Home studio tricks: How to measure your room's acoustics with Room EQ Wizard

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EnochLight
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Post 06 Feb 2015

Fantastic article, and I highly recommend the free software for measuring:

http://www.musicradar.com/tuition/tech/ ... ard-612779


An excerpt:

Going in blind with acoustic treatment is always a gamble, but we can take the guesswork out of the equation by measuring our progress with acoustic measurement software like the free Room EQ Wizard (REW). To get going, you'll need an omnidirectional mic (a cheap one like the Behringer ECM8000 can had for under £50), a stand to hold it, and an audio interface with the necessary mic input.
The basic idea behind REW is to play a sine sweep through the frequency spectrum. Behind the scenes, some fancy calculations are then performed to generate a series of data plots that show us exactly where the problems in the room are. The ones we're interested in are the frequency plot, the waterfall plot and the Energy Time Curve (ETC) plot.

The frequency plot displays the frequency response of the room. We're usually interested in the sub-300Hz region (showing how the room modes are affecting bass response), checking to see if there are any excessive peaks or nulls in the spectrum that can be addressed through speaker, listener and acoustic treatment placement. In a well-treated room, we'd expect the difference between the largest peaks and troughs of our modal region to be under 10dB, but anything under 20dB is a good start.

Read more a the link above!
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djfm1983
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Post 06 Feb 2015

EnochLight wrote:Fantastic article, and I highly recommend the free software for measuring:

http://www.musicradar.com/tuition/tech/ ... ard-612779


An excerpt:

Going in blind with acoustic treatment is always a gamble, but we can take the guesswork out of the equation by measuring our progress with acoustic measurement software like the free Room EQ Wizard (REW). To get going, you'll need an omnidirectional mic (a cheap one like the Behringer ECM8000 can had for under £50), a stand to hold it, and an audio interface with the necessary mic input.
The basic idea behind REW is to play a sine sweep through the frequency spectrum. Behind the scenes, some fancy calculations are then performed to generate a series of data plots that show us exactly where the problems in the room are. The ones we're interested in are the frequency plot, the waterfall plot and the Energy Time Curve (ETC) plot.

The frequency plot displays the frequency response of the room. We're usually interested in the sub-300Hz region (showing how the room modes are affecting bass response), checking to see if there are any excessive peaks or nulls in the spectrum that can be addressed through speaker, listener and acoustic treatment placement. In a well-treated room, we'd expect the difference between the largest peaks and troughs of our modal region to be under 10dB, but anything under 20dB is a good start.

Read more a the link above!
REW is a great software. I bought an rta mic and had mine sent out to be calibrated so I could get an accurate measurement.
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Julibee
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Post 06 Feb 2015

I'm glad you posted this, Enoch-- since we've redone the floors, and my studio area has moved around, I been wanting to see (hear? Lol) how things stand now. I didn't measure before, because I KNEW it was horrible... Will be doing this soon. :)
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selig
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Post 06 Feb 2015

Here's some quick tips from someone who's been messing with software like this and home and professional studio setups for a decade now!

Remember that with a home studio/budget, you're not trying to get the graph "perfectly flat" or even necessarily to get it to match some ideal curve. You are comparing all of your options and choosing the best from among them. At least that's what's worked for me in the past.

The placement of your monitors and sub (if used) can affect things greatly. The problem is that, even for those with trained ears, the time between comparisons when moving things around a room is too long to accurately judge the sometimes subtle differences. Enter room analysis software!

Again, the goal at this level is to compare all of your options and find the best one. Sometimes it's best to first narrow down your options by trying to eliminate some of the more obvious "not gonna work" choices. Then make a final choice from among the best options by comparing graphs and listening to your favorite mixes. Give yourself at least one full day for the initial work (once you've learned the software and are getting good results), and try to get a friend to help, not only to move things around but also as a second set of ears as this work can get rather tedious over time!

One example; in my current space I initially moved the sub woofer around to just about every possible position in front of my desk (in 6" increments in some cases), including in an alcove/closet (there aren't any doors) behind the desk. Sometimes just moving it forward even 6" made a noticeable difference, sometimes it didn't sound different at all! 

In the end, the closet position worked best, which was perfect from a space saving perspective. From there I added the main speakers (Equator D8s), and adjusted their levels, positions, and boundary position switch, in addition to adjusting the subwoofer's crossover frequency and level. There's millions of combinations here, so at one point I turned off the sub and "shot" the Equators separately to see what these controls actually did (they were new to me at the time). In the end I narrowed it down to a few combinations, did some more listening, finally settling on one that's worked great so far. 

One other thing that really helps with fine tuning is to be able to adjust things from the listening position. I can't adjust the subwoofer crossover from my mix position, but my Presonus Central Station has speaker trims on the front, which came in quite handy as it sits right at arms length on my desk. I used it to fine tune the critical sub/main monitor balance, and I can of course modify it quickly if I want, say, to crank up the sub for my own personal rave or whatever.

Also, if you update or change something in your studio in the future, you can test it against the former setup to see what (if anything) has changed. 

Finally, a reminder that the waterfall display is your friend when dealing with troublesome low frequency issues - the main display can hide serious issues that the waterfall reveals at a glance! BTW, I use that Behringer ECM8000 mic for the past 10 years or so that I've be doing this sort of thing, throwing it in my bag without a case and even dropping it a few times. It's a bit noisy by recording standards, but perfectly fine for testing!
:)
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Julibee
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Post 06 Feb 2015

Selig, I see you've been reclassified as "Radministrator". That's about right. Thanks again, you.
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