Mono to Mono Compatible Stereo

I use a couple of techniques, depends on what the source is. For example, with a solo instrument (or even a small ensemble), sometimes it's enough to just pan the lows left and the highs right. Alternatively, for a more subtle, or just different effect, run the signal through (or buss to) a pair of L/R panned reverbs, one filtered low, one filtered high. (Craig Anderton has outlined fancy versions of this EQ-ing-left-and-right method, as have other sources.)
 
The VC-64 plugin has a couple of presets for "placing" a sound in the L/R image, using its dual compressor/ EQ that I sometimes use as a starting point. 
 
There are plugins--feebies, cheapos, pricey--that do the channel separations for you with a couple of clicks. I use the stereo mixpack set (I think that's the title) from PSP audioware, but there are others. These plugins use paired comb filters and such to achieve a separation, which could probably be done by hand, but the plugins make it easier.
 
The introduction of the channel tools plugin (sonar 8.5?) made this kind of work a whole lot easier to do inside sonar (in case anyone forgot about channel tools).
 
Delaying one side by a few (dozen) ms. can work, too. Again, it really depends on the source material. Actually, it REALLY depends on trying things out and listening and picking what sounds to closest to what you want.
 
AND THEN...monitor the whole faux stereo thing you've put together IN MONO, to make sure, for example, that your one-sided delay tactic, which adds loads of space in stereo, doesn't just smear the whole mono listening experience. Jeff Evans, on these boards, recommends--with good cause--listening to the mono result from ONE speaker

I have been using the Brainworx stereomaker for my single solo spot mics and it does a fantastic job of widening the sound while maintaining complete mono compatibility.  

I use the SHEPPi free VST that uses a form of early reflections manipluations to create a wider stereo image from a mono source.  I have been working with a singer guitarist who tracks all her own stuff.  She uses two mono tracks for acoustic guitar and vocals.  I have been working on ways to add some space around the acoustic guitar and this plugin has helped me quite a bit.  It gives it a nice subtle sense of space without getting too carried away with reverb effects.  It's mono compatible too.
 
http://www.kvraudio.com/p..._open_ambience_project
 
Also a clever Bob Katz idea. He makes a more (expensive) but impressive stereo enhancer plugin.
 
 

Dave, Jeff, Mike, et al;
 
Ok i'm working through this info.  Dave - nice article - right on.  To reiterate my issue - I am working on a film that will be shown in film festivals in Europe and most likely around the world.  Our delivery platform is DCP.  The mono tracks i want to 'stereoize' are ambience field captures of the environments (both indoor and outdoor) where we shot the film in Portugal.  The Sound Crew mistakenly captured everything in mono.  I'd like to make some of that ambience natural sounding stereo.  So I'm not dealing with adding space to a solo guitar or vocal, I've got 'complex' sounding mono that I'd like to make randomly stereo but mono compatible since some theater systems will play the product in mono (either by accident or because their house system is configured improperly)
 
I was considering the Advanced Ozone - which promises mono compatibility, I will check out the other plugs y'all mentioned.  I don't think the multiple bandpass EQ's will work in my case since the material may comb too much when resumed to mono.  
 
Ok, let me know if you guys think of anything else - totally cool to be back on this forum and hearing from smart folks like y'all.
 
-D

Jeff Evans
The fact that ambience tracks were captured in mono means someone was not vigilant and listening to everything in headphones while they were doing it.  Such a common mistake and people should be smacked for this!  I bet McCue uses his headphones all the time on the job.
 
Anyway one trick I have got away with in terms of mono ambiences is suppose a mono ambience track is say 5 minutes long.  I might cut that in half and paste the first 2 1/2 minutes to the Left channel and the second 2 1/2 minutes to the right channel.
 
Now I know this will make the ambience twice as busy but if it is quiet and reasonably relaxed it can work. You will get a mega wide image that is mono compatible at the same time.
 
Otherwise if you are going to treat a mono track then try using plugins that split things according to frequency rather than time related tricks. Once you have got sound with some width then you could try widening that image a little further.
 
I would be summing into mono and listening through one speaker to check stuff as well.

Jeff:
This is definitely a technique I have been experimenting with in this project.  I have the first mix session for the film with the directors this weekend.  I have done some multiple mono composite stereo examples just as you have suggested.  Your advice is 'comforting'.  You're right that the location crew were not conscious of their settings.  I even gave them one of my H4N's to take with them during the last month of shooting in Lisbon.  They never took it out of the case.  Ok, much good info from this thread for sure.
-D