brundlefly
From the Ref. Guide:
 
To change a project’s tempo
1. Use the File > Open command to open the desired project.
2. Use the Edit > Select > All command.
3. Press ALT+A to open the AudioSnap palette.
4. Zoom in (or press F) to get a better look at your clips.
5. With all clips still selected, enable the Clip Follows Project Tempo button in the AudioSnap palette.
All the clips display the Auto Stretch icon , and will now conform to any new or future tempo changes.
6. In the Control Bar’s Transport module, click the Tempo value , type the desired tempo value, and
press ENTER.

 
Ok, I think I've read that before, but dismissed the method as most of my projects contain tempo changes, in which case slip-stretching works perfectly if I slip-edit the clips that exist in the tempo change section beforehand.

Seems to me the slip-stretching and Process > Length methods are only workable if the recording isn't synced to the project timeline to begin with. Maybe it isn't in the OP's case, but I assumed it was recorded to a click since he mentioned a specific tempo.

Listen up everybody, there are edits and cut and pasted clips and stuff.
 
First thing would be to bounce each track down into a SINGLE clip, one clip per track, then cut them/move them so all start at 0 time, and THEN use the length process.
 
R

Separate clips with random start times are not a problem for the method I posted or the one quoted from the Ref. Guide. And, as mentioned, Process > Length will not keep the content in sync with the timeline.

eikelbijter
Listen up everybody, there are edits and cut and pasted clips and stuff.
 
First thing would be to bounce each track down into a SINGLE clip, one clip per track, then cut them/move them so all start at 0 time, and THEN use the length process.
 
R

 
  Well, I can tell you I tried all I could think of and in the end Once I highlighted and used "bounce to clips" on each track individually, then slip edited the beginning of each track to start at zero, then the end of each track to the same length, I was then able to change the tempo from 162 to 159 and everything stayed sync'd.  However, the guitars and bass sounded like crap, like a warbley old tape playing a bit too slow.  Solo'd the drums probably would be fine as I can't hear any noticeable artifacts even in the cymbal/cymbal wash and I listened hard for it.   They sound like they were tuned a little lower than they were but certainly usable.  But alas... my band got the willies about what it had done to the stringed instruments figuring it had to have been detrimental to the sound of the drums too even if we can't yet hear it clearly.  They are concerned that with EQ,compression, FX, and mastering that little demons will rear their ugly heads later on and it was decided to scrap the track and re-track the drums and the entire song from the start.  Thank you guys anyway!  This community is (as always) awesome as hell!
 

@ChuckC
 
Might be worth getting even the free version of Ableton Live. In situations like this it can change tempo on actual audio tracks amazingly easily and well....

For future reference, and this was mentioned/alluded to here, this is what I've done and it works (if the song is in time to a click already).
 
1) Set Now Time to 00:00:00
2) Use the Export Tracks option or Bounce to clips to export the tracks (disable all effects in Sonar, center pan, make sure all mono tracks export/bounce as mono and all stereo tracks export as stereo, etc... you want essentially the original tracks but each in one long clip that spans the project)
3) Import the new tracks into a new project (I prefer this because it's less messy/confusing) or archive and hide the original tracks
4) Set your snap resolution to Measures and snip ALL the tracks to the closest measure after the song ends (include any tails/fade outs on the original waves)
5) Split at that measure across ALL the tracks/clips so they are all the same length (so now you have tracks that all start at 00:00:00 and at an exact end point with no breaks at all... this may mean long runs of silence on some tracks but all clips MUST be one long chunk of equal length)
6) Change the project tempo to your new tempo
7) With Snap still enabled to Measures select ALL the clips in the project
8) Hover over the end of one of the clips until the Smart Tool turns into the "Crop" tool (the end of clip will turn into a blue line)
9) Hold the Ctrl Key on your keyboard and that line will turn yellow indicating it is now the Stretching tool (or whatever it's called... this stretches audio clips.
10) Drag the end of the track to the appropriate measure point. This could be closer or further away from the start depending on whether you are speeding up or slowing down th track.
11) Right Click on the clips (with all clips selected) and choose "Bounce to Clip(s)". This may throw a prompt warning of "trimming". Accept the prompt.
 
You have just stretched your entire song.
 
HOWEVER two things should be paid attention to...
 
1) When stretching multiple tracks it may crush your system. The stretching can be done one clip/track at a time. Just make sure you have snap enabled and all the clips end up the same length.
 
2) Not all material responds the same to the Offline Render options applied in step 11. You can do these one track/clip at a time as well and try the different Offline Render algorithms in the Clips Inspector under the "Audiosnap" submenu (so press I to open the Inspector > Select the Clips tab at the top of the Inspector > click the "Audiosnap" submenu > Change the Offline Render option to try different algorithms). To do this one clip at a time you select the clip (and make sure no other clips are selected), change the render option then bounce. You can do multiple clips while excluding others as well this way to save time. So if you find an algo that works for your guitar tracks select all the guitar track clips and do as stated above. The "Clips" Inspector goes into Omni mode (or Multi... I forget) and all changes made apply to all clips selected at that point in time.
 
The bounce is extremely important to getting rid of artifacts.
 
For small changes like you are describing (a 2bpm tempo change) there should be absolutely no problems if you use the correct algos. I'd say you can reasonably expect up to 5bpm changes with absolutely no loss in quality and up to 10bpm with insignificant to no loss in quality (if you really watch your render options). Beyond that it depends on the material.
 
 
I've done this and it works. It's a pain in the balls... but it works.
 
Cheers.

BTW... I'd imagine all that works even better at higher samplerates because the algorithms have more sonic material to work with. Essentially more samples means the samples can be spread out more evenly. Less samples and the computer has less to work with and thus has to do more guesswork to fill in the gaps.
 
That is just a theory of mine though and I'm a numbskull.
 
;-)