[nodiak]

One thing I've always done with any OB I've tried is to listen to it "raw" as well as listened for changes that occur with material draped over the back of the baffle/drivers. I do this as an empirical method of learning about the interaction of room reflections and the ob system. I've had ob's in two very different rooms (24' x 30' x 12', and 11.5' x 26.5' x 7.5' ) and learn alot by doing this "tuning"/treatment. 
Also by using a thick material (and then removing it) I can get a quick lesson/reminder of what the new ob system, and it's backwave, is doing in the room. I think it may help me judge how much and where to put absorption/diffusion on the walls (to season the system to my tastes).
I guess if defined it could be on a scale of Open Baffle toward an Aperiodic cabinet. At least that's the way I unscientifically consider it. But mostly I just do it and listen.
Some things I use are thin flannel, layers of fiberfill, and thick carpet padding. Sometimes enclosing the drivers, sometimes leaving areas open.
The thinner materials of course effect the openness of the ob sound the least, and certain combos of drivers, distance to walls, light material and how it's draped have worked out to sound better than the raw ob...sometimes. This helps point out the particular rooms treatment needs, as well as give ideas for speaker position changes.
Like most I enjoy trying different drivers and baffles, and am at times trying different sources, pres and amps as well. This method can be helpful for tuning the equipment to the room for me.
Time willing (the biggest factor) I may build an ob panel with framed sides and back for easier experimenting.
Probably the most important thing that this experimenting has taught me is the importance of treating the room. And with OB's this should involve some different considerations than a boxed speaker system. So my next endeavor is just that, to focus on treating the room.
I know this idea may sound like a challenge to some of the ob tribe as anything but a raw ob isn't ob ("open back"), but I'm doing it for the music. I'm not religious about ob's, even though I prefer them I still work with other types of speakers. Ultimately the goal is to use an ob without backing, and have the room treated to help that aim.
This may be helpful, or at least interesting to others. I'm sure as always it works for some and not others...or maybe just doesn't fit their philosophy. (Did I cover all the bases ?!)
Again, for the most part this has been a great example of the value of room treatments, and that's what I'm going to work on next.
 
Viva la musica!

Don

[Bob in St. Louis]

Probably the most important thing that this experimenting has taught me is the importance of treating the room. And with OB's this should involve some different considerations than a boxed speaker system.

Thanks for posting that Don.
I've been kicking around the idea of posing a question regarding room treatments for an OB set-up.
I assume rear wall would be the same as any system.
Side walls, I could see being different??
Front wall treatments for OB baffle me (sorry, bad joke).
I can see the front wall being totally different with OB.

I've not experimented yet. (Just got the Augie's yesterday) When all speakers are operational, I'll play with treatments.
I'd like to hear others opinions too Don.  {bpape? aa}

Bob

[nodiak]

Bob, The other thought was to place different diffusers around the back of the ob speakers. Again to deal with manipulating the rear wave to work with the room.
I linkied to this thread on the Acoustic Circle. Maybe some of them have ob experience or ideas. Would be great to have their input.

[Bob in St. Louis]

It would be nice to hear from 'the treatment pros'.
Realising of course that only general rules of thumb would apply for everyone since no two rooms are the same.
The mystical land of controlling waves has baffled me (bad pun), but throwing OB in the equation makes it even more bizarre since that wall is supposed to be your friend.
In my mind I'm thinking, "Wouldn't you want a wall that tends to be more reflective so the wave bounces, and comes back to you as opposed to an absorptive wall that 'sucks up' your wave?"

I've yet to build any form of treatment panels to play with. A very knowledgeable gentileman in the industry shot down all my 'el cheapo' ideas for room treatments by saying, "you'll be treating such a small HZ band that you'd be wasting your time."

I've actually thought about bringing in the patio furniture cushions and using them for experiments.

Bob

I suppose what I'm looking for are genreal rules of thumb for OB applications so I don't waste a bunch of time, and confusing myself.

[nodiak]

I first started putting fleece blankets behind baffles that were close (30 inches or less) to the front wall by neccessity. The point was to delay and diminish the rear wave to give a nice ambience instead of an overwhelming one.
It's about balance to me, definitely wouldn't want to completely absorb the rearwave and lose the atmosphere ob's provide. Just dial it in to where your senses say "just right".
Amount of reflection  vs. absorption to me is a matter of taste, but in certain rooms it it seems the echoes need dealt with first.
After 4 corner bass traps my thought is to make 2 absorption panels and 2 diffusion ones (each ~ 36" x 36") and try them in different spots around the room. I definitely look to others for their advice and experience but in the end I'm my own authority on what sounds good (sorry Bob, my first post may have come off insulting, hope this edit's an improvement).

[Bob in St. Louis]

(sorry Bob, my first post may have come off insulting, hope this edit's an improvement).

  It's all good man...You've just about got to call me a four letter word before I take offence.
If I ever think someone "has a 'tude" with me, I'll ask. I'm not the type to get bent out of shape easily.

The idea of building your 2 absorption panels and 2 diffusion panels is a good one. However I've got very limited funds, and time, ... bla bla bla to buy materials and build something until I get some reassurance from somebody smarter than me that I'm doing the right thing.
My reasons for this 'state of mind' are due to the fact that I build a HT room (4 year project) before I knew diddly about audio/video. Since, I've found this wonderful thing called the internet. It's full of smart people that have shown me the error in my ways. (Imaging telling your wife that all that money spent was done wrong. 

So now, I tend to be more cautious. Know what I mean.

Bob

[hurdy_gurdyman]

Hey nodiak,

I'm interested in hearing about your bass traps and how they are doing. I'm considering a pair in the corners behind my OB's, and then maybe some bookshelves coming off them along the walls for deflection. I'd like to hear about how these bass traps are working out for OB's from any who have tried it.

Dave

[nodiak]

Hi Dave, I'm working on them and have started a thread - "Closet for bass traps" in acoustic forum. Those are rear corner closets. For front corners I'll go full height and either stradle the corners (unless I don't like the angled look) or make 2 panels put together in a rectangular column (~ 12"w x 16"d).
I found this cotton "Quiet Batt", made for in wall insulation. I'm not sure if it's too dense to work and am asking in Acoustic forum thread. If they get the ok that'd be great as the cost would be under $50 a trap I think, which would be good imo.
I'll try diffusion and absorption on the trap faces and next to them to see what works. All that is ob placement, room and taste dependent I would think. Bookshelves sound like a good idea. I have hanging plants and plant shelves to help break things up.
Don