Acoustic Treatment

[ninjamonkey]

I'm thinking about acoustically treating my home studio mixing room (it's also the performance room), but I'm not so sure what I would need.

 

The room itself is about 14 ft by 35 ft with an 8 ft ceiling. The ceiling is textured - similar to this picture

 

My monitors are on my desk on auralex MoPads. The tweeters are aimed 8 degrees up at my ears. The monitors are facing the long part of the room, and are about 9-10 feet away from the front wall and about 25 feet from the back wall. The front wall left corner is filled by a couch, and the right corner has a bookshelf. The back wall is actually inaccessible as boxes, chairs, and others storage items are filling that space 6 feet out. Perhaps all this storage is acting a huge and oddly-shaped diffusor? ). The right monitor is about 5 feet away from the right wall, which at this location happens to be a bookshelf filled with books. (Possibly acting as another diffusor )

The left monitor is about 1.5 feet away from my PC tower, though the driver itself is slightly in front of the PC tower. About 3 feet to the left of the PC tower is another desk.

 

The floor is carpeted.

 

Any advice on how to treat this room? I'm not experiencing any acoustic problems that I know of, but I often hear how important it is to acoustically treat a mixing/control room.

 

I will try to post some pictures later and provide more accurate measurements.

 

Thanks for your help

[mrbrown49]

Are you up to making your own? I made some like in the thread below. Its the best bargain in the treatment arena, and its really effective.

 

http://acapella.harmony-central.com/forums/showthread.php?t=1982170

[nerol1st]

When you clap your hands in this room is there a sharp slap back? This is what you want to get rid of as best you can. Sounds awful when my room is empty.

[ninjamonkey]

I'm certainly open to making my own.

 

I hear no slap back delay, just a slight reverb (half a second or less)

[nerol1st]

Other than it being alot of work, the DIY stuff is alot cheaper than auralex equivalent.

 

Auralex quoted me a package that runs for $900 for the room I have. I am spending less than $350 total on everything. Although I can't say it will be this cheap for you because your room is larger and I doubt you will get the wood for free (I did).

[ninjamonkey]

I figured it's a lot cheaper to DIY.

 

However, I don't know what I need for the room. That's the point of this thread. I haven't looked at any products to buy or materials for DIY because I don't even know what will be necessary for this room

[Ethan Winer]

 

I don't know what I need for the room. That's the point of this thread.

 

 

You have a big room, so that means you need a lot of treatment. Room treatment is a deep subject, and a complete answer requires far more than will fit into a single reply here. So here's the short version which will get you 99 percent of the way there. All rooms need:

 

* Broadband (not tuned) bass traps straddling as many corners as you can manage, including the wall-ceiling corners. More bass traps on the rear wall behind helps even further. You simply cannot have too much bass trapping. Real bass trapping, that is - thin foam and thin fiberglass don't work to a low enough frequency.

 

* Mid/high frequency absorption at the first reflection points on the side walls and ceiling.

 

* Some additional amount of mid/high absorption and/or diffusion on any large areas of bare parallel surfaces, such as opposing walls or the ceiling if the floor is reflective. Diffusion on the rear wall behind you is also useful in larger rooms.

 

For the complete story see my Acoustics FAQ.

 

There's a lot of additional non-sales technical information on my company's web site - articles, videos, test tones and other downloads, and much more.

 

--Ethan

[Weasel9992]

 

The left monitor is about 1.5 feet away from my PC tower, though the driver itself is slightly in front of the PC tower. About 3 feet to the left of the PC tower is another desk.

 

 

If you can somehow even your positioning out a little, that'll help some, i.e. walls 2.25' out on each side rather than 3' on one side, 1.5' on the other.

 

Ethan's got the rest of the great advice in the bag!

 

Frank

[baadman28]

Very good!!! Support !

 

(Edited by Phil to remove URL's and to say - "buh-bye spammer! )

[Weasel9992]

Now there's a completely random bit of SPAM. Nice.

 

Frank

[Todzilla]

I also believe that DIY yields a lot better results than just putting some Auralex foam up. DIY approaches that encompass bass trapping yield better broad band absorption as opposed to the quick and dirty (not to mention expensive) foam that tends to stop somewhere around mid-range.

[MrKnobs]

 

I also believe that DIY yields a lot better results than just putting some Auralex foam up. DIY approaches that encompass bass trapping yield better broad band absorption as opposed to the quick and dirty (not to mention expensive) foam that tends to stop somewhere around mid-range.

 

 

That's true for thin foam.

 

Auralex MegaLNRDs are hard to beat for bass trapping all the way down to 50Hz. They're wedges and 2 ft on a side. The best solution I've found yet, though a bit pricey.

 

Terry D.

[ninjamonkey]

Ok so I'm really thinking about this acoustic treatment stuff now, but I was wondering something. I'm reading a lot about thick fiberglass, particularly on Ethan's site (very good resource, thank you!). I know carpet is generally a poor absorber because it doesn't absorb low frequencies, but what If I l had many layers of carpet?

 

I've got some fiberglass laying around in my home, but I've got even more carpet, which will be easier to work with. If I layer carpet on top of each other, and get it about 6 inches thick, will that work as a good bass trap just like thick fiberglass insulation?

 

Also, I discovered my walls have 6-inch fiberglass insulation built into the walls. however, I suspect that serves more as sound isolation, rather than room treatment? ( dumb i know)

 

EDIT: I should also mention - it seems like a lot of people do acoustical treatment because their room is very echoey and reverberant. I do not have this problem whatsoever. My room is filled with stuff, and I believe this cuts down on echoes. So I don't believe I need much treatment for instruments, but maybe just a bit of treatment since this is also my control room.

[Weasel9992]

 

EDIT: I should also mention - it seems like a lot of people do acoustical treatment because their room is very echoey and reverberant. I do not have this problem whatsoever. My room is filled with stuff, and I believe this cuts down on echoes. So I don't believe I need much treatment for instruments, but maybe just a bit of treatment since this is also my control room.

 

 

Actually, this isn't true. I've done a bunch of design work for large spaces: churches, schools, theaters, that sort of thing, but the average studio or home AV person is more interested in low-end control (i.e. accurate frequency response and decay time), imagine and generally accurate room response. There are a few now and again where long reverb times are an issue, but they're relatively uncommon.

 

Frank

[ninjamonkey]

Thank you for your response

 

I think this weekend I am going to build a few rigid fiberglass bass traps/absorbers with my dad.

Considering the fact that the nearest corners to my speakers are at least 10 feet away, I think the first reflection points are more important to take care of at first than bass trapping the corners. Would you agree?

[Weasel9992]

 

Thank you for your response I think this weekend I am going to build a few rigid fiberglass bass traps/absorbers with my dad. Considering the fact that the nearest corners to my speakers are at least 10 feet away, I think the first reflection points are more important to take care of at first than bass trapping the corners. Would you agree?

 

 

Nope. Low end first...always. The reason we do it first is because you can't even tell how a room sounds until you have some degree of low end control, and that's especially true in a small room. After that's done you can tell where you're really ringing in the high end.

 

Low end first.

 

Frank

[ninjamonkey]

Hmmm

 

Here's a test i did with a small diaphragm condenser where my head normally is in the room. I played pink noise through the monitors. (this is all with no acoustical treatment)

 

Here's the frequency response chart for the mic

 

 

Here's the frequency analysis for the pink noise file (brown), and the pink noise recorded with the mic (blue)

 

 

I provided the freq response graph of the mic so that it can be "subtracted"; however, the room, monitors, and preamps are all coloring the sound also.

 

What do you think? To me, it looks more like the mids and highs that are out of control, and that may be the monitors response rather than the room.

[Weasel9992]

That room response curve isn't right. According to that analysis you have no modal issues at all below about 400Hz, which wouldn't even be true of the best tuned rooms in the world.

 

Try downloading Room EQ Wizard, run that test again, then post the results. It'll be an eye opener.

 

Frank

[Ethan Winer]

 

the nearest corners to my speakers are at least 10 feet away

 

 

Doesn't matter. My home studio is one large room 33 feet long by 18 feet wide, and I have bass traps all over the place including the rear.

 

I also agree with Frank that your graph does not reflect reality. You need to measure at a much higher resolution - minimum 1/12 octave but preferably 1/24 octave or even higher.

 

--Ethan

[MrKnobs]

Measuring room response with a directional microphone? Yikes!

 

Terry D.

[ninjamonkey]

I will be getting an omni mic soon. Any suggestions?

 

I was planning on building at least 5 2X4 4" thick Owens Corning 703 boards, but I just discovered something.

 

Why does everyone dismiss the "fluffy pink" Owens Corning stuff? I found these test numbers - http://www.bobgolds.com/AbsorptionCoefficients.htm

 

The "fluffy pink" OC stuff has similar absorption coefficients to 703, no? I've already got the 6" fluffy stuff, so all I would need to buy is fabric to cover it.

[Ethan Winer]

 

I will be getting an omni mic soon. Any suggestions?

 

 

Heh, perfect timing, this just in:

 

Comparison of Ten Measuring Microphones

 

--Ethan

[Weasel9992]

 

I will be getting an omni mic soon. Any suggestions? I was planning on building at least 5 2X4 4" thick Owens Corning 703 boards, but I just discovered something. Why does everyone dismiss the "fluffy pink" Owens Corning stuff? I found these test numbers - http://www.bobgolds.com/AbsorptionCoefficients.htm The "fluffy pink" OC stuff has similar absorption coefficients to 703, no? I've already got the 6" fluffy stuff, so all I would need to buy is fabric to cover it.

 

 

It does down to 125Hz, but we're talking about 6.25" of fluffy stuff with a 16" air gap compared to 4" of 703 with a 16" air gap. I'd also suspect that the absorption falls off steeply below 125Hz too.

 

Frank

[mrbrown49]

 

Heh, perfect timing, this just in: Comparison of Ten Measuring Microphones --Ethan

 

 

Great work Ethan!

[ninjamonkey]

 

It does down to 125Hz, but we're talking about 6.25" of fluffy stuff with a 16" air gap compared to 4" of 703 with a 16" air gap. I'd also suspect that the absorption falls off steeply below 125Hz too. Frank

 

The space is not a big issue to me. I'm in a big room. Why do you suspect the absorption rolls off very quickly? Is there any data below 125 Hz for "fluffy pink" or 703?

 

Thanks