Acoustic panel placement quandry

strube

strube

Audioholic Field Marshall
The time has come for me to look to the experts!

For anyone who hasn't seen my HT thread, my room is set up rather uniquely due to space constraints. Due to the layout of the approximately 12'x12' room, the way things are set up are how they have to be, and I have accepted the impact the setup will have on sound. Hopefully a little acoustic treatment will help. Here are a few pictures:





This was taken before the fourth chair or back acoustic panels/window shades were added.



After my rear sliding window covering panels, I have 5.5 Owens Corning 703-equivalent fiberglass panels remaining to make treatments.

I have kind of been out of the Audioholic self-education game for a while and never dug incredibly deep into setting up good room treatments because I have been somewhat of a nomad until now.

I guess what I am looking for is comments or suggestions on how to proceed with treatments. Asthetics are more important to my wife, so I may have to make some audio-sacrifices to maintain symmetry and avoid any really wild panel placement, including ceiling treatments. I don't really have any space for corner bass traps either.

Also note that the poor, sad Paradigm PS1200 that has served me well for about 7 years is moving out. Following that, on either side of the center channel will appear a shiny pair of Velodyne DD15s.

I kind of assumed first reflections on the side walls were a given, but began to wonder if the proximity of the right channel to the right wall would make it undesirable (or extra desirable) to treat the right wall so near the speaker...

I planned on using the half panel on the wall next to the closet, and a panel on the outside closet door.

Any comments and recommendations on how to proceed would be greatly appreciated!

  • Do I put three panels on the right wall for first reflections of each of the front three speakers (or is that right channel proximity a reason not to treat the right wall for that speaker)?
  • Do I bother putting panels in the closet of the adjacent room behind the L/R speakers?
  • Should I have panels behind the sealed center channel or sub?
  • Is there somewhere else besides any of the places I have thought of that might better suit a panel location?

Thanks for your help! :)

strube
 
J

jostenmeat

Audioholic Spartan
I'm just a non-expert enthusiast, but I've spent a decent amount of time picking up little scraps of knowledge off the floor that the experts leave for me. The most immediate issue in most rooms is bass. This becomes even more true with a smaller room. 12x12 as a square is particularly bad, but since your room doesn't look to be a perfect square, maybe it's not so bad after all.

Some would say that it's impossible to go overkill with bass trapping. You are in a pickle with nice paint and trim, with one corner being the entrance. See, the corners are the best place to trap bass in many cases, usually with the front two getting more focus.

However, certain experts like b pape have never wavered so far as I have seen in saying that the back wall is extremely important, perhaps the most important, place to treat when you are up against it. Given the very limited placements you have to begin with, you might consider just continuing with the back wall.

Now you want to be assured that you place them in the best places. Well, it was nice for me to see Savant say that it's a lot like anything we do: taste. Like salt and pepper, add to taste, and experiment with placements too. When you have traps built, try them in the back, then prop them on the sidewall, then other places, and hey, where do they seem to make the most positive effect?

I could not tell you what the thresholds are, but the need for treating any particular boundary boils down to the delta in SPL between the direct audio and reflected audio, as well as the delta with time/delay. Of course, the closer the reflection is in SPL or time, the more likely it needs to be treated.

I am curious, how much open space is there right behind the speakers, and how much distance is there between the backs of the mains to the boundary?
 
just-some-guy

just-some-guy

Audioholic Field Marshall
that screen wall. is it a type of false wall ?
looks too me it is.

is the ceiling bare ?
 
strube

strube

Audioholic Field Marshall
I'm just a non-expert enthusiast, but I've spent a decent amount of time picking up little scraps of knowledge off the floor that the experts leave for me. The most immediate issue in most rooms is bass. This becomes even more true with a smaller room. 12x12 as a square is particularly bad, but since your room doesn't look to be a perfect square, maybe it's not so bad after all.

Some would say that it's impossible to go overkill with bass trapping. You are in a pickle with nice paint and trim, with one corner being the entrance. See, the corners are the best place to trap bass in many cases, usually with the front two getting more focus.
Thank you for your insight, sir.

Closer to true dimensions, ignoring the angled entry area: 12' wide (seating axis), 11' long (viewing axis) and 9' high.

You could probably say my room is one big acoustic compromise. I am pretty much going to have to rely on my seating for most of the bass trapping - no space in any corners of the room for traps. I am wondering, though, if putting traps in the corners of the closet would help any.

However, certain experts like b pape have never wavered so far as I have seen in saying that the back wall is extremely important, perhaps the most important, place to treat when you are up against it. Given the very limited placements you have to begin with, you might consider just continuing with the back wall.
I certainly have room to throw a couple more panels on the back wall. I need to consider how it will affect my sliding window panels, though. My wife likes to open up that window to air out the house more often then I was expecting. If they were hung by velcro, that should work - they could be easily hung and removed as needed.

Now you want to be assured that you place them in the best places. Well, it was nice for me to see Savant say that it's a lot like anything we do: taste. Like salt and pepper, add to taste, and experiment with placements too. When you have traps built, try them in the back, then prop them on the sidewall, then other places, and hey, where do they seem to make the most positive effect?
This is a great suggestion, and is probably my best plan of attack. I am wondering though, how will EQ affect the placement? Should I re-run Audyssey every time I move panels around?

I could not tell you what the thresholds are, but the need for treating any particular boundary boils down to the delta in SPL between the direct audio and reflected audio, as well as the delta with time/delay. Of course, the closer the reflection is in SPL or time, the more likely it needs to be treated.
I think it sounds like for sure I need to at least treat the left wall for the left speaker's first reflection and similarly for the right wall/right speaker since they are so near the wall. Because of the aspect ratio of the room and layout, treating either side wall for the opposite main or the center may be less important than the back wall.

I am curious, how much open space is there right behind the speakers, and how much distance is there between the backs of the mains to the boundary?
There is 17.5 inches from the back of the mains to the back wall of the closet, and there is about 2" of clearance around the sides and tops of the mains to the boundary of the holes in the wall. Both speakers are toed in a little. On the left speaker, since it is in an angled hole, the back of the speaker is fairly close to the front of the hole on the left side. Here are some pictures.

Left channel in the angled wall:








Right channel:





that screen wall. is it a type of false wall ?
looks too me it is.

is the ceiling bare ?
The wall is very real. The theater was originally intended as a bedroom, and I cut holes in that wall for the speakers. The backs of the speakers are in the closet of the adjacent bedroom.

Ceiling treatments have been vetoed. :)
 
J

jostenmeat

Audioholic Spartan
You could probably say my room is one big acoustic compromise. I am pretty much going to have to rely on my seating for most of the bass trapping - no space in any corners of the room for traps. I am wondering, though, if putting traps in the corners of the closet would help any.
I would bet good money that treating for bass inside the closet will help a lot. I could be wrong, and I'd PM an expert or two so that they can chime in. My instinct is to say that you will want somewhere between most and all of your remaining material to go in there.
This is a great suggestion, and is probably my best plan of attack. I am wondering though, how will EQ affect the placement? Should I re-run Audyssey every time I move panels around?
EQ is last. Rerunning Audyssey every time would be an utter nightmare, and I don't think you need to anyways. Just defeat it. Then play around. Once you have decided on placements for sure, then run AS at the end.
I think it sounds like for sure I need to at least treat the left wall for the left speaker's first reflection and similarly for the right wall/right speaker since they are so near the wall. Because of the aspect ratio of the room and layout, treating either side wall for the opposite main or the center may be less important than the back wall.
I'm going to vote for throwing all of the material in the closet. I am even thinking superchunk traps maybe. At the very least, panels at the closet corners straddling. What I would be curious about is how much positive effect throwing up a large panel directly behind each of the speakers would sound; or what I mean is that I'm curious if all of it should go towards corner bass, or if the material should be split up. I'm going to guess some splitting up would be ideal, but I suppose it also depends how much you have. The corner trapping, as my enthusiast guess, is mandatory. For bass, you will want the traps to be thick enough. If you are planning on going with the same thickness as the traps you now have, well I don't recall their thickness, but by the photo here my guess is that it's not thick enough to be effective for bass in there.
 
Alex2507

Alex2507

Audioholic Slumlord
I'm with JM on straddling the corners. A while ago I read through a bunch of nibhaz's posts. He produced info stating that for that application lower density (the cheap stuff) FG actually worked better for LF.

Leaning a panel up against the wall behind each speaker seems like a good plan too. It's more effective if you pull the bottom out like a foot from the wall. I'm pretty sure JM mentioned the bags that Ready Acoustics sells as being a convenient method of containment for experimental placement of panels.

I think some Grammas are called for in room as well. Reading nibhaz's posts was pretty enlightening for me. Your room looks great. Boldly cutting into a shear wall where no man has cut before paid off. Congrats on having Monster Balls. :D

Oh yeah ... pull your seating away from the back wall as much as you can ... even if it's only 6 inches. ;)
 
just-some-guy

just-some-guy

Audioholic Field Marshall
if that is a closet, fill it with cloths = free bass trapping.

i would do something on the closet doors. that white has too be a major reflection.

no ceiling treatments. is that because 2x4 panels are considered ugly ?

how about some panels on the front wall ?
 
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