# New Home Theater - Poor Room Response help needed



## ryeaustin (Jun 15, 2015)

Hi,

This is a first post so I hope the question is provided with some relevant details, but if not please let me know.

The room is a 3.8m wide, 5m long and 2.5m high.
Walls are plasterboard and the floor is solid wood covered mostly in a 1" thick rug.
Front wall has 2mx2m double glazed doors in the middle of it.

The equipment is all in now and the next step is to apply some acoustic treatment but this is my first time trying this and I have read a lot of conflicting views as to the quantity, type and location of treatment and would welcome the views of people here that have been through this process before. Its is very hard to get a feel for how much treatment would be a real improvement. The response chart looks bad compared to some I have seen on here so clearly it does need lots of help. Ideally I would be looking for ready made products from the likes of GIK with DIY being a last result if something custom is required.

I have recently run the Room EQ software with a calibrated microphone and the results are attached.

The room is a dual purpose room, but there is space for bass traps on the front wall and providing it can me made to look good will be happy to put any diffusion/panels on the side and back walls. 

I would be happy to add pictures of the room if this would help and or run more tests with different speaker positions.

Thanks in advance for any help and advice you can offer


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## bpape (Sep 14, 2006)

Check your sub phase - null at 80 looks like that might be fixable. Other than that you have a couple of peaks which are easier to EQ than nulls so then you can just work on reflections and decay times.

Maybe post some pics and/or a top view sketch of the room?


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## ryeaustin (Jun 15, 2015)

Thanks for the response. I have attached a room layout which I hope will help.

I have also included a couple of in room pictures before the room was completed. At the back of the room is only a leather sofa. In the pics, the speakers I was running as rears are up next to the fronts, this is not how they setup were for the test 

The response I took was only with the left speaker running so no sub in play to cause phase issues unless I misread the question. This was run direct to my 2 channel pre amp so no processing form any AV kit in the way either. I only run the sub with the AV processor to keep the 2 channel listening as clean as possible.

Is there anything I could try to help isolate the cause of this? I have tried moving speaker positions, opening doors etc. and while I can move the peaks and dips around I still have large variations in the low end with peaks and dips. If I could work out what boundaries were causing the problems I guess I could focus the efforts. With it being a smallish room I guess all the boundaries will be causing problems. 

I would be happy to buy some recommended treatment as a starting point and see how this changes things but until now I was assuming I would need lots of bass traps or very dense material to deal with the low end. Good to hear this may not be needed.

From the size of the room is it possible to work out what products I may need to bring to decay times down to a more appropriate level. I am guessing 2-3ms?

Thanks again
Rye


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## chashint (Jan 12, 2011)

The graph says left speaker only. Is that accurate?

BTW...you have a very nice system.


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## chashint (Jan 12, 2011)

I see it is only the left speaker.
Considering the hard flat surfaces of the room your response isn't all that bad.
Is there anything on the walls? Bookcases, pictures, furniture...anything to soften the room ?
Have you tried moving the speakers around a little or changing the toe in ?
Are all four speakers still in the front of the room ?


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## ryeaustin (Jun 15, 2015)

thanks 

Its changed a bit since then as I managed to get a third single 804d so its just them up front with the sub now with everything else built into ceilings and walls to keep floor/play space.

The response was just left speaker as I thought this would remove complications for the measurements, but happy to run both speakers and post the charts for that if it would be helpful?

Rye


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## chashint (Jan 12, 2011)

I need to pay better attention to everything you post.
Sorry for the questions you have already answered.


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## ryeaustin (Jun 15, 2015)

the bookshelf speakers are gone now, they were only in the photo as my new rears and back speakers were being installed into the walls and I wanted to keep them out of the way and not get damaged. Its the only picture of the room I had to hand but will look to get some more tomorrow which will be more accurate as to how the room is now.


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## ryeaustin (Jun 15, 2015)

Not at all, happy to have some input


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## chashint (Jan 12, 2011)

I have looked at some measurements for the 804D and I think the peak you are getting at 30 Hz is coming from the port.
If you have the bung are you willing to try plugging the port and seeing what happens ?


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## ryeaustin (Jun 15, 2015)

That's a good point, I had forgotten about the bungs. I will dig them out and retest, if that can resolve or help reduce the 30hz bump that's one big out the way.


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## ryeaustin (Jun 15, 2015)

If it will help at all this is the back of the room. There is a bookshelf in the rear left corner but aside from that its a pretty bare room at this point.

Rye


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## bpape (Sep 14, 2006)

You should measure L, R, then both together. both is how you listen and you need to be able to identify what if any issues are being caused by the interaction of the 2.


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## ryeaustin (Jun 15, 2015)

Hi Bryan

I have take some more measurements of the left speaker only, right only and both together. In this chart the green line is the left speaker, purple is right. Oddly the right speaker has a suck out at 50hz that is not present on the left channel but the left channel has a very specific null at 83.8hz. Both speakers are identical spacing from rear and side walls but there is a sub (not run in tests) and bookshelf on the left hand side of the room and the right side of the room is bare.

I also ran a test as suggested earlier with the speaker bungs in place. There are three of these in total. First with a full open bass port (orange), second with the outer part of the bung and no center section (green) and the third with the full bung in place (blue). The bungs do limit the peak at 30hz but the also reduce low end power upto 80hz so not sure if its best just equalise out the peak?

No smoothing was applied to either chart and I have added the REQ files in case these will help.

Bryan, do you still think I am ok to focus on reflections and not worry about the low end/bass traps? If so can you recommend what type of GIK products and quantity so I can get some ordered?

Thanks again for all your help
Rye


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## chashint (Jan 12, 2011)

How does it sound to you?


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## bpape (Sep 14, 2006)

That's a valid question certainly. Also, if you are going to be running a sub, then that needs to be measured by itself and then again blended with the mains. Testing in setups that do not replicate what you are listening to are purely to identify issues - but the one that is set up how you listen is the most important.


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## ryeaustin (Jun 15, 2015)

To me the system sounds pretty good compared to other systems I have listened to, but fast parts of music hang for longer than they should such as drum hits, claps etc. which I know is down to a decay time in the room and I have some unevenness to the low end which is most apparent with switches of low notes where its as if the volume is being turned up or down on the low end. Having said that I am really enjoying the system and it helps me to relax to get some listening in most days of the week. I could live with the low end as it is (its not that bad), but if it can be improved I would be keen to push for that and I am also looking to form a greater understanding of how the room interacts with sound as I have essentially ignored the room in my previous systems and homes. 

The last part of the build now is to add some treatment to aid the room sound yet not effect the usability of the room. Once this is done I can rest for the time being knowing that I am getting the most from my investment and music given constraints on money and space. I don't plan to change this any time soon so would rather complete the build to a good standard and cover all the bases now.


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## ryeaustin (Jun 15, 2015)

Hi Bryan

While the room is also used for home cinema my priority for the room treatment is the 2ch sound. I don't run the sub with 2ch as the main 2 speakers give me just enough bass for me to not want a sub. Also, I have never been able to achieve the same level integration with subs as I get with a good full range speakers out of the box. But that's another topic...

I am very happy with the sound for movies but this is not as critical listening for me. The sub only covers my LFE for the surround system and as long its gives me a cinematic sound and adds impact to films I am not too concerned with the accuracy of the system in surround mode.

From the feedback, it sounds like I am best to focus on the delay times and reflection points on the side walls as a starting point and then see what impact this has before trying to work out a final plan for the room.

Thanks again for the input. I will get some 2" thick panels and start trying things out.


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