November 4, 2009

Aural Realm, Auralex MetroFusor Diffuser Panels.

Auralex MetroFusor diffuser panel. Moulded from humble foam!

Did you know that, in room treatment, other than the first reflection points at both the side walls next to the speakers, the back wall to the throne is next most effective area to apply treatment?

There are 2 ways to treat the back wall. Some say the back wall to throne a.k.a. "sweet spot" should be total absorption.

My previously installed full absorption back wall treatment from the throne.

Some time ago, I started to treat my back wall to the throne, by having 3 absorption panels lined the back wall. The idea was that there is less back wall sound reflection, which can effect the imaging focus quality within the perceived sound stage. Once I did that, I could hear more focused imaging quality, less high mid sibilants and an overall quieter musical noise floor. Listening to my hifi system became more rewarding sonically and less distracting, leading to a more enjoy able aural experience.

Lately, I have heard another group proposing to use a combo of absorption and diffuser treatment for the back wall to the throne. The argument is that the combo treatment will yield a more "live" like hall/studio acoustic environment. There is more airiness to the sound stage, so to speak.

Armed with this latest thinking, I asked Sky Wong of Centre Circle Audio to loan me 2 pcs of 2 x 2ft foam diffuser panels called MetroFusor Diffuser, manufactured by Auralex. They have some fancier diffuser designs fashioned out of wood squares called SpaceArray, but those proved too costly for my measly budget.

The 2 side absorption panels replaced by the Auralex MetroFusor foam panels for initial sound trials.

I went home, and immediately started work on the back wall. I pulled down 2 side mounted absorption panels of the existing treatment leaving only the middle absorption panel on the wall. I then proceeded to stick on the Auralex MetroFusor diffuser panels to replace both the side panels. The Auralex panels are very light weight and easy to work with.

I then proceeded to play some music and I noticed some improvement to the perception of sound staging depth. with the deeper, airier sound stage, the images of vocalist and instrument gained an aura of air around them, making each instrument behind the vocalist, that very bit more realistic. With CDs that are well recorded with hall ambiance, like the ever green Harry Belafonte, Live at Carnegie Hall, I noticed the biggest sonic pay off. Hall reverbs are now un-truncated and hand claps in between the songs seems more "alive" and the whole experience of listening to the CD is more 3D projected than before. It seems that bit of reverb sound deflected off the diffuser panels just behind our ears, can contribute so much to a more realistic concert like aural experience.

Encouraged by the Auralex experiment, I then think that, what if I could do another DIY diffuser(like my earlier shoe rack project on the speaker's back wall which turned out pretty well), say like hanging some DIY CD racks on the back wall, where both the current diffuser panels now reside, as I could use some extra CD storage space too. As some may say anything that is not a flat surface can be used as a diffuser panel. I went to Jusco Department store and found a DIY assembly required wooden CD rack, about the size of the diffuser panels. I bought 2 sets for about RM$30 each. I carefully assembled the two CD racks with the help of my little girls. DIY audio can help to unite the family too, who knows?

The cheaper, but less sonically effective alternative, DIY CD racks(the black ones on both sides the absorption panel), available from Jusco Departmental Stores.

Once assembly is completed, I proceeded to replace both the Auralex diffuser panels with the CD racks. I then proceeded to play the same Harry Belafonte CD again. This time I have found the hall ambiance of Carnegie Hall to have suffered and sounding slightly compressed instead. Having said that, some diffusion is still some what better than all absorption only. I also found some of that high mid sibilants resurfacing again, even though just barely. The CD racks are more practical, as they can hold another 50 pcs of CDs or so, but for me sonically and aurally, they just didn't do enough. At least, not after hearing what the "real deal", purpose designed Auralex MetroFusor diffuser panels are capable of anyway.

The Auralex panels went back on to the back wall of the throne. For permanent installation, I sprayed the Auralex panels with matching grey coloured spray paint, to suit the over all peach/grey paint scheme of my listening room.

Note: For those intending to spray paint their foam panels after reading this. You need to know that spray paints contain solvents, which can melt the foam panels, if paint is applied excessively at once. It is also very important to do the spray work out doors, if possible. Other wise, do so in a well ventilated place, for health reasons, wear a face mask. When spraying, first apply as thin a coat as evenly as possible. Then wait for the painted panel to cure, about 20-30 minutes is all it needs on a sunny day. Repeat this two steps several times, i.e. apply several thin coats, each time allowing the panel to cure before proceeding with the next coat. If you observed the above spray painting instruction, you should have a very uniform coating of any colour you choose, with very professional looking results.

The finished project, in matching grey paint scheme!

Retailing at RM$110.00 per panel, these Auralex MetroFusor diffuser panels are a bargain, if used correctly to achieve great aural results. Needless to say, I bought the review samples, and are now a permanent part of my room treatment system.

Auralex acoustic treatment products is sold by Centre Circle Audio, contact Sky Wong, Tel: 03 77282686

8 comments:

kkthen said...

thanks for your review.
I am using egg box for diffuser, result is better than none. May be next time should try auralex panel.

unker vic said...

Hi big E,

Different people have different takes on where to place the diffusers based on their past experiences, and variously different perceptions of sound reproductions amongst different persons! It still comes down to measurements and charting the sound response of the resultant sound in the room in question, to have an indepth understanding and analysis of the music reproduced in that room, though the final arbitrations may still be made by listenings. And the final decision as to how far one wants to go the room treatment way will still fall back on how much we want to spend on the project! And approved by the home minister! ;-p

unker vic said...

Hi big E,

Different people have different takes on where to place the diffusers based on their past experiences, and variously different perceptions of sound reproductions amongst different persons! It still comes down to measurements and charting the sound response of the resultant sound in the room in question, to have an indepth understanding and analysis of the music reproduced in that room, though the final arbitrations may still be made by listenings. And the final decision as to how far one wants to go the room treatment way will still fall back on how much we want to spend on the project! And approved by the home minister! ;-p

PuchongWong said...

Big E,

Wah,you are borned with a pair of super eair, your passion about hifi make me proud to be you friend, I believe it will be a great loss to hifi if one day we loss you

unker vic said...

wah, dear bro wong, u are thinking of the worst case scenario la. don't la. we need big e around to mess up our life with suggestions once in a while la. keeps the blood pressure going la.

unker vic said...

This should be interesting to readers who follow equipment reviews.........

read it from an article.....


"Here’s how I look at it: Hi-fi reviewers exist to provide a small but important service to their readers. Namely, to provide consistent, succinct and credible guidance on equipment; to cut through the waffly blather of manufacturers’ advertising copy with the cool, impartial insight of the independent investigator; and ultimately, to save potential buyers time, perhaps even money, by making it easier for them to choose equipment that will delight them.

And above all, as should be the case with any expert communicating with a non-expert audience, the key is to simplify and de-mystify: to strip away barriers to comprehension and enjoyment."


Big E & Odiosleuth sure did a good job. ;-p

Big E said...

Unker Vic,

Thanks for your kind words and support.

kkthen,

Egg box diffusers, Ah!.... that was a long, long time ago since I used those.

Puchong Wong,

I have no super ears, slightly psycho acoustic maybe? But passion and craziness is certainly in breed.

69A said...

The acoustic panels look good.