Originally Posted by veger69
Unfortunately I have three. two VTF-15HMK2 and one LMF-1 EX, all decent subs and all individual sweeps showing a dip at 40-60hrz. For a 16x12 room that should be more than enough. I have one shot left I’m going to place the front subs in the corner and see if that helps
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Why I find most interesting is that all three subs, which are placed in different spots in the room, are all showing the same dip in the 40-60Hz range. I would think that to be highly unlikely.
Being an amateur detective, I would devise a test to figure out what is going on. For example, launch REW, open up the tone generator, and set it up to generate a 50Hz sine wave on HDMI4 (LFE). Place the mic near the center of the room, say 2ft to the left of the MLP. Turn off all but one sub. Output the 50Hz tone and record the output level as shown on the REW SPL meter. Without moving the mic, turn off the first sub and turn on the second sub. Output the test tone again and measure the level. Continue until all subs have been measured at position 1. Now move the mic to a second position, say 3ft behind the MLP. Re-run the level test for each sub at this new location.
After you have gone through this exercise for at least two mic positions (or more), compare the output results. There should be a significant variance among the measurements, from sub to sub, and from mic position to mic position. In my room, for one position and for four subs, I received measurements of 70, 74, 82, and 80. You should see the same variability. And as you move from one mic position to another, the output level for 50Hz should change. In other words, there is no way that you should see low levels at 50Hz for all subs at all positions, unless something is wrong with your measurement gear.
So what does this exercise prove? It shows that there has to be someplace
in your listening room where the 40-60Hz dip doesn’t exist. Of course, that may be in a spot where it is impossible to locate a sub. If that is the case, then that is bad luck indeed.