Enough Space...

[GO-NAD!]

...for some room treatment? I'm now wondering if I can convince my wife that some acoustic treatment behind my mains is doable, effective and unobtrusive. The total space behind each speaker and under the shelf (the ones above the speakers) is about 5.5ft^2. Is that sufficient area to cover with 4" rockwool and be effective? I only need it to be effective down to 80Hz, or slightly below, as the speakers are crossed over with the subs at that point. The sub FR is much smoother than the mains, so I could apply some EQ to tighten that up. But the mains FR is pretty bad, as you could probably guess, just by looking at the placement.

I'd like some opinions to determine if it's worth the effort, before I bring up the proposal with head office. If it's not enough area, I won't bother to mention it and I'll keep my powder dry for later.

 

[STRONGBADF1]

I'd make some white panels and slide them in there and see what happens...or better yet ask her to pick out the fabric for you.

The only way you'll know is to do it and measure it...unfortunately.

 

[GO-NAD!]

I'd make some white panels and slide them in there and see what happens...or better yet ask her to pick out the fabric for you.

The only way you'll know is to do it and measure it...unfortunately.

I was afraid of that. I wanted to find out if there was a strong potential for improvement before starting. It may come down to simply trying it. If she agrees...

 

[BoredSysAdmin]

Well besides Rives consultation or our dear in-house expert - bpape
you can try this tool:
http://www.atsacoustics.com/page--Free-Online-Room-Acoustics-Analysis--ora.html

 

[westcott]

The only way to know what you need and where to place room treatments is to do some testing. Primarily, your subwoofer placement. Keep moving it around the room until you have the flattest frequency response possible for the listening position(s). Once you have done all your SPL meter testing, then you should know what frequencies need secondary solutions like acoustic panels.

I do not recommend using EQ. Your first priority is to get it flat with speaker placement.

P.S. Sorry, jst saw you had placed your subs in the ceiling. Not much you can do with fixed sub position.

 

[GO-NAD!]

The only way to know what you need and where to place room treatments is to do some testing. Primarily, your subwoofer placement. Keep moving it around the room until you have the flattest frequency response possible for the listening position(s). Once you have done all your SPL meter testing, then you should know what frequencies need secondary solutions like acoustic panels.

I do not recommend using EQ. Your first priority is to get it flat with speaker placement.

P.S. Sorry, jst saw you had placed your subs in the ceiling. Not much you can do with fixed sub position.

The subs aren't really a problem. The FR I get from them is far better than I was getting with my old sub. As for acoustic treatment, panels anywhere else in the room are a non-starter. The only spots that might get approval for, are as mentioned in my first post. I realize that EQ is not everyone's cup of tea. But in my circumstances, it'll be required. I was just wondering if the minimal treatment I was thinking about would be worthwhile in that it would reduce the degree of EQ I would have to apply to the mains.

Thanks for the response!

 

[highfigh]

I was afraid of that. I wanted to find out if there was a strong potential for improvement before starting. It may come down to simply trying it. If she agrees...

Potential for improvement? Absolutely. Stand near a wall and clap your hands. What do you hear after the clap? Move through the room and repeat this, noting what you hear. Play source material with a lot of sharp transient sounds, like gunshots, drums, metal on metal (or other hard materials hitting hard materials). You should be able to hear a definite repeat if the room needs treatment. How long after the initial sound will determine how much treatment and in what range.

To test the effect of room treatments, hang some heavy blankets at the place where the sound would normally hit the walls. You should hear a definite improvement in localization, immediately. If you were hearing a lof of sound coming from the right of your right speaker, left of your left speaker, etc, it should stop. If you have a room that's wider than deep, the back walls will need help, too. Do the same thing and if you need, use graph paper, a straightedge and a protractor. The angle of incidence equals the angle of reflection, just like optics.

What the final treatment looks like is up to you- look around online and you'll see a lot of different ways to not make it obvious. I did mine as a temporary measure because I had to make some panels for a client demonstration but I had also thought my room was better than it is. Now, I need to make them look better.

It made a huge difference in my room, but I do have a calibrated mic and RTA software (TrueRTA, 1/12 octave resolution and REW).

 

[highfigh]

The subs aren't really a problem. The FR I get from them is far better than I was getting with my old sub. As for acoustic treatment, panels anywhere else in the room are a non-starter. The only spots that might get approval for, are as mentioned in my first post. I realize that EQ is not everyone's cup of tea. But in my circumstances, it'll be required. I was just wondering if the minimal treatment I was thinking about would be worthwhile in that it would reduce the degree of EQ I would have to apply to the mains.

Thanks for the response!

The problem with subs isn't first reflections, it's standing waves and the room's dimensions are what affect this. If the sound can be absorbed in the corners (especially when the sub is right next to a wall), it will smooth the response considerably. It's all about the room's dimensions- divide the speed of sound (shown as lower case c)by the three dimensions and you'll find the first mode (standing wave frequency). Divide c by 1, 1.5, 2, 3, 4 and other multiples to find the frequencies that will be problematic. You can also use Ethan Winer's ModeCalc software to see this much faster. That also shows how it affects the sound's amplitude- positively, or negatively.

Don't aim for flat- aim, for smooth.

 

[GO-NAD!]

The problem with subs isn't first reflections, it's standing waves and the room's dimensions are what affect this. If the sound can be absorbed in the corners (especially when the sub is right next to a wall), it will smooth the response considerably. It's all about the room's dimensions- divide the speed of sound (shown as lower case c)by the three dimensions and you'll find the first mode (standing wave frequency). Divide c by 1, 1.5, 2, 3, 4 and other multiples to find the frequencies that will be problematic. You can also use Ethan Winer's ModeCalc software to see this much faster. That also shows how it affects the sound's amplitude- positively, or negatively.

Don't aim for flat- aim, for smooth.

I have my subs crossed over with the mains at 80Hz and the standing wave starts at about 100Hz. Below that, the FR isn't too bad at all. I was fortunate in choosing good locations for the in-ceiling installations. So again, I'm not concerned about the subs. It's the mains that have the standing wave problem. I'm getting significant peaks and dips in the mid to upper bass region. We're talking 8 to 10 dB above and below zero dB. Behind each main speaker, I have 5.5ft^2 of area to play with, including the space under the shelves sited above each speaker.

So, the question stands: is that area (and that area only)sufficient to make treatment a worthwhile investment in time and money? If treating that space is likely to provide negligible results in attenuating the standing wave, I'll not bother with it and I'll just do what I can with the DCX. I don't expect that treatment will do the job entirely. But, if there is a realistic possibility that treatment can knock 3 dB off those peaks and dips from the standing wave, then for me that would be worthwhile.

Thanks again!

 

[lsiberian]

The best place to treat is behind your head. This is the sound that bounces back and makes the sound track sound weird.

 

[GO-NAD!]

The best place to treat is behind your head. This is the sound that bounces back and makes the sound track sound weird.

The space behind the listening position is wide open. It leads to the dining room and front hallway.

 

[jostenmeat]

The space behind the listening position is wide open. It leads to the dining room and front hallway.

Then don't worry about it. Regardless, I disagree with lsiberian's blanket statement. It starts becoming imperative to treat the back wall when you are right up against it, or are very close to it; the places to treat can really vary from setup to setup.

Doug (strongbadf1) probably gave you the best advice yet. Have her pick it out. nibhaz has recommended this method as well.

You can try a DIY kit, and use dye to make your art, if you are so inclined.
http://www.readyacoustics.com/index.php?main_page=index&cPath=26_11

You can also send a pic of choice to GIK for their custom printed panels, though the price gets steep. Here are pics of Glenn's own panels, for instance:
http://forums.audioholics.com/forums/showthread.php?t=52332

Finally, and I know you said the FR is very good from the subs already, but if it was easy enough to accommodate, I'd still aim to treat below 80hz if it was easy enough there. Just me.

 

[GO-NAD!]

Then don't worry about it. Regardless, I disagree with lsiberian's blanket statement. It starts becoming imperative to treat the back wall when you are right up against it, or are very close to it; the places to treat can really vary from setup to setup.

Doug (strongbadf1) probably gave you the best advice yet. Have her pick it out. nibhaz has recommended this method as well.

You can try a DIY kit, and use dye to make your art, if you are so inclined.
http://www.readyacoustics.com/index.php?main_page=index&cPath=26_11

You can also send a pic of choice to GIK for their custom printed panels, though the price gets steep. Here are pics of Glenn's own panels, for instance:
http://forums.audioholics.com/forums/showthread.php?t=52332

Finally, and I know you said the FR is very good from the subs already, but if it was easy enough to accommodate, I'd still aim to treat below 80hz if it was easy enough there. Just me.

I thought about using some acoustic insulation and wrapping it in fabric. As for treating below 80Hz, I suspect I'd have to use far more than I really have space for, in order to be effective. Since it's mid-upper bass that I would like to treat for, I was hoping the available space would be sufficient. I guess I'll make a proposal to head office and see if it'll fly.

Thanks!