Me too! Thanks 
Well, from what I think I know I’d say the difference is this:
When Nuendo gets a signal from the converters, it’ll be a digital signal. Nuendo then “translates” that into floating point. Now, Nuendo doesn’t apply any “processing” in and by itself other than raise/lower the level as you change the faders (etc). And by virtue of being floating point instead of fixed point it has a tremendous headroom. So we really don’t need to worry about the “calibration” WITHIN Nuendo itself. The only real issue is when you interface with the ADAC… .and…
Your plugins aren’t all desigend the same way. When UAD programs a plugin they want to emulate the hardware its based on. Since the hardware has certain distortion characteristics, so will the plugin. The headroom the plugin has is in one sense completely arbitrary, because it is a digital signal. I’m guessing they could scale the signal any way they’d want to within the plugin. The 0VU that you’re looking at in the plugin is for your convenience. If your signal is at 0VU on the plugin meter, then you’re where UAD programmed the plugin to have nominal operating level (right term?).
Now, it doesn’t really matter if you push your signal up 6dB within Nuendo to hit that, because you’re still in the floating point digital domain. Your only concern is how you hit the plugin. So since UAD programmed their plug a certain way what they say is correct.
If Softube’s plugin has a 0dBVU = -18dBFS then that’s correct too. Same principle applies. They’re both “right” at the same time. It’s like having two pieces of hardware that operate using different input sensitivity. Except in this case you’re not losing anything by changing the gain.
You changing the level inside Nuendo doesn’t really hurt or help in and by itself because of the huge headroom. But it does of course help just how you hit the plugins. Fortunately many plugins come with input/output trims that help deal with this issue.
I think the only approach that makes sense is to calibrate your entire setup minus plugins. By that I mean that you have your ADAC set up so that -XdBFS on the output of Nuendo equals exactly the level that your analog gear needs. If you want to calibrate it so that your 0 analog = -18dBFS then that’s fine. And of course your speakers and outboard etc follows.
But don’t worry about the internals of Nuendo. You can’t change it anyways. And don’t worry about dropping level in Nuendo. You’re not really going to lose a bit everytime you cut 3dB (I think it’s 6.x dB btw, not 3). It all has to do with floating point and how singals are summed together etc. Even in Pro Tools you don’t have to worry that much about your summing since the summing has a higher bit depth than the recorded tracks. So even though you’re recording 16bit audio for example your summing bus will have at least 48bits to store those signals in… But someone else can explain that better and more accurately…
As for plugins you’ll just have to ge used to the fact that they display differently, and you’ll have to send to them different amounts of signal…
that’s my understanding anyways…
Hi Robin,
That is fairly easy and you have already answered your own question in your posts above. Proceed as follows:
- Measure a 1kHz tone on one output of your audio hardware (or external audio device such as a CD player) at 0dBu (0.775V) using a voltmeter or other measurement device
- Route this signal into an input of your audio hardware (unity gain at hardware input)
- Connect this audio input to a mono input bus in Nuendo
- Select Meter Input in Global Meter Settings
- Make sure the input gain and fader are set to unity gain on the input bus
- the meters on this bus now tell you what Nuendo reads for a 1kHz tone at 0dBu (0.775V)
(in this process you are measuring the level at the hardware input)
Good luck.
There are no levels within a DAW, just numbers.
Digital 1’s and 0’s.
Fredo
I’d like to thank you all for clearing that up for me.
What I have learnt is that purely ‘digital’ plugins (yes, I know that it is all digital) and transformer/circuit modelling plugins have a different approach.
In the case of the analog modelling plugs it is important to calibrate levels to what the PLUGIN MANUFACTURER considers to be their ‘digital’ 0dBu. This level can differ between manufacturers because ‘digital’ dBu doesn’t exist as it does in the analog world (as pointed out by Lydiot - thanks!). Now I get it!! 
This is also why they have calibration levels in their plugin/info/manuals for those specific plugs. For example: UAD Ampex and Slate VCC. This way you also get the best representation when going through their presets. These plugs are affected hugely by the levels, as would their analog counterparts. This is the point of the specific modelling.
So, now I understand why these plugs have calibration levels. And, that it is not dependent on any calibration within the actual design of the Nuendo DAW platform - because, also it also doesn’t exist (as Vocalpoint so correctly pointed out earlier - thanks!)
Purely ‘digital’ plugs don’t care. As long as you’re obviously working within respectable level limits. Example: Steinberg Studio EQ, UAD Cambridge, etc, etc…
My confusion came about with two manufacturers having different dBFS levels for ‘dBU’. Now I understand why.
Thanks, once again, to you guys!!!
R
No problem. I am always happy to help out on any topics that reference “nothing” 