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need guidance on room treatments

post #1 of 17
7/2/09 at 6:15pm
Thread Starter 
i have my system all setup and tuned as good as it's going to get without any room treatments.

now my first concern is that i can't really do anything permanent as i am renting this room. i have been here for 4 years and will probably be here for at least a few more. so as long as the treatments aren't permanent in any way i would like to add some. the room is sealed and is 21x14x8 (2400 cu ft). it isn't a dedicated theater. it's more of a big bedroom that i setup as best i could for sound (but there is a bed in the room).

now i really don't know much about this or where to start. i know i'd like to fix uneven stuff in the midbass area and was told bass traps are the solution to that. if bass traps are something i can just hang on the wall like a picture frame that would work.

anybody want to let me know where to get started?

i can provide pics and response graphs for my room if that helps in choosing what i need and where to put them.

here is a quick sketch of my layout:
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post #2 of 17
7/2/09 at 8:51pm
A very good place to start would be right here. Ethan and the RealTraps folks have put together a number of invaluable articles you should read. Ethan, as well as folks from GIK Acoutics, contributes here often, and may well see this and post. He'll likely tell you to start with bass traps in as many corners as you can tolerate, as well as H/F absorbtion at the first reflection points. Most of these can be free-standing, such that there's no damage to your landlord's walls.

Have fun! Proper room treatment will have a profound effect on your system.
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post #3 of 17
7/2/09 at 11:40pm
Thread Starter 
cool, i'll read up on that.

i actually got bored tonight and redid my whole layout. i moved the bed to the back of the room against the back wall and then shifted the couch, tv, and all the front speakers to the left so now everything is symmetrical like a dedicated HT room would be. now both mains are the same distance from the side walls and this also let me pull the mains out from the back wall a few more inches.

initial testing and tuning is already showing much better results than before. i used to have a few ripples in my midbass, and now i just have one narrow null that i'm thinking i still need bass traps to fix. so far the whole system seems to image better and more clearly now that everything is as symmetrical as can be.

i have also read that if the sub is to be placed along the front wall, the best spot is in 1/3 increments and luckily enough now it is and my bass response is smother and more extended than before.

i always knew in the back of my mind that making everything more symmetrical would have better results, but i was never willing to rearrange my room to do it but tonight came up with an idea that would work well.

i'm still planning to do room treatments but now i think it will be even easier now that things are symmetrical.

i do have one more question though. my top end above 10k seems to drop off a little quicker than i'd like. from 10k to 12k it drops down about 6-8db and then stays flat like that all the way to 20k. is that normal? do i want it flat to 20k, and if so, any tips to make it happen?
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post #4 of 17
7/3/09 at 6:34am
Call up Ethan. Get a couple of 2 to 4 inch panel absorbers for the wall behind the mains first. What it will do for your imaging I can't even describe. Then you will be a believer so solidly you will not flinch at the cost of the next steps.
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post #5 of 17
7/3/09 at 6:47am
Thread Starter 
Quote:
Originally Posted by tvrgeek View Post

Call up Ethan. Get a couple of 2 to 4 inch panel absorbers for the wall behind the mains first. What it will do for your imaging I can't even describe. Then you will be a believer so solidly you will not flinch at the cost of the next steps.

cool, sounds like a plan. not sure when i'll be buying, right now i'm just trying to research and find info. once i get a job again it'll be first on my list, followed by a second subwoofer.
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post #6 of 17
7/3/09 at 9:02am
Quote:
Originally Posted by RUR View Post

He'll likely tell you to start with bass traps in as many corners as you can tolerate, as well as H/F absorbtion at the first reflection points.

Indeed I would.

Quote:


Most of these can be free-standing, such that there's no damage to your landlord's walls.

That too. Acoustic panels can hang on the walls like a picture, or can be placed on stands. They even work just sitting on the floor leaning into corners and against the walls.

--Ethan
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post #7 of 17
7/3/09 at 10:59am
Thread Starter 
Quote:
Originally Posted by Ethan Winer View Post

Indeed I would.



That too. Acoustic panels can hang on the walls like a picture, or can be placed on stands. They even work just sitting on the floor leaning into corners and against the walls.

--Ethan

what do the corner bass traps look like? the only problem i see is that the doorway to this room is right on a corner. from the corner to the door frame is 3 inches or so.

hanging the treatments on the wall like a picture would be ideal for the other stuff. is it complicated to figure out where the first reflection point is? i'm a total newb when it comes to room treatments. the only acoustic stuff i have done so far is put an Auralex GRAMMA under my sub which made an amazing difference.

i'd definitely like to continue to make this system sound even more amazing. i think i have done all i could do, short of treatments. i'm ready for the next step.
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post #8 of 17
7/3/09 at 12:08pm
You can use the mirror trick to find first reflection points. But it requires a friend to help.

With you in your listening seat, have your friend run a mirror along the walls (and floor and ceiling if you really want) until you can see your speakers reflected by the mirror. That's the first reflection point and where you want to put treatments.

I have a Ethan Winer-inspired bass panel trap and about a dozen DIY acoustic panels. Even talking in one room versus the other, the difference is tremendous. The panel trap required holes in the wall, but the acoustic panels are just held in place with string and eye hooks about the size of what you'd expect for hanging a picture.
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post #9 of 17
7/3/09 at 12:40pm
Thread Starter 
Quote:
Originally Posted by NekoAudio View Post

You can use the mirror trick to find first reflection points. But it requires a friend to help.

With you in your listening seat, have your friend run a mirror along the walls (and floor and ceiling if you really want) until you can see your speakers reflected by the mirror. That's the first reflection point and where you want to put treatments.

I have a Ethan Winer-inspired bass panel trap and about a dozen DIY acoustic panels. Even talking in one room versus the other, the difference is tremendous. The panel trap required holes in the wall, but the acoustic panels are just held in place with string and eye hooks about the size of what you'd expect for hanging a picture.

the mirror trick sounds simple. good trick. i was hoping that there wasn't math involved.

what does the treatments do to the freq response and imaging? i keep reading that it all makes a huge difference. my freq response is already 90% of my goal, and my imaging after rearranging thing last night is amazing already as well.

i was cranking my system today louder than i ever have and it was simply amazing. such a huge difference after placing the speakers where they belong.
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post #10 of 17
7/3/09 at 5:44pm
If you've ever heard an outdoor concert or singing in the shower, then you have heard the difference created by sounds bouncing around. At an outdoor concert, the sound is not being reflected. In the shower, the sound is being reflected a lot.

Now, obviously shower singing tends to sound good to people. It's full, vibrant, and a surround experience. But it is not an accurate or precise reproduction of your singing voice.

Room treatments make your room more like the outdoors. The frequency response you hear will be closer to what is coming out of the speaker / instrument. You won't have reflections from all over the place making it sound like there is additional sound or that sounds are coming from different locations. It will be more difficult for room modes to form, removing echo and preventing nulls.

So it might take some getting used to, and it may change things in ways you don't like. But it will be more accurate and precise, and it isn't going to sound like that vibrant shower singing which you may like.
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post #11 of 17
7/3/09 at 6:09pm
Thread Starter 
cool. thanks
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post #12 of 17
7/5/09 at 12:27pm
Quote:
Originally Posted by mcjasonb View Post

what do the corner bass traps look like?

There are many types, but they need to be fairly large to be effective at bass frequencies. The most common type is a flat panel, typically 3 inches thick or more, and 2 by 4 feet or larger. Most rooms need at least four of them to get a meaningful improvement.

Quote:


the only problem i see is that the doorway to this room is right on a corner. from the corner to the door frame is 3 inches or so.

In that case you can use two traps, one flat on the wall and another on the door. Or skip the door and just have one on the wall. That works well as long as it's near to a corner.

Quote:


hanging the treatments on the wall like a picture would be ideal for the other stuff.

Bass traps can be mounted that way too. It's not a big deal to mount them. The larger problem is usually convincing the spouse to "allow" them in the room. Unless you have a dedicated room.

--Ethan
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post #13 of 17
7/5/09 at 12:40pm
Thread Starter 
There are many types, but they need to be fairly large to be effective at bass frequencies. The most common type is a flat panel, typically 3 inches thick or more, and 2 by 4 feet or larger. Most rooms need at least four of them to get a meaningful improvement.

sounds good

In that case you can use two traps, one flat on the wall and another on the door. Or skip the door and just have one on the wall. That works well as long as it's near to a corner.

i could put a panel on the wall near the corner and the door itself, that should work.

Bass traps can be mounted that way too. It's not a big deal to mount them. The larger problem is usually convincing the spouse to "allow" them in the room. Unless you have a dedicated room.

no problem there, this room is mine and mine alone. i can do anything i want with it, as long as it's not permanently damaging the walls.

--Ethan
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post #14 of 17
7/6/09 at 10:35pm
Quote:
Originally Posted by Ethan Winer View Post

There are many types, but they need to be fairly large to be effective at bass frequencies. The most common type is a flat panel, typically 3 inches thick or more, and 2 by 4 feet or larger. Most rooms need at least four of them to get a meaningful improvement.



In that case you can use two traps, one flat on the wall and another on the door. Or skip the door and just have one on the wall. That works well as long as it's near to a corner.



Bass traps can be mounted that way too. It's not a big deal to mount them. The larger problem is usually convincing the spouse to "allow" them in the room. Unless you have a dedicated room.

--Ethan


Can you hang a cloth or canvas over a bass trap to 'hide' them without affecting how they work?

For instance something like a wall scroll: http://farm3.static.flickr.com/2166/...a63b7def58.jpg
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post #15 of 17
7/7/09 at 8:45am
Quote:
Originally Posted by Audio_Newbies View Post

Can you hang a cloth or canvas over a bass trap to 'hide' them without affecting how they work?

For instance something like a wall scroll: http://farm3.static.flickr.com/2166/...a63b7def58.jpg

Yes, you can. My informal testing has shown you should use wall scrolls featuring Bubblegum Crisis: Tokyo 2040 for maximum rock absorption, Haibane Renmei for maximum jazz absorption, Princess Mononoke for maximum classical absorption, and GitS:SAC for maximum electronic absorption.

You should have them wrapped in something anyway, because otherwise bumping into them can knock off parts of the semi-rigid fiberglass. Also, wall scrolls are about 3' wide, 4' tall. So you'd need to make sure your panels are the right size to avoid making your wall scrolls non-flat.
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post #16 of 17
7/7/09 at 7:21pm
Quote:
Originally Posted by NekoAudio View Post

Yes, you can. My informal testing has shown you should use wall scrolls featuring Bubblegum Crisis: Tokyo 2040 for maximum rock absorption, Haibane Renmei for maximum jazz absorption, Princess Mononoke for maximum classical absorption, and GitS:SAC for maximum electronic absorption.

You should have them wrapped in something anyway, because otherwise bumping into them can knock off parts of the semi-rigid fiberglass. Also, wall scrolls are about 3' wide, 4' tall. So you'd need to make sure your panels are the right size to avoid making your wall scrolls non-flat.

Great! I have a small listening area so I think small traps might work for me.
I didn't know certain anime was better at absorbing certain types of sound than others! Speaking of which color can affect temperature, like black traps in heat better than white. Can color affect sound absorbtion?

Sorry for all the dumb questions but as you can see I'm an audio newbies.
What type of materials are bass traps typically made from? Are any materials typically used potentially hazardous or cancerous?
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post #17 of 17
7/7/09 at 7:47pm
Well, typical acoustic panels are 2' wide x 4' tall, because that's the size of semi-rigid fiberglass. That doesn't match wall scroll size. Color won't affect sound absorption. Color absorbs light (since color is the presence of light) and converts it to heat. Black absorbs lots of light and so it has a lot to convert to heat.

Semi-rigid fiberglass was thought to be cancerous because it is fibrous like asbestos. However long-term studies have now shown it to only be an irritant. I purchase my semi-rigid fiberglass from a local commercial insulation company and this is what their tech guy told me last time I was there.

Anyway, that probably answers your other question as well. Acoustic panels are typical built of semi-rigid fiberglass, but some people use mineral wool (there's a section in that link on health risks) or standard foam. Standard foam isn't as good. There are a number of companies, Ethan Winer's RealTraps included, that sell pre-built panels.
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