The term "MID" is used for two different things in this conversation - the M in M/S and also Midrange. Please be sure to specify, if you don't mind, these new techniques are a bit confusing to read about anyhow!
Yes, good point! I'd try to say
midrange when referring to frequency.
.....I typically start mixing that way with the omnis- EQ and level balance the omni pair alone to best effect, then add the center pair. But you can also do it the other way around if your recording is stronger that way- make the Front/Back, Mid/Side pair primary and bring in the omnis in support of that. The EQ on the omnis might then be somewhat different, possibly with less midrange emphasis (getting more of that from the M/S pair), rather than boosted lows and mids with a carefully cut "mud and boom" region in-between, typically centered somewhere around 300Hz. ..... [edited]
And agreed with rocksuitcase, except that when dialing in that upper bass/lower midrange cut (which is often significant indoors and can range anywhere from 120 to 500Hz), I almost always carefully boost the lows below that range to restore the deep bass which is a big part of the realism I feel the omnis uniquely provide. I may cut the very lowest frequencies if its only non-musical noise, but I'm probably boosting between there and the upper bass/lower midrange reduction, else the overall solid bass which the omnis are supposed to contribute gets anemic. With a cut on either side, that range gets pulled down along with its neighboring regions and needs a boost to bring it back to where it should be.
Of all the raw tracks you posted, that the Mid/Side mixed front/back pair sounds best to me prior to any other manipulation, so using that as your starting point here seems apt. I often bump the 2-3kHz area of my omnis for clarity and that seems relatively common for most omnis. Its the frequency range above 3kHz where different mics seem to behave quite differently and its harder to make general statements about what to expect there. Quite frequently I'm reducing the omni content in that region if the center mics are taking care of it nicely, yet bring the omni level back up in the high treble around 14kHz or so to get some nice open diffuse ambient air. But that really depends on the mics and situation. Might make sense to smoothly reduce all the highs from the omnis above 3kHz if they are bright sounding to begin with or if that content conflicts with the same frequency range provided by the center pair.
If I get into this, I'll want more than 4 channels soon enough... may have to fire up the laptop and MOTU 828 again!?
One of the keys to not going crazy with complications is keeping things manageable. If you can do that with a laptop and interface, great. Everyone needs to find their own comfort level, and even 4 channels is more than many tapers want to have to manage. Nothing wrong with that. The only way I can do 6, 8 or more channels is to set most of it up beforehand so I can pretty much just roll at the event. For the last two open-setup recordings I posted about above, the first using the 4 mics took me about 4 times as long to arrange and setup at the show, and also break-down afterwards, compared to the 6-channel pre-wired miniature mic setup I ran a couple days later. For that one I just popped up the stand and pointed the mics, fired up the recorder, adjusted levels and rolled. Quick and easy on the recording side of things. More to manage on the back side once recorded, but that's the nature of these setups.
I think front mic is in the left channel. I'm not sure about one hundred percent. When I set my microphones, I did not mark it. I'll mark it next time.
Thanks. I may be able to tell by listening. You'd think it would be obvious, but it can be amazing how similar the different channels can sound in isolation. It's the interaction between them where identity arises. And yes, always keeping the forward facing mic in the left channel and rear-facing in the right is good practice, and it makes Mid/Side decoding straight-forward.
I've found that as the mic count increases, its extremely helpful to do a mic check either just before or just after the performance, all setup in place, snapping fingers or speaking directly into each mic to ID which channel in a short separate recorded file-set. More often than I would have expected or care to admit, I've found accidental left/right channel pair swaps or even messier channel mis-routings I did not intend and might not have noticed otherwise. That's another complication pre-wiring everything helps me avoid, yet I still like to do the check. I actually keep a dog-clicker in my bag which helps with those mic IDs in loud environments.