# Help with my first REW measurement



## ntran (Mar 25, 2015)

I just completed my first REW measurement yesterday and would like to ask for advice on how to improve the acoustic performance of my room.

Some background: the room is 10Wx17Lx8H with the middle of the right wall open to living room (no door). My MLP is 6" from the back, which is a window cover with foam (for light control) and bamboo blind. After my first REW measurement, which was done properly to my understanding, I saw found some issues as below

1. Too much refection on my main speaker: all my speakers are wall mounted and above screen, so first near field reflections are unavoidable (wall and ceiling). I plan to somehow fix this with absorption (DIY panel 3" Roxul Safe n Sound)

2. My bass is boomy especially in the 28 - 50Hz area. I am not sure if that was because of my sub placement, which is currently placed in an in-wall shelf (2 have 2 little kids, and they are pretty active, so don't want to put anything in my room). My initial thought would be putting corner bass trap at the back wall (can't do the front wall as it could block my screen). If I should do that then what type of bass trap would you recommend? The waterfall graph was done with all three FLC speakers and the Sub, with YPAO on.

3. For the main speaker: I don't know if if the FR looks ok or if there is anything I should be aware of?

I am a newbie in room acoustic, so any advice is greatly appreciated.


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## bpape (Sep 14, 2006)

You're getting a ton of boundary gain from the wall mounting - hence the broad peak up to about 300Hz. Treating the front wall will help with that and with surround reflections off the front wall messing up your soundstage.

Impulse response shows a lot of reflections in the first 20ms that are higher in level than they should be.

Seating position that close (assume that is not a typo and it's really 6 inches) is always going to be very boomy and sloppy. Ideally your head would be no closer than 25% of the room length though 30-38% is better if you can swing it.


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## ntran (Mar 25, 2015)

Thank you, Bryan. I have attached some photos of my room to show how limited in option I have regarding speaker and seat placement. I will try to do some sound absorption between the speaker and the wall and behind my seat to see if it helps.

For the ringing in the low frequencies as showed in the waterfall graph, is there any suggested solution?


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## bpape (Sep 14, 2006)

Yeah - kind of boxed yourself into that by putting the equipment rack where it is. Best thing you can do at this point is make the absorber behind you where the window is as thick as possible.

The screen being so big for that narrow of a room forced the speakers to be mounted to the wall giving the boundary interactions. Take the screen down and put 2-3" of OC703 or equivalent on the entire front wall.


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## ntran (Mar 25, 2015)

Bryan, my screen is not AT, so would it help if I put absorption behind the screen? My screen is the Elite Fixed.


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## bpape (Sep 14, 2006)

If it's not AT, then no. But help these old eyes figure out where your speakers are???


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## ntran (Mar 25, 2015)

The front speakers are not showed in the photo. But the L and R are wall mounted 3 ft from the screen and the center is above the speaker mounted close to the ceiling and tilted down to my MLP. I know that those are not not ideal, if not worst, places for speaker, but don't have much option right now. In the future, I will get an AT screen and hide the speakers behind it. Bur for now, I am trying my best to make whatever I can to improve the acoustics of my room. Your advice is appreciated with many thanks.


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## bpape (Sep 14, 2006)

Fill in behind you as I said before. Ceiling reflection and side reflections will be very quick and intense. At least 4" absorption just in the reflection zone for the 3 of them.


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## ntran (Mar 25, 2015)

Thanks, Bryan. I'll do the panels and post back the result. In the meantime, happy Eastern!!!


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## ntran (Mar 25, 2015)

I did the treatment for the side and back walls, not the ceiling due to WAF factor. Below is the new measurement.

I have a few questions

1. Is the null on my low frequency was due to sub displacement? Would it only be fixed if with new placement? how about adding another sub?

2. Looks like early reflection on main speakers was from the ceiling

Is there anything that I should pay attention to, based on the measurement?

After all of this, I have decided to go with AT screen and move my speakers behind it, treat the front wall. Thanks REW for getting me into this :crying:


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