If you're planning on mixing the coincident pairs at equal levels to form L & R channels, this could be reduced to a pair of opposite-facing wide cardioids, spaced 20cm.

Not saying it's a good/bad thing, just that the setup could be simplified.


Chris

Unfortunately the PSpatialAudio Stereo Lab ware seems to be Mac only ?

Yes, unfortunately. There are a lot of very useful options in that cheap app, basically replacing the much more expensive hardware, plus some extras that cannot be done in hardware. The hardware is handy for straight to record use, of course, but it is a small effort to run your Blumlein small AB tracks through the app in post. On headphones the small AB can be judged very well without being decoded, so there isn't much guessing work in employing that technique.

There are PC shuffling options explored in this thread:
Blumlein Delta Shuffler settings

I think I'll try this technique at some point soon, since I have the mics. (Scratching my head for how to mount it on a single stand with my current gear.)

It seems to be great for phase, but I'm wondering what happens to the folks in the two end quadrants (the ones bisected by the stereo bar)? Since these musicians will all be beyond the +/-50 deg SRA of their respective LR pair, should I expect that they'll all be smashed to the edges of the stereo image?

Thanks for all the replies and ideas, everyone. I think I'll go ahead and record six channels with this config. Not sure how high I'll raise it. They will be standing on a rug over concrete.

Don't concern yourself so much with the SRA; the two coincident DIN pairs I described will simply give you the stereo image you see on Sengpiel for both the front half of the circle and the back half. All the players will be spread L to R as the top Sengpiel graphic shows (as though they were all standing in the 'front' half of the circle); none will be 'smashed to the edges'.

As far as mounting the 'Double-DIN', it simplifies things if you think of it as two XY pairs; so all you need is a pair of XY mic clips (like the ones below) on your stereo bar, 20cm apart.
https://www.ebay.com/itm/383766117065

I'm not concerned with the SRA only, but the apparent spacial distortion when you change the orchestra angle to 180. Am I misunderstanding the stereo imaging for this config?

So it would seem; I hadn't taken 'orchestra angle' into account; I'm not sure if it's directly applicable to an evenly-spaced circle of players or not.

The AB spacing shown in your pic looks to be about 2'; that spacing with an orch angle of 180 degrees will also "smash to the edges" according to the Visualizer.

According to the tool, bringing the 'DIN' to only 2" apart results in an even spread for a 180 degree orch angle. Theory and practice may diverge in this case.

Were I doing this, in my first shot at it I would stick with 12" spacing to get the rich, enveloping sound at low frequencies that spacing would provide, then just correct the stereo image if too wide, by a bit of in-panning. You'll probably need to do this with your AB pair, too.

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I would suspect the most useful thing you'll get with the OC818 pair will be as a front XY pair and a back XY pair - doing Blumlein with it will have the problems already discussed.

My first choice would still be the Jecklin approach, though; simply move the players closer or further from it to get the balance with the room that you want.

They are 35cm (on a 66cm bar).