Obstacles between subwoofers

[fabiocz]

I was researching the Internet about subwoofer placements and one detail no one talks about just caught my eye:

Between one subwoofer and another, is it better to have or not have an obstacle between them?
- No obstacles will be canceled because both emit sound waves that are in the middle?
- With obstacles will be better or worse?

Note:
For those who use REW or RTA is simple to analyze this, but for those who do not have, what would be the indication?

Image for better copreension.

 

[j_garcia]

Placement relative to the room will affect it more than whether is open or not. It WILL have an effect, but bass frequencies are so much longer than the length of the room that I would not worry about it. Nobody talks about it because it isn't that big of a deal.

 

[ryanosaur]

The less stuff on your front wall, the better for your other speakers. Diffraction effects will affect the Center channel the most. Also, sometimes the front wall and corner loading can be the worst placement for your subs. You should experiment with placing them strategically away from your mains; asymmetric placement per Geddes is most ideal, IMO. Cheers!

 

[fabiocz]

Placement relative to the room will affect it more than whether is open or not. It WILL have an effect, but bass frequencies are so much longer than the length of the room that I would not worry about it. Nobody talks about it because it isn't that big of a deal.

it's good to hear it
But in general.. which of the two modes would be the most correct way ?

The less stuff on your front wall, the better for your other speakers. Diffraction effects will affect the Center channel the most. Also, sometimes the front wall and corner loading can be the worst placement for your subs. You should experiment with placing them strategically away from your mains; asymmetric placement per Geddes is most ideal, IMO. Cheers!

That's what I thought, I think the less hurdles between one subwoofer and another, the better the results should be, but I'm still wondering if this would cause cancellations between them = /

Note:
I'm talking generalized, of course each case will be a case.

 

[ryanosaur]

That's what I thought, I think the less hurdles between one subwoofer and another, the better the results should be, but I'm still wondering if this would cause cancellations between them = /

No. You are misunderstanding. The low frequency waves are omni-directional. They don't care what is in your room. (For example, this is why down-firing subs still exist: they work just fine aimed at the floor. I've heard of another guy that turned one of his subs to fire straight into a wall...) Diffraction is much more of a concern for your Center: Mid-Woofers and Tweeters are going to be affected much more significantly.
Your concern with Subwoofers should be at learning about your room resonances, and the Modes you will have to work with. Placing your subs next to a tower that is generating some lower frequencies is more likely to create a cancelation. Having your subs equally spaced so that the soundwaves bounce back and interact with each other can be just as destructive. The idea of spreading multiple subs around is to excite as many of those room modes as possible, thus evening out the bass response throughout more of the room.
Multiple Subwoofer after Geddes
http://seriousaudioblog.blogspot.com/2012/05/two-great-articles-on-multiple.html
You don't have to do this to get good results, however, I have found in my room, the front wall with almost full-range towers, and corner loading to be pointless. I used the subwoofer crawl to find good placement location, then I put my subs there and tweeked them slightly. I have not done much in the way of room measuring since, but my Bass is much better than by the more traditional/dogmatic approaches.

So to answer your repeated question. Neither of those is necessarily correct. Without measurements to show how they perform, its just a photo. I would not pattern my room after those.