how to deal with a corner door?

[Sean Shannon]

maybe i came off a little wrong in my post.

That's cool. I come to these forums to try to help. I've been in this business longer than I care to admit. When I see a post that actually helps no one, and stabs at the guy trying to help, I wonder, what's your point? Sorry for that.

yeah, i see the mention bass traps and the corner door in the first paragraph of the post, you might have missed that.

No, I didn't. If you re-read my post, I was talking specifically about bass trapping. An open door is a bass trap, and "bass traps" that hang on walls or corners are designed for a closed room. After designing and building many studios, I have learned a few things about this, and I was genuinely interested in helping.

and no, i have no suggestions, merely waiting for yours.

I realize that. That's why you have no business attacking me.

[Sean Shannon]

Back to the topic at hand-

What are you trying to accomplish? Is the room a cube? Does the room sound bad? Boomy, reverb-y? Have you measured to see what frequencies are building up or cancelling out? Are you looking to bring the RT60 measurement down all across the spectrum? Maybe if you give us a width x height x length dimensions of the room, and what you will primarily be working on in there, we can better assist you. For example, do you record vocalists in the same room with you? Are you tracking live players? Are they in a separate room? Is this a room in which you will primarily be mixing? What is your budget? etc.

There are many ways to approach this. Give us all the details you can before you blindly buy into any advertising hype and spend too much money on mediocre results.

[Sean Shannon]

dont mean to hijack, but isnt asymmetry better regarding diffusion, etc?

or did i miss something in my skimming over acoustics?

Symmetry is a good thing in a control room, but not necessarily a good thing in the live tracking room. By symmetry, I don't mean a square room. What I mean is, the distance from the listening position to the side walls, the equilateral positioning of the monitors, etc. If your listening space is asymmetrical, you may get longer reflections from one side than the other, for example, and that could skew your persective.

You are correct that asymmetrical surfaces will scatter reflections, well, asymmetrically, and that certainly aids in diffusion, if that is what you are after. But even then, in a control room, you want the overall shape of the left half of the room to approximately mirror the right half, if at all possible. Go to www.moultonlabs.com, and see what Dave has to say about his room theories.

[Phiz]

Have you measured to see what frequencies are building up or cancelling out? Are you looking to bring the RT60 measurement down all across the spectrum? Maybe if you give us a width x height x length dimensions of the room, and what you will primarily be working on in there, we can better assist you.

Some words of wisdom from one one of our room acoustics experts on another TOMB thread:

But no matter what you calculate (or even measure), the solution is always the same: As much broadband bass trapping as possible in the corners, plus absorption at the first reflection points on the side walls and ceiling. This "formula" works well for pretty much any room, regardless of the room's characteristics.

[Sean Shannon]

Have you measured to see what frequencies are building up or cancelling out? Are you looking to bring the RT60 measurement down all across the spectrum? Maybe if you give us a width x height x length dimensions of the room, and what you will primarily be working on in there, we can better assist you.

Some words of wisdom from one one of our room acoustics experts on another TOMB thread:

But no matter what you calculate (or even measure), the solution is always the same: As much broadband bass trapping as possible in the corners, plus absorption at the first reflection points on the side walls and ceiling. This "formula" works well for pretty much any room, regardless of the room's characteristics.

Thank you for pointing that out. Let me say that I know many respected engineers who disagree with Mr. Winer. I personally don't find a blanket statement like that to be the end all be all of acoustic treatment. I have live side walls and very little "broadband absorption" in my corners of my busiest room, and the mixes translate fantastically. Check out the "Moulton Room", and read what Dave has to say about those side reflections. Ask John Storyk about that, and see what he says. Don't just blindly follow the marketing hype of the day, Ethan is pushing acoustic products, too, so he is biased. Don't kid yourself, treating a room that's 40 x 31 x 26 is way different than treating a room that's 10 x 11 x 8. That's why I asked for the sizes, or "characteristics".

Giving us measurements of the room will point out obvious frequencies that are troublesome, like it or not, and a give us a place to start. Guys mixing in rooms with a serious deficiency at 72 Hz at the mix position, for example, will tend to have mixes that are heavy in the 72, 144, 288, etc. cycle areas. A spectrum analyzer is a great tool for figuring out your room's own problem areas and balancing them. No room is "perfect", either, which is why people use multiple sets of reference monitors, and mix at different SPL levels, even in million dollar rooms. And why we still use Mastering Engineers to finish the project.

Also, it is important to note that much of the room isn't excited at low monitoring levels. Cranking up the volume excites the room more, and makes the problems more evident. If he is working on jazz all day, and mixes at 80db SPL, he may not need as much "trapping", which is why I asked what he does in there. Tile or carpet, low or high mix volumes, closed or open doors, you get the idea. If it was that easy, every major studio would just buy his products and pack the corners.

[trodden]

maybe i came off a little wrong in my post.

That's cool. I come to these forums to try to help. I've been in this business longer than I care to admit. When I see a post that actually helps no one, and stabs at the guy trying to help, I wonder, what's your point? Sorry for that.

yeah, i see the mention bass traps and the corner door in the first paragraph of the post, you might have missed that.

No, I didn't. If you re-read my post, I was talking specifically about bass trapping. An open door is a bass trap, and "bass traps" that hang on walls or corners are designed for a closed room. After designing and building many studios, I have learned a few things about this, and I was genuinely interested in helping.

and no, i have no suggestions, merely waiting for yours.

I realize that. That's why you have no business attacking me.

tis cool, i know you're trying to help, EVERYONE is trying to help, just egging you on that is all. Carry on now.

[trodden]

dont mean to hijack, but isnt asymmetry better regarding diffusion, etc?

or did i miss something in my skimming over acoustics?

Symmetry is a good thing in a control room, but not necessarily a good thing in the live tracking room. By symmetry, I don't mean a square room. What I mean is, the distance from the listening position to the side walls, the equilateral positioning of the monitors, etc. If your listening space is asymmetrical, you may get longer reflections from one side than the other, for example, and that could skew your persective.

You are correct that asymmetrical surfaces will scatter reflections, well, asymmetrically, and that certainly aids in diffusion, if that is what you are after. But even then, in a control room, you want the overall shape of the left half of the room to approximately mirror the right half, if at all possible. Go to www.moultonlabs.com, and see what Dave has to say about his room theories.

so what do you do if you can't have symmetry in the control room? That is what i'm dealing with.

[Phiz]

Don't just blindly follow the marketing hype of the day, Ethan is pushing acoustic products, too, so he is biased.

I am not. I have done reading and thinking about the issue and have come to the conclusion that I generally agree with Ethan's assesment. But I'm not an acoustic expert, so I don't claim my thoughts hold as much weight as Ethan's do.

Giving us measurements of the room will point out obvious frequencies that are troublesome, like it or not, and a give us a place to start. Guys mixing in rooms with a serious deficiency at 72 Hz at the mix position, for example, will tend to have mixes that are heavy in the 72, 144, 288, etc. cycle areas. A spectrum analyzer is a great tool for figuring out your room's own problem areas and balancing them.

Are you then going to recommend the installation of tuned adsorbers? In an ideal world I'd agree that would give great results, but I'd hate to try to actually implement that and deal with needing everything to be carefully tuned.

Also, it is important to note that much of the room isn't excited at low monitoring levels. Cranking up the volume excites the room more, and makes the problems more evident.

The resonant frequencies will get excited at any level of play back, but their amplitudes will be proportional to the source amplitude. Thus the ratios of the amplitudes of the playback to the undesired resonances will remain constant. Therefore increasing or decreasing monitoring levels does nothing to help the problem. I use low monitoring levels to prevent fatigue.

Check out the "Moulton Room", and read what Dave has to say about those side reflections.

I read it. (Your link to is is broken.) Most of what Dave is talking about is high frequency reflections. While Dave and Ethan may differ on how to treat first reflections off of side walls (and here room side does matter), they don't appear to differ on dealing with low frequencies. Dave states he wants his rooms to be dead after 50ms. That won't happen without bass trapping, and I think broadband bass trapping is the easiest and most intelligent way to approach the problem.

[james4954]

phew . . .

thanks for the input everybody - I guess I should have given more info in my original post but i wanted to keep it brief.

yes, this is a home studio - sorry for the confusion. the room is approx 12 x 10 with an 8' ceiling. it is asymmetrical on the side as i have removed the door on what was a closet, so I have a portion of a side wall (approx 5') that extends 2' deeper than the rest of the wall and extends all the way to the ceiling. I'm not sure if this makes things better or worse acoustically. . .

I use the room for tracking and mixing. my major concern is having my mixes translate better and the standout issue is the low end response in the room - my mixes always translate with much more low end than I want because I'm just not hearing it in the room, so I find myself guessing a lot.

The obvious remedy (to me anyway) is installing some bass traps (to start with) but the issue immediately came up of the rear corner with the doorframe in it. I guess I could always make a custom trap but it could only be about 10" wide so I'm not sure if there's any point. Alternatively, I might try and make a trap that I can hang from the wall when I need it, then take it down when I want to be able to use the door. . . .

Either way, it sounds like I'm best off trying to treat those rear corners as best I can and not worry so much about symmetry because I'm primarily treating the lower frequencies. Does that sound about right?

cheers,

James

[Phiz]

Either way, it sounds like I'm best off trying to treat those rear corners as best I can and not worry so much about symmetry because I'm primarily treating the lower frequencies.

Remember that when doing bass trapping, the corner where the wall and ceiling (or floor) meet, is as good as a corner formed by two walls. In many small rooms it's probably a better use of space to put traps at a wall and ceiling junction.

[Ethan Winer]

You guys are doing fine on your own, but I do need to address a few things:

> Don't just blindly follow the marketing hype of the day, Ethan is pushing acoustic products, too, so he is biased. <

I "push" the solution I believe in, not the other way around. A lot has changed over the past 10-20 years in the way room treatment is approached, mostly because so many people are now using very small rooms. Guys like Storyk and Moulton and other "big guns" work on million dollar rooms that are much larger than what most of us have to work with. I agree with you that treating a large room is different from treating a small room, for a variety of reasons. As it turns out, broadband absorption is almost always the best approach in large rooms too, but we can leave that discussion for another day.

> A spectrum analyzer is a great tool for figuring out your room's own problem areas and balancing them. <

More current thinking recognizes that raw low frequency response is only one part of the equation. Equally important are reducing modal ringing and avoiding early reflections.

> much of the room isn't excited at low monitoring levels. <

This simply is not true. Perhaps you could argue that at very low levels the room's artifacts are below the threshold of audibility, but the proportion of original sound to artifacts remains exactly the same. Of course, by the time you reduce the level so low that an early reflection is inaudible, the music is then way too soft to be able to mix well. And the comb filtering from those reflections is still present and audible. More to the point, one of the biggest problems in all small rooms is multiple deep nulls at the mix position. Listening softly can only make those nulls appear worse.

> If it was that easy, every major studio would just buy his products and pack the corners. <

This is exactly what we're now seeing happen. Again, folks with million dollar rooms will hire pro carpenters and build all the treatment into the walls, and cover it with nice looking fabric. You can't charge $300 per hour if the room doesn't look as great as it sounds! But we're selling to many very famous producers and engineers when they need to treat their personal mix rooms. We've sold a room full of traps to Charles Dye, Nile Rodgers, Barry Gibb, David Schwartz, Peter Moshay, and most recently to Tony Maserati for his personal studio in upstate New York. We also did two control rooms for audiophile record label Chesky records. Other prominent clients are listed on our web site.

--Ethan

[Cojonesonasteek]

We encountered the same problem (a water heater closet in the front left corner of the CR) and designed a frame on piano hinges that simply hides the door completely; the same frame without hinges is in the opposite corner. We mounted cloth-wrapped 4" 703 inside the frames. The hinged trap frame may not work if the door in your CR has heavy traffic rather than closet access.

[trodden]

We encountered the same problem (a water heater closet in the front left corner of the CR) and designed a frame on piano hinges that simply hides the door completely; the same frame without hinges is in the opposite corner. We mounted cloth-wrapped 4" 703 inside the frames. The hinged trap frame may not work if the door in your CR has heavy traffic rather than closet access.

that is a wonderful idea!

Thanks Ethan for your input as well.

[Sean Shannon]

With all due respect, marketing hype is coming from from all acoustic product manufacturers, and not just you. Do you personally believe what all the other manufacturers say? People who don't know for sure believe what the ad says, in many cases. Your solutions are good, I just don't like to see people blindly following acoustic treatment recommendations from manufacturers without knowing the exact problems within the room that need to be addressed. No offense.

Every room has a different sonic signature, an it is easy to chase your tail fixing one problem while avoiding another, or even making the room worse by creating new issues. In many cases, there are less expensive solutions available for the do-it-yourselfer. I'm not dissing you, I'm just pointing these things out. I would love to chat at length with you about all this sometime.

Storyk and Moulton also work on small rooms with lower budgets. And many of them apply different techniques than what you offer, like room shape, diffusion, etc. Don't take me wrong, I believe your system is good in many cases, but I also believe some rooms don't need all that. Besides, once you open a door, all bets are off in the low end department. If it is possible to change the shape of the room, for example, that may be more effective than insulation in the corners.

A spectrum analyzer will show peaks and valleys in the frequency response of the room, and modal ringing will exacerbate those as you move about the room. They can also help a fledgling engineer see what he is hearing. It's important to know exactly where your room's problems lie before throwing stuff on the walls, especially expensive foams and stuff. Throwing insulation in the corner of a room does not guarantee that the peaks and valleys at the mix position will magically disappear.

Early reflections are not all bad, either. That's why a blanket statement is not an end all be all answer. It depends on a number of factors, not the least of which is the size and shape of the room. Million dollar rooms aren't built in the shape of a cube, like bedroom studios, so many of the acoustic problem are minimized by room shape.

I disagree with your statement that low listening levels makes nulls appear worse. When listening at low levels, the effects of the room are greatly reduced, as you say, at the mix position, especially when listening close to the speakers, but of course, the speakers and the room combine to form a complete system, no matter what. They may not disappear entirely, but are reduced many times to the point of being able to work in the room. A boomy room is still boomy at low volumes, but cranking the volume really makes the bass ringing take off.

To summarize, I'm not saying you don't have good plan, and I'm glad for you that some high-profile people have been helped by your system, but other systems have worked well, too. Best of luck!

[Ethan Winer]

Sean,

> Do you personally believe what all the other manufacturers say? <

Heck no! I'd say that 90 percent of these vendors are absolutely clueless. I know many of them personally.

> I just don't like to see people blindly following acoustic treatment recommendations from manufacturers <

I agree completely. See above.

> In many cases, there are less expensive solutions available for the do-it-yourselfer. <

Of course, but that's not the issue. Heck, why spend $4,000 for a high-end tube preamp when you could build it yourself for only $100? Why pay Dell or Gateway to build you a computer when you could buy a motherboard and power supply and RAM etc and DIY for hundreds less? No question, DIY is a great way to save money if you know what you're doing and your time is worth less than the price difference. I've been pushing DIY room treatment since before the Internet.

> I would love to chat at length with you about all this sometime. <

That's exactly why I'm here, so let's discuss. I see a lot of misinformation about acoustics and treatment from people who have little knowledge but express strong opinions anyway. I'm currently involved in a dissusion elsewhere with a guy who believes EQ is a satisfactory substitute for bass traps, yet he freely admits he's never even heard a room with bass traps. Think about that! I promise you my only agenda is educational, not commercial.

> Storyk and Moulton ... apply different techniques than what you offer, like room shape <

I never said that room shape is not important! But the vast majority of people I help have no choice but to work in an existing room. As for diffusion, I'm all for diffusion given a room large enough to support it. The main "problem" with diffusion is that good diffusors are complicated - either expensive to buy or difficult and time-consuming to build properly - and the simpler diffusors are worse than a bare wall IMO. Further, as great as diffusion is, it's more icing on the cake than a staple. All rooms need substantial bass trapping much more than they need diffusion. And absorption does 90 percent of what diffusion does anyway. In my opinion of course. And I agree that this is one area where opinion is as valid as the science.

> I also believe some rooms don't need all that. <

All what? A bunch of bass traps? Here's a friendly challenge for you: Show me a low frequency waterfall plot for any smallish room that has no bass traps, where the response does not vary by at least 20 dB and there is not severe high-Q ringing.

> If it is possible to change the shape of the room, for example, that may be more effective than insulation in the corners. <

In fact, the best solution is always both.

> Throwing insulation in the corner of a room does not guarantee that the peaks and valleys at the mix position will magically disappear. <

It does! Well, maybe not disappear, because it's impossible to make any small room even close to flat. But adding eight good broadband bass traps in the corners of a room always makes the response and ringing better, and never makes them worse.

> Early reflections are not all bad, either. <

Okay, here's another friendly challenge for you: Show me a room - any room - that does not benefit from absorption (or diffusion) at the first reflection points.

> I disagree with your statement that low listening levels makes nulls appear worse. <

There's nothing to disagree with, and this can be proven with a simple test. Measure the room once at a low level and again at a high level. You'll see that the relative response and ringing are exactly the same. The nulls are just as deep at low levels, the peaks are just as big, and the ringing sustains for just as long. (Until you get below the room's noise floor of course.)

--Ethan