Works well if you are in a good position in a good sounding venue and can manage the wind.
A couple obvious and non-obvious things (or perhaps not):
Obvious- Significant differences between Blumlien 8's and spaced omnis in the nature of the stereo imaging and the significant rolloff of the bottom octave or two with 8's in comparison to the extended flat low end response of omnis.
Not obvious- I find envelopment and openness to be somewhat similar between spaced omnis and Blumlein; much more so than between either of those and configurations. Probably due to both providing equal pickup of sound from all
horizontal directions and reduced signal correlation between channels for the reverberant sound from all directions.
Obvious- Potential for wind noise problems as figure 8 is the pattern most susceptible to handling/wind-noise.
Not obvious- I find a great advantage of 8’s over all other patterns (omnis especially, other patterns, somewhat less so) when used for AUD recordings is reduced level of pickup of
nearby crowd noise immediately surrounding the recording position. There is no other stereo configuration that does a better job of suppressing the pickup of sound originating directly underneath and surrounding the mics. The nulls of both 8’s are aligned in the vertical axis, pointing directly up and down. Up to a ~45 degree angle away from vertical, 8’s are still significantly less sensitive than other patterns and that reduced sensitivity is symmetrical in a cone all the way around the mic stand, not just to the rear. More distant crowd noise will be picked up with equal sensitivity from all directions like omnis, but the close, in-your face, especially annoying offenders are maximally suppressed, more than all other mic choices. That also makes the crowd reaction sound more even, more balanced and generally 'farther away' sounding than other AUDs from the same spot. Obviously the mics must be higher than head-height, but as long as it’s reasonably high enough it can be lower than any other mic pattern for all around sound. With the mics at 8-9’ high the near crowd sounds more like cardioids at 12’, at least for sound to the sides and front, and omnis at maybe 15’.
One other thing- You needn’t orient the mics at exactly 90 degrees, though most of the time that would be the obvious choice. I can’t think of a common situation in which you’d want to go to a wider angle, but several good reasons for going narrower.*
Less angle between mics can be advantageous for a few reasons:
1) Produces a recording angle (SRA) which is wider than 90 degrees (Stereo Zoom stuff)
2) Solidifies the center of the image (sometimes Blumlein can get a 'soft spot' if not a full-on hole in the middle, even if only in comparison to typical cardioid setups which are often quite mono-heavy)
3) Begins to make the configuration less sensitive to sources directly to the sides, helpful if there is a bad reflection or sound source to be minimized directly to either side, but no problems to the rear and you want to run Blumlein.
*Actually I just thought of one application where going wider than 90 degrees would make sense, and that’s on-stage, directly in front of an over-loud source, like a guitar amp or a close drum kit setup center stage. In that case going wider would lower the sensitivity of pickup for that central source in comparison to sources arranged off to either side to help balance things in terms of level, and also do something to manage high-velocity kick whump air blasts.
That angle adjustment is identical to making a Mid/Side adjustment, so in many cases (excluding kick-whump protection) maybe that’s the best way to approach it, dialing things in after the fact. Blumlein is the only Mid/Side 2-channel pair that doesn’t alter the individual pickup patterns when the M/S ratio is readjusted, only the combined pattern changes. All Mid = a single forward facing 8, all Side = a single side facing 8, other ratios just rotate the two 8’s between those extremes, each mic pattern remaining 8 shaped.
Edit- Just followed the link posted to the earlier thread and had almost forgotten about that one. So apologies for rehashing some of what I posted previously over there.
and thanks for the reminder, I still want to hear this-No discussion of Blumlein can be complete without mentioning the Kentucky Colonel's Appalachian Swing!