Acoustic panel advice

[Loudly Does It]

Need some help with setting up acoustic panels.  I have a 17 x 23 x 20 living room.  Even with a 9 piece sectional and a 7' x 10' rug in front of the sectional, the echo in this room is unbearable.  Conversations are annoying and when I turn up a good movie, it can be annoying too.  Above 8 feet there is just too much bare wall.  Tv and main speakers are on one of the long walls and the sectional is about a foot off the adjacent short wall and opposite long wall.  One wall, partially opens to the rest of the house and then stairs that lead up so there is a partial wall at the 23 ft and then half way up I'm assuming 30 feet because of the stairs.  I need help setting up my panels.  I know the horn loaded tweeters are a little different.  There isn't as much reflection to worry about.  I have convinced the wife to set something up directly behind the listening position.  I'm making panels from roxul 2 in. thick rockwool.   She finds them too thick if we go three.  She found some fabric that will work and I've made some panels to make patterns she wanted that we're setting up.  So I want to know if there is anything other than behind my head I should worry about.  My fronts are Rf-5 for mains and Rc-7 for center.  I'm using the quintents I have for side surrounds.  I may experiment with one behind the couch after its all set up and see if I notice an improvement, but otherwise 5.1 is what I'm worried about for now.  Eventually I want to upgrade my rears.  Thanks.

[RoboKlipsch]

How "bad" a room is can often be defined roughly by clapping very loud (one clap at a time).  

You hear "ringing" when you do this in a bad room, and the worse the room the more the ringing.

 

I would guess, depending upon where you stand when you clap, you have a pretty serious ring and the sound of the ring itself may be smearing.  

Go into a different room now and clap and hear the difference.  it can be incredible to hear the contrast.

 

I've spent a lot of time in the last 9 months treating one of my theaters, I would be happy to share what I learned.

 

As far as building the panels, I recently built another set using Roxul 60, and I will tell you in the room you are describing, you want to use as many 4" thick panels as possible.

if a compromise needs to be reached, then 2" is the minimum but I strongly recommend 4".   There's a lot of long explanations to things but the short version is, when treating a room and doing it minimally (as in, not using 20+ panels to really go at it) you need to trap the bass frequencies at least as much as the higher frequencies.  To do so you need thicker panels.  3" is the bare minimum and 4" is really kind of the standard for what is often called a "broadband absorber."  

 

If you could share a sketch of the room, or some pictures, it would go a long way towards figuring out the basics of treatment.

 

The most common issues to treat, of roughly equal importance are:

 

1) Early reflections.  This is what hits your ears right after the direct sound from the speakers.  Typically these are on the side walls between you and the source.  They are also located, depending upon the room and layout, on the front wall, the back wall, the ceiling, and the floor.  People often use a mirror test to gauge these, where a mirror is held flat against a wall and moved until the person sitting at the listening position can see the speaker.  At roughly that point, there is an early reflection that should be treated.

 

2) Low frequency decay times.  Bass traps, or really most often, broadband absorbers are used to reduce the decay time in the low frequency region.  As much as you think you hear echoes and reflections of the higher tones (you do), the bass in the room is an even bigger killer of clarity and comfortable listening.

 

Tell me you have only 2 panels to deploy without me knowing much else, I recommend you place them at the side wall early reflection points to absorb reflections in as many listening seats as possible (you may need 2 per side if there is a big listening area).  Given only 2 I would again say I want 4" panels but if the wife won't have it, 2" is still OK (but misses out on absorbing the low end).

 

I would then want to deploy as many broadband (4") absorbers as possible in other places, ideally some in the corners if the wife can allow it.  

 

Pictures or a sketch would help tremendously, having an idea what you can and can't change would help, and knowing how many panels you are building or think you could get into the room before the wife explodes would help too   

 

[minermark]

Good common sense advice, i like it.

 

 

[hsosdrummer]

You don't mention if the floor is carpeted or not. If it isn't, you need to put some area rugs in there. Reflections off of wood or tile floors can play havoc with an audio system.

 

As for acoustic absorber panels, they will effectively absorb frequencies with wavelengths up to 2x their thickness — half the wave gets absorbed on its way in, the other half gets absorbed on its way out after reflecting off the wall. For example, a 2-in thick panel will absorb up to 4-in wavelengths (roughly 3kHz and higher). A 4-in thick panel will absorb down to about 1.5kHz. These relatively thin panels will do very little for frequencies near and below 1kHz (roughly a 1-ft wavelength, requiring a 6-in thick panel for absorption).

 

Except at the areas of first reflection — all of which should receive absorption or diffusion (see below) — don't place absorbers directly across from one another. This can overly dampen a listening space, making it sound unnaturally dull. (I know this isn't your current problem, but overdoing absorption can simply trade one acoustics problem for another.) If you use absorbers on the bare walls above 8 ft, I recommend staggering them so that the wall space directly opposite of each absorber contains no absorption. This will help the room sound like a more natural listening environment.

 

In my opinion your best bet for dealing with surface reflections in a large room is to diffuse them, rather than absorb them. Using the mirror trick described earlier in this thread, find the areas of first reflections and place bookcases or other irregularly-shaped furniture items there. This will randomize the reflections, reducing their amplitude before they reach the listening position. Another advantage to diffusion is that it generally works down to lower frequencies than absorption, since diffusers that are effective down to or below 1kHz are generally less expensive and more décor-friendly than absorbers that are equally effective down that low.

 

If your room has serious problems below 100Hz, the only real cure is taking accurate measurements and using narrow-Q parametric EQ to reduce the large response peaks. If you measure large valleys in bass response DON'T attempt to use EQ to increase their output. You'll drive your amp(s) into clipping and will likely damage the speakers without having much real impact on the response. Placing your speakers in the room corners will minimize the number and intensity of bass response valleys, which can't be fixed with EQ, and will maximize the number and intensity of bass response peaks, which can be fixed with EQ. BTW, this type of sophisticated EQ to fix the bass is only available digitally. If you want to stay all-analog you're SOL and will have to use speaker placement, listening location placement and/or brute-force bass trapping (very large and very expensive) to fix bass response problems.

 

 

[JohnA]

Easy Peasey!  Buy some open weave fabric like you see on cubicle walls.  Make wooden frames 2" thick, install 2" duct board and wrap with your fabric to make it pretty. 

 

http://www.owenscorning.com/NetworkShare/EIS/57577-QuietR-Duct-Board-Data-Sheet.pdf

http://www.soundproofcow.com/acoustic-panels/

 

You can also hang tapestries on the walls.  Less effective, but potentially more attractive. 

 

If you have an issue with tones below 125 Hz, you need bass traps.  I imagine your issue is in the 500 to 4000 Hz range. 

[Loudly Does It]

5 hours ago, RoboKlipsch said:

 

 

Pictures or a sketch would help tremendously, having an idea what you can and can't change would help, and knowing how many panels you are building or think you could get into the room before the wife explodes would help too   

 

 

Thanks for the info.  I'll upload a sketch tomorrow.  I don't even have a tape measure in the house.  It's all at a job site right now.  What other info do you need me to provide?  

[Loudly Does It]

53 minutes ago, hsosdrummer said:

You don't mention if the floor is carpeted or not. If it isn't, you need to put some area rugs in there. Reflections off of wood or tile floors can play havoc with an audio system.

 

 

If your room has serious problems below 100Hz, the only real cure is taking accurate measurements and using narrow-Q parametric EQ to reduce the large response peaks.

 

 

Tile floors.  I live in South Florida, so it's all tile.  I did put a carpet in front of the couch.  Not a very thick one, so absorption is probably minimal. 

 

Also how do I determine what frequencies I am having trouble with?  I've been researching that topic but have struggled with getting info on figuring it out.  Thanks. 

[RoboKlipsch]

Buy a umik for about 90bucks and use REW its terrific

[Loudly Does It]

Here's the floor plan of the living room.  The ceiling is 20 ft high.  There is 5 1/4" crown mouldings around the entire perimeter of the living room.  Even over the small section where the second floor jets out into the living room with an opening.  I forgot the measure of the stairs but they are 42" wide.  Windows have blinds.  I don't know if I am missing anything else.  If anything is unclear, let me know.  Thanks. 

[Loudly Does It]

10 hours ago, RoboKlipsch said:

Buy a umik for about 90bucks and use REW its terrific

 

Thanks.  

[RoboKlipsch]

No problem.   The UMIK is actually super easy to use, as is REW.  There are a lot of features in REW but you don't need to use them all right away.

 

 

The only things you want to learn to start really is how to take a basic measurement, and how to read an SPL graph and a waterfall decay graph.  Those two things will tell you pretty much everything you want to know at this point.  With a room that big, it would take a massive amount of treatment to really fine tune it.  But with that said, a minimal amount of treatment can and will dramatically improve the sound space.

 

A few things to consider now:

> Can you move the couch forward, even just a bit?  A foot?  2 feet?  I know that how it looks is key, it's just a question.  The back wall is commonly a place where bass builds up.  

> Is the back right surround (in the picture) there for a reason or could it be on the side wall?  

 

With a couch that far back, even if moved up a bit, you will need to treat some of the back wall in order to improve clarity and speed the decay back there.

With the couch that close to the left wall, you will want to treat some of that wall where the couch is in order to improve the clarity there.  In doing so you may also be treating the side wall reflection on that side.  Front wall treatment will likely only be minimal or none, due to the seating position being so far back.   If the right surround can be moved to the side that will further help and reduce the need for much if any front wall treatment.    For the front wall to really be a key issue in that space, either the back speakers would be pointing at it (which causes interference) or you would need to be sitting much closer.  If nobody usually sits closer than the couch than the distance from the front speakers to the back wall and then back again is far past the point of being an early reflection.

 

To go along with that line of thinking, if the speakers up front sound good and are far from the front wall, there will be almost no issues with SBIR, which can sometimes be a problem with front speaker placement.  

 

Anyway, that's my initial thoughts from the diagram without measurements.  The 10' couch may need treatment all along that wall in order to reduce the strong reflections right behind your head, same for the back wall.  The key thing here is we are at least initially talking about EARLY reflections, not all reflections. A room that big with high walls would take a huge amount of treatment to truly tame fully.  But the goal I assume is to vastly improve the sound overall and greatly imrpove the clarity of dialog.  I can see say 4 or 5 panels on the left wall, perhaps 5 or 6 on the back wall, and then a few on the right wall to limit early reflections especially front the front right speaker (but all of them, really).   

 

Last thought for now...that discussion about panel thickness comes back into play.  A 2" Roxul panel will do a great job of hugely improving the dialog and reducing the powerful reflections from the left and back walls.  A 4" panel will go further in absorbing some of the bass that is lingering in the room.  If only a few 4" panels are to be used, that back left corner is key, as would be the back right corner (if available).  If neither can be used then the 4" panels would go best on the back wall (but would be best in all locations).   If you can mount them a few inches off the wall, they work better, but again that's not the key here the key is a good panel on the wall at all.  

 

[Loudly Does It]

5 hours ago, RoboKlipsch said:

No problem.   The UMIK is actually super easy to use, as is REW.  There are a lot of features in REW but you don't need to use them all right away.

 

 

The only things you want to learn to start really is how to take a basic measurement, and how to read an SPL graph and a waterfall decay graph.  Those two things will tell you pretty much everything you want to know at this point.  With a room that big, it would take a massive amount of treatment to really fine tune it.  But with that said, a minimal amount of treatment can and will dramatically improve the sound space.

 

A few things to consider now:

> Can you move the couch forward, even just a bit?  A foot?  2 feet?  I know that how it looks is key, it's just a question.  The back wall is commonly a place where bass builds up.  

> Is the back right surround (in the picture) there for a reason or could it be on the side wall?  

 

With a couch that far back, even if moved up a bit, you will need to treat some of the back wall in order to improve clarity and speed the decay back there.

With the couch that close to the left wall, you will want to treat some of that wall where the couch is in order to improve the clarity there.  In doing so you may also be treating the side wall reflection on that side.  Front wall treatment will likely only be minimal or none, due to the seating position being so far back.   If the right surround can be moved to the side that will further help and reduce the need for much if any front wall treatment.    For the front wall to really be a key issue in that space, either the back speakers would be pointing at it (which causes interference) or you would need to be sitting much closer.  If nobody usually sits closer than the couch than the distance from the front speakers to the back wall and then back again is far past the point of being an early reflection.

 

To go along with that line of thinking, if the speakers up front sound good and are far from the front wall, there will be almost no issues with SBIR, which can sometimes be a problem with front speaker placement.  

 

Anyway, that's my initial thoughts from the diagram without measurements.  The 10' couch may need treatment all along that wall in order to reduce the strong reflections right behind your head, same for the back wall.  The key thing here is we are at least initially talking about EARLY reflections, not all reflections. A room that big with high walls would take a huge amount of treatment to truly tame fully.  But the goal I assume is to vastly improve the sound overall and greatly imrpove the clarity of dialog.  I can see say 4 or 5 panels on the left wall, perhaps 5 or 6 on the back wall, and then a few on the right wall to limit early reflections especially front the front right speaker (but all of them, really).   

 

Last thought for now...that discussion about panel thickness comes back into play.  A 2" Roxul panel will do a great job of hugely improving the dialog and reducing the powerful reflections from the left and back walls.  A 4" panel will go further in absorbing some of the bass that is lingering in the room.  If only a few 4" panels are to be used, that back left corner is key, as would be the back right corner (if available).  If neither can be used then the 4" panels would go best on the back wall (but would be best in all locations).   If you can mount them a few inches off the wall, they work better, but again that's not the key here the key is a good panel on the wall at all.  

 

 

Thanks for the response.  The couch is about 8 inches off the wall all around.  The towers are 14 inches at their closest point to the wall (they're toed in towards the main listening position) and the center channel 17 inches from the back wall.  I am not sure what "SBIR" means.  Sorry for the newbie response.  The towers have a foot of clearance from the entertainment center and from the little table each has next to it.  I don't know if that's sufficient space though.  Being that it's a living room, it's a trade off to have a living room and home entertainment system in it.  The reason for the right surround being on the back wall is because I really don't have a right wall as that is where my stairs are.  Originally I had a work desk in that corner, which has since been removed.  I was considering moving that speaker to the right wall.  At the landing it is 69 inches high though.  I would just need to get a bracket that would elevate it to get it at the appropriate height.  Treating that reflection point may be difficult because of the wooden banisters.  Or would they help to diffuse the sound a bit?  I'm going to check for the left one later.  Hopefully it's not over the window blinds.  I put a a two inch panel and another two inch but with a three inch frame behind me and I could notice more clarity.  Clarity in the sense of more detail compared to before.   I might use the 3 inch in the middle and surround it with the two inch.  The four inch won't work for aesthetic reasons.   At least that's what the Misses says.  The front wall we might put some panels above the tv, to not have so much bare wall in here.  It wouldn't be directly across from the panels behind the listening position, so as not to have them directly facing each other.   I know that corners are important for bass and low frequencies, but will they help in another location which is not so inconspicuous?  

[Loudly Does It]

Added note.  The right surround on the rear wall doesn't face forward though.  It is on a shelf and facing the seating position.  

[RoboKlipsch]

If you can, take a picture of that staircase area by that surround.   The staircase can help as far as reducing some reflections but staircases (unless carpeted, and even when carpeted), are notorious for major ringing.  We can look at that too potentially.  You're doing it all right so far!

 

With regards to the SBIR, save that for when you have a UMIK later.  It's speaker boundary interference, related to when a speaker is close to a boundary it has reflections that sum with the original source....so for example the main speaker at the front wall will project sound at you but also the reflection off that front wall will do the same just a ms or 2 afterwards....anyway, save that for later.  

[Loudly Does It]

20 hours ago, RoboKlipsch said:

If you can, take a picture of that staircase area by that surround.  

Here's the living room looking towards the stairs.  at the extreme right end of the picture is my right surround.   

 

 

[JohnA]

One thing to remember is that you don't need to "Absorb" all reflections, just significantly attenuate them.  Aside from the rear, panels along the side walls near where the HF might get it's first reflection would be the next place. 

 

And I'd move the listening position at *least* 3 feet off the back wall to avoid bass reinforcement from that wall. 

[RoboKlipsch]

I can't tell the height but would consider moving that right surround to the wall beneath the staircase if that would be above ear level.

On the right side there may be less need to absorb the reflections with the open areas, that is helpful in reducing the # of panels.

 

EIther that is one huge room or  a really small surround...or both!  Can you hear the surrounds with movie playback?

[Loudly Does It]

5 hours ago, RoboKlipsch said:

I can't tell the height but would consider moving that right surround to the wall beneath the staircase if that would be above ear level.

On the right side there may be less need to absorb the reflections with the open areas, that is helpful in reducing the # of panels.

 

EIther that is one huge room or  a really small surround...or both!  Can you hear the surrounds with movie playback?

It's a little of both.  The rear is a Quintent. Eventually I'll upgrade, but until I fix the room acoustics some, a bigger, pricier rear speaker won't be worth it.  I can hear it fine.  They are pretty powerful little speakers.  The room is also 18' x 23' x 20'

[Loudly Does It]

On 5/26/2017 at 11:46 AM, RoboKlipsch said:

I can't tell the height but would consider moving that right surround to the wall beneath the staircase if that would be above ear level.

On the right side there may be less need to absorb the reflections with the open areas, that is helpful in reducing the # of panels.

 

EIther that is one huge room or  a really small surround...or both!  Can you hear the surrounds with movie playback?

 

I put up some panels behind my listening position and a few others spread around just to see both for functionality can give it an "art work type" look to make the room still look good and wow I can already notice a difference.  I just sat down and watch a few scenes from Transformers Dark of the Moon and I've noticed so much more detail.  The surrounds have come alive.  A few times it has felt as if there is a speaker behind me.  I was wondering if adding one behind the couch pointed up would help with 7.1 movies but I don't know if it will improve much now.  I'll experiment with that after everything else is set up.  

[RoboKlipsch]

22 hours ago, Loudnobnoxious said:

 

I put up some panels behind my listening position and a few others spread around just to see both for functionality can give it an "art work type" look to make the room still look good and wow I can already notice a difference.  I just sat down and watch a few scenes from Transformers Dark of the Moon and I've noticed so much more detail.  The surrounds have come alive.  A few times it has felt as if there is a speaker behind me.  I was wondering if adding one behind the couch pointed up would help with 7.1 movies but I don't know if it will improve much now.  I'll experiment with that after everything else is set up.  

That's great to hear!  A few panels in the right places is starting to improve the clarity.  Hopefully your lady will hear it too and understand/appreciate what you're working on.

 

The question earlier about moving the couch came directly from knowing that would be the case about the back wall.  Moving the couch forward would achieve a similar and likely superior experience, but there's compromises with a living room.  You're doing it right by treating problem areas that can't be fixed otherwise (like moving things).  Sitting anywhere along the left wall couch would also be markedly improved with panels absorbing those early reflections.  

 

The right surround would be improved a lot (potentially) by moving it to the hard wall just beneath the staircase, a few feet forward from the back wall.  You would want the left surround to match the distance roughly but both be high enough that nobody would get sound directly in their ears.  This would be a test but I think there would be a huge improvement still.  You might expect surrounds to only work behind or to the side but they do work well still a bit in front of the listening position.  

 

In your current layout you will not gain anything with back surrounds.  This is coming from a guy that loves his back surrounds.  I want you to have back surrounds.  But they won't work with the couch on the back wall.    Move the side surrounds forward, and if you can manage even a few feet behind the couch, back surrounds would work amazingly well then.  With the side surrounds in front of the listening position, the back surrounds would really anchor the sweeping surround effects that begin slightly in front of where you sit.   But this won't work without moving the couch forward so the back surrounds have a bit of room to work.