I was working on a project and I realized that the overall volume was considerably lower compared to an earlier copy of the same project. 
  All the settings being the same the output volume of each track (synth and audio tracks) actually was much lower than they should have been.
  For example: in the older copy one of the tracks with the track fader set to zero, instrument volume 75% and the output of the track sent directly to my audio output, bypassing the master measures -7.2db. In the original (bad) project the same track with the same settings measures -24db.
 I measured the pre fader volume for the original (bad project) track and that actually measures -7.2db just as the older good copy...  So it seems to me that something between the VST instrument output and the track output attenuates the volume  and this is common to all my 36 tracks in the project.
  There is no automation on the tracks so the automation offset is not the reason and also I disabled all my effects, and for testing all faders were set to zero... 
  If I insert a new track with the same instrument and settings in the problematic  project than the output volume of that track measures OK , the output volume from the track being the same as the pre fader volume. If I clone that track instead, than the volume remains the same, low.
  I deleted my audio.ins and I restarted pressing the "ctrl" but it didn't fixed it.
  In the "preferences" I disabled my audio output than hit apply and than play and than I re-enabled my audio output  and when I hit play again the volume was a few db (5-6?) louder for about 2 seconds than the volume decreased back to its initial low level...strange .
 If my audio card would be bad than it wouldn't play well the older copy either and otherwise I have no problems with it. 
 It seems to me that at one point the project was saved with some kind of weird settings ... I had in the past something similar when my master was still affected by an effect I inserted after I deleted that effect and the project was saved like that. Then I just created another master and it "fixed" the problem.
My audio card is a Focusrite Scarlett 2i2 with ASIO at 4 ms and my project is made at 48Khz, 24bit . There is no other audio cards in my computer.
 Does anybody have an idea of what could be the cause of this volume drop?

Hi. I have not had this issue. You did not happen to hide / archive any tracks with automation or fade? Does it happen in the same spot every time? That was what I had from the top of my head.
Best of luck.

Hi Ken! I have no hidden or archived tracks in this project and all my old tracks are affected. If I add new tracks to the project than their volume is good. It seems like there is some kind of "hidden" gain control in each track that was turned down, and the project was saved like that. I'm not even really surprised after the countless crashes this project went through.....I'm probably going to end up recreating the whole project.
Thanks for you thought anyway ...!

Is this a project created in an older version of SONAR and brought into a new version? Is there any chance some parameter could have been quick grouped by mistake?
 
Also you say you're not using automation, but that doesn't mean there isn't a steady-state automation line with a single node at the beginning. First place I'd start is unfolding the automation tracks and deleting the envelopes...on a copy, of course 

Hi Craig ! So I created a new copy of the project and I deleted everything (FX, sends , Master, buses) and I only left two tracks with the output straight to my audio card. I left Dropzone 32bit and Rapture 64bit and than I inserted another two (Dropzone and Rapture) tracks and I set these exactly as the original tracks and with the same midi clips.  I deleted the volume automation from the automation lanes and nothing changed. The original tracks volume is much lower than the volume of the newly inserted tracks... I probably will send this project to Cakewalk to take a look at it....
 
 

I submitted a problem report for this , here .

ChrisX
I submitted a problem report for this , here .

haha, i clicked that link and saw my own reports from 2012! (current status: submitted to development)
to share a problem report you have to post it separately in the forum, if you want other users to try & repro :-)