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Discussion Starter · #1 · (Edited)
I'm trying to figure out my room before the new sub arrives. Moving around a 40lb sub (TheSpeakerCompany T300) is going to be a lot easier then moving around a 120lb sub (Rythmik FV15).

Please refer to the floor plan diagram for room setup. Black boxes indicate speaker placement. Boxes with "S" indicate the two positions for the measured curves.


Please see the attached graph for the following curves:
Purple #1 --- Sub next to left front tower, approx 9.5ft away, crossover at 80Hz, Audyssey enabled

Black #2 --- Sub on left side wall, approx 13.5ft away, crossover at 80Hz, Audyssey enabled

Red #3 --- Sub on left side wall, approx 13.5ft away (same as above), crossover at 80Hz, No Audyssey




Originally, my sub was located next to my Left tower (#1) and I have been having problems in that I've been lacking the punchy feel with bass. After measuring with REW, it seems the culprit is the huge dip at 80Hz. I'm guessing that is a room mode/null. When running my towers alone, I get a similar dip in the same region.

So I tried a few different positions and the best I could find was against a side wall (its actually a half way that separates the listening room and kitchen). I am guessing the sub in the new position takes care of the 80Hz null from the previous position, but now I have dip at 49Hz.

Looking forward to some comments/suggestions and interpretations from others. :help:
 

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I'm afraid you are going to have to move the 120 lb. sub around as well. The best location for one sub may not be the best location for another.
 

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The purple would have been great, if your mains took care of the 80hz dip. It also goes to fairly low frequqncies. If moving the mains is not an option, then teh black one.

It would be intersting to see if everything changed radically with th enew sub.
 

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Discussion Starter · #5 · (Edited)
The purple would have been great, if your mains took care of the 80hz dip. It also goes to fairly low frequqncies. If moving the mains is not an option, then teh black one.

It would be intersting to see if everything changed radically with th enew sub.
Unfortunately, I think any place on that front wall is going to give me the 80Hz null. The one thing I thought of just a few minutes ago was if I moved my mains forward or backward towards the front wall. They are rear ported and currently about 12" from the wall.

Also, these graphs were made with the receiver volume at -18 (which is my typical listening volume), but is there a specific volume sweeps should be run at?
 

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Discussion Starter · #7 · (Edited)
Well, I think I may be on to something....

The Rythmik FV15 arrived, I placed it in a different location, and used the 1-band PEQ to apply a 3dB boost to the 37-43Hz range. Applied Audyssey MultiEQ. Then adjusted the distance setting on the receiver to 14.5ft (sub is actually about 9ft away) and this is what I came up...




I'm not sure if there are any ill-effects of such a large discrepancy in adjusting the speaker distance for what I believe to be the effects of phase shift.
 

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The tricky thing can be knowing the cause of a dip sometimes. SBIR, phase shift or modes are all possibilities! If you have a phase related dip, then manipulating distance settings applies delay that can correct phase issues at a crossover point, as shown on the phase alignment article on the Rythmik website (I assume you've read it).

BTW you can put a sub in the listening position, then move the mic instead of the sub, and take a stack of measurements. If you do it with a sealed sub, you can also take a nearfield and you will see the relative room impact. It's a good idea to start there.

Your response looks pretty good. A bit of PEQ at 55 and 95 could make it even better. The dip around 140 may be related to boundary issues (SBIR) and with tweaking you may be able to improve it a little.

I'd also be interested to see a waterfall, which will show how your room is performing in terms of decay.
 
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