SBIR placement and image depth?

tony22

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Nov 4, 2019
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Now that my room treatments are more or less complete (with analysis and assistance from GIK), I’ve been moving my speakers around based on a few things - what I’m hearing, what I’m seeing via REW measurements, and (to a smaller degree because I dont know how good it is) REW’s own simulation feature. Trying to find the spot that locks things together the best I can get.

I’d been reading a bit about the SBIR phenomenon and placement recommendations based on this, in part to tame an aggressive 38Hz peak in my room. Sure enough the simulator shows that with close placement to the front wall, and the commensurate seating position, the peak is effectively (along with other bumps and dips in the low end) dealt with. So I figured I’d give it a go. The surprise I got (apart from what did seem like a smoother low end) was a complete collapse of front to back staging, plus a smaller but still noticeable shrinking of soundstage width.

Have others trying SBIR placement experienced this? My speakers do have rear ambient tweeters, so that may be a factor - but I don’t think so, as when the speakers are further into the room the stage depth is just fine (albeit different) with or without the rears active. I guess I’m wondering if SBIR placement is really better suited to a recording studio situation, where it seems to be the focus of a number of sites that talk about this approach, over a home listening room.
 

sbnx

Well-Known Member
Mar 28, 2017
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Hello,

If you are looking to use SBIR to get rid of a peak at 38Hz then either your speakers need to be about 7 feet from the front wall or your head needs to e about 7 feet from the rear wall.

How long is your room?
 

Al M.

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Sep 10, 2013
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Greater Boston
May I ask what is SBIR?
 

sbnx

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Mar 28, 2017
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Speaker Boundary Interference Response. Originally called the Allison effect. It causes nulls and peaks in the frequecny response as the sound bounced off the wall at 1/4 wavelength intervals.
 

Al M.

VIP/Donor
Sep 10, 2013
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Greater Boston
Speaker Boundary Interference Response. Originally called the Allison effect. It causes nulls and peaks in the frequecny response as the sound bounced off the wall at 1/4 wavelength intervals.

Ok, thanks.
 

tony22

Well-Known Member
Nov 4, 2019
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Hello,

If you are looking to use SBIR to get rid of a peak at 38Hz then either your speakers need to be about 7 feet from the front wall or your head needs to e about 7 feet from the rear wall.

How long is your room?
Yes, you are correct. If I place the speakers very close to the front wall, I’d be sitting at the 7’10” mark from the rear wall. Theoretically I could do the opposite, but I’ve listened against the rear wall in enough rooms over the years to drop that from consideration. Given the two “best” options for the SBIR scenario, it seems neither one is really great for my 14x16 room. But I was hoping to see if this flattening of the soundstage was heard by anyone else trying this.
 

sbnx

Well-Known Member
Mar 28, 2017
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Yes, if you shove the speakers up against the wall you will get a flat soundstage.
 

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