Sub crawl > pub crawl? Sub placement help. Will pay in karma. - AVS Forum
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post #1 of 10 Old 02-13-2013, 07:49 AM - Thread Starter
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Ok here is my deal. I am prewiring my basement for 7.1. I know a sub crawl is the only way to properly locate my sub, but that seems useless since the flooring, drywall, ceilings and furniture are not there.

I need to run the sub cable and install the wall plate now. Any thoughts where the best place would be?

Here is a floor plan. 7'6" ceilings.

For now I have the Denon 2113, BIC 76, 26, and 66 5.1 setup with a Klipsch rw-12d sub.

I also have 2 monoprice in ceiling speakers in another room as zone 2. Will add an amp for zone 2 and 2 more 66 for 7.1 down the road.

Thanks in advance.
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post #2 of 10 Old 02-13-2013, 07:55 AM
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Originally Posted by jvh4 View Post

Ok here is my deal. I am prewiring my basement for 7.1. I know a sub crawl is the only way to properly locate my sub, but that seems useless since the flooring, drywall, ceilings and furniture are not there.
Put in the ceiling first, then do the crawl. The low frequency response of the room won't be all that much different after that, as it's mainly based on the distance relationships between the sub, the walls and ceiling, and the LP. Keep in mind that using only one sub you can't get great results over more than a small LP.

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post #3 of 10 Old 02-13-2013, 08:04 AM
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If you only install one cable, I'd put the plate at the red "X". If you install multiple cables - which gives you the option of connecting more than one sub and/or running shorter cables from the wall plate(s) to the sub(s) - I'd put the plates at the green circles.

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post #4 of 10 Old 02-13-2013, 08:21 AM - Thread Starter
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Originally Posted by Bill Fitzmaurice View Post

Put in the ceiling first, then do the crawl. The low frequency response of the room won't be all that much different after that, as it's mainly based on the distance relationships between the sub, the walls and ceiling, and the LP. Keep in mind that using only one sub you can't get great results over more than a small LP.

That's great to know, thanks. Maybe I'll wire everything but the sub for now, get the ceiling up and do a quick crawl before drywalling the walls. Will it make a big difference that the walls to adjacent room won't be drywalled? And sound will more easily pass into them effectively making the room bigger?
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post #5 of 10 Old 02-13-2013, 09:56 AM - Thread Starter
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Originally Posted by eljaycanuck View Post

If you only install one cable, I'd put the plate at the red "X". If you install multiple cables - which gives you the option of connecting more than one sub and/or running shorter cables from the wall plate(s) to the sub(s) - I'd put the plates at the green circles.


Upgrading to 2 subs in the future is good possibility so multiple plates is a good idea. I understand your recommended locations, but it seems front loaded. With a 2 sub set up are you looking for separation? I.E. should I put a plate in the back of the room, or behind the bar?
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post #6 of 10 Old 02-13-2013, 10:05 AM
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The advantage of dual (or multiple) subs is FR smoothing - not separation - at the primary listening position. You should be able to get that with duals placed in the appropriate locations up front. But if you think you may want / need to place a sub at the back, run a cable to the back. Cables aren't that costly, so one more + a wall-plate won't (shouldn't) break the bank.
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post #7 of 10 Old 02-13-2013, 10:17 AM - Thread Starter
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Originally Posted by eljaycanuck View Post

The advantage of dual (or multiple) subs is FR smoothing - not separation - at the primary listening position. You should be able to get that with duals placed in the appropriate locations up front. But if you think you may want / need to place a sub at the back, run a cable to the back. Cables aren't that costly, so one more + a wall-plate won't (shouldn't) break the bank.

Ok. Makes sense but does smoothing out the FR relate to expanding the LP as mentioned by Bill? Or are there additional considerations if I want to expand the LP.

Thanks for all the awesome info.
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post #8 of 10 Old 02-13-2013, 10:51 AM
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Will it make a big difference that the walls to adjacent room won't be drywalled?
All the difference in the world if you do so later on.
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but does smoothing out the FR relate to expanding the LP as mentioned by Bill? Or are there additional considerations if I want to expand the LP.
As I said, room modes are caused by the distance relationships between the sub, walls, ceiling and listening position. If you move the listening position, as in sliding over two seats, you change those relationships, and response along with it. Using more subs reduces the room mode issue as when you move away from the sweet spot of the one you move into the sweet spot of the other. With enough subs, at least four, the entire room becomes a sweet spot, while the placement of the individual subs becomes less and less critical with each additional sub.

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post #9 of 10 Old 02-13-2013, 11:00 AM - Thread Starter
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All the difference in the world if you do so later on.
As I said, room modes are caused by the distance relationships between the sub, walls, ceiling and listening position. If you move the listening position, as in sliding over two seats, you change those relationships, and response along with it. Using more subs reduces the room mode issue as when you move away from the sweet spot of the one you move into the sweet spot of the other. With enough subs, at least four, the entire room becomes a sweet spot, while the placement of the individual subs becomes less and less critical with each additional sub.

Ok. Gotcha, so the best case is I wire everything but the sub, drywall the ceiling and partition walls, sub crawl and wire sub, throw an extra plate or two up for future use, then drywall remaining walls.

Down the road when I add the second sub, location will be less important, but I can find the best location , by leaving sub 1 where it is and sub crawl sub 2?
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post #10 of 10 Old 02-13-2013, 12:30 PM
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Down the road when I add the second sub, location will be less important, but I can find the best location , by leaving sub 1 where it is and sub crawl sub 2?
The first one is fairly easy to find the best spot for. With the second you really need to have response measuring tools to get the best result.

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