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Subwoofer Placement Dilemma


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#1 of 11 TexasStation

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Posted November 12 2008 - 11:07 AM

Kind of have a perplexing issue. I have a dedicated media room approx. 16'X18', with 8 seats (row of 4 in the front and 4 in the back on a 6' riser). I've tried placing my SVS PB-10 NSD sub in the back right corner, and also in the front left corner of the room. Problem is, after running the Audyssey calibration on my Denon receiver, the bass seems boomy and overpowering in the back row, especially the left rear seat, and a little weak in the front row (except for the left seat which is closest to the sub). If I lower the output level it would just weaken it more in the front row. I've been trying for awhile to get a good balance throughout the room. I've tried different phase settings and also moving the sub away from the corner a bit, but didn't resolve anything. I may try swapping out the SVS sub with the Paradigm Ultracube 10 which I'm using in the living room to see if it fares any better. Does anybody have any tricks or suggestions on how to get a little more consistency for the bass output in the room?

#2 of 11 chuckg

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Posted November 13 2008 - 03:54 AM

You are probably experiencing the peaks and nulls in the bass from room size and shape. Seats near the corners will have louder bass, a seat near the center of the room will have less.

I would guess that any sub you try will have the same trouble.

Two things you can do:
--keep trying different locations for the sub
--treat the room with acoustic panels to even out the peaks and nulls (and have with with that one, it seems more art than science!)
--ignore the man behind the curtain

#3 of 11 Robert_J

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Posted November 13 2008 - 04:23 AM

I would plot the sub's resonse for each location. That will easily tell you if you have some bad nulls.

Like Chuck said, you may need to move your sub around. You may need a second sub to smooth out everything.

-Robert

#4 of 11 TexasStation

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Posted November 13 2008 - 08:38 AM

Sounds reasonable. I will try the sub more toward the center of the room between the main and the center speaker and see how things shake out there.

#5 of 11 David Willow

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Posted November 13 2008 - 11:08 AM

As you move the sub, make sure you are testing with Audyssey turned off (unless you re-run it for each test). Audyssey's measurements were derived from the location you had the sub in when you ran the setup and therefor will be way off as you move the sub.

#6 of 11 Jasonp31

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Posted November 20 2008 - 07:13 AM

Suggestions so far are good.

If possible, put the subwoofer in the middle of all the possible seating positions. Again, if possible, put it at ear height.

Now, put on a good song with bass sweeps or something that will hit a good range of bass. With this playing, crawl around on your hands and knees throughout the entire room. The place you find where it sounds the best is where you should put the sub. From there, play with EQ and other adjustments necessary to fine tune.
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#7 of 11 TexasStation

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Posted November 22 2008 - 03:52 AM

Ok, this is about my third weekend working on this and not sure where to go from here. This is what I've tried so far...
I've tried moving the sub from the left front corner to the middle of the front wall (between the center and left main speakers). I also tried running the MultiEQ calibration using different seats as the main listening position. I even tried replacing the SVS with the Ultracube 10, which is down-firing to see if that would improve things. I've really used all my options as far as moving the sub to different locations, since it's a room with a lot of seating. I've already tried the sub at the back of the room. but I still have the same issue. Example...during the scene in Iron Man where he comes out of the cave right before the flamethrower scene, when I'm sitting in the right rear seat, the footsteps sound like one long, loud, booming base tone, whereas, in the front seats, the footsteps sound natural and it could even use a bit more bass output at that location. I'm starting to think it's an issue with the room rather than the equipment, and I'm considering hiring some kind of professional to come in and evaluate it, but if anybody knows of something else I can try, please let me know.

#8 of 11 TexasStation

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Posted November 22 2008 - 04:47 AM

Also, could all this be happening because of the riser for the back row of seats?
The only thing I haven't tried yet is taking the sub off the floor and putting it on a table. Anybody think that might solve it?

#9 of 11 Robert_J

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Posted November 22 2008 - 12:57 PM

I would plot the response of the sub before I did anything else. Having a pro audio guy come out will cost hundreds if not more. You can go as cheap as $45 for a DIY plotting session. If you want to go up to about $100, you can use Room EQ Wizard and with a nice sound card. A calibrated mic is nice but an SPL meter will work as well.

If you have nulls, borrow a sub from a friend and run two to see if you can clean things up. Or you can do like me and make it sound good in your seat. Screw everyone else.

-Robert

#10 of 11 JohnRice

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Posted November 23 2008 - 05:23 AM

I agree with Robert. I suspect with one sub you will only get a limited result, so go that way and optimize it for where you want to sit. Two subs properly situated will probably go a long way to solving the problem.

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#11 of 11 TexasStation

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Posted November 23 2008 - 09:37 AM

I tried moving the sub again (now it's near the right rear corner) and it actually sounds pretty good at my main listening position (front row, middle seat), but still all the seats in the back row (which are right near the back row) are just way overblown. Next thing will be to get a splitter so I can run two subs in the opposite corners, but it just seems no matter where I put a sub in that room, the back of the room (especially the back corners) just gets loose, boomy bass response. The room is almost square, which I understand is not a good thing, and I'm wondering if I'm getting standing waves in the back corners. Would two subs combat that sort of thing, or should I be looking at some kind of acoustical panels for, I'm guessing the back wall and corners. If so, can anybody steer me toward some good panels, bass traps, etc? I would need to know where to position them on the walls, too.




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