You have absolutely no idea what happens with the "vu" meters of these hardware emulation plugins under the hood.
I have been working on a project to recreate the meters of all 3 plugins you showed here and the first two have whacky, totally crazy curves. This has nothing to do with "vu".

 

VU is not a matter of faith, but clearly defined.

0 VU is equal to 1kHz sine at 1.23 volts (+4dBu)
1kHz sine at -18dBFS peak is 1.23 volts output by the vast majority of converters.

That means:
+4dBu=1,23v=-18dBFS Peak=-21dBFS RMS= -18dBFS+3 RMS= 0VU !!!

End of the discussion.

 

Last edited: Nov 28, 2020

Thank you.

For many other queries. Read this.
http://www.sengpielaudio.com/calculator-db-volt.htm#:~:text=The conversion from level L,log (V/0.775).

https://www.ranecommercial.com/kb_article.php?article=2146





My point from the beginning is this (The image is taken from the site I mentioned).
VU meter is related to dBu values and mentioning peak values in dBu is not correct.
This is what I was trying to say.

 

Last edited: Nov 28, 2020

I know what sengpiel said. It is 100% correct and does not contradict my statement. What I have described refers to sine reference levels. You should pay attention to the nuances of what is said.

0VU is ALWAYS given as -18dBFS peak. This is exactly why dBFS+3 RMS was introduced. To end the VU=Peak confusion.

 

Sorry. Didn't mean to say that.
Just shared this things so that others can read without searching too much.

 

GS has beaten this to death in multiple threads. Here's a good one from a decade ago :

https://www.gearslutz.com/board/so-much-gear-so-little-time/557439-gain-staging-plug-ins.html

 

This is proper gain staging in short and simple terms. Try and see where it gets you. I make mostly crazy distorted stuff and I don't think setting all digital channels peak at 0 will make your mixes sound better. Yes, there is infinite dynamics, but following this method will make you mix easier, achieve better sounding mixes, and really use all that available dynamics properly. Loudness is on it's way out anyway, but what I mean is: you have a complete choice of what you want your music to sound like these days. If you want it squashed, you can still nicely squash it even better by using gain staging, if you want it moderately squashed you can do that, too, and if you don't want it squashed you can do that also when you use gain staging. So here it goes:

1) Put a VU meter of your choice calibrated to -18dB RMS on the master bus.*
2) Solo the loudest channels, usually bass and kick, and make them go to 0 on the VU meter. Find the best loudness balance between these channels, then turn your volume control up to a most comfortable level for you.
3) Make all other instruments fit the mix nicely with the loudest channels set like that.

You will end up with a mix that most probably won't peak above -6dBFS. That's your "master tape" you can process however you want perfectly.

Cheers!

Edit: TBProAudio dpMeter 4 is great free meter for gain staging and as a master meter. It has all the different metering standards you'll ever need.

*Instead of VU, you can use K-14, or short-term max LUFS. What you feel most comfortable with. LUFS is the standard now, and it's here to stay.

 

Last edited: Nov 28, 2020

Well,
this one thing cleared my all doubts.
https://www.digido.com/ufaqs/zero-dbfs-defined/



This is a by Bob Katz.



Now I know, both me and @No Avenger were right.
The scale is set in such a way, that, for Sin wave, -18dBFS peak should yeild -18dBFS RMS.
But as VU is related to dBu, VU is related to RMS value and not peak values.

 

Last edited: Nov 28, 2020

According to this logic (and oh believe me, this logic is very familiar to me: "psst..shut up, damn brain!") VU has no relation to digital, because VU refers to analog voltage levels.
But if we stay in the digital world and follow the -18dBFS reference standard, @No Avenger is right, because -18dBFS RMS does not result in 0VU unless Full Scale +3 RMS standart is applied to the meter.

So, yes, you're both right. Who is right and when depends on which digial meter calibration standard is used.

I hate this topic... it will still cause confusion even in 10 years.

 

Last edited: Nov 28, 2020

I know. Scientific brains make the whole AES logic render moot.
But then, AES sets the audio related standard and what IUPAC is to Chemistry, AES is to Audio.
AES has set this 'Full Scale +3 RMS' standard and so there's no way but accept it sadly. It has made my own brain consume itself.

But I have full faith as well, that there will always be confusion, in this sector.

But atleast, through AES17 documentation (pdf can be found in internet through thorough searching because otherwise it will cost $100 for non AES members), this thread can be concluded conclusively.

 

That's why it's called calibration, they can all do whatever they want. It can even go as far as this (made it some time ago), all fed with the same signal (and all switched to input, ofc)