Dennis covered the calibration questions pretty well (of course). Those particular pics are just snapshots of time. The microphone matched/calibrated specifically to the meter gets moved around depending on the type of measurement being performed. Part of the calibration process includes verification that every component in the chain is performing properly. This includes impedance sweeps, near field plots, polarity of each individual driver, individual driver plots, etc. No sense in starting a calibration project if a speaker is mis-wired internally, or the x-overs are sketchy in one speaker. I can also verify that the AVR or pre-pro is working correctly, and more importantly, HOW it is working. Many manufacturers play games with x-over slopes for bass management, depending on the mode selected.
I can already tell this is going to be too long. Perhaps one day I will start a thread detailing the process that I use for calibration, as I am certain it is largely misunderstood. 70+lbs of test equipment matched with dual QSC 322's, Quest Acoustical Lens System, and Dennis' excellent room and system design is pretty much a win-win scenario for someone like me! Two 12 hour days go by quick..
Back to specific questions asked then. Once I have set the mic locations, the positions are fixed. I do change the angle of mics, depending on what info I need. All four mics in this rig are identical. I also have an 8 mic rig used in other circumstances. Spatial averaging is a critical part of the tool set.
That particular fabric will have no outcome on the measurements, although it can have some effect on how the different acoustical panels "work". The perfed screen definitely has an effect, as the room now has a GIANT reflective surface at one end. But as Dennis stated, it is a known, predictable, and did exactly what I hoped with the Procella's compression drivers. Easily measured, and compensated for. Since there is no room behind the screen, I needed the screen removed so I could play with the gain settings on the mains and subs, and toe-in of course.
The whole process is very iterative. If I change some filters on the left channel, chances are I have also now changed the output level, so level matching is re-checked, and then most likely need to re-check sub integration and phase, etc etc. And hours of just listening. That is usually when someone walks in, and wonders if all I really do is listen to music and watch movies in other people's houses...
Terrasond3/Sencore SP495 and SPLink for real time, Digital Audio Generator to create the signals needed, sent to the channel(s) I need, mic mux, mics of course, BSS Blu32 running ARCOS/HATS, also an HDMI signal generator (video and audio). The SP495 also doubles as a very high quality sound card, for when I need ARTA, SysTune, REW, etc.
I suppose someone also wants to know how the room turned out?
Amazing. I would have loved to spend an entire 3rd day JUST listening to music. Focus, Response, Envelopment, Clarity, Dynamics...this room scored high in every category. The Procellas simply perform. Having known dispersion, and tremendous off-axis frequency response is so valuable, especially when combined with the right acoustical treatments to take advantage of that tasty indirect sound that contributes so much to a good listening environment. The twin subs...Wow. Having a system able to truly extend down to 20Hz is a luxury very few get to experience. The room is quiet, and all the subtle nuances and ambiance cues get you completely engaged in the experience. Listening to an intimate jazz recording, followed by a massive organ piece with your eyes closed could be a confusing spatial experience!
Top that off with an excellent projector lighting up a ~13ft wide 2.35 screen and this is a room to be extremely proud of.