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Discussion Starter #1
When I measure my subs in my HT I get a dip at 60Hz. When I measure my sub in my bedroom I also get a dip at 60Hz. When I measure my Polk Towers in my bedroom I get a dip at 60Hz and also when measuring a single boombox speaker I think cost around $40.00 for the entire radio. Is it possible my RS Digital mic was damaged somehow when I had dropped it before? Is it because the battery insert is missing? Is 60Hz just a reacurring problem I have? Some other kind of problem?



The tiny boombox speaker got a 30dB offset. The crossover was 120Hz on each measured as a subwoofer, except I limited the Polk Rti70 and boombox speaker to 20Hz. I did not change the levels.
 

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Discussion Starter #3
Those are all measured in my bedroom with the speakers 3 feet behind me about 45 degrees with the mic next to my ear.

This one is from the HT room. I just didn't expect them to look so similar right off.

 

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When I do that in my bedroom I noticed a dip with both the sub and the Polk at around 40Hz. The odd thing is that I had done nearfield measurements with my meter before in the HT and they had never showed any large dips. More recently I did a nearfield of one of my subs in the HT and it showed a large null at near 60Hz. I thought nothing of it and thought it may have been to close to the wall for measurement at the time. I'm using a different amp here than I use in the HT which shows a somewhat smooth response from 10Hz that slowly rises when I did a loopback of the highpass output. Here is a nearfield of my Polk tower at nearfield. I am using a headphone out into RCA splitters so that I can listen to headphones right now with the sub in my bedroom so it is not a standard REW connection. I was not looking at something very critical so thought it might not make a large difference. The wire I am using is also very small on the Polk. It looks like an 18 AWG or less and there are like 3 strands, but the distance is short. Only the bass drivers are hooked up. The amp does not have a serial number or model number on it but I could look up the name from where I bought it. It is a 200W plate amp rated for 4ohm.

Here is the nearfield and another measurement at my ear. Red = at my ear, purple = mic on the tv, the lower blue measurement is with the mic on the first step outside my door leading down the steps with the door open.
 

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Discussion Starter #6
Does anyone have a similar problem? Was the nearfield measurement well enough to prove if my RS meter is capable or not?
 
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