Im interested in experimenting with anechoic wall wedges, but commercial products seem to be highly specialized and limited to professional installation (above my pupose)
So I was thinking about making a form and casting some wedges of my own design.
The physics I understand ok, and have seen (not heard) walls made of steel - so I know they can be quite dense.
the depth of the wedges I have studied range from 6" to 4.5'. For practical purposes I want to first attempt 1' depth.
I figure with some ingenuitive use of wallpaper, masonite, and some expandable foam I can get a decent result.
but Im having some trouble finding data on the foam. It needs to be an insulation type suited to being in an enclosed room ( for fire purposes)
See if you can follow my sketch. top is a view down into the form as if your just about to pour in foam.
the white parts would be a piece of wall paper along the angled sections
and the brown sections wouidl be trangular pieces of 1/8" masonite (not angled, perpendicular to top plane(red))
The red top plane woudl be the part affixed to the wall
The second pic is a cross section of the front side.
Thick folded drapes hung on walls work really well. They are roughly wedge in shape when properly hung. An old army blanket works also, but looks like ****. I imagine all the wedge **** that is pushed today is just a cheapskate way of avoiding hanging thick folded drapes. The folded drapes worked for the masters who designed the world's best concert halls, and looked a lot better than plywood or molded wedges.
Some expanding foams are actually toxic, so be careful there. I'll take the wool drapes any day over techno geek wedges. You might consider placing dowel rods in an offset pattern between two boards that hold them in place, then pulling a wool blanket around the rods to make a wedge shaped wool acoustic trap.
yeah Ill agree with you about the wedges being an eyesore, but as a diffusion device you cant beat it. other then doing a similar idea with cones.
(PVC pipe halfs also work well as cheap diffusion devices, but tend to look like corrogated plastic)
The deeper your wedge, the lower the frequencies it will diffuse.
Drapes work well for mid to highs, so would carpet with a thinkpad. but I got a full range problem, and lows are the worst as thety travel the furthest
The room Im attempting to tame a bit is about 3000 sqft (appx 50' X 60')
Really my first goal is only to tame the walls behing the group, so their moniter will stop bouncing back into the audience.
the floor is hard tile,
the ceiling is vaulted but made of solid timber
(6" at the thinnest before the roofing material)
and the walls are concrete popcorn block.
I was considering streaching fabric over the wedges after they are on the wall, to make a flat surface.
Im probably going to attempt the ceiling first because the beams holding the ceiling will hide most of my handiwork from those that will complain of my efforts.
Yeah it seems all polyurethane foams are toxic when they burn. some have fire retarders.
Ill have to keep looking and thinking.
the risk is minimal given the 4 2-door direct exits to outdoors, and 3 indirect exits in the room, but still
Diffractors made from insulation material hung on an outside facing wall could cause moisture buildup inside the wall, with possible disastrous consequences.
I spent 5 minutes in a neighbor's apartment and found him 4 moldy places (he smokes and can't smell very well and I'm like a bloodhound when it comes to mold). Acoustic treatments are the least of your concerns when you live in a place like Texas that is whacked out by mold everywhere you look. I mean there are stores and homes here I can't spend even 5 minutes in without getting zapped by mold and getting stuffy sinuses and worse. A local strip mall has recently been dozed to the ground because of mold and is being hauled off in dump trucks. Acoustic tiles and faulty HVAC units were major offenders. Two people are dead with about 40 more sueing the New York (damn yankee to the locals) owner in a class action lawsuit. FWIW, acoustic tiles are one of the worst offenders for harboring mold as cellulose is mold's favorite food and the soft composition lets it establish itself very quickly. In damp places in Europe, I never saw these severe moldy conditions in old buildings of traditional construction methods. I was in the Hermitage which sits right on the Neva River and it was neglected for years under the Communist government. It never degenerated into a mold heap. I would NEVER install area carpeting to solve an acoustic problem. The health problems aren't worth it. I grew up with tile and wood floors and that's what I'm going back to.
I noticed in the Liverpool Club in St. Petersburg they didn't have acoustic tiles and the floors were hard surfaced. The sound was good. People and furniture can do away with the need for lots of acoustic treatment. Bookshelves are one of the things that can act as sound diffractors, as well as plants with lots of leaves, large chandeliers, ceiling fans (put a little Pignose next to one and you get a Leslie effect), etc.
It is a known fact that the humidity of air in a concert hall will affect the sound. High frequencies transmit better through moist air, and dry winter air will give a concert hall a "dry" sound in the upper frequencies. Thus, halls in northern regions do not need as much attention to taming high frequencies as heated air has very low humidity. I have a dehumidifier that I run in the damp months here and I ALWAYS keep the relative humidity of indoor air below 50%, because if you don't you will definitely have mold problems in a building with modern sheetrock wall construction because surface humidity can be much higher than air humidity due to temperature differentials and faulty moisture barriers. Stuffy sinuses and ringing ears (or worse) from mold will quickly offset any gains made in acoustic treatment if it generates mold growth. Blown-in expanding urethane foam also figures highly in mold growth and will soon be banned in Texas (and elsewhere) if it already hasn't been. My physician handed me a stack of materials to review and I noticed how insulation figured prominently in mold growth. One nurse at work had one of her parents killed by mold in ceiling insulation. People in Russia have leaky roofs also, but don't have thick moisture-holding insulation piled above their ceilings. Americans do that ****, so they can keep the room 75 degrees in winter. Russians sit closer to the fire, and maybe play their violin instead of the stereo. Your walls should be solid.......wood, concrete, stone or whatever. Hollow walls not only sound bad, they are unhealthy if they are damp inside and support mold growth. Ever notice how old houses built solidly from full cut old growth oak lumber, stone, thick solid wood paneling, etc. tend to sound the best? Thin sheetrock panels nailed to flimsy fast growth pine studs are **** for sound (per an article in Audio magazine by an acoustical engineer), as well as being potential toxic traps. Cheapness and fast build time are the only advantages. I'll put MY money into sound basic construction from here on out, thank you very much. I heard an orchestra play in the Mariinsky Theater, and the old ways of doing things work mighty fine to my ears. I think a lot of modern acoustic treatments are band aids for bad basic design and cheap, flimsy modern construction methods. I have seen supposedly nice homes here in Texas that I wouldn't give two cents for if I had to live in them, now that I know the future health consequences they hold. The old methods of high mass construction generally yield a better sounding building, besides all the other benefits down the road.
Yeah, I know, the old ways of building are now the more expensive ways of building in most instances. Fast food, fast cars, fast built buildings, fast profits, fast lifestyle in general.....it's all mostly **** in the end. Buy now.....pay later.
I wana house made outta steel, concrete, brick and stone.
old time monks were notoriuos for adjusting accoustics, and they learned a lot that many old concert halls and theaters were based off their findings.
They would use hollow columns and fill the innards with sand to tune them to a specific frequency that they wanted rid of, not to mention the accoustic benefits of teh shape of the column.
similar ideas were used with stone plant urns and nooks in walls. They would find a way to tune everything, and would design their buildings around accoustics!
Old building had a lot of thought that most dont give credit, now we no longer have time for thought.
JP
Ive decided against expanding foam due to its burining problems.
Jim, I was in Lima Peru when it happened but it even made the papers over there, but I didn't see the videos or anyhting on US news at all. A friend of mine lost his drummer in that fire.
Hi Bob,
Was a bad, bad night, I think in all it took less than 15 seconds to go from a pyro show, to roof, and backstage catching fire to the whole stage engulfed.
FWIW, here are three things we put in public buildings that are basically banned in parts of Europe, as least old builders never used them: Fluorescent lighting other than full spectrum daylight (my building was changed to energy efficient fluorescent lighting at considerable cost to "save money", which basically helps drive people mad, helping to produce SAD, seasonal affective disorder and other problems), area carpeting (banned in public buildings in Europe for obvious reasons), and wood cellulose acoustic ceiling tiles.
Suspended acoustic tile ceilings are a bad idea, helping to spread fire very quickly unless fast acting sprinkler systems are installed. Their low mass and insulating properties allow nearly instantaneous heat buildup on the exposed surface toward the heat source. One sprinkler system at work has already failed, flooding that area before it could be turned off.....causing further mold problems in wallboard that was soaked. That hallway has a constant mold smell now. People who do not speak English did a lot of the installation work, and those living in Texas know what I mean. Water still runs downhill as well, endangering lower floors. You can find mold spots throughout the facility in ceiling tiles, due to AC leaks and condensation. Running cold water pipes through hollow walls and ceilings containing wood products is beyond stupid.
The latest research proves that sunlight prevents skin cancer, and fluorescent lighting promotes skin cancer. I find that lighting also helps set the mood when listening to music, and almost nobody talks about it. You will NOT be using fluorescent lighting to set a good musical mood. I use quartz halogen lighting throughout my home. Maybe skylights and tall windows will make a comeback someday. Area carpeting is a good acoustic sponge, but it is not frequency specific as Josh explains, besides being so chemically toxic and so biologically nasty that you would have a hard time jusifying it under any circumstance to a sane person concerned about their health. I guess it's helping to save Social Security, as those who keep engaging in these unhealthy environmental practices will not be collecting much of it. Therefore, the government has little reason to convince you to do the right things, as people are basically "pulling the trigger" on themselves voluntarily and these things I talk of take years or decades to get you and are just as sure as they are slow. Therefore, largely undiagnosed. Mycotoxin induced health damage is largely irreversible, and your average physician has nary a clue on how to go about treating it.
I'm right there with Josh in realizing that people no longer have time for thought. This thread has gone beyond acoustic wedges and expanding foam. Keep that fiberglass dry, Josh, because it was named as a top source of mold growth in homes when I reviewed some data on mold in homes. It cannot be cleaned, and dirt that collects in it will start growing mold as soon as humidity tops 60%. It cannot be exposed to contaminating air or water contact in any way, so basically it has to be put away where sound waves normally don't contact it, Inside a dry speaker box controlling the backwave is about the only way you can safely use it acoustically.
FWIW, one of the first things that my environmentally knowledgeable physician asked me when I showed up with a mold induced problem was, "Do you have gas heat"? My parents have it and it's causing some mold problems. She sees this problem over and over again. The byproduct of burning gas is carbon dioxide and water. The moisture promotes mold growth. Besides that, it lowers your home oxygen levels which is carcinogenic among other things. Aspergillus mold (gray or black mold in your air conditioner) produces aflatoxin which is the most carcinogenic mycotoxin in existence. Low oxygen and aflatoxin is a great recipe for cancer. Any mold can wipe out your immune system over time, giving you AIDS, much like HIV does. One of the biggest coverups is that HIV is the biggest cause of AIDS in our society. Don't use any BS acoustic treatments that promote mold in any way, especially in the damp and warm south. I will not even put foam wedges on my walls, because the foam itself may not promote mold growth, but the dirt it collects most certainly does.
I don't ever recall where common modern acoustic treatments were ever made for producing more musical sound, but only for making a building quieter (one person not disturbing another). Therefore, it would fly in the face of the old masters' ways of acoustic design, which was to preserve the good things and produce an overall balance to the sound. Now we just soak up everything in most buildings and blast away with more power to overcome it while ruining our health. What progress!!!
