I've found Sonar's console emulator and tape sim meters, very accurate and useful.  I tend to ignore the RMS ones but have them there for another reference.  But that's just my opinion.
 
Ben 

Can the T-RackS Meter and/or the meters in O5/6/7 be trusted?  Or other metering plugins?

olemon
Can the T-RackS Meter and/or the meters in O5/6/7 be trusted?  Or other metering plugins?

Pretty much any of them can be trusted to accurately represent what it is that they are measuring with sufficient accuracy.
 
IMO the issue is understanding exactly what they are (and aren't) measuring, and whether what is measured and how it is displayed is useful or appropriate for a given task. 
 
Unfortunately even if one reads the documentation it is often obtuse, confusing and/or leaves out key information so one might have to run some known test signals through them and see what kind of reading is obtained. 

that's why,
if you simply ALWAYS record with ample headroom,
you will be alright.

What I would be wondering say using the console emulator meters   (and is that a good idea? Do you have to go through console emulation in order to get the use of meters)  is what ref rms level is required in order to get the meters to show 0 dB VU.  (with the Trim control set normal eg no Trim)  eg what is the rms ref level for the console meters.  Is it -20, -18, -14 etc...  Do they tell you?   Can it be changed?  If it is fixed then Sonar is expecting you to work at a certain ref level.  (at least if you use the console emulation)
 
I would be running some test tones at various levels to see.

Jeff Evans
What I would be wondering say using the console emulator meters   (and is that a good idea? Do you have to go through console emulation in order to get the use of meters)  is what ref rms level is required in order to get the meters to show 0 dB VU.  (with the Trim control set normal eg no Trim)  eg what is the rms ref level for the console meters.  Is it -20, -18, -14 etc...  Do they tell you?   Can it be changed?  If it is fixed then Sonar is expecting you to work at a certain ref level.  (at least if you use the console emulation)
 
I would be running some test tones at various levels to see.

Yes you can use the console emulators meters without engaging them...they only activate when you use the trim and the other knob.  I actually use those meters for setting up the gain stage when mixing, they are fantastic...for me I aim for around -6 for main tracks...and -12 for everything else.  They have helped sort out my mixing technique...amazing.  Oh in mastering invaluable too!  
 
Ben 

Thanks for the replies.
 
The thing that is really confusing me is why there is a difference in the way different programmes measure the RMS.  
Sonar (and also Cubase) shows the lower figure (in my example -14-5) as does Sound Forge, but Ozone shows the higher figure (-11.5).   Fab Filter Pro L (if you have it, go check) shows -11.5 if in K-scale mode, but -14.5 if in the normal digital scale.   2 different in the same programme??
 
So, if the aim was to make a song "-14.5 db RMS" you could easily be -3db up or down louder depending on which programme you were using.

As I do not work for any of the named companies I can't tell you what they are doing with their metering.
 
What I can tell you is that there are very specific, and agreed upon definitions for most of the terms that get tossed around, and all of these definitions can be found in various standards from IEEE, AES, SMPTE, EBU, etc.

Before you go down that path you have to first appreciate that analog voltages are usually measured over time, while digitized signals lend themselves to instantaneous measurement. Both have appeal, and applications to music production. But they are different methods, with different results for the same signal. You need to know when to use one or the other regardless of the domain.
 
Other things you need to think about:

1. a sine wave is cyclic, music is not. nor is music completely random, it is, for our purposes, considered periodic, but that is stretching things a bit. This is one of the key factors, I think, behind different meters displaying different levels for the same material. There are others - for example a sine wave has a crest factor of 3 dB, a square wave has a rest factor of 0dB, and audio can have a crest factor anywhere from 0 (highly unlikely, more like 12 dB) to as high as 20 dB. All RMS level meters and many RMS power meters, can stumble over different crest factors. Put another way, the ratio of RMS to peak value needs to be taken into consideration!
2. dB is ratio, and if you want to be really pedantic, it is a power ratio, although it can be used to describe any ratio. For our purposes it really is not important that it is a logarithmic ratio, except to remember that it is logarithmic because our hearing is logarithmic.
3. dB is a ratio, so it you want to know amplitude or power or whatever you must have a reference
4. common references include dBu, dBV, dBFS, and dB-SPL, among others - each provides a reference from which the ratio is derived. For example, if 0 dBV = 1V the 6 dBV = 2V.
5. dB is an RMS measurement, by definition. You can man-handle it into representing peak values, but you must do so carefully, and document completely.
6. VU stands for Volume Unit, and is an arbitrary scale, based loosely on mechanical meter ballistics, that is intended to represent - very roughly - the way the ear reacts to changes in level. 0VU = +4 dBu in most professional audio applications, +8 dBu for broadcasters, and -10 dBV for semi-professional gear. They are NOT the same!
7. In general, when we are metering in the digital domain we really are interested in how many bits we are using, because if we use all of them for any period of time things start to sound really ugly. But that is a generalization, there is no reason why digital metering can't convey apparent loudness, for example. And there are a number of reasons why digital metering ought to be able to convey a whole lot more!
8. Metering, and measurement in general, REQUIRE that everything use the same reference in order to be meaningful. In the bad old days we would spend time before each session setting (or at least checking) levels so that 0 dBu at the tape deck outputs was 0 dBu at the console input, and 0 dBu at the console output was 0 dBu at the tape deck inputs. It did not hurt if 0 dBu at a channel output appeared as 0 dBu at the compressor inputs either!

It would be a very interesting experiment too see how different software tools I have at my disposal represent levels... I need to find time to do that again!
 

wst3
It would be a very interesting experiment too see how different software tools I have at my disposal represent levels... I need to find time to do that again!
 

You'll likely find lots of different results. But apart from the "take the RMS and then add 3dB but still call it RMS" situation discussed here, most of the differences should be small enough to generally be irrelevant.
 
For RMS measurements, the integration times used can vary significantly (though sometimes it can be adjusted by the user) as well as the rate at which the screen is updated. 
 
Believe it or not, I've even seen different results with simple peak meters. 

accuracy is over rated.
 
i've said it previously,
track with conservative levels, 
you'll be fine.