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Discussion Starter #1
Hidee ho, fellow bass-junkies! I have a DIY vented sub built around a Dayton RSS390HF, in a 7.5 cu ft ported box tuned to about 18 hz. Definitely thumps, however, I am getting some nearfield effect since the sub is located to the "right-rear" of the seating area, about 4 ft from the primary seating location. Moving the sub is not an option, and I really don't want to tear the box apart and start over with a new cabinet or design.

I'm wondering if adding a second sub in the room may help to better distribute the bass and make it harder to localize the big box. Unfortunately, I don't have room for another identical sub, so I'm wondering if I could do some "mix and match" with a smaller ported or sealed box, possibly built with a different driver. My AVR has two subwoofer outputs (Onkyo 707) so I'm covered there. Any thoughts?
 

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Generally you don't want to mix subs and/or sub alignments for the same frequency range, it can work but it can also have unforseen phasing issues. What you've got is a pretty nice build already.

I'd suggest EQ and REW first, also. You could have some booming going on. Can you describe in ebtter detail the issue you are having?
 

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Generally you don't want to mix subs and/or sub alignments for the same frequency range, it can work but it can also have unforseen phasing issues. What you've got is a pretty nice build already.

I'd suggest EQ and REW first, also. You could have some booming going on. Can you describe in ebtter detail the issue you are having?
:T
 

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Discussion Starter #5
The issue, in essence, is that the bass pretty clearly comes from "behind" the seats. I've got the crossover on the AVR set to the lowest setting (40 hz?) and I can still localize the sub during movies.
 

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sounds like a room problem, your listening location is likely in a spot where anything above your 40Hz range is cancelling out. Can you try a new location for your sub?
 

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If you can "localize" the sub, then it seems to me to be a system integration problem. Could be the sub phase, level, room node, or maybe the front speakers can't go to 40 leaving a drop-out area. I try to cross from main to sub so there's an octave overlap, so the first thing I suggest is raising the sub cross freq. and matching the levels. REW (from what I understand) is the tool for the job.
G'luck,
Tom
 

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My 10" sub is maybe 8ft' away and can't tell where the bass is coming from unless i go sit by it. I'd say try to put frequency at 80hz as well as the mains and see how it comes out.:T
 

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My 10" sub is maybe 8ft' away and can't tell where the bass is coming from unless i go sit by it. I'd say try to put frequency at 80hz as well as the mains and see how it comes out.:T
I would definitely endorse this approach instead of overlapping xover points.
 

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Discussion Starter #10
Hmmm... seems to me that raising the Xover point would be counterintuitive as the lower the frequency, the less "directional" the sound, correct? So wouldn't raising the Xover force higher (and presumably more directional) frequencies to the sub?

FWIW, the mains are floorstanding Boston Acoustics VR30s, which should reach 40hz without undue effort (as I understand it).
 
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