Soundwave properties, looking for answers.

Stopping bass transmission is not easy.

I presume you share a wall with your neighbor. Mechanical transmission through the wall is one route. If you share a heating or cooling system with your neighbor, acoustic transmission through the heating or cooling ductwork is possible. Presumably your floors are pretty solid, but ceilings sometimes are not very solid, and permit bass energy to "leak" around over the wall.

Your idea of concrete corners may well improve the midbass and upper bass of your speakers, but I doubt it would have any significant effect on bass energy passing into your neighbor's living space. The bass energy will just go around the fake corners sort of like water flows around an obstacle.

To significantly reduce the transmission of bass energy requires first figuring out how it's getting into your neighbor's home, and then attacking those transmission routes. Assuming the wall is a significant one, you may have to build a double wall, such that the two walls are physically separated. That way vibration of your wall isn't mechanically tranmsitted to your neighbor's. You can use resiliant channels to hang sheetrock off of the wall on a flexible, bass-lossy support. You can make your own constrained layer damped sheetrock panels using a glue that stays soft - "Quietglue" is one such brand but I think some types of Liquid Nails will also work. Then you have to seal off passageways such as where the electirical outlets are, if you and your neighbor both have electrical outlets along the same wall. Expanding foam is one way.

You mentioned that the bass is poor in your listening position. That's probably an acoustical characteristic of your room, and will not be easy to change without major construction work. I suggest moving your listening position to where the bass is - probably up against a wall. If the mountain won't come to you, then you must go to the mountain.

Resources you might look at include the Rives Audio "Resources" page:

http://www.rivesaudio.com/resources/links/frame.html

In particular, look at the article on "Sound Isolation and Noise Control", here:

http://www.6moons.com/ramef/12.html

Also, you might consider the book "Premium Home Theater: Design and Construction" by Earl Geddes, which includes chapters on acoustics, noise control, room design, and room construction:

http://www.gedlee.com/Home_theatre.htm

I don't think there are quick, easy answers to what you are trying to do. Maybe Richard Bird will join in and prove me wrong. If you see a post later on in this thread by "Rives", pay attention to whatever it says. It is free advice from one of the leading experts in this field. It will be worth more than a hundred non-expert opinions, including my own.

Best of luck to you,

Duke

ps - the links look like they're all the same, but I tried them and they seem to work.

"...better yet to get the bass to reach me in my listening sweet spot and not the corners where I hear them much more than in my listening position"

The bass will always be strongest in the corners and near walls. The less leaky of bass -- i.e., the more solid -- your walls are, the more this will be true. Without pretending that I can suggest just what you should do and how you should do it, the general idea is to experiment with your listening position and speaker positioning to try and find another 'sweet spot' that has better overall bass response. Short of electronic equalization, repositioning is really the only way to improve weak perceived bass response. It's a common dilemma that best (strongest, most even) bass response is pretty frequently at odds with best imaging/soundstaging (as well as best midrange response) when trying to locate real speakers and real listeners within real rooms, where practical choices are often limited.