The first three things that I would do are the following:
#1: temporarily place something in the corners, behind the speakers to absorb some of the sound eminating out of the corner (a tall plant, hang a large beach towel, etc. nothing permanent). Listen for change, if none, remove for now.
#2: place something under the rear of the speaker to angle it downward (or adjust the spikes accordingly). Listen for a lowered soundstage. Then add #1 back and listen again. Then remove if not satisfied.
#3: Toe in the speakers more, so that the speakers are just aiming at each ear. Listen, then add #1 back into the mix, then add #2 back as well into the mix, then leave #2 and remove #1.
If none of these items reflect any improvement, you will liekly need to play around a bit with moving the speakers in smaller increments forward and back, side to side. The toe in should help taking care of side wall reflecting and the forward tilting of the speakers should take care or change the reflection of the floor. Also, you can play around with just angling the upper module as well, either in conjunction with the bass module changes, which may be necessary to optimize to your goals.
Do you have the 4 JRs filled with shot? If not, I would do that, it definately helps in other areas and tightens the bass. Perhaps you have an undefined bass response and your have a couple of room issues that further magnifies this at different heights.
Also, you are sitting virtually against the rear wall, based on your measurements. What happens if you move your seat forward, combined with a bit more toe in?
Thats a super narrow room.. And I would assume no matter what you do the Side walls and corners are within 18" of your speakers.. Its gonna be tuff, I got away with a room of the exact same dimensions but one foot wider at 12.5 feet opposed to the 11.5 and it was pretty tight, and the bottom of the barrel bass was not obtainable without a very Large "L" Type couch acting as a very big bass trap. Any room that small will benifit greatly from room and ceiling treatments of just about any type because you will have a ton of early reflections.
CKoffend: Thank you for the ideas. I've tried large towels in the ceiling corners, behind the speakers and between the wall corners. I couldn't honestly say I heard any improvements. I tried lifting the back of the speakers about an 1" with and without the towels I did not hear any improvement. Changing the toe-in to 4" with towels behind the speakers increased bass slightly but the bass I hear at standing head level is still much fuller and louder. I will continue to try other options.
Yes, the speakers are loaded with lead shot. My listening position is approximately 5'from the back wall.
Undertow: Our couch is pretty normal sized so no help there. I also have a problem of windows on one side of the room. I hope new blinds will help with that a little bit. What types of room treatments did you end up with in your room or did just the couch solve your problem.
It's very frustrating because I can hear the bass response I want, just not at my listening height.
The Big puffy couch can help a lot, or added big chairs.. However for the best case from what you explain some really good Wood vertical or horizontal blinds for some diffusion, and maybe heavy drapes for the windows as a dressing would help quite a bit too.. As for real treatments, tons of options but most affordable are gonna stick out like a sore thumb of your standard Foam studio types etc... to hang from the ceiling to help drop your soundstage and clean up the echo and reflection your experiencing.. Not sure but you don't mention your floor, if its hardwood or tile, or anything but a pretty thick carpet you would have some room here to got and get a good roll of carpeting about 9 feet wide by 15 ft or 12 ft long to put between the listening position and the center of the speakers, Helps a lot too depending on the situation.
Funny story, I used to have the same problem in a different house from where I now live. I noticed that when I stood up the music sounded better. So, being too lazy to stand and listen, I put my couch up on four kitchen chairs, hopped up and had a listen. I had to eat on the kitchen floor the rest of the time I lived in that house it sounded so good. Yes, I was single at the time so I didn't have to get approval from anyone and I didn't care that all my friends thought I was nuts. So if you have a dedicated room, the easy fix is prop up your couch and happy listening.
My room dimensions are almost similiar to yours at 11'x17'x8'. With your speakers on the short wall, it would be worthwhile to do something about the side walls. Forget about cables, they won't help even a bit before you successfully address room issues. You would need absorption panels on the side walls. Front and back walls can be a mix of either absorption or diffusion. I personally feel towels won't help much as absorption levels would be extremely low to hear an audible effect. As for bass issues, the usual recommendation would be bass traps.
Thanks everyone for your responses and ideas. I'll try to update with my progress.
Due to the high cost of room treatments I'm going to try the DIY route. There seems to be a lot of info out there. It'll take awhile to digest it all.
The idea with the towels, bunched up and hung was purely a temporary test, free! Also, the towels if bunched up with dampen the bass and all sound waves quite a bit - no, not as much as product specific solutions will. But it is free and will/should begin to show what some absorbtion will contribute to the phenomina he is experiencing. Short term - free testing only!
2 , 4inch abs. first reflections - side wall.
2 , bass traps rear corners.
2 , skyline diffusers on the ceiling - 1st ref. points.
Good point was made about window treatment, do that.
+ experiment with spks placement and listening position.
(sorry for any typo, i used my s.....t phone to wrighte it)
You may have success with 2-D type diffusors but I would think about diffusion after treating the room with as many bass traps as you can build.
If you want any chance of good frequency response, treat all 4 corners with bass traps (floor to ceiling if possible) and the ceiling/wall junctions if you want even more improvement, but at the very least all 4 corners.
Yes, the good thing about towels is that they are free short-term solution to test things out. Sorry about that CKoffend as I forgot to mention that.
There are many products out there and some of them are indeed quite costly. Actually, you can try out Auralex products as they are quite reasonably priced. There is another product you could consider -I normally don't recommend this for long-term use as most folks do not endorse it, but if you want to test things out the cheapest way, try this
either the 2"-3" wedges or pyramids. Ugly on its own but much more effective in absoprtion levels. For short-term testing only, much more effective than towels, not free but the cheapest.
For aesthetic reasons, these can be framed up and covered with acoustically-transparent fabric, but then again it would cost quite a bit.
Why not get a consultation from Rives Audio. That's what I did. It was well worth it...http://www.rivesaudio.com/services/servframe.html