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Hello all,

I recently started playing with REW to correct any nulls or peaks from my subwoofer, a SVS PC-12 Plus. I ran it for the first time tonight and the results were really surprising.

SETUP​

ROOM:
I just moved into a new apartment with concrete floors and carpeting. The walls only have a few photos on them so it's a pretty lively room. When one walks through the room you can notice notes changing (I'm not sure if they change in pitch or volume).



REW:
I have my Macbook Pro running REW 5.0. I've set the MIDI to output through a USB audio interface (Link to amazon listing). I have a Radio Shack SPL meter and its' range is set to 80 and it's in the C octave. It's outputting to the right input of the USB interface. REW is loaded with the correct calibration file for the SPL meter.

The right channel is connected to my Yamaha receiver that has any effects turned off. It's in normal stereo mode.

I've made sure to turn it up as much as possible without disturbing my neighbors (actually they probably can hear the test sounds clearly). The SPL meter is on a tripod in the listening position pointed towards the center of the TV.

RESULTS



GREEN: Indicates the first measurement without any adjustment. Notice the peak at 87 Hz (73dB) and how anything lower than 32 Hz is hardly above 20dB.

BLUE: I adjusted the onboard PEQ of the SVS PC-12 Plus. It was never an intention of mine to get a separate piece of hardware to load an EQ filter on. I thought the 2 PEQ adjustments would be enough.

I set the first adjustment is at 90 Hz to lower -12dB across a 2Q range. The second adjustment is at 21 Hz increasing +3dB. My goal was to flatten out the curve as much as possible.

I swear after watching Oblivion that this thing did well at low frequencies, but after looking at this graph I'm thinking I need to do some adjustments. Should I look into room treatments? Should I do another subwoofer crawl to look for a better location? Or should I invest in a receiver with Audacity?

Thanks for reading!
 

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Bass trapping, sub crawl with measurements, second sub, in that order. Call Bryan at GIK acoustics. "Free" advice that will get you going in the right direction.
Plus one. I would also try moving the main speakers back, almost touching the wall. You will get boundary reflections off the back of the speaker so having them close to the wall moves the problem up in frequency. More about SBIR here.
http://www.gikacoustics.com/speaker-boundary-interference-response-sbir/

But yes, BASS TRAPPING for sure.
http://www.gikacoustics.com/video_bass-traps/
 
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Should I look into room treatments? Should I do another subwoofer crawl to look for a better location? Or should I invest in a receiver with Audacity?
Yes to room treatments, especially bass traps. The graph below shows a small room with and without (a lot of) bass traps, and the improvement is obvious:



The only way to know where your subwoofer gives the flattest response is to measure your room while you experiment. Listening alone doesn't work very well for many reasons, including that the key of the music probably doesn't align with the problem frequencies in your room. More here:

Subwoofer Placement
Room Measuring Primer

As for Audyssey (not Audacity, which is audio editing software), some people swear by it, but it's definitely not as effective as bass traps.

--Ethan
 

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First of all, I can't even read that graph. the horizontal scale is all wrong (should be 5db increments) and you have the freq axis set wrong. Even worse, I can't even see the HZ scale at the bottom of the graph!

Second, that Radio Shack SPL meter can not be trusted as a REW microphone for the low frequency stuff, even with the cal file it could be way off. Get a calibrated mic if you want to be sure.

Repost the graph with the correct settings and maybe we can offer some advice!
 
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Oh, and if you haven't already (and I don't think you have), you need to read this thread. ;)
 
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