Acoustic Room Treatment

audiojerry · « **Reply #40 on:** 5 Feb 2003, 02:40 pm »

I'm getting in on this thread late, so maybe this has already been covered, but I'm too lazy read back through the whole thing:

My listening room is the opposite of most rooms in that it is way too dead. It is more like an anechoic chamber with all its absortive materials. It is in a finished basement. The walls are built out with 2x4's with R12 fiberglas insulation between the studs, covered by a layer of plastic vapor barrier, covered by 1/2" drywall, covered by 1x12 rough sawn cedar boards horizontally laid. The rough texture of the cedar boards makes them absorptive and deflective. The ceiling has 1x10 joists with R16 fiberglass loosely laide between the joists and covered by 1x12x1/2" acoustic ceiling panels. The ceiling panels are purous and rough textured. The cement floor is covered by a thick layer of foam padding covered by dense wall to wall carpeting. There are several pieces of heavily padded furniture and lots of objects hanging on the walls. Just about everything in this room absorbs sound instead of reflects it.

Believe me, there is no slap echo down there. This is not a good thing, but the room was not designed for audio. On the plus side imaging and soundstage is very precise. The downside is that music lacks a good deal of life. Energy is noticeably muted and there is a lack of punch. This is why I listen in the near field even though my room is fairly large. I have temporary use of two Bag End and two Earthquake subs for home theater, and even with all that output, the bass is not all that impressive.

My question is: does anyone have any suggestions or experience with sound diffussors or deflectors that would not greatly compromise the room's appearance to keep the wife happy?

Dan Banquer · « **Reply #41 on:** 5 Feb 2003, 03:57 pm »

This is a very interesting problem. I must admit that I have a hard time with wooden walls being this absoptive, and I suspect that something else is going on that we are presently not aware of. However; There are such beasts as RPG diffusers. I am not familiar with these items but a web search may be in order.

tmd · « **Reply #42 on:** 5 Feb 2003, 04:02 pm »

If you are handy with woodworking you might want to try the Decware panels. Steve will readily tell you if they will help or not.
I built the CWALS for bass absorbtion and they were very effective. I have to believe that the two forms of diffusion would be equally effective.
Neil.

nathanm · « **Reply #43 on:** 5 Feb 2003, 04:37 pm »

My idea for diffusion was to reverse engineer the RPG Skylines (otherwise about 300-400 bucks for two panels!!!

) using square sticks of styrofoam in random various heights glued together. Only thing I'd need is a nice hot wire table "saw" which I seem to recall seeing a DIY plan for somewheres out in cyberspace. I can add this to my list of uncompleted projects.

audiojerry · « **Reply #44 on:** 5 Feb 2003, 05:55 pm »

Quote from: nathanm

My idea for diffusion was to reverse engineer the RPG Skylines (otherwise about 300-400 bucks for two panels!!! ) using square sticks of styrofoam in random various heights glued together. Only thing I'd need is a nice hot wire table "saw" which I seem to recall seeing a DIY plan for somewheres out in cyberspace. I can add this to my list of uncompleted projects.

Nathan, I can't picture how this would look. Is the styrofoam supposed to be reflective of sound?

tmd, I'll go visit the Decware site.

nathanm · « **Reply #45 on:** 5 Feb 2003, 06:05 pm »

Something like this:

http://www.rpginc.com/products/skyline/index.htm

I am not certain of the specs of the material but I know that styrofoam is not as absorptive as one might think. Wood would be great, but way too heavy in this application.

Doh! Polystyrene is what the real thing is made of anyway!

Quote

The solid expanded polystyrene core of the Skyline® provides useful low frequency absorption.

Hantra · « **Reply #46 on:** 5 Feb 2003, 07:54 pm »

Yikes!!!!!

Has anyone priced that stuff? It's gotta be out of sight if it's in line with their other stuff.

I got some really reasonable corner treatments from Eighth Nerve last week. I wanted to see how they compare to my corner PZC's. I am sort of wondering about the corner PZC's because of their size. They have a gap to them between the wall, and while the burn material may take care of that pressure, I doubt it gets all of the nasty horn-loading in the corner behind it.

I like wood, and would prefer to stop the pressure from building in the corner, but until I can actually sit down and build some prototypes, I will have to go this route. These are quite a bit less absorbent than most of the other stuff.

I'm gonna try these, and I'll report back. As soon as I get some time. .

They are much cheaper than anything I have seen out there from credible companies.

L8z,

B

nathanm · « **Reply #47 on:** 5 Feb 2003, 08:08 pm »

RPG sells to big money clients like recording studios, hence the prices which make working people faint. As far as the Skylines go, I figure a savings of $380-some bucks is worth a few hours of labor making lumpy chunks of styrofoam! What's really super cool is their Trifusor device - three different surfaces on a swivel. A wall full of those would be sweet. Surely a straightforward DIY project if you've got the tools and time.

The studio-in-a-box package might make sense for most of us. I think that's around 2 grand or less. Auralex also has a whole-room package dealie too.

Hantra · « **Reply #48 on:** 5 Feb 2003, 08:16 pm »

I'd relly have to try to make any educated determination as to the value of the product, but judging from what I read, and see, it just looks too absorbent, and would result in a room that was too dead.

Of course, some people like that. But those are the people who don't really ever go hear live music.

B

nathanm · « **Reply #49 on:** 5 Feb 2003, 08:34 pm »

Well if you subscribe to the idea that recordings should represent what a band sounds like playing live in a room then you wouldn't want to play that reproduction back in a similarly live room cause then you are doubling up on the reverb\space\ambience. If you have a deader room you are going to get more of the recording directly and less of your own room sound.

If you want live sound at home, strip the room bare of all wall coverings and furniture, invite as many people as will fit inside the room shoulder to shoulder, put up a two stacks of PA cabs, crank the amps and press play!

The Skylines are designed to be diffusors not absorbers though. Every material does different degrees of both.

DVV · « **Reply #50 on:** 5 Feb 2003, 09:31 pm »

Here's a thought in general.

Treating your room acoustically will solve certain problems, to be sure, but could also introduce some problems of its own.

For example, moving your speakers away from back walls and corners will cure many a problem (though not all) and will allow your speakers to reproduce recorded space and ambience much better, especially if you have a reflex system with a back-firing tuning port.

I have experiemnted much with loudspeaker positioning in my own rooms (I live in an apartment) and have found that adding back damping does reduce problems with muddy and/or overblown bass, but that it can also reduce the space quotient - which I definitely do NOT want to happen.

In the end, in my room, which is app. 14x11 feet, due to its specific architecture and furnishing, the best overall result is to move the speakers about 3 feet from back walls and use no acoustic damping. This allows for outstanding space effect if present in recordings.

Cheers,
DVV

Rob Babcock · « **Reply #51 on:** 5 Feb 2003, 11:16 pm »

I guess the pricing of the Skylines didn't only bother me! I've been hanging out at Home Depot checking out sheets of foam with the same idea of replicating the Skylines. A person could cut a sheet into strips and glue them all or maybe one could cut the big sheet into, say, 6" X 3-4'. Then you could randomly notch each peice, then laminate them all together. I think one should be able to duplicate the characteristics pretty closely for a lot less cash.

I'm definately in the camp that favors some acoustic treatment. Properly implemented, this will solve more problems than it creates. Slap echoes and room modes are the most destructive to good sound, IMO. It isn't easy to deal with large peaks or suckouts in the bass end with just room treatment; this will sometimes require some eq'ing. This can be especially tough in a small room, which is what I'm dealing with now in my 2nd system. I will probably add a parametric eq for the bass (this approach has worked wonders in my main system). My room isn't as excessively live as it could be, mostly due to a lot of diffusive elements in the room. But I still need some absorption, as will as a couple of bass traps.

Luckily there are some good sources of info for the DIYer who wants to experiment with acoustic treatment. One is the >Klone-audio.com< site; lot's of links to DIY. I'd also suggest that the Master Handbook of Acoustics, by Everest, is near-required reading.

I haven't gotten too far into the treatment of my 2nd listening room yet, still planning/saving my pennies. Even DIY isn't free, unfortunately. But I'm convinced that $400 in room treatments can be more useful than $4000 spent on more gear. The system is only as strong as the weakest link, and that link is often the listening room.

Dan Banquer · « **Reply #52 on:** 6 Feb 2003, 01:40 pm »

Your last paragraph says it all Rob. I can only hope that more audiophiles pay attention to the wisdom you have imparted.

JoshK · « **Reply #53 on:** 6 Feb 2003, 02:47 pm »

I'll add that my weakest link is my room. It isn't a bad room but it still imparts its signature on the music more than any one component in my system does. This is why I quit looking for more or different components. I am happy with the way my system sounds now but can also see what I need to do to get the last ounce out of it and it isn't spending another $1000 on a DAC, or $600 on cables, it starts with my room.

hairofthedawg · « **Reply #54 on:** 6 Feb 2003, 05:08 pm »

My first effort at taming my room was pretty simple, just repositioned things. It's kind of a pain folding the rug in half to slide my chair forward but it's now got a very deep soundstage and does pretty good on width. I was a little surprised to find a couple of bloomy bass frequencies in the after positon, when the reason I had moved them to before in the first place was to get rid of the bloom, which it did. Fortunately it's not at a frequency I commonly hear. Now the fun part, coming up with something to put over the glass and in the empty spaces...

188" room width, woofers are 84" from the back wall and 52" from the side, listen from about 96" away. It still sounds good from the before listening spot, but once I get rid of the bloom, I think this is the spot.

cheers,

Dick

before

and after

Dan Banquer · « **Reply #55 on:** 6 Feb 2003, 05:47 pm »

Hi Dick;
I would try some very heavy drapes over the windows, find the ones that can open and close. If you can find some cosmetically appealing foam, cover the rest of the back wall and come up on the sides about 3 to 4 feet. Some of the posts on this thread link to web sites that have some pretty nice looking stuff.
I can't see from the picture but putting the speakers up on spikes could help with decoupling the speaker from the floor and help lower the bass boom, and possibly clean up the midrange a bit. You may also wish to try toeing in your speakers.
Keep us posted on your results.

nathanm · « **Reply #56 on:** 6 Feb 2003, 06:53 pm »

How come you folded the rug in half? Wouldn't you just put the chair on top of the rug? Or is that just a temp positioning-ease thing?

hairofthedawg · « **Reply #57 on:** 6 Feb 2003, 08:02 pm »

http://www.wildwoodrugby.com/during.jpgHey Dan, Nathan,

I know on the drapes, been waiting for my girlfriend to get here, but she may just end up living with my taste... What's the best fabric for drapes?

I've been checking various websites, but it's a bit of a problem getting things to me here, especially if they are bulky. I'll find a way, I always do!

If you look at the after shot and see the chair with a sheet and albums on it, that's where my room opens up to another pretty large room. Should I adjust my speaker positioning for the opening? Some things I've read said to move the speakers a bit toward the opening. I'm still playing with the positioning, but, man, does it take patience...

I don't know if you've read my website, but one of the things I wrote about was my surprise that legos came with the speakers. They come with a baseplate and 4 of the 4-lug legos are supposed to go beneath each baseplate, then 4 more on top of the baseplate and the speakers go on those. It's a major pain to keep anything in place when adjusting, so I only have them between the baseplate and speakers at the moment. I do need some adjustable spikes though since my floor is rarely level. What's nice is that it's a pleasure listening no matter where they are positioned.

Thanks again for the suggestions and the audioperfectionist link.

Nathan, you're right partially, it was easier at the moment to fold the rug than move the chair. It's not light, liftable, but I had just spent quite a bit of time disconnecting and reconnecting and such and thought it was the easiest way to hear things quick. I don't know if having the rug covering the floor behind the chair would make a difference or not. Might try it someday....

Here's what a mess it was..

Dan Banquer · « **Reply #58 on:** 6 Feb 2003, 09:09 pm »

Hi Dick;
Well I really don't know what to tell you about drapes. The acoustic foam, If I remember correctly, is an open cell urethane. I don't think you want drapes made from that material. I think that would be more the style of Pimp Daddy Marbles. I think the best we can do here is go with a heavy cloth of some type. By the way have you thought about "Whorehouse Red" for the drapes. You could be the envy of many here at audiocircle.

markC · « **Reply #59 on:** 6 Feb 2003, 09:23 pm »

Moving speaks to find "THE" sweet spot is a pain, for sure. When I did mine, I didn't use the spikes until I found the positioning that I liked the best. I listened for the best imaging and bass response, etc. and then wound the spikes into place. After the speaks where up on the spikes, it was that much better, and I was able to sit back, listen and smile knowing that it was all worth while! So, you might want to loose the legos until you find the "G" spot and them put them back in.