View Single Post
Old 03-31-2007, 05:29 PM   #7
scottdru
Human being with feelings
 
scottdru's Avatar
 
Join Date: Feb 2007
Posts: 1,314
Default

The others are *absolutely* correct that EQ is *not* a good way to address the problems you are experiencing, which are acoustics issues.

Here are a couple of articles that show what EQ can and cannot do with regard to addressing room mode problems:

http://www.realtraps.com/eq-traps.htm

http://www.realtraps.com/art_audyssey.htm

The bottom line is that:

1) The results of EQ used in this way are EXTREMELY positionally dependent (i.e., if you move your head as little as an inch, or in some cases even less, you will end up with a different result. Further, while you may be able to tame an unruly modal peak at a given frequency in one position with EQ, you may actually exacerbate a different problem somewhere else in the room.

2) While EQ may be able to bring down some modal peaks, it cannot fix modal ringing, and it cannot fix nulls (dips in the frequency response) caused by room modes.

As the guys said above, the best way (and really the ONLY way) to handle this is indeed with acoustic treatment.

All small rooms (i.e., the size you will find in a typical home, and indeed pretty much in anything smaller than a large concert hall or stadium, etc.) need bass traps to get anything close to a flat response. And, while you CAN put too much high and mid frequency absorption in a room, it is pretty much impossible to put too many bass traps in a room.

As an example, I know of someone who designed and built his home studio such that he literally filled 1/3 of the *volume* of his room with dense mineral fiber (the rockwool equivalent of Owens-Corning 703 rigid fiberglass panels). And what I'm saying here is that this was just covering 1/3 of the wall space, but actually 1/3 of the *volume* of the room -- that's a lot of bass trapping. The final result in this room was that his frequency response was within something like 8 or 10 dB of flat across the entire frequency spectrum, and decay times in the low frequencies were very even.

Now . . . I'm not suggesting that everybody needs to go to those extremes to get good results in their studios. You can certainly get huge improvements by adding far less bass trapping in your room than that. After you get to a certain point, the law of diminishing returns does start to apply.

But what most people don't realise is that most small rooms will have a frequency response that looks like the Swiss Alps, with peaks and dips in the frequency response of as much as 30 to 35 dB from top to bottom. Most acousticians worth their salt will tell you (if they are being honest) that, if they've managed to get a room response to within 10 dB of flat, and relatively even decay time across the spectrum, they consider it a job *very* well done -- *especially* when it comes to small rooms!

I always have to laugh when I see people have spent crazy amounts of money on monitors, expensive mics, esoteric/vintage high end preamps and the like, and have done NOTHING to treat their acoustics. And then they don't understand why their recordings still sound like shit and their mixes don't travel well. And then they balk at spending even a grand or two on acoustics treatments. Believe me . . . $1000 (or even less if you are building DIY panels) invested in proper, balanced acoustics treatment will give you exponentially greater improvement than spending the same amount upgrading your electronics.

If you think I'm exaggerating all of this, let me show you something. Here are some screen shots of my "before" acoustical analysis of the control room of a certain multi-platinum, grammy nominated hip hop producer whose studio I treated a while back:

20-200 Hz range:

http://www.esnips.com/doc/a438d63f-6...ment,-20-200Hz

160-320 Hz range:

http://www.esnips.com/doc/b96d6c95-6...ent,-160-320Hz

Here's a slightly different view of the waterfall plot for the 20-200 Hz range, shown at a higher resolution of analysis:

http://www.esnips.com/doc/71d1dd54-5...,-no-treatment

The monitors in this studio were Mackie HR824s, so there is no problem with the monitors not being flat.

In case you are not sure how to understand the waterfall plots above, the vertical plot (delineated in dB) is the frequency response of the room showing the amplitude of the reflected sound at all frequencies across the spectrum, and the horizontal plot (from back to front) indicates the decay time of the reflected sounds after the initial impulse that is played into the room. These tests are done with a sine wave sweep.

Placement of speakers and the listening position in your room can also make a HUGE difference. There's a very good article on that subject here:

http://www.realtraps.com/art_room-setup.htm

Also, there's a very good article that discusses some of the most important fundamentals of acoustics (without getting bogged down in the more complicated math/physics) here:

http://www.realtraps.com/facts.htm

That article would be a great starting point for anybody who is just getting acquainted with this subject area.

There's actually a whole bunch of good articles here:

http://www.realtraps.com/articles.htm

Hehe . . . sorry to drop a huge bunch of stuff on you, here, but it's all stuff that bears repeating over and over (because far to many people are unaware of this stuff, and it doesn't get talked about as much because it's not as glamourous as shiny new boxes), and hopefully it will help you sort out some of the confusion you are having (as do many others) on these issues.

The actual treatment of these problems is actually fairly simple if you take a broadband approach (i.e., using panels that are designed for absorption across the spectrum, including the low frequencies). You can get commercially available panels, or, if you have the time and inclination, you can build DIY broadband/bass traps with Owens-Corning 703 or 705 panels.

From there, the two most important things will be to treat your corners with broadband/bass traps and treat your first reflection points (as discussed in the articles I've linked above). The most important corners to treat will be the vertical wall/wall corners, and then from there you can also treat wall/ceiling corners and/or wall/floor corners if you want to get additional improvement. All room corners are valid for treatment of low frequency room modes.

Basically, the more bass traps you put in your room, the flatter and flatter the frequency response will become, and the more even your decay times will become. And, again, you don't have to go crazy with it to get a very noticeable improvement. And this will help not only your mixes, but also the sound of anything you actually record in that room.

But even if you treated only the four wall/wall corners and the first reflection points with broadband panels, you would get a very noticeable improvement in the low and low mids, and treating those first reflection points with absorption will make a *big* difference in your imaging as well as the acoustic distortion of the frequency response that you are experiencing -- you will be able to hear *much* deeper into the mix.

Last edited by scottdru; 03-31-2007 at 06:00 PM.
scottdru is offline   Reply With Quote