Thought I'd post and update - although I'm not sure this is really the right place to do it.
(Kal, I'm anxiously awaiting your write up on DiracLive3 and your new subs.)
But, here goes...
From the earlier posts in this thread I upgraded speakers last year. I've never heard speakers sound so good. Simply stunning to go from Polk LSi9s to Revel Studio2s. That said, Amir and other's have talked about how much room treatments and digital room correction can make a significant difference. So I decided I should spend some time trying to figure out how much better can Studio2s really sound? I downloaded REW, went through Amir's first tutorials and started playing with it from there, reading, searching, running sweeps, moving things around, etc. Figure 1 shows a 1/24 smoothed SPL from one of my very early measurements. No treatments, no sub - just left and right channels.
Figure 1 - SPL for FL & FR Speakers from Initial REW Sweeps - Before Making Changes
So I ordered some 2'x4' Corning sound absorbing panels, and I also got a couple of packages of Rockwool Safe-n-Sound. I put the panels and rock wool at different locations in the room running many REW sweeps. Much to my dismay, there was very little observable changes to the SPL - sure, I'd get a 1dB shift here, a 0.5dB shift there, ... but no major corrections to the huge SPL nulls above.
In REW I discover the Room Sim button. The room is relatively large - think large square with a longer rectangle attached to it. Bar counter, covers half the back room, ... lots of asymmetry. but I put in the rectangular dimensions to see what I can learn. Neglecting the asymmetry we have 31'3" ~18Hz, 20'10" ~27Hz, 8'7" ~65Hz. Sadly 3*18Hz = 54Hz = 2*27Hz ... so the length and width modes are going to intersect on the 3rd and 2nd (6th and 4th, etc...) harmonic combinations. Because of the bar, one side of the room ends up a lot different from the other side of the room.
No, I haven't bought any bass traps (at least not yet). At this point I'm pretty disappointed as I've spent a fair amount of money on these sound absorbing panels which seem to have very little effect on the SPL. Yet, if I put the panels in some locations I seem to hear a difference in the sound, subtle, but it seems to be real. I have a friend come over, he can hear it too. Is it in our minds? I keep reading and poking around and find the ETC section of the REW docs. Figure 2 shows the ETC plots corresponding to the SPL measurements (of Figure 1).
Figure 2 - ETC for FL & FR Speakers from Initial REW Sweeps - Before Making Changes
Reading on I learn I can take the speed of sound (~1130ft/sec) multiplied by the x-axis time (in seconds) and figure out where the reflections are located. I quickly discover that the floor and ceiling are major contributors.
I end up making a lot of other changes - move speakers, move AV case, move TV, move primary seating position ... but this movements are all small (less than 2' ... sometimes just 6" or so). The goal here was to get a little more symmetric in the room & I found that at least one of the front speaker's SPL nulls improved (more on that later). Figure 3 shows the ETC after moving things around and strategic placement of the sound absorbing panels (ceiling & walls) and Rockwool (laying on the floor). Rockwool just laying on the floor isn't a final solution (my wife asked to confirm!) but it's cheap and is allowing me to experiment and see how good I can make things sound.
A little more detail on the ceiling placement. I did a little math and computed all the potential reflections starting from the top and bottom of the speakers to the top and bottom (heads, depending on chair & people height) of potential listening positions. I ended up hanging the ceiling panels at angles to either block early reflections (that reach the ceiling first but then hit the back of the panel) or deflect incident sound waves away from the listening positions. It worked extremely well. I measured the ETC at all nine locations (not shown) and the ceiling reflections (at -8dB & ~4.2ms in Figure 2) were squashed.
Figure 3 - ETC for FL & FR Speakers from REW Sweeps - After Making Room Changes & Placing Sound Absorbing Panels & Rockwool
That's a pretty significant reduction in reflections. Seems I was hearing the reduction in reflection energy, but not observing it (very much) in the SPL portion of the measurements. Okay, maybe I'm not faking myself out! Figure 4 shows the SPL (1/24 smoothing) after moving things around and getting the panels, Rockwool placed.
Figure 4 - SPL After Moving Things Around in the Room but No EQ. (Note 54Hz & 108Hz are where the long and wide room harmonics add up.)
Comparing Figure 4 to Figure 1 (and adjusting for the volume difference in the measurement) the severe null at 50Hz has been eliminated (due to speaker movement). While Figure 1 had ~26dB spread (84dB at ~80Hz - 58dB at ~100Hz), Figure 4 shows ~24dB spread (94dB at ~54Hz & 108Hz - 70dB at ~80Hz). The width and length room harmonics at 54Hz and 108Hz are profound.
It is now abundantly clear that I'm either going to need a lot of bass traps and or some sort of EQ. I really do not want to spend a lot more money at this point - certainly not on an unknown number of bass traps (with unknown effectiveness in my space). I'm not sure I want (I'm pretty sure my wife does not want) large triangles in the corners of the room, under the bar, etc... either. So, I download JRiver (free 90 day demo trial) and manually create filters to try and improve the SPL. Without too much effort I achieve a SPL improvement as shown in Figure 5 (1/24 smoothing).
Figure 5 - Manual EQ in JRiver (using same room setup, and measuring locations, as Figure 3)
Figure 5 (with manual EQ) was taken with the same volume settings and everything else as Figure 4 (no EQ). However different volume levels were used in Figure 1 previously, so things are shifted a bit. Yes, it worked. Yes, it sounded better. But the Studio2 speakers are supposed to be within +/-0.5dB from 31Hz to 18KHz - I'm not even close in this room as it is. I also know that just manually adding poles and zeros to adjust magnitude is messing with phase. So it still seems like it should be possible to make this better. Will it sounds better? If there is a sound improvement will it be worth it in time and money?
Earlier in this thread Kal indicated he is reviewing DiracLive3. (At the time I'm writing this I believe Kal's review is yet to be published). There was another recent post of someone experimenting with three other room correction, equalization, software techniques. (Sorry, tried to find it again to link and couldn't). In the comments someone asked about AudioLense and Acourate. So I started poking around and reading about those. The notion of being able to fix time domain and frequency domain measurements seemed to make sense as well. Furthermore, Audiolense will create a filter that can be directly plugged in to JRiver. This means I could try things out with my computer and hardware I already own (keeping my experimental costs down).
So I downloaded the Audiolense demo. I was able to verify I could get it working under Windows 10 running in Parallels on my Mac Book Pro. I was able to verify Audiolense was getting the same SPL results as REW. Audiolense will let you create a digital filter and process 90 seconds of a .wav file you give it. It creates a new .wav file (that's the first 90 seconds of your original .wav file) with the filter applied. I only have one album ripped as a .wav. Everything else is .m4a (Apple lossless), FLAC or DSD. I rationalized to myself that buying Audiolense was cheaper than a basstrap (or two) and bought a license. It really did not take too long (half a day) to get an initial digital filter configuration from Audiolense. I spent another day or two learning more about the various JRiver settings for playback (much of this before I bought the Audiolense SW license). The Audiolense help document was very helpful (I'm still learning though!) There was also a nice article (linked in the aforementioned post) on Audiolense - which I found very helpful:
https://audiophilestyle.com/ca/ca-a...nd-room-correction-software-walkthrough-r682/
The room is still set up as it was in Figures 4 & Figures 5. I changed the volume levels again though, so it's going to shift the SPL... After applying my first Audiolense digital filter I was able to get the SPL shown in Figure 6 (the corresponding ETC for this is actually Figure 3 above).
Figure 6 - SPL (1/24 smoothing) with Audiolense Digital Filter (and Sound Absorbing Panels on Ceiling/Walls, Rockwool on Floor)
Figure 6 shows just a 10dB spread (80dB at a few places - 68dB at ~170Hz) -- but most of the range only has a 6dB spread. Looking at the psychoacoustic smoothed result is shown in Figure 7.
Figure 7 - SPL (PSY smoothing) with Audiolense Digital Filter (and Sound Absorbing Panels on Ceiling/Walls, Rockwool on Floor).
Finally, let me touch on the time domain corrections. Figure 8 shows the impulse response after applying the Audiolense digital filter - this filter includes the use of the TTD (True Time Domain) correction capabilities. Compare this with Figure 9 which shows the impulse response of the original measurements (corresponding to the SPL of Figure 1 & ETC of Figure 2).
Figure 8 - Impulse Response with Audiolense Digital Filter and True Time Domain Corrections Applied (and Sound Absorbing Panels on Ceiling/Walls, Rockwool on Floor).
Figure 9 - Impulse Response for FL & FR Speakers from Initial REW Sweeps - Before Making Changes
So there is a pretty significant improvement in the measurements. I cannot do A/B testing as I have to stop JRiver to dis/en-able the filter. Subjectively it is hard to believe that my new Revel Studio2s could sound better than when I first brought them home; but there is definitely an improvement. I have a lot of DSDs in the Rock, Jazz & Classical genres. The sound improvement spans all genres - but my best Classical and Jazz recordings now really shine. So, I've convinced myself at this point I need to continue trying to treat/improve the room (within acceptable aesthetic requirements). I also need to learn a lot more about the Audiolense so I can extract more goodness out of it. Oh, and then I can do this for full 5.1 - cannot wait to get that done and listen to my favorite multichannel DSDs!
Hopefully this helps someone else along their journey. Thanks to Amir and the many others on this forum who have helped me along the way!