If you record several instruments in mono you can
pan these to different positions within the final
stereo mix. 
If you on the other side record two acoustic istruments
each in stereo and at separate stereo tracks.
Can you pan these two stereo tracks?
For example one to the left and the other to the right. 
( Please do not answer:
“listen and let your ears decide” 
)
Maybe this is possible for coincident stereo tracks
(X/Y and M/S). But I don’t know.
But I can’t see how this can be possible with
non-coincident recordings (ORTF, spaced pairs, …)
where there is phase-differeces in the stereo track.
/Goran Sweden
Panning stereo tracks is like moving the Balance control on a stereo rather than placing the instrument in an audio plane.
Try this tool: http://www.kvraudio.com/get/1128.html
It give you much greater control over the position of stereo tracks.
HTH
Mark
I suppose the pan-control function the same way on mono and stereo tracks. The volume of one channel is increased and the other is dereased. (Balance control on a stereo.)
And a mono track is just a stereo track with two identical channels.
/Goran Sweden.
With X/Y (or “LR”) coincident pair, you can definitely pan the stereo track. Just be aware that as you pan away from one side, that side just gets attenuated. Usually that’s fine, but for example I use a stereo piano patch where the piano sound was sampled from the players perspective, so higher notes are to the right and lower notes to the left. If it gets panned too far either way, it upsets the balance. Use the plug mentioned above to overcome that. X/Y is a simple case because X/Y uses amplitude as the only direction cue, and panning adjusts amplitude as the direction cue.
With M/S, panning works fine although you lose the “stereo cancels when summed to mono” behavior of M/S. If that’s OK, just pan that puppy. Panning full either way will not lose either side of the signal completely – at most you’ll get a 6dB (or is it 3dB?) reduction for the Side mike. Another great option with M/S, giving you even more control, is to use the MDA “image” plugin. That plugin works for either M/S or X/Y input modes, and converts it internally to M/S mode. All controls affect the internal MS signals, and then you get to select the output mode, which would normally be LR.
With spaced pair, panning doesn’t move the image as much as it normally would, because you have two direction cues (delay, from the spaced pair, and amplitude, from panning) working against each other. That is, if a sound came from the left, it is delayed (but as or nearly as loud) in the right mike. If you pan it left, the delay stays the same but the amplitude changes. I suspect it’s best to avoid giving the brain conflicting signals this way, and to use the plugin mentioned above to put one side in center and pan the other all the way over, and then adjust volume. (Of course, sometimes it’s fun to fool the brain for artistic reasons. As usual, rules are best when understood and then broken whenever there’s a good reason.)
In any case, obviously, the further you pan away from center, the less stereo the sound is. This shouldn’t bother you if it sounds right in the end, but it probably means you don’t want to pan hard if you bothered to record stereo. Or conversely, don’t bother to record stereo if you expect to hard pan.
That panning plugin is roughly equivalent to splitting a stereo track into two mono tracks (assuming you use the same plugins & etc).
In n-Track, you’re right that a mono track is equivalent to a stereo track with the same signal in both sides, except that plugins remain mono unless you check “expand mono track to stereo”. When you check that box, a mono track becomes identical to a stereo one in the rest of the signal path.
On n-Track, I believe that mono pan and stereo balance are implemented the same. Note that this is not true on all mixers. Some mixers will attenuate both sides by 3dB when a mono track is panned center, and as you pan to one side, that side increases to 0dB while the other side fades out. This is unusual on pro-sumer and low-end pro gear, in my experience. The advantage of this option is that when summed to mono, panning makes no difference. With the typical (simpler) pan law used by n-Track and all the mixers I’ve had over the decades, panning does make a volume difference when monitored in mono mode. Since we normally readjust the fader after adjusting pan anyway, and since we always double-check our mixes in mono (right?) this isn’t a big issue.
Thank You Jeff
I have the http://www.kellyindustries.com/stereo_tools.html plug.
But what is and where to find this ‘MDA “image” plugin’
I just started to try to record my solo acoustic guitar compositions (simple stuff) in stereo.
I was recording in mono for some years because my timing was very bad. 
Now it has become quite good 
so I will work with tone stereo recording. 
I am quite satisfied with M/S.
I have 3 mics: ADK-GC1, ADK-Hamburg and Rode Nt2-A.
I use ADK-Hamburg and Rode Nt2-A for M/S.
I have tried x/y and many different styles of ORTF. But maybe you should have matched pairs for that ?
I will read your “Jeff’s PC Recording Tips”.
/Goran Sweden
Well, one of these days … I’ll get around to organizing & adding …
Yes, when the two mikes don’t match very closely, M/S is by far the best and quite workable. For all other stereo setups, not only should they be the same model but they should be matched. Many manufacturers (esp low cost) simply classify their mikes into 3 or 4 groups with color stickers, and if you get two with the same color that’s as good as you’ll find. For more expensive mikes you can buy a matched pair. Lack of a good match leads to a tone imbalance. Sometimes it’s annoying but practically (with color-sticker-matched pairs) the tone difference can be less than the tone difference between L and R in the room itself, in which case who the heck cares? Well, fussy people and perfectionists. Not me, but if I were paying big bux to record my next smash hit record, I’d want a fussy perfectionist as my engineer!
'Course, first I gotta record my FIRST smash hit record …
mda-vst.com