Acoustic treatment for corners.

Has anyone acoustically treated a corner, so that it is identical to an open area? If so, what did you use?
If you mean that it will have the same acoustic properties as an open wall/corner, down to DC, no or not without Herculean measures.

Corners are notorious for bass reflections. Treat these areas and your bass response will improve.
Indeed. Corner treatment is effective and important.

Mmakshak, I have found corner traps to be very effective in my room. They are especially important where the walls are heavy and rigid (e.g., concrete blocks) and the bass reflects off the walls and the energy keeps reflecting around the room. A good corner trap makes the corner appear to be the same as if it were open to the outside or another larger room. It does not reduce the bass, but only the build up of modes.

Here is a link to a DIY article on how to build such traps simply and inexpensively. I chose the Super Traps which are described in Part II and made them with Thermafiber Safing Insulation which is available in local building supply houses. I recommend you buy the insulation and cut it into triangles as described and stack them in the corners to see if you like the change. You can try more or less at different heights. Then if you like the way it works, you can procede to build the front screens which are also quite simple.

See my system for pictures of the finished product. The total cost of both traps was under $150.
I have corner tunes in my downstairs listening room, and these are one tweek that you can really immediately hear a difference in sound quality, and that difference is an improvement.. Recommended...
I admire your electrical handywork Zargon. It has given me some ideas for my own implications.
Thanks, Vandermeulen. For me, everything starts with effective power conditioning and proper attention to the room and acoustics. Together, they set the foundation for evaluating, selecting and assembling a system to my taste.
Thanks for the ideas. I have two ASC tube traps and a pair of Cathedral Sound Panels in the corner. If you look at Zargon's back wall(minus the bookcase), that is what is behind my speakers-the corner and the open doorway. It seems like the image(or some treble)is pulled more to the open side, or goes further to the open side than the corner side. There is more open space on the doorway side. There is also slightly more distance to the first reflection on the doorway side than to the corner side(I'm afraid I can't do much about that.).

If the doorway has a door, you might try closing it. I assume not from your posts.

You might also try toeing the speakers in slightly to minimize the uneven reflections off the sidewalls.

Another suggestion is to add diffusion at the reflection point on the sidewalls. This better distributes the reflection and will help with the imbalance.
I put 4 record cubes im each corner I feel that it helps some. It at least breaks up the waves and is 5 foot high full of records. Mike
So the differences between an open area and a more closed area with a corner might be due to bass differences and maybe first reflection?
Consider a door or window the perfect bass trap and if your corner has a door or window then open it and you'll then have the "identical to an open area" which you seek.

For the rest of us, bass traps and usually lots of them if they are of the resistive kind are the necessity. Diaphragmatic traps will take up much less footprint and most people incorrectly set up their resistive bass traps so as not to work at peak efficiency. They need to be pulled away from the wall equal to one-quarter the wavelength of the transition zone (i.e. Schroeder frequency) which is usually 300-500Hz and extend into the room as far as you can to work below this transition zone frequency. Get a hold of Dr Floyd Toole's latest book and it'll set you straight.
Wow! What a room, Kevinzoe. Without doing the work, what would that mean in inches, for say an ASC tube trap in a corner. I gather that it would be pulled out less than 7.5 inches? Do Cathedral Sound Panels act as a Diaphragmatic bass trap? In my case, the problem corner(closed area) has about 3 feet of wall before it hits a sliding glass door. There is a little bit of improvement with the glass door open.
Thanks Wmakshak. If you plan on putting a resistive-type bass trap which I believe ASC are (but I could be wrong) then the maximize its effectiveness it would need to out from the wall 1/4 the wavelength of the transition zone frequency which could range from 500Hz for a smallish room to 200Hz for a larger domestic room. Below is some handy info:

Hz 1/4 wavelength (")
500 6.8
400 8.5
300 11.3
250 13.6
200 17

Note: a door (even a closed one) or wall of different construction type as the other walls could impact these theoretical distances. In my room I have a door at one end of the room so the "acoustical length" appears longer than the actual room length. A test tone disk and SPL meter will help detect which distance is best at reducing a peak bass mode.

Keep in mind that these are the starting points and that absorption should extend further INTO the room to affect lower frequencies. Clearly you need a good deal of real estate or a very tolerent significant-other.

Regarding Cathedral Sound Panels, I'm not familiar with them and their website is a bit sketchy on how they're made other than they're 2" thick. 2" may be sufficient for a true membrane trap but clearly not thick enough for a resistive bass trap. RPG makes membrane traps but they're costly.