Hi gswitz,
Yep, you can trust the gain knob. In fact, from a purely technical point of view, you can clip the crap out of any number of tracks and busses and as long as you're not getting overs on your master out it will be fine. You can try this by putting a multi-out drum synth in a project, directing all of the outputs to a drum bus and then the drum bus to your master out. Now turn up the outputs on all the tracks and the drum bus until you're constantly clipping but also drop the fader on your master out until it isn't clipping. It sounds fine (I've just tried this again to make sure).
 
That said, there are a whole bunch of reasons to not clip tracks and busses. For example, just becuase Sonar's mix architecture allows internal clipping doesn't mean that fx will allow it without sounding horrible, and heaven knows that any external hardware won't like it much. Also with 24 bit drivers there just isn't any reason to mix hot.
 
So, certainly the gain knob in the master will work fine, but as others have said you probably should just turn down the tracks feeding the master. I do that by using the track manager to hide the MIDI tracks in a project, selecting all the tracks, holding the control key to make a quick group and dragging one fader down a few DB (which drags all the faders down a few db). Do be careful when doing that though, you may mess up your gain staging in your busses and that can cause problems with bus comps and such.
 
Shorter answer: if there's not a good way to just lower your volume in the tracks the gain knob will work fine.
 
Dean

can you fix a clip on the input into the master bus with the bus gain?

Of course it's always better to keep levels under control at the track level, but in reality you can't clip the master bus.
 
You can go over 0dbFS, but it won't actually clip. Not until it's converted to 24-bit integer data and sent to the audio interface. So yes, you can lower the input to the master bus or to your final limiter and "fix" a too-hot mix. Unless it's waaay over, this'll work just fine.
 
I like to see signals on the master peak at < -6dB. Hotter than that and the limiter has no headroom to work with, and will be in limiting mode most if not all of the time. The result is flat-topped files that lack detail and clarity. But I have no problem fixing such a situation by simply lowering the input via either the gain slider or the input level attenuator on the limiter itself (if it has one).

Thanks guys!

I use a MAIN OUT bus for analysis and consistent volume level:

The MAIN OUT bus:
    is the first bus, easy to see,... This is the listening bus   
    controls the monitoring volume sent to the audio device
    does NOT have "effects." And no envelopes
    has monitoring tools: Voxengo Span, vintage meter, Panipulator
 
The MASTER MIX bus is next, it is used for bounces, exports,....  ALL final effects are in the bin.
 
This bus is output to the MAIN OUT bus.
 
The MASTER MIX bus may have volume envelopes for fades and misc. adjustments.
 
"Bounce to tracks" mixes and Export from the MASTER MIX bus.
----------------
Only two buses feed the MASTER MIX bus:  VOCALS ALL, and INSTRUMENTS ALL.
 
I follow this logic for all instruments as well. Each has its final bus feeding INSTRUMENTS ALL. This provide quick adjustment for each grouping: muting, volume, EQ, effects,...
 
(I have track templates to create all or some of the various instrument buses: strings, purc, piano,...)
---------------------
For bounces::
I add at least two blank tracks labeled MIX1 and MIX2, to projects. These output to the MAIN OUT. NOT
directly to the sound device.
I change the name of the mix tracks (and add the date) BEFORE bouncing-to-tracks so the created wav file will have a name that reflects the name of the track. This is useful.
 
I then solo the mix track to listen to the mix(s). Which is routed through the MAIN OUT bus.
And all the analysis tools are the same, and quick to open.
 
Since the mix tracks are output to the MAIN OUT bus, there is no need to bypass the effects/eq, or change the volume setting of the MASTER MIX bus when listening to a mix track.
 
And because the MAIN OUT bus volume is the same, I can compare, audibly and visually, the mix with the original tracks.
 
((Per CJ's insight, if the bounced track/mix does not sound correct, before I do anything else, I use
control-z (undo) to remove the mix clip, and the wav file from the disk. This means I have fewer
orphaned audio files.))
 
Simplified example:
http://logicalarts.com/temp/SonarRouting0913c.jpg
 

 
 

jm24, that's awesome!
 
I try to keep my mixes as simple as I can and still get the mix I want. I don't do anything every time.
 
I've tried project templates, but I just almost never use them.
 
I do use some track templates for multiple synth arrangements and SD3 stuff or multiple takes of a multi tracked recording where there is bleed between the tracks.
 
I love your graphic and everything. Very useful to see it that way. And sometimes I separate the vocals from instruments too, but I wait until I need to for some reason. I don't start out that way.

Also if you use K system correctly you will never clip anything. The VU meters on the tracks should all be showing the K ref level. The VU's on the buses will also only be reaching ref level. The VU's on the masterbuss will also only be showing the K ref level.
 
The ref level means you are creating the rms component around the K ref level and you still have headroom to spare above that. eg 14 or 20 dB depending on your K ref level choice. Nothing will clip anywhere when you operate this way.
 
You end up with a nice master that is averaging your rms level on the master buss with peaks only just reaching -6 dB or -3 dB at worst. Still with headroom present. If you were starting to overload the masterbuss the VU's on the masterbuss would start swinging wildly over the ref level or the 0dB Vu mark telling you straight away to start pulling tracks and busses down slighty in your mix. The Vu's actually warn you before you even get close to finishing your mix.
 
Can't go wrong really. Peak only metering does not show you this sort of information. RMS metering that is way down on the scale is also not very helpful.
 
It is a bit if a juggling act actually to get everything showing the right things everywhere and still you are hearing a great mix but it is possible and with practice it gets easier.

Jeff, I appreciate your post. As long as you can twiddle the master bus input gain nob, isn't it easy to switch between twenty, fourteen and twelve? After an initial mix, you could adjust input gain to use close to every available bit at the loudest moment and see where you have landed with regards to rms. Then you could work too further compress as necessary or tweak to get the mix you want.

Firstly I think it is Ok to tweak the master gain if you need to but I tend to not want to move it far from unity gain.
 
I don't like switching K reference levels during a project or near the end of a project. I much prefer to choose the K ref level before I start a project. The new test  alignment ref level needs to be put onto a track and the VU's on tracks, buses and the masterbus all have to be set for the new ref level. With a digital mixer it is easy, all you have to do is select the test tone and change the ref level there and as I have hardware meters I just recalibrate them with a variable control.
 
The loudest point in the music only reaches the rms K system ref level so you are not using every available bit as such. You don't have to do that especially at 24 bit. There is no guessing involved you are just at the right level and you know you have the headroom above to cope with transients usually without any clipping taking place anywhere.
 
It is a good system because it prevents clipping usually. The Vu's tell you what is going on with buses and the masterbus especially. You will soon see of you are overloading buses because the VU's start to swing past where they are meant to land most of the time.
 
The VU's also tell you from the ballistics of the meters too if your compressors are set correctly. When they are, the loudest parts just reach 0 dB Vu and don't go much past that. If they do then you have got a problem that needs to be sorted.

gswitz
As long as you can twiddle the master bus input gain nob, isn't it easy to switch between twenty, fourteen and twelve? 

Sure. If you're shooting for K-14 but it's a little hot, just call it K-12 and you're done!

Bit, I love easy answers!

Jeff, this is a dumb question, but I have to use vu right? Rms is not sufficient.

I Do use rme digicheck for leveling tracks at times, but it is so much faster to do it by ear.