Boy, a picture really would be worth a thousand words here.

Unfortunately, "double-sided cardioid" really doesn't tell me much- there are mics which generate different directional patterns by combining the outputs of two oppositely-facing cardioid capsules with appropriate proportions and polarity. You can generate all of the first-order mic patterns in this way, from omni through card to bidirectional (you can do the same by summing an omni and a bi). Examples include the Neumann U67 and U87, or the AKG C414. In condensor mics the contribution of each capsule is usually controlled by varying the polarization voltage on the back diaphragm, which allows for remote pattern control, a' la the AKG C12 and Neumann M49 and M269. Unless you check the pattern selection control, there's no way to tell by eye what pattern such a mic is producing.

If the setup was two coincident mics with the axes arranged at 90 degrees apart in the horizontal plane and the line bisecting this angle as the stereo centerline, that would be either an XY or a Blumlein. The difference is that XY uses two cardioids and Blumlein uses two bidirectionals. Since the Blumlein configuration has live lobes in the rear half-plane, it's a bit better for picking up ambience from the rear. I've found it very useful for room micing when recording drums.

OTOH, if the axis of one mic was pointed straight ahead, and the other mic was pointed side-to-side, that would most likely be an M-S (mid-sides) configuration. The mid mic (the one pointed ahead) is a cardioid and the sides mic (the other one) is a bidirectional. The left and right signals have to be derived by matrixing the mid and sides signals- if the front of the bidirectional mic is pointed to the left, then left = mid + sides and right = mid - sides.

The neat thing about this method is that the width of the stereo image can be manipulated by controlling the proportions of mid and side signals used to derive the left and right- if the sides signal is reduced to zero while keeping the mid signal, you get a mono image; if the mid is reduced to zero while keeping the sides signal, you get the your-speakers-are-out-of-polarity sound. In between the two extremes there's a useful range of image widths, and, if you record the M & S signals instead of the derived L & R signals, you can do this manipulation in post-production.

My guess is that the 30 degree tilt you describe was probably the engineer's way of controlling the balance of direct versus reflected sound picked up by the front mics.

As to the use of the term "phased", an awful lot of recording engineers incorrectly use "phase" in place of "polarity"- a usage which has won quite a few assistant engineers my fifty-cent lecture on the difference. [-X

But, without a good close photo of the setup, I can only make some moderately-educated guesses about it. :wink: