How do you know what room treatments to use?

This is one of those things where once you’ve done it, seen and heard, its easy - but until then it takes forever to explain. Owens Corning 703 acoustic panel is sold in a lot of hardware stores. A couple of the 1" thick sheets 2x3ft will be dirt cheap. This is almost exactly whats inside expensive GIK, they wrap in nice fabric with a frame and add a couple zeroes to the price.

Try the raw sheets in different locations in your room. Side walls at first reflection and ceiling corners are great places to try. With full sheets the effect will be obvious, and probably too much, which is why you experiment. Its very light weight, can be held temporarily with pins, just great stuff.

Your experiments with the raw sheets might look something like this. https://www.theanalogdept.com/c_miller.htm

Then when you figure it out you can cut them the size you want and cover with fabric and be done. It might look something like this. https://systems.audiogon.com/systems/8367

Or you might find your problem is something else. Or you might decide to go with GIK. Either way you will learn a lot and have a whole lot better idea what is going on than to just buy GIK on pure faith.

You should also strongly consider Synergistic Research HFT. These go way beyond any conventional panel type treatments and will get you 3D clarity no amount of acoustic panels can touch. 

Mike, I think most of the companies that sell room treatments will tell you that accurate diagnostics of acoustical problems is highly dependent upon measurement.  In the absence of measurement, about all they can do is sell you a treatment package and make suggestions about placement.  Sometimes that is enough to fix the issue.  How lucky do you feel?  Downloading the free REW software and learning to use it, if you haven't already done so, will greatly facilitate getting your room problems mitigated.  There is a learning curve, but not one that is insurmountable. 

Each situation is somewhat different.  Do you perceive the problems to be more high frequency issues or low frequency?  High frequency problems are usually not hard to fix.  Slap echo is common in rooms that have uncarpeted floors and plaster or drywall ceilings, and the lower the ceiling, the worse the problem.   Adding area rugs can be an attractive solution or at least partial mitigation for that problem.  Also, parallel side walls that are untreated can be offenders.  There are companies including GIK that offer artwork backed by fiberglass absorption.   Again, this can be an attractive solution for slap echo. 

Slap echo and/or a frequency response that is elevated in the high frequencies can make you want to turn the music down in a hurry.   In my own room, I'm still working on the high frequency problems.   Things sound pretty decent until average dB levels get up above 83 or so, then I start wanting to turn things down for a more relaxed and natural sound.   My room isn't carpeted, I have 8' drywall ceilings, and I have relatively little absorbent furniture.  I also have a lot of low frequency absorption intended to mitigate some pretty serious low frequency ringing.  By the time I got the low frequencies straightened out,  my overall frequency response was tilted up in the high frequencies. 

Another important question-- How much latitude do you have in placement of speakers and main listening position?  Those are the most important levers you have for dealing with low frequency problems.  You can do far more with placement modifications than you will ever accomplish with treatment.  Low frequency issues are hard to treat.  This is especially true if you are not in a dedicated audio room.  Low frequency absorbers aren't, to my knowledge, available in designs that look at home in a typical living room. 

I chose to go with DSP in my living room in order to ensure domestic tranquility.  But personally, I wouldn't want to introduce DSP into a high end system. 


  

Ditto the GIK suggestion.

Go to Youtube, search Acoustic Fields and start learning.

@ FALCONQUEST, +1