Room Too Dead

I selected the right product to tame about 90-100 hz and covered with a gauzy, decorative fabric.  .  So yes, insulation can absorb lows if it's what the sound reflects from. 

That’s just mid bass and not what I’d consider “lows.”  The worst bass issues typically occur well below 90Hz — think bass guitar, drums, cello, tuba, lower piano registers, etc.  Around 100Hz you’re looking at things like the lower regions of the electric guitar, tenor sax, male vocals, etc. that don’t tend to cause major issues in most rooms.  Absorptive panels can’t do anything to deal with the lower bass issues that frequently plague listening rooms.

Simple answer:

Diffusers.

My room was too dead to start with with too many absorbers. Adding diffusers at first reflection points made a major difference. Then I kept adding more on back wall and back of sidewalls.

If you had vintage speakers, they would have brilliance (tweeters) and presence (mid driver) level controls, adjustments would perk the frequencies to your liking. They were made because they might end up in a live room, or a dead room, and your particular preferences.

Alas, most modern speakers do not provide level controls

I would start, perhaps finish with a multi-band equalizer

here's an inexpensive rockville 21 band from Amazon (try it, anything can be returned) (they make a 32 band, but enough is enough)

https://www.amazon.com/Rockville-REQ42-B-Equalizer-Spectrum-Analyzer/dp/B00LZDSL7U/ref=asc_df_B00LZDSL7U/?tag=hyprod-20&linkCode=df0&hvadid=312069187648&hvpos=&hvnetw=g&hvrand=13668772867094839483&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9003512&hvtargid=pla-570384384433&th=1

You will learn about your room, specifically what's missing, what boost/cut makes the biggest difference at your listening positions.

For home theater, if the equalizer makes the system sound darn good, I would be done. 

@rael1313 

Unless experimenting with different methods of controlling your room is part of the fun for you I wound highly recommend consulting an acoustician for the best results   There are members here who have spent years trying to dial in their rooms which is something I wouldn’t like to do. Jeff at hdacoustics is very good and his pricing is very reasonable. Good luck! 

I think you may have a complicated issue. It’s not just too dead, it’s got a mid-range suckout. I have heard this in rooms with too many Tube Traps.  It happens when the absorbers perform too well in some bands but not as well in others.

Your problem may be that you aren’t taking out enough of the high end, so the room sounds too bright, and lacking in midrange only by comparison.

You may actually need to add better absorbers in the high end.

Diffusors are a good idea, generally speaking. placed behind and directly tot he sides of speakers they can really enhance imaging. One thing you can do is to try to create a quasi diffused pattern by removing some of the curtains you are using, at random intervals, with more removed towards the back than the front.

If you have any sort of tone control you can test this by reducing the treble to see if you find hte tonal balance more to your liking.

Measurements are good, but IMHO really hard to interpret for this type of issue.