# Help with room accoustics



## fireanimal (Dec 21, 2006)

Just looking for some input to how my room treatments are performing. I have taking measurements of the individual LCR speakers, sub, sub and center, and sub with both mains. They are all saved under one measurement set. The sub measurement is after EQ.

My Main LCR speakers are Ascend CMT-340 SE’s they are installed behind my screen. My sub is 4xMJ18 in a sealed box, at the front of the room under my screen.

My room is 11.5Hx10.5Wx7.5H. I have built wedged bass traps in all corners of the room that go from floor to ceiling. The front wall of the room is treated in 2” Roxul AFB, and I have built panels on the sides and rear of the room from 2 layers of 2” Roxul AFB. In total there are 2 panels on each wall, and 3 on the rear wall.

I think I need to add one more panel on the side walls were the doors are to help with the impulse response, but I am not 100% sure. I was also wondering about treatments for the ceiling.

If there are any other details needed, just let me know. I will also get some pics of the room as well.

Here are the current filters I am using

Filter 1: ON PEQ Fc 20.7Hz Gain 4.0dB BW Oct 0.333
Filter 2: ON PEQ Fc 390.0Hz Gain -18.0dB BW Oct 10.0
Filter 3: ON PEQ Fc 42.8Hz Gain -13.0dB BW Oct 0.500
Filter 4: ON PEQ Fc 68.6Hz Gain 5.5dB BW Oct 0.250
Filter 5: ON PEQ Fc 76.9Hz Gain -5.0dB BW Oct 0.143
Filter 6: ON PEQ Fc 85.3Hz Gain 2.5dB BW Oct 0.111

And here are my measurements

*LCR SUB MEASURMENTS*


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## fireanimal (Dec 21, 2006)

Here are the pictures of the room with current treatments. I have also remeasured the room and the dimensions are 13'6"L10'8"W7'4"H with 16" from the front of the screen surface to the wall.

Also the bottom halves of the surround columns are filled with Roxul, and I still need to do the top halves and install speaker grills.

Forgive the bad pics.

Thanks.


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## eugovector (Sep 4, 2006)

Looks like you have a mic. Post a couple shots from REW, Your frequency response, waterfall plots, and impulse response.


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## fireanimal (Dec 21, 2006)

fireanimal said:


> *LCR SUB MEASURMENTS*



Instead of a bunch of graphs, you can download and view my entire measurement set.


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## eugovector (Sep 4, 2006)

A ha, even better.

Sorry about that, I missed that link, looked like a random sig link to my eyes.


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## fireanimal (Dec 21, 2006)

No prob.


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## eugovector (Sep 4, 2006)

What are you areas of concern? Everything looks pretty good in my amateur opinion. Maybe more bass trapping where you can, but that's always true.

Any expert opinions?

Posting some pics would be helpful, even with the data set provided. The really knowledgeable guys on here may be a little too busy to open up REW and load your data set.


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## fireanimal (Dec 21, 2006)

Main concerns are the impulse response, maybe with the sidewall reflections off of the doors, and the ceiling. But I am just not sure if it a major problem or not.

I will post some graphs as well.

Thanks for your input.


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## fireanimal (Dec 21, 2006)

Here are some graphs.

Orange = LEFT
Black = CENTER
Yellow = RIGHT

Thanks.


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## JohnM (Apr 11, 2006)

A few unusual filters in that set. I'm presuming they are for an FBQ2496 in the path to the sub? Do you have a measurement file for the sub without any EQ applied? What were you addressing with that 390Hz filter?

A good plot to use when tracking down places for absorption panels is the Energy-Time curve. Set the Y axis to % FS, the spikes show reflections. You can get an idea of how much further the sound travelled via a reflected path by measuring the time from the main spike to the reflected spike, multiplying by the speed of sound then gives you the additional distance. REW can handle that for you, if you place the cursor at the tip of the main spike, then hold down the Ctrl key and press and hold the right mouse button you go into measure mode, REW will show you the time difference and the equivalent distance in metres and feet. To get an idea of which surface a particular reflection is from make new measurements after moving the mic a foot or so, if you have moved closer to the surface that the spike you are looking at is reflecting from it will have moved closer to the main spike, if you have moved away it will have moved further away from the main spike. You can also place panels on likely surfaces and see which spikes they affect.

You may have some problems with reflections from the wooden frame behind the screen. The further forward you can place the speakers the less of a problem that will be.


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## fireanimal (Dec 21, 2006)

JohnM said:


> A few unusual filters in that set. I'm presuming they are for an FBQ2496 in the path to the sub? Do you have a measurement file for the sub without any EQ applied? What were you addressing with that 390Hz filter?
> 
> A good plot to use when tracking down places for absorption panels is the Energy-Time curve. Set the Y axis to % FS, the spikes show reflections. You can get an idea of how much further the sound travelled via a reflected path by measuring the time from the main spike to the reflected spike, multiplying by the speed of sound then gives you the additional distance. REW can handle that for you, if you place the cursor at the tip of the main spike, then hold down the Ctrl key and press and hold the right mouse button you go into measure mode, REW will show you the time difference and the equivalent distance in metres and feet. To get an idea of which surface a particular reflection is from make new measurements after moving the mic a foot or so, if you have moved closer to the surface that the spike you are looking at is reflecting from it will have moved closer to the main spike, if you have moved away it will have moved further away from the main spike. You can also place panels on likely surfaces and see which spikes they affect.
> 
> You may have some problems with reflections from the wooden frame behind the screen. The further forward you can place the speakers the less of a problem that will be.



I am using a FBQ2496, and the 390hz filter acts as a shelving filter. Also here is the unfiltered measurement of the sub.

Thanks for the suggestions, on using the impulse graph, and the excellent software!!


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## JohnM (Apr 11, 2006)

Could you post an mdat file of the unfiltered sub measurement, or put a copy in your Yahoo briefcase? It's helpful to have a variety of measurements to work with as I develop the next REW version.


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## fireanimal (Dec 21, 2006)

Sure no problem, I attached the file for the subs.

Thanks.


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