# best way to even out subs for all seating



## pietsch288 (Sep 10, 2006)

background time.......I have 4 svs cs ultras running off of 1 ep2500, two dead center of the front wall and two dead center of the back wall. But I was thinking of moving the subs so 1 sub would be dead center of all 4 of the walls (front-back-each side). I all ready have a second ep2500 so each sub can have its own channel but I am assuming that I will need to adjust phase for each sub individually. The frond and back subs are opposite polarity so I've been reversing them on the amp (works perfectely) but if I move two of them to side subs I assume I would need to do some adjusting. First of all is it worth the extra money to have 1 sub dead center of all 4 walls or is it just as good having them center of the front and back walls??? I do have a front couch and a back couch so my thinking is that by moving a sub to the center of all 4 walls the bass will be more even between the two couch's:huh:. The difference between REW graph's are almost upsetting between the two couch's :teeth:so I would like to even out the bass for both couch's if at all possible, thanks rich


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## thewire (Jun 28, 2007)

I have a subwoofer sitting directly between and behind my back row now. The rear sub fires between the back row seats. This corrects some problems I was having using my corners previously. No matter if I ran my subs in the corners in-phase..










or out-of-phase.. (these two were without eq)










for my front row and back row, they would never match. The only way I could get them to match was to average the results and eq them both the same, but that resulted in problems related to levels with the other speakers somehow. Now the back row with a sub at each walls midpoints (green)..








still has dips and there is seemingly the bass coming from the front of the room, while the sound can be a bit more felt than heard the way I have my sub on the riser back there. It is difficult to feel bass from the side walls midpoints subs at each seat, and the front of the room I must postion my sub within a half inch equal distance between my mains or the bass is more to one direction.

I have not tried adjusting the back row subwoofer much, or adding more isolation to the subwoofer yet. I think it sounds much smoother than when I had also tried two in the front, and two in the back, which made those peaks and dips shown more different than having my subs in the corners.


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## pietsch288 (Sep 10, 2006)

So I'm a little confused......you have two dead center of the back wall and one sub inches away from each main????? Inside or outside of the main???? Do you have the back subs ON THE RISER??


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## thewire (Jun 28, 2007)

pietsch288 said:


> So I'm a little confused......you have two dead center of the back wall and one sub inches away from each main????? Inside or outside of the main???? Do you have the back subs ON THE RISER??


My room continues to undergo some changes. I was saying simply that it may be important that the sub up front be centered between the mains for proper phase since it is ported. I probobly need to place my center sub vertical again so that the ports at the rear are firing centered between the mains as well, but I was busy on my stage. The other subs currently sit on the riser or older speaker platforms (homemade stands) with concrete/fabric/subdude's. The measurements earlier were before the isolation and the holes in my front stage.







It sounds good in the back row, and bass timing is actually sounding in sync with the front mains, at least for music that I heard so far. I still could use some more absorption on my back wall I think, but that's another subject.


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## pietsch288 (Sep 10, 2006)

Do the back subs give a buttkicker type feel being on the riser???? Or are the back subs "on a riser" meaning not coupled with the back couch's riser.


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## thewire (Jun 28, 2007)

pietsch288 said:


> Do the back subs give a buttkicker type feel being on the riser???? Or are the back subs "on a riser" meaning not coupled with the back couch's riser.


 Not sure as I have not watched a movie in those seats, and I am also not sure what qualifies as Buttkicker type feel but if by meaning transducers, I think that I may have noticed some slight tactile response. The tactile type response did not increase as the sound appeared to go deeper in frequency.:dunno:

My riser is not decoupled from the sub. That's why I'm using the layer of concrete with the pair of subdude's for the sub on it. The entire mass extends to the back walls room treatmetent, and it is directly attached to the concrete bellow. There seemed to be the most bass felt when standing in the center area of the room, probobly some in the 30Hz - 35Hz area where my subs begin to roll-off and the subs at the side of the room begin to match even with the front and back rooms subs. The further they are from walls that are shorter, the less gain there is. Placing them at the walls midpoints results in less gain.


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## pietsch288 (Sep 10, 2006)

"the wire wrote" Placing them at the walls midpoints results in less gain.


But does the whole room have the same amount????


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## thewire (Jun 28, 2007)

pietsch288 said:


> "the wire wrote" Placing them at the walls midpoints results in less gain.
> 
> 
> But does the whole room have the same amount????


When I play the limited bandwidth pink noise to calibrate the subwoofer level it sounds like the gain is fairly even. There is a slight rumble from the front center of the room where the mains also get some of the signal. I use all my subs gain matched, which means they are set to the same gain on each sub.

The best way to determine whether each seat is resulting in the same combined total output of each sub is to measure. Instead of adjusting the gain on each sub to match, you might also adjust the seating locations or the positions of the subwoofers. Listening to some sweeps that transition from the mains to the subwoofers you should be able to also tell if it a smooth sounding intergration between them. There could be some contributions by the room itself that may result in more gain at one location than to the next. Room treatments can help smooth out the dips or peaks caused by the room, and equalization can help to control them.

Each walls midpoint may not be the best option, and it is not always an option to consider due to placement with seating and furniture being in the way. Each walls midpoint in a setup and room that is considered workable for this type of arrangement results in the smoothest response from both left to right, and front to back.


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## pietsch288 (Sep 10, 2006)

I agree, really the only way to tell what is going on is to REW all the seats to see whats happening. I'm just trying to save myself some work (I pretty much have my room set) and some expense. My room is wide enough to put a sub at each sidewalls but since I run all my subs with a dj amp I have no way to adjust phase other than O or 180 (reversing at the amp). I do have most of the room treatments completed---traps in all 4 corners, first reflection points, entire front wall, center of back wall. But what I've noticed is that I have alot more bass than I actually need (doesn't blend with the screen/sound) (of course I realize I could turn it down a bit) so my goal is to go lower (I'm at 16hz cutoff now so I'm going to try 12hz) but I need to get the subs away from the corners to get rid of as much room gain as possible. In my room I start to get room gain at 22-25hz well hell I've got too much of that allready so in order to eliminate room gain and create 12hz bass I have to do something diff than what I am currently doing.....Unless what I am doing is "as good as it gets". thanks rich


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## thewire (Jun 28, 2007)

When you do get them out of the corners and tune them lower you may want to keep a careful lookout for movies that have boost in the lower subwoofer range. The movie may not seem that loud but it could be pushing your subs harder than you may realize. Just something that occurred to me the other day while watching Lakeview Terrace and I felt some slight tapping on my shoulders. I checked the subs and they were moving so far I couldn't touch them so I turned it down a few notches.


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