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Auralex Room Analysis Plus Implimentation and Conclusion

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Auralex wanted additional bass trapping in all four corners. There's a problem there. First, in my left front corner I keep an equipment rack. This is for all the gear that doesn't fit in the component rack. It is easier to get to and frankly, I need the extra storage. While most people have a receiver and a few sources, I have a receiver, processor, amp, two DVD players, an HD-DVD player, the Veloydyne SMS-1, two APC power conditioners (the H15 and the H10), a cable box, an Xbox 360 and various other equipment and accessories to make the whole thing work (see my reference system on Audioholics for specifics). An AV Geek's dream? Sure. But there isn't a display stand big enough to hold all of it without the interior getting as hot as the sun. The best I could do was to move one of my 8' tall panels to that corner. A tri-trap just would have been too big.

The right front corner has two problems. First, there is an outlet in use there. The second is that the sub is located near there. While it is theoretically possible to get a Tri-Trap in the corner, it wouldn't look right and it would make an already cluttered corner (what with the sub and the speaker) just too tight. Again, I was only able to get one of my 8' panels in there. The back corners already had panels in them so switching them out for a GiK Tri-Trap is not a problem. No outlets are covered and the one vent is only partially covered so I don't care.

Everything's fixed right? Case closed.

Not exactly. I've harped over and over again about a rectangular enclosed room. This is because modern modeling techniques rely on this shape in order to predict room interactions. Additional measurements were taken in the room and the results?

Plus_barevsfinal.png
Green - before Auralex suggested changes, Red - after

Please remember that the "after" measurement was taken at a later date and while I tried my best to match the before speakers/mic/furniture placement, it could very well be that some of the differences are due to my placement inaccuracies. As you can clearly see, in almost all areas, the changes were positive. The peaks and dips while not eliminated are reduced in severity in almost every case. It this a flat line? Not by a long shot but this also isn't an ideal room nor has the room been professionally treated. This is more akin to a DIY project that just about anyone (with a little recording equipment) can do. That being said, I decided to take a measurement at the (subjectively) worse seat in the house. The results? No real difference between the treated and untreated versions. Sure, there were some changes, some good and some bad but overall the summary is above 200Hz things got a bit better but below, things stayed about the same.

How could this be?

Too often on the forums and with the uninitiated you'll get the impression (if not the outright assertion) that placing passive room treatments in your room will ALWAYS help. That may be partially true, but not as much as you'd think. Passive room treatments are broadband absorbers. Their function is to absorb sound from a multitude of frequencies. The problem is that you have no control over the absorption and where it is applied. In my room, there is a lot going on. There is sound bouncing around the listening space but also out into the adjacent rooms some of which is reflected back in. When broadband absorption is applied, it is affecting all those frequencies. Some of the reflected sound is causing problems by adding or canceling other sound. Other reflections are actually helping through the same process. With an odd shaped room, it is near impossible to tell what is happening and what to do about it without a more hands on trial and error approach. One thing is sure, broadband absorption is not the panacea that some make it out to be.

Backup Measurement

Plus_Axiom.JPGOne thing lacking from the Room Analysis Plus measurement is the sub. While I could have sent them a reading with just the sub and had them try to put them together (and this may be something that is worth spending one of your five measurements on), I didn't. Plus, you really aren't getting a picture of the whole room - it is one speaker at a time from one seated position. As a backup, I decided to bust out the mic for the Velodyne SMS-1 and recalibrate and measure my room. While my speakers have changed and so has the room treatments, the sub is the same and the basic layout hasn't changed much. In addition, Auralex sent me a SubDude HD. This is basically a 15" x 15" x 2.5" platform for your sub. The idea is to reduce vibration transmission through the floor cutting down on vibrations from other objects in the room like windows and such. While this makes my Axiom EP500 look a little like it is wearing one of those wooden shoes from samurai movies, it did seem to reduce vibrations. This was especially noticeable with a light fixture (another thing I've been meaning to replace - so many projects, so little money) in the foyer and a loose windowpane in an adjoining room. While the vibrations weren't completely suppressed, I was able to turn the sub up louder before they became noticeable. When I reviewed the Mic-5 add-on for the SMS-1, I took a lot of measurements. The best I could do at the time with a single mic at the prime listening position was this:

Plus_sms_b4.jpg

SMS-1 1 Mic Calibration Before Auralex

Now remember the Velodyne measures at 1/3rd octave smoothed rather than 1/12th of the Auralex graphs. The 1/3rd smoothing really hides a lot more of the problems than the 1/12th. That being said, here is the post Auralex graphs:

Plus_sms_a.JPG

SMS-1 1 Mic Calibration After Auralex

The Velodyne really only affects sound below the crossover (which is set at 80Hz). Other than the expected (and Auralex predicted) dip around 75Hz, the line is remarkably straight.

Listening Evaluation

I often use Yello - the eye during my reviews because of a bass run that often shows the deficiencies with a speaker's low end response. I've had to compensate because of a suckout in my room - no longer. While I can still hear the room's affect on the sound, it is not nearly as pronounced. The improvement on this one song - 200%. Easy. Maybe more. My next step was to bust out an oldie but goodie - Star Wars: Attack of the Clones. While I don't accept that Episodes 1-3 were in any way connected to 4-6 (why, oh why George did you abandon us?), the fact remains that the flyover of the ship at the beginning of that movie is not only an easy and accessible extended bass run, it was also one of the earliest hints to me that I had a problem in my room. It wasn't until I visited Gene and Clint's rooms that I discovered what it was really supposed to sound like. My own room treatments and the SMS-1 helped tame some of the suckouts and inaccuracies from this scene - but it was far from perfect. With the GiK panels and the Auralex Room Analysis Plus? Wow. Just wow. While there was still the ~75Hz suckout, the rest was so clear and linear - something that I've not experienced in my home before. The uninitiated would come over and marvel at the bass - me, I would scowl knowing how much better it could be. And now it is. Much better at least if not perfect.

Without gross effects like the one above, it is hard to say with any degree of certainty that the Room Analysis Plus changes were making the difference. With a 3 second memory for audio, I'm loath to make the sort of attributions that other magazine reviewers seem to have in their "big chocolaty dancing cable" speaker review thesaurus. What I will say, without reservation is that imaging in general seemed to be better. The overall response of the room seemed to be cleaner and more uniform. But the biggest change was the smoothing of the bass response.

Sometimes you don't "know" you have a problem until it's fixed. In this case, I knew that I was getting additional reverb in some of my bass. Diana Krall's Love Scenes has a stand up bass that often seemed to make my room ring. With the changes made to the room based on the Room Analysis Plus I was hearing much tighter and less reverberant bass. The bass guitar was more lifelike and cleaner and the reduction in reverb allowed didn't cloud the soundstage as much (didn't realize it was until now but apparently it was) or obfuscate the other instruments.

Next Steps

Auralex remains convinced that the curtains will make a fairly impressive difference. I'm honestly a bit skeptical (though they are the experts and I'm not about to argue with them) but I'm really at my wife's suffrage on this one. Of course, they wanted to close the room off completely but as stated, not an option. Second, and more importantly, they suggested targeted absorption.

Diaphragmatic absorbers are sealed (or sometimes perforated or vented) boxes that vibrate at a specific frequency. This is a targeted approach to room treatment that will take a specific frequency (or small grouping of frequencies) that are problem areas and address them specifically. It will not help in any other way. The problem is that the tolerances on this type of absorber are very tight. If you are off as little as a 1/16th of an inch you could be not only not treating the frequencies you want to but also will be adding noise to your room. While I may be waiting for a while for the curtains, the diaphragmatic absorber will be underway very soon.

Word of Caution

One thing that is often overlooked with adding absorptive material to your room is the affect this will have on your receiver or amplifier. In order to pump out the same volume in a treated room versus untreated, an amplifier will have to put out more power. That's because some of the energy is being absorbed. Makes sense when you think about it. Too much absorption and you may find your mid level receiver is having a hard time reaching reference level with your moderately efficient speakers. Case in point - when my room was untreated, I could barely see the cone move on my Axiom EP500 subwoofer. Now, the EP is working much harder and I can tell. While far from reaching the limits of its capabilities, I am certainly happy that I overbought a sub for my room. If I had gone smaller, who knows where I'd be now?

Conclusion

The standard free Room Analysis service is a no-brainer for any home theater enthusiast. The Room Analysis Plus requires either the user own, purchase, or borrow a mic and preamp setup. The Room Analysis Plus Kit gives you a mic and easy access to the test tones for just about $50 over the price of the service. You'll still need a preamp, cables, recording device, and stand however. If you have some or all of this additional equipment, I can't recommend the Room Analysis Plus enough. It gives you real feedback about your actual room. While Auralex is going to make suggestions to optimize your room, you probably won't be able to do all of them. What you will be able to do is make intelligent purchasing decisions based on actual data. Of course, Auralex will be happy to sell you any of the treatments you'd like.

Auralex Room Analysis Plus
$250 for up to 5 measurement locations

Auralex Acoustics, Inc.
6853 Hillsdale Court
Indianapolis, IN 46250
317-842-2600

About Auralex Acoustics, Inc.
Located in Indianapolis, Auralex Acoustics was founded in 1977 with a mission to provide top-performing acoustical treatment products at the best value. Since then, thousands of satisfied Auralex customers have experienced improved acoustics, expert advice and exceptional customer service. Auralex products enjoy widespread use among prominent artists, producers, engineers, corporations, celebrities and government agencies.

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As Associate Editor at Audioholics, Tom promises to the best of his ability to give each review the same amount of attention, consideration, and thoughtfulness as possible and keep his writings free from undue bias and preconceptions. Any indication, either internally or from another, that bias has entered into his review will be immediately investigated. Substantiation of mistakes or bias will be immediately corrected regardless of personal stake, feelings, or ego.

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Recent Forum Posts:

bsaxman posts on July 10, 2009 19:00
Anyone try this product?

Anyone try this product yet? I might try the free version without the mic. The thought of having to record the sweep is daunting (I don't have any recording devices except an ancient circa 1985 Sony tape deck) so I anticipate it will be frustrating for me.

My issue is that I have an almost perfectly square room, concrete floors, and the ceiling is dropped down to about 7 ft across the front and along one side (a basement room with bulkheads for HVAC and plumbing) so I'm thinking the room will definitely need to be tamed.

Does anyone know if the microphone can be plugged into the ‘mic in’ on a laptop and use Sound Recorder or something like that to record the sweep?

Heck does Windows Vista even still have Sound Recorder? ….well if not, I'm sure there's freeware somewhere and Google might rescue me (again!)

Comments?
fredk posts on April 10, 2009 11:57
An article on the thing that most influences sound quality (after the speaker) and… silence…
Weasel9992 posts on April 09, 2009 11:24
I'd kinda have to agree with Fred here. I mean, it's a good thing to know the specific issues in any room, but it's not terribly relevant in most cases because the solution will be the same in all but the most unusual cases. After all the basics are covered in terms of room treatments, then measurements become useful in terms of finding the nagging problems, and avoiding over treating one particular area or another.

Frank
fredk posts on April 07, 2009 20:49
Bass trapping in the corner: as much as you can. Absorbtion/diffusion at first reflection points.

This is the standard advice you see in most posts asking for room treatment help. Every room will benefit from these basic treatments.

In fact, if you go onto forums for people setting up in home recording studios, the advice is much the same.

As intriguing an idea as this service is, if you are going to spend money, spend it on treatments.

If you are inclined to see what your rooms acoustic profile, download REW (freeware), pick up the mic etc. and measure AND graph to your hearts content. Spend some of that $250 on your significant other so she is more likely to tolerate your obsession.
gene posts on April 07, 2009 15:27
Its fixed now. Check it again. thx.
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