My plan is to eventually have 2 subs but I will only have one to begin with. My dilema is that all the wires will need to be ran prior to setup since all wires will be in wall and terminated at wall plates. So I will need to have a good idea of where both subs will be at before listening to them to figure out the best location. I hope this makes sense.
My initial plan was to have both subs at the back of the room.
This is the layout of the room (15x17) and this is where I would place the 1st sub.
Then add an additional sub here.
But after some research, I am confused as to where the subs should go.
Would option 2 be better
Or maybe option 3.
If option 2 or 3 is better where do I need to add the additional sub when I get it down the road. There will not be enough room behind my 2nd row of seats to place the 2nd sub there.
Thanks in advance for your help
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From a theoretical perspective, start with one in a corner - I like position 2 - but 1 could work as well. The sub in the corner excites all the room modes and thereby gets you the strongest overall response. If the distribution of room modes amounts to overall bass response of tolerable smoothness, then you're done. Great. If it doesn't, then you can add another at a place that will work to cancel the major peaks and nulls in the response at your seating positions. Usually the best spot for this in the midpoint of an opposite wall. This should get you most of the way there. In almost all cases, a third sub, placed pretty much anywhere else, will get you to a smooth response, but it will be most effective if one of the subs can be brought up off the ground by at least a foot or two. This is an approximate summary of the approach advocated and tested by Dr. Earl Geddes. You can read about it here. His research is not the only recommendation you can find - and there is success to be had with other approaches, but he did earn his PhD for this work (if I understand correctly).
Placing a sub in a corner is the worst thing you can do. You'll have to calculate the room modes, including the seperate modes for the cutout area, and place your seating and subs in the areas with the smoothest response or the area that yields the nearly the same response for both rows. It is best to use excel or something like it to calculate the sine waves associated with all three axial modes, I would calculate up to 4 modes, then look to see where these waves intersect in the room and place your seating in that area. Then place the subs near the null are of the first or second mode. Hope this helps.
Is this a common rule of thumb? I am wrapping my mind around Some of Toole's writings(trying) and thought that 1/4 wave locations were preferred over 1/2 wave for sub locations? So your suggesting 1/4 wave locations for seating and 1/2 wave for subs? Is that correct?
However, in any case, placing listeners right against the back wall will cause problems for bass uniformity (not to mention creating a decent 7.1 surround effect). If you can move them even 2' away from the wall, it will help on both counts.
Dennis Erskine CFI, CFII, MEI
Subject Matter Expert
Certified Home Theater Designer
CEDIA Board of Directors