Room treaments

Yes. To my mind you are right on track. What are the dimensions of your room and system. But in general sounds perfect. Do one at a time if you completely know the sound of your system.

Make sure you listen before the addition of the (Ownes Corning 703?) panels, and after. Don't overdo it as it's possible to overdamp the space and suck the life from the music. Never use acoustic foam.

What type of speakers, size of room? Diffraction might be better at first reflection or nothing at all. 

Each room is different so IMO it's best to experiment a little first (location & type) before properly securing the room treatments in place. Also, noromance is spot on about using absorption type panels... A little can go a long way. I use a combination of diffusion/absorption on the side walls & behind (between) the speakers. Absorption on the ceiling & some behind me. Floor is slate with a leather rug between the speakers.

The room is so important to overall sound quality.

Have fun with it, it's certainly a learning experience.  

My room is 12 wide by 18 long and ceiling is fairly low at just under 7 foot
I built the room specifically for my 2 channel system .
I have Salk Sound SS-6M 2 way monitors with all YBA solid state seperates
I will play around with absorption and difraction/ diffusion.
I made the diy 2 by 4 sound panels and will play around with placement but I was thinking more absorption at first relation points rather than diffusion.
On the back wall behind my listening chair I ideally want both absorption and difraction so I might experiment with some DIY diffusers and maybe a home brew quadratic diffuser. I have seen a few designs on you tube that I might try.
But as far as corner treatment I haven't given that much thought. All the bass traps I have seen take up a lot of re estate. 
I guess it is a fine line between a lively room and a sonically dead room.
I appreciate the advice 

I have a theater room your size.  I added 4x8 wall panels from 4seating.com.  I have plush carpet on the floor and nothing on the ceilings.  Believe it or not it is almost to much.  It is great for the theater room but not for a two channel room.
I just added cinema round panels from Vicoustic Acoustics in my very large great room where my two channel area is.  My room is 25'w by 40'L with 16' ceilings.  Just adding 4 2'x8' cinema round panels helped my room substantially.  Vicoustic provided a whole analsis of my room after providing them a video.  I have used GIK and Audiomute.  With your low ceilings, I don't think you will need that much.  Do it in stages....see how it sounds.  

Reach out to GIK Acoustics for one on one free consultation. Once they make their recommendations, do it in stages. I did my room in three phases! 

I love GIK.


From what I’m reading I suggest the following: More diffusion and don’t ignore the floor between/behind the speakers. Lot of hash lives there.

Do bass traps carefully. You can overdamp, leaving you with a lean system, but smoothing out the response is critical to a good system. If you can measure as you go you’ll be in a better place.

If you have no bass resonances, or well controlled one's you are done.

Best,

Erik

GIK is excellent, but I'm using Vicoustic now. Check them out before making your decision. https://vicoustic.com

The ' corner bass traps ' floor to ceiling may introduce issues in terms of balance.
Tackling 20 - 200 Hz will be the most difficult but a relatively low reduction in level should be smooth enough.
Absorption behind the ' mains ' should help a bit as well.
My sense of a rooms ' sound ' tells me that diffusion on the side walls could be a better solution than absorption.
Even absorption on one side and diffusion on the opposite wall at first reflection points - ' A Symmetric ' could be effective.

@fiesta75,

I have explored vicoustic and my experience with them was not good. They rely on dealer network, so you’re dealing with a middle man who may or may not be a subject matter expert. Whereas GIK is direct sales and you are consulting with their in-house room designers. That alone to me is a biggest differentiator! With GIK, you can count on a solid advise, no more guess work on your part.

OK, here we go again....

Go to "At Home," "Hobby Lobby" or other discount home dec store and buy a dozen or more 6' - 8' tall artificial Ficus trees.  Scatter them wall-to-wall between the speakers and the wall behind the speakers.  Then place a tree on each side at the first reflection point.  Place the remaining trees between the listening position and wall behind the listening position.  

Artificial Ficus trees both absorb and diffuse the sound waves.  And they are visually appealing.  No need to spend a lot on small panels in specific locations.  These artificials cost between $40 and $50 each.  So a dozen of them are the same cost as only a few sound absorbing panels and in my opinion are more effective.

My room size is 14' x 24' and slightly irregular ceiling height between 7' 8" and 8' 10".

Diffusion at first reflection points . Absorption behind listening position.

Good luck, 
Jose