Doubting Sound Treatment ?


3 years ago I purchased an 11 piece Kit from a reputable company. I noticed improvements, but wasn’t instantly blown away. Now 3 years later I took it all down for a home move. Bass definition noticeably less. Instrument placement less good. Overall coherence less. Not a as intimate. Far less enjoyable, simply put. If your on the fence, get past it. Better improvements with the treatment than most of us hope for when we change Preamp, Amp, or Speakers. Doubt no more !
Cheers ! 
fact33
Thought I'd add my two cents to the discussion.
There's no doubt in my mind that acoustical treatment can make a world of difference that both the ears and eyes can detect (from pre and post measurement graphs).  Best start with some education I found.  I have examples in my systems of reflective baffles, diffusion (QRD and Skylines) and absorption.  Below are some of my learnings:

Measurements first: You can't manage what you can't measure plays a role here. At the very least measure frequency response (ideally a flat response is better) and reverb time (to avoid over dampening the room with things that absorb too much sound). I use Dayton Audio OmniMic which allows me to see the troubling frequencies so speaker placement and acoustic treatment placement experimentation can begin and note its affect. Often solving one problem frequency creates a new problem so it'll take patience to try and optimize speaker and acoustical treatment placement.

Treatment strategy: for most domestic sized rooms absorption of low frequencies and reflection and or diffusion of mid to high frequencies works well. This avoids over dampening. The transition frequency range for most home rooms where sound waves transition to "beams" due to smaller wavelengths is about 300-500Hz so you'll need bass traps to work below this range and diffusion to work above it.

Thickness matters: Too often manufacturers sell absorbers and diffusers that are too thin. And the reason you want them thick (at least 6") is so they don't act like a low-pass filter and only operate on some of the frequencies hitting it. You want the absorber or diffuser to work as broadband as possible so as not to skew the frequency range of its reflections and reflections of those reflections. For a diffuser, the depth of its slots or wells (for a QRD or Skyline type) determines its lowest frequency, so for example a 6.75" depth will work down to 500Hz as it is one-quarter of a 500Hz wavelength.

Sitting distance from treatments: Normally you can sit much closer to an absorber than a diffuser which needs more space for the scattering to occur so the sound coalesces by the time you hear it. If you need to be close to a diffuser - say on the ceiling or side walls which are near your listening position - then choose a 2-dimensional one (diffuses both horizontally and vertically) so that only about half of the reflections are coming your way.

@jdeickhoff, I’m currently planning for an Acoustic-Fields-designed, dedicated listening room to be added onto the back of my 2-car garage, building to begin in a month or so. My GC will be looking at how much it will cost me to frame the room, as Dennis suggests, in 2"x12" instead of 2"x4" - that to allow the needed depth for the in-wall carbon filters (100 Hz down to 30 Hz). When I get a fixed idea for that part of the budget, Dennis will run the dimensions for me and can tell me how many filters of what type I will need and where in the walls they will need to go to. 

I will finish out the inside myself using 3/4", finish-grade plywood. (Dennis tells me that, sound-wise, drywall is, like, the spawn of satan). The room will end up being medium-sized, but it should be well controlled by the time I’m through with it. I will be building the carbon filters, a few foam absorbers and a few quadratic diffusers myself from his plans, so I will need to buy a good table saw and teach myself the hows ($500). The filters and all can be built for $2-4k, depending on how many Dennis tells me I’ll need. The pricey part will be for the framing aspect of the construction, but nearly all of it will be paid for with the equity in my home. So, I’m currently looking at just the materials cost and some time...unless my GC comes back with a truly budget-busting number...keeping my fingers crossed for now.
@ivan_nosnibor, it sounds like you have quite the project on your hands!  But it also sounds like you have a good plan and the proper guidance. I wish you all the best for the desired outcome. I would be interested to see/hear how your progress is coming along. 
Thanks @jdeickhoff. Yes, it is definitely going to be a hatful. Originally I thought I would post the whole thing after it was done, but now I think it would be too much to try to explain in retrospect, so I may post it, pics and all, in one place somewhere, after construction starts and provide updates as I go.