In-wall sub placement - AVS Forum
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post #1 of 5 Old 03-11-2013, 06:54 PM - Thread Starter
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I'm thinking of getting a couple in-wall subs ( to match my speakers) and thinking if putting them perpendicular to the front speakers. Probably on both sides of the room at the front. What do you guys think?
In the picture that is the whole wall so there is a corner on each side.
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post #2 of 5 Old 03-12-2013, 01:27 PM
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An in-wall sub located in a room corner is one of the most efficient placements possible as you're directly energizing all room modes, and all energy is radiated into a pi/2 space (1/8 of omnidirectional) so there's good energy injection. But common sense applies; the sub has to output a frequency first, and small sealed sub's don't do much by way of infrasonics, so choose wisely if you want things to vibrate.

The downside is placement flexibility. Unless you know your room modes, you may be picking a disadvantaged location. Granted, 4-corner subs is one of Harman's optimal placements (slide 75)...
http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White%20Papers/multsubs.pdf

Speaking of room modes, what are your dimensions, and what's your wall construction or are there other ways for bass to leak and dissipate? If you're building speakers into walls, you may want to consider adding some acoustic treatment to the mix, especially below 100Hz where the vast majority of stuff we put in rooms has no effect.

Have fun,
Frank
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post #3 of 5 Old 03-13-2013, 07:17 AM - Thread Starter
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Thanks for your time to reply. I should have been more clear on my setup. The " listening" arra is about 12 x 12 with a large opening to the back ( behind the surround speakers) and a five foot opening on the right side. And just wood construction and drywall. This is far from any home theatre setup on here. Right now it is just a 7.0 system. I guess what I'm really wondering is would it make sense to put the subs pointing at each other on opposite sides of the room or diagonally front to back. Thanks for the link, I haven't looked real close yet but I will.
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post #4 of 5 Old 03-13-2013, 08:39 AM
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Your seating area is 12x12, but your listening area is determined by the walls. There's no way to remove the acoustic effect of the large opening behind the seats without adding a wall, so take advantage of it, and the doorway to the right. These spaces will suck out bass, but they'll also smooth bass modes as a result. Stick construction has advantages in this regard as well. Good sound doesn't require a dedicated space, just a little care in setting up the space.

Since you have location options, I'll point you to Welti's analysis that identifies 3 optimal choices
- 4 corners
- 4 midwalls
- 2 mid side wall

My room has the screen on the long wall, with a doorway and a fireplace on the side walls, so my subs are front and back, offset toward the fireplace but not in the corners. Measurements show very benign low frequency modes, but with the telltale of a secondary resonance - the leakage through the doorway - at a frequency too low to fit in the room. Bass response is very flat below 40Hz, with rapid temporal decay and mild room modes. Above 40Hz is lumpy, and above 100Hz fairly chaotic, but that's not subwoofer territory.

HAve fun,
Frank
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post #5 of 5 Old 03-13-2013, 12:47 PM - Thread Starter
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Wow! You have way more knowledge than I ever will with this stuff. There were some big words in there for me. 😕 But I appreciate it and will do a little more research. Thanks
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