I use the 17cm spacing when I am running hypers and the 20 cm spacing when I am running cards....helps to avoid getting a dead spot in the middle of the sound stage due to the pickup patterns...

I can see why you would want to use a smaller separation with the hypers, but would using cards be ok with the 17cm separation?

in theory, I am sure you could...this would be more of a point outside the stacks type method I would think...all it would really do is reduce the amount of seperation you are going to get (i.e. the soundstage), but in some cases, it could be the best option...

does the distance make a whole lotta difference in this?  at the main bar here where most of the bands come...i am at least 40 ft back...no taping allowed fob...when i put my mics at 90 deg...they are pointed at the damn walls...same for XY, and TONS of crowd chatter, esp on quieter songs.  I have only taped 2 shows..one here and one in a much smaller bar(DIN there)  any suggestions on a distance of 30-50 ft?  is DIN fine for this?

does the distance make a whole lotta difference in this?  

Yes.  The relationship between distance, angle and spacing all play a role and if you increase the distance, you have to adjust the other two if you're trying to capture an equivalent recording angle (sort of the width of the soundstage).

I'll try and dig up some info tomorrow...

What would be the difference, sound wise? What does that 3cm give you?

Thanks

by the way... this is in reference to the custom schoep bars at cascademedia.net

Direct A/B tests will present several sonic differences between the two configurations, as applied to both hypers and cards.  Without having my field notes in front of me, this is what I remember from the top of my head:

1.  mk41s run on both 20cm(A) & 17cm(B) on an ams-22 mount (meaning that both pairs of mk41s are only 20mm(approx) apart on the vertical plane.  The 41s(A) presented to be more muffled with mids buried moreso than the 41s(B), highs were less brilliant (but not too brittle) than the 41s(B), and the low end became sloppier than the 41s(B).  Overall, the sound of the 41s(B) was more accurate, less reverberant, and more pleasing to listen to with cans or playback (in this case two HR824s per side(L/R) with one (per side) rolled off to the "B" setting.)  The sloppiness created by spreading the mk41s apart goes against known physics of frequency dependence where the wide will create a deeper tone.  Widening the hypers created a sloppier tone, not necessarily deeper and warm - I attributed this to be because of the polar pattern of the supers mk41s.

2.  In the case of the mk4s at 20cm(A) & 17cm(B) on the same ams-22 mount...the cards did not demonstrate that much of a difference except for the low end which because less prominent in the recording.  The high ends, what was analyzed to be beyond 10Khz became a little too brittle thatn the cards positioned at 20cm.

These tests were run in a theater with a vdosc array and also in a baffled basement studio with microphones aimed towards aformentioned playback system at 20 & 30ft.

Again, this is off the top of my head.

Edit:
A note.  All monitoring is done at a reference level only using calibrated monitors (also sent in for re-calibration every 12months - on average depending on usage and how hot the S.E. summers get   )  What happens between my reference monitoring and your playback system is your own ball of wax...

I run DINS(DIN stealth).  I don't have the measurements down, but it's pretty fucking ingenious, pictures to come.

I just got some good (IMO) results with my cheap little SP AT933 hypers running DINA (17cm/90*) for MMW last Sunday. From my spot, 90* was just outside the stacks. It didn't pick up as much of the really chatty crowd as I was expecting.