20dBFS = +4dBm or +4dBu = 0VU.
 
With VU meters there is a long tradition of clearly defined calibration specifications for professional use, but there is also a long tradition of consumer grade gear providing uncalibrated or very loosely calibrated VU meters. For example; better grade consumer level stereos in the 1970s often times provided VU meters that were calibrated to -10dBv.
 
What does this mean? How does it apply to your question?
 
It means that you are free to calibrate your concept of a VU to anything you like, and you may also calibrate it to specific output levels if and when you find it useful or necessary. You made no mention of output levels so I suspect you may be satisfied with the former choice until you find a need to specifically consider output levels.
 
Good luck!
  

"You made no mention of output levels so I suspect you may be satisfied with the former choice until you find a need to specifically consider output levels."
 
Thanks for the reply. By "output," if you mean levels in a final stereo mastering of my mix (the song), than yes, I'm interested in output levels. What I'm trying to do is get the best results in my song "output." I'm working on the mix so various elements are balanced and working to have everything converge (summed?) on the master bus (from which I'll create my stereo final song) in the best shape possible. 

Bingo! dBFS is, without any additional information, ambiguous.

dB is an RMS power ratio. That's it, and that's all it will ever be, in spite  of some mis-use along the way<G>.

0 dBFS in the digital domain refers to "all bits on" - the maximum instantaneous value that can be represented. Among other things that  means it is is a peak value, so we will need to (later) change it to RMS.
 
0 dBFS, with the addition of the analog domain, still represents the maximum value that can be represented, but now we assume that  it is also the maximum instantaneous voltage that can be produced by a D/A converter (or the maximum value that can be read by an A/D converter.) And that is a function of the converter architecture, and the power supply.
 
Do you see where this gets complex?
 
So what most folks have settled on is simply this:
1) there is no direct correlation between dBFS and dBu or dBV, it must be established on a system by system basis.
2) one needs to set 0VU (an entirely different concept) to be equal to some level lower than 0 dBFS. The common wisdom sees to hold that  it should be somewhere between -14 dBFS and -18 dBFS, maybe -20 dBFS. The  difference between the 0 VU reference and 0 dBFS is your headroom.

make sense?

The other thing which is not considered here yet is the interface itself. All interfaces produce a maximum output voltage (rms) for 0 dBFS. Yours produces +10 dBu at 0 dB FS. Mine produces +18 dBu for 0dB FS.  A top of the line RME might put out +24 dBu or more at 0 dB FS.  (by the way this is where serious mains powered interfaces actually do much better with proper power supplies in them. Typical USB powered devices are only likely to reach +4 dBu at 0dB FS) Can you see here that the obvious ref level for the RME should be -20 dBFS. Because at that ref level it is going to put out +4 dBu which is serious!)
 
My Yamaha digital mixer puts out +18 dBu at 0 dBFS so at +4 dBu I need to running my digital ref down at -14 which I do a lot for most things.
 
Of course you can still set any ref level you like to be 0 dB VU but what level that actually comes out of your interface at that ref level will vary. So If I want to work say at -20 which I like because of the K System ref then it means that I am only going to get  -2 dBu at that level which is still OK.
 
For your Scarlett interface max output is +10 dBu at 0dB FS. If you wanted to produce +4 dBu at your ref level then your ref level would have to be -6 dBFS which is not great obviously. Lets take your ref level down to say -18 dB FS. That will work fine too but you will only get -8 dBu at that ref level. (which is very close to -10 dBv by the way) 
 
All good as long as you realise that at your-18 dB FS ref level you are only putting out that amount of voltage. The next question is it going to be enough to drive a pair of active monitors. I would say yes because with most active monitors when you turn them up as high as they will go the input sensitivity will be around -10 or so. The volume controls should work over a range of input voltage levels and that is the very reason they give you that facility.
 
So if you wanted to produce 85 dB SPL in your room you might have to crank your speakers up to the -10 input sensitivity. When I am producing 85 dB SPL in my room I might have my speakers set around +4 dBu sensitivity. (for -14 ref or -2 dBu for -20) We are both producing the same amount of SPL but you are adding in more gain within your monitors in order to do it.
 
To cut along story short -18 is a known good ref. I like -14/-20 only because in Studio One they have K system meters which can be set to either of those. -14 is good for me also because my Yamaha digital mixer all tallies up at -14 with everything too. If I know I am going to be producing a loudish master at the end of the day I may start at -14 because then it is not too hard to master up to higher levels such as -10 or higher even. -14 is great level because it is quite loud and punchy but will retains nice dynamics and transients. -20 is better still though for transients and dynamics. 
 
 
 
 

wst3
Bingo! dBFS is, without any additional information, ambiguous.

dB is an RMS power ratio. That's it, and that's all it will ever be, in spite  of some mis-use along the way<G>.

0 dBFS in the digital domain refers to "all bits on" - the maximum instantaneous value that can be represented. Among other things that  means it is is a peak value, so we will need to (later) change it to RMS.
 
0 dBFS, with the addition of the analog domain, still represents the maximum value that can be represented, but now we assume that  it is also the maximum instantaneous voltage that can be produced by a D/A converter (or the maximum value that can be read by an A/D converter.) And that is a function of the converter architecture, and the power supply.
 
Do you see where this gets complex?
 
So what most folks have settled on is simply this:
1) there is no direct correlation between dBFS and dBu or dBV, it must be established on a system by system basis.
2) one needs to set 0VU (an entirely different concept) to be equal to some level lower than 0 dBFS. The common wisdom sees to hold that  it should be somewhere between -14 dBFS and -18 dBFS, maybe -20 dBFS. The  difference between the 0 VU reference and 0 dBFS is your headroom.

make sense?

Yes, it's starting to make sense. Thank you for the perspective!

because once you load metering plug ins in sonars master bus section they read +3db peak of what sonars meters read. to even this off, I create a new bus for analyzing and metering plug ins only.
 
Do a test.
Put "Waves peak meter" in the master bus of sonar platinum.
it reads +3 db. higher than what sonars meters are reading.
 

Idea for having the VU-meters in the prochannel being displayed properly, so to better see 0VU:
http://bakery.cakewalk.co...nels-console-emulation