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Discussion Starter · #1 ·
I was reading the .pdf paper by Todd Welti and it suggested that the best 2-sub configuration is by placing the subs at opposing walls in the front and back, right in the mid point of the wall.


My question is, won't the subs then cancel each other out?


Anyone?
 

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While white paper is a great way to explore different locations for subwoofers nothing replaces experimenting with the two on hand.


My last videoroom worked well with two subs up front, one to the left ,one to the right. I placed them in the same location in my new video room and there was a huge null centered at 50hz and in either direction 15hz.


I think the best spot for subwoofers is out in the room and centered.Corners are to unpredictable.They offer huge SPL's but very unstable.


Do you have two subs on hand now?
 

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Quote:
Originally Posted by kgveteran
While white paper is a great way to explore different locations for subwoofers nothing replaces experimenting with the two on hand.


My last videoroom worked well with two subs up front, one to the left ,one to the right. I placed them in the same location in my new video room and there was a huge null centered at 50hz and in either direction 15hz.


I think the best spot for subwoofers is out in the room and centered.Corners are to unpredictable.They offer huge SPL's but very unstable.


Do you have two subs on hand now?



Sounds to me like that your 50Hz mode was either a length mode or a height mode (or both). The dual subs should have eliminated the width mode(s) if they were properly placed in the room!
 

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Quote:
I was reading the .pdf paper by Todd Welti and it suggested that the best 2-sub configuration is by placing the subs at opposing walls in the front and back, right in the mid point of the wall.


My question is, won't the subs then cancel each other out?
Depend on room size and shape, the best location for my 2 subs at opposing walls 1 one the left the other one on the right corner, my room has one side open.
 

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This could have well been an issue in my last room that went undetected because of my lack of computer software and knowledge.


I ended up with them (2) infront of the center channel on the floor.I never bothered to research why the problem occured but was very satisfies with the new results.


Russ Hershelman from SGHT took alot of heat for poo-pooing corner placement and I would have to agree with him.
 

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Discussion Starter · #6 ·
Thanx guys! I guess experimenting is 3/4 of the fun right?? :)


I actually have 4 subs, but I am going to do a 2-sub configuration by stacking each pair, so that they will act as one. It'll be SUPER easy to stack them at opposing walls in the center, but I don't want to have them cancel each other out. I guess testing would tell me for sure though.


I'll let you guys know the details of what my ears tell me. Thanx. :)
 

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I've heard centered on adjacent walls, not opposing. It was also said that raising the subs to 1/4 the room height was optimal. This of course assumes a sealed rectangular room. Results may vary.
 

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Discussion Starter · #8 ·
Hmmm...interesting. I'll definitely try the raised thing and compare with just floor level. Sounds interesting indeed!
 

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Quote:
Originally Posted by Favelle
I was reading the .pdf paper by Todd Welti and it suggested that the best 2-sub configuration is by placing the subs at opposing walls in the front and back, right in the mid point of the wall.


My question is, won't the subs then cancel each other out?


Anyone?
Hi Favelle,


No, the subs will not cancel each other out, per se. Odd lengthwise modes will have opposite phase and cancel, while even lengthwise modes will have the same phase and reinforce. However, even in the case of odd mode cancellation, there is still the direct sound from the subwoofers. The room modes may cancel, but the overall sound does not.


Todd's study was to optimize frequency flatness over a significant listening area without the use of EQ. This may not be the same goal as yours, so his results may not apply to your theater.


Regards,

Terry
 

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Discussion Starter · #10 ·
Thanx Terry!! :) That's what I got to thinking because I will be directly in the "line of fire" of both subs, so they will have to pass through me to get to each other, therefore I shouldn't hear any cancellation. I wonder if they should be equidistant from me (ie. I'm sitting in the exact middle)?? I guess some experimentation is in order.


Is direct sound enough for the LFE channel? Do you not need room nodes to make the bass more full? Sorry for the noob questions.


Thanks all.


JF
 

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Quote:
Originally Posted by Favelle
Thanx Terry!! :) That's what I got to thinking because I will be directly in the "line of fire" of both subs, so they will have to pass through me to get to each other, therefore I shouldn't hear any cancellation. I wonder if they should be equidistant from me (ie. I'm sitting in the exact middle)?? I guess some experimentation is in order.
Subwoofer frequencies have no trouble passing through a mere mortal. :)

Quote:
Is direct sound enough for the LFE channel? Do you not need room nodes to make the bass more full? Sorry for the noob questions.


Thanks all.


JF
Room modes are a mixed blessing for subwoofers. On the one hand, they increase the bass above the level of the direct sound. On the other hand, such an increase will be uneven, and stand in the way of a flat frequency response.


Regards,

Terry
 
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