Advice on accoustic panel placement - AVS Forum
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post #1 of 17 Old 12-06-2013, 02:38 AM - Thread Starter
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This weekend I'm installing floor to ceiling corner bass traps and 6 Gik 244 bass traps. 2 on each side wall and 2 on the ceiling. These are 5" in depth

I was originally planning to install the panels like pic1, but after measuring my reflection points with a mirror - ideal panel placement is not going to be as practical as I would like. Plus the WAF, and she helped me locate the reflection points.

Pic2 has numbered stars for the 6 RP's, and I can wall mount them horizontally in these spots with a few challenges. However, the ceiling is ONLY 6.5ft high and it's even lower on the right side, so the ceiling panels would fit best - closer to the TV where the ceiling is all one height.

My question is - if I place my panels like pic1 rather than hitting the all true RP's (pic2), am I wasting panels? I would be able to keep them away from the couch and mount them all vertically and symmetrically, but if their not effective, then what's the point.




Room Dimensions:
L30 X W11 X H6.5
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post #2 of 17 Old 12-06-2013, 03:17 AM
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Call GIK directly, you paid for this type of service Q&A when you bought their panels.
Glenn will 100% agree.

My Q:
I assume you gave GIK your exact room dimensions, speaker locations, and seat locations.
If so, their ray trace analysis and panel location should be spot on, what am I missing??
or, is the GIK image you supplied a generic one not your specific analysis.
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post #3 of 17 Old 12-06-2013, 03:30 AM - Thread Starter
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It is a generic image. Should have noted that.

GIk has been extremely helpful.
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post #4 of 17 Old 12-06-2013, 03:40 AM
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You want to manage your first reflections, so if you do not place them where they belong, are you managing your sound reflections?

Simple answer: no

nice write up's
http://gikacoustics.com/early-reflection-points/
http://ethanwiner.com/acoustics.html#rfz

reflections are a good thing, they add ambiance and depth to a room, your task is to manage them

member fotto (Floyd) did a great thread here, read up Room Measurement & Treatment
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post #5 of 17 Old 12-06-2013, 03:50 AM - Thread Starter
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What about just moving the ceiling panels towards the TV area? Probably defeating the purpose, right?
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post #6 of 17 Old 12-06-2013, 03:59 AM
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Guess I'm truly missing what the issue is here.
The panels need to go where they do their task, not what looks right.

Put the side walls on first, get used to that.

The ceiling, yours will go from 6'6" to 6'1" where these are, then you Gotta duck eek.gif
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post #7 of 17 Old 12-06-2013, 08:03 AM - Thread Starter
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The issue is that the ceiling panels will be too low in the center of the room. We also use XBOX kinect.

So if I put the ceiling panels near the front, out of the way - will they still serve ANY purpose for absorption and/or reflection? If not I may re-purpose them on the walls.

Just trying to weigh out all my options here. Thanks
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post #8 of 17 Old 12-06-2013, 09:38 AM
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Acoustic treatments are put in place for a reason

Technically, you want the first reflections to be -20db below the direct sound in the first 20-30ms or so, hence people use the ETC chart to verify that.
Doing that can be accomplished by:
-speaker selection and placement
-room design/layout features
-acoustic panel type ; absorption, diffusion, B.A.D. panels, etc

Putting panels where the do NOT impact the above may/may not be a bad thing, it depends....but why spend $ if not needed?
If applying absorbers, then putting them where not needed will absorb some sound energy, possible making your room too "dead" sounding

Ray trace simulation of my room, showing where first reflections are:
Reflections%2520side%2520view.jpg . Reflections%2520Frt%2520view.jpg

My room layout sketch, see my side wall panels and my ceiling cloud panels:
HT%2520Plan%25202x4%2520Seats-Riser-acoustics%2520Nov-2013_subs.jpg

screen shot:
HT%252011.3%2520cover%2520off%2520Pano-b.jpg


If you have 2 rows of seats, then possible you do need some treatments for the 2nd row.
Can you post a plan view to scale layout of your room?
Hard in a picture to grasp details.

Are you going willing to spend $80 for a USB measurement mic and really know your acoustics?
http://www.avsforum.com/t/1449924/simplified-rew-setup-and-use-usb-mic-hdmi-connection-including-measurement-techniques-and-how-to-interpret-graphs
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post #9 of 17 Old 12-06-2013, 12:15 PM - Thread Starter
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I only have one row of seats. I am willing to spend $80 to do this right. Maybe I'll hold off a while on mounting the ceiling panels - to avoid unnecessary holes in the ceiling.

Is the software (trace) from your screenshots the XP app that a forum member developed? Or is that the REW? I'll do some research and read the thread you posted this weekend.

I would imagine the app is much more accurate than the mirror trick and also accounts for center channel RF points. Appreciate all the info.
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post #10 of 17 Old 12-06-2013, 01:58 PM
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look here for the ray tracing software http://www.avsforum.com/t/822273/free-software-to-help-determine-your-first-reflection-points/240#post_22619555

Have fun, after all it's a hobby not world peace rolleyes.gif
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post #11 of 17 Old 12-06-2013, 03:58 PM
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I just used a drawing package on the PC, with triangles (apex at wall/ceiling/floor, sides intersecting speaker and listening positions), sizing the triangles to ensure angles of incidence and reflection were matched. It sounds more complicated that it is to do.

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post #12 of 17 Old 12-08-2013, 04:59 AM
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Schuyler: you also need to space those side walls panels out from the wall by at least 2" and if you want to do it right, they need a 4" air gap between the panel and wall.

I have constructed absorbing panels for both myself, and probably a half dozen of my friends, absorbing panels that are 4" thick and have a 4" air gap between the panel and the wall. This is a critical step when it comes to applying absorbing panels.
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post #13 of 17 Old 12-08-2013, 06:00 AM - Thread Starter
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I plan play to around with different placements. I'm looking at REW and Dayton UMM-6 USB microphone. I understand that by using this I can better treat my room, but will this enable me to further adjust Audyssey MultEQ XT32 or just see exactly what it's doing - in relation to the changes I make in the room?

Other than a laptop and USB mic, would I need anything else with my AVR (Onkyo TX-NR5008)? I have a tripod - shouldn't need a mic stand/boom right?
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post #14 of 17 Old 12-09-2013, 12:34 PM
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Quote:
Originally Posted by Martycool007 View Post

Schuyler: you also need to space those side walls panels out from the wall by at least 2" and if you want to do it right, they need a 4" air gap between the panel and wall.

I have constructed absorbing panels for both myself, and probably a half dozen of my friends, absorbing panels that are 4" thick and have a 4" air gap between the panel and the wall. This is a critical step when it comes to applying absorbing panels.
+1, hence I made this to explain.
As can be seen truly needs 4" material + 4" air gap to go down to 300hz, however many can't go that so I always say 2" material + 2" air gap, which gets you to 600hz, is the minimum acceptable
Acoustic%2520treatment%2520material%2520plus%2520airgap%2520explain.jpg

related to
Interactive-Frequency-Chart.jpg

Quote:
Originally Posted by Schuyler Bain View Post

I plan play to around with different placements. I'm looking at REW and Dayton UMM-6 USB microphone. I understand that by using this I can better treat my room, but will this enable me to further adjust Audyssey MultEQ XT32 or just see exactly what it's doing - in relation to the changes I make in the room?

Other than a laptop and USB mic, would I need anything else with my AVR (Onkyo TX-NR5008)? I have a tripod - shouldn't need a mic stand/boom right?

Well, if you have minidsp or a PEQ unit you can do some tweaks before MultEQ XT32, aka, flatten the peaks below 200hz to help MultEQ XT32 .... if not then REW/Mic helps you with acoustic treatment placement and verification.

Tripod works fine, just put it in the seat, I've done that many times.
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post #15 of 17 Old 12-11-2013, 07:47 PM
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Is 4"of material as good as 2"and 2"air gap?
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post #16 of 17 Old 12-12-2013, 09:56 AM
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Quote:
Originally Posted by a|F View Post

Is 4"of material as good as 2"and 2"air gap?
Yes, the point of the air gap is taking advantage of physics and wave mechanics, you can get more performance for "free".
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post #17 of 17 Old 12-12-2013, 09:59 AM
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Quote:
Originally Posted by a|F View Post

Is 4"of material as good as 2"and 2"air gap?

Better in fact (depending on the exact material used).

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