| Author | Message | ||
| jalevinemd
Senior Member Username: jalevinemd Post Number: 849 Registered: 12-2003 |
The room I play in at home is my den. It's above the garage and has a 15 foot ceiling shaped like this: / \ I'm losing a lot of sound and wanted to put acoustic panels on both sides of the sloped ceiling. Any idea how much needs to be covered? How far apart should the panels be? | ||
| mario_farufyno
Senior Member Username: mario_farufyno Post Number: 843 Registered: 9-2008 |
Acoustic panels are usually used to adjust how a room should sounds, to tune his "tone" and control its reverberant field. If you need to improve sound proofing, you must think in terms of increase walls/floor/ceiling's mass. Drywalls are an efficient way to gain mass and keep highs and mids trapped in the room. Efficience will depend on how carefully you cover inside surfaces. Remember that any thinner wall will be where sound will drain out, as windows and doors (one weak ring in the chain is where all our efforts will fail). Opting for double pane window, thicker and heavier glasses and doors, will help. Avoid openings below doors or even keyholes, you would be amazed how much sound energy can escape by such tiny openings. In studios, people use neoprene rings to seal doors and windows when closed to their backstop. If air can get out, sound will too. Unfortunately, lows can put things shaking too easily, so it is considerably harder to inprison them. As they get out by vibrating walls/floor/structure, you must get ways to decouple inner isolation from outer walls. You can hang drywalls on metal trails, reducing its contact points to the wall, or use wires to suspend them on the ceiling. There is even kinds of hangers that have rubber cushions to help dampen vibrations. There are many ways to isolate sound, but sky is the limit. Consider how much you intend to spend and how much sound proofing you need. | ||
| eligilam
Advanced Member Username: eligilam Post Number: 398 Registered: 2-2006 |
Are you looking to soundproof or to cut down on wall reverberations? | ||
| jalevinemd
Senior Member Username: jalevinemd Post Number: 850 Registered: 12-2003 |
Cut down on wall reverb. Not looking to soundproof. | ||
| lbpesq
Senior Member Username: lbpesq Post Number: 5277 Registered: 7-2004 |
In the old days we used egg crate. Bill, tgo | ||
| jalevinemd
Senior Member Username: jalevinemd Post Number: 851 Registered: 12-2003 |
I want it to be functional as well as aesthetically pleasing. | ||
| lbpesq
Senior Member Username: lbpesq Post Number: 5278 Registered: 7-2004 |
Dark grey foam egg crate? More expensive than the cardboard stuff, but I always thought it looked cool! Bill, tgo | ||
| jalevinemd
Senior Member Username: jalevinemd Post Number: 852 Registered: 12-2003 |
Hmmmm... Don't think I've ever seen foam egg crate. I'll take a look around. | ||
| sonicus
Senior Member Username: sonicus Post Number: 2714 Registered: 5-2009 |
Egg Crate Link availability; http://www.allegromedical.com/hospital-discharge-favorites-c5000/eggcrate-foam-mattress-pad-p191438.html | ||
| keith_h
Senior Member Username: keith_h Post Number: 1811 Registered: 2-2005 |
You need to be careful with what foam products you use. Many of the lower cost foams are highly flammable. While they will all burn the ones specifically designed for sound absorption are flame resistant. Keith | ||
| sonicus
Senior Member Username: sonicus Post Number: 2715 Registered: 5-2009 |
Here is the preferred alternative; http://www.acousticalsolutions.com/?gclid=CMDD56Gw1rMCFYZM4AodM0EAIg | ||
| cje
Intermediate Member Username: cje Post Number: 123 Registered: 5-2009 |
One functional thing you could do is get some absorptive material like Sonex or egg crate, and attach them to plywood panels of the same size with a spray adhesive. Then, hang them from the ceiling, say 4-6 feet down, perhaps at different angles. This way, you eliminate much of the cavernous sound that your 15ft ceiling is creating, but you are still letting some sound travel up, and it won't feel like you are in a small room. I'd start with just a few, maybe 4 at first, and see if it provides enough dampening. You can always add more, add a bit of treatment to the walls, or maybe some bass traps. Eliminating parallel surfaces by attaching things to the walls of different depths will go a long way to eliminate reverberation and standing waves. In acoustics, those things are called diffusers. Don't go overboard and cover 100% of your surfaces with absorptive material. It's usually best to add just enough so it sounds good, but leave some reflective material exposed so your room doesn't sound lifeless. Let us know how it works out! | ||
| cozmik_cowboy
Senior Member Username: cozmik_cowboy Post Number: 1336 Registered: 10-2006 |
Pull off the drywall between every other stud (try to get opposing walls opposite - drywall facing torn off) , fill the space with insulation (if it's not already), and cover with burlap/tie-dye/faux leopard/your cloth of choice. Now you're half reflective, half absorbtive, and looking groovy. If this not a dedicated studio space, though, you may want to get prior approval from senior management. Peter | ||
| edwin
Senior Member Username: edwin Post Number: 1356 Registered: 5-2002 |
Foam doesn't really do all that much to improve acoustics. I've looked into this extensively and foam might affect some high frequency reflections, but it leaves your wallet empty and the room largely unaffected. While I'm not specifically recommending this company over others, check out http://www.gikacoustics.com. I do have a couple of their 2x4 2" panels and they are very nice. I also made a bunch out of 5" deep cotton acoustic insulation. Much cheaper and very effective. While this forum deals with mostly studio issues, there are lots of ideas applicable to your situation and some real experts (including Glenn of GIK) hang here and so your questions can get some good answer. So, I'll just reiterate, stay away from foam, you'd be wasting time and money. Believe me, I've been there. I spent a lot of money on Auralex, trying to do it on the cheap and ending up taking a loss on all of it and starting over right. I'm definitely not the only one to have found this out the hard way and I'd hate for you to walk down that path as well. | ||
| jalevinemd
Senior Member Username: jalevinemd Post Number: 853 Registered: 12-2003 |
Edwin, Thanks for the link. I'm going to call them on Monday and see what their thoughts are regarding my needs and budget. Funny you should mention Auralex...that was the direction I was heading! Regards, Jonathan | ||
| edwin
Senior Member Username: edwin Post Number: 1358 Registered: 5-2002 |
Yeah, I spent probably $500 on Auralex about 10 years ago for my basement jam room/studio. I ended up giving it all away with an apology that no matter how excited they were about putting all that stuff up, not much was going to happen. I then spent $50 on a huge bale of the acoustic cotton (which was a lot cheaper then for some reason. It was also local), went to Home Depot and had them cut some 1x6 to length and got a bunch of muslin. An afternoon later I had 2 2x6' panes and 4 2x4' panels. I also discovered I could hear my monitor speakers for the first time, which I had wasted tons of money trying different speakers in the room. I later bought two of the GIK 2x4' panels and put them right over my head to help kill floor to ceiling reflections. Very helpful and the construction they use allows them to be hung safely overhead. Total cost: way less than $500. | ||
| edwin
Senior Member Username: edwin Post Number: 1359 Registered: 5-2002 |
Oh yeah, Ethan Winer is also considered an expert in the field. His products, RealTraps, are excellent, but a bit pricier. His website has a lot of good info and he's got a pretty good general audio book out. http://www.realtraps.com | ||
| keith_h
Senior Member Username: keith_h Post Number: 1812 Registered: 2-2005 |
Here's a do it yourself site. http://acousticsfreq.com/blog/?p=62 Keith | ||
| ies_2000
New Username: ies_2000 Post Number: 1 Registered: 11-2012 |
[no commercial postings on the board., please] (Message edited by adriaan on November 19, 2012) | ||
| 5sicks
Junior Username: 5sicks Post Number: 39 Registered: 8-2010 |
I use 2X3' 3" open cell packing panels at odd angles on the walls and ceiling. Styrofoam packing in various shapes kill the bass in corners. The goal is to diffuse and scatter the sound waves much like stealth technology on military aircraft. | ||
| edwin
Senior Member Username: edwin Post Number: 1360 Registered: 5-2002 |
I've never heard of styrofoam being used as a bass trap before. Interesting. I've always heard that you need absorbent and compressible material for that kind of function. Styrofoam strikes me as pretty reflective at low frequencies, in fact at most frequencies. I think Keith's link is pretty right on. It's similar to what I did. I will say that controlling reflections was very useful, but the bass traps were even more effective. His stuff can be adapted to bass trap duty by layering the rigid fiberglass to 6 or more inches and then placing it across wall or floor/wall or wall/ceiling boundaries. Unless you have 4" inches or more of absorption, your device is going to be limited at the lower end to the very upper midrange at best. Overall, though, I'd recommend not wasting time with foam, styro and otherwise, egg crates, etc. If you look over the acoustical forum at Gearslutz, you'll find that pretty much everything you can imagine has been tried and 99.9% of it doesn't measure up to good old rigid fiberglas or acoustical cotton. It's a fun place to read the threads: http://www.gearslutz.com/board/studio-building-acoustics/ | ||
| hankster
Advanced Member Username: hankster Post Number: 298 Registered: 6-2004 |
Think about tube traps: http://www.tubetrap.com/ R. | ||
| mario_farufyno
Senior Member Username: mario_farufyno Post Number: 846 Registered: 9-2008 |
You have to distinguish what problems you're having (or which frequencies are exceding). Lows in excess is usually related to a problem known as Standing Waves. This can only be really eliminated by changing room's proportions in order to spread any reinforcements in some low frequencies the best possible, which is not in question (you will not rebuild your room, I supose). But you can use sound absorbers to tame them a little. Even in appropriate proportioned rooms is known that Lows will sound exaggerated near walls and even more in the corners (where walls join). So it is common to use sound absorbers exactly on these spots. The problem is that porous absorbers (such as foams and fibers) are not as effective in decreasing bass resonances. | ||
| mario_farufyno
Senior Member Username: mario_farufyno Post Number: 847 Registered: 9-2008 |
A simple rule teaches us that a porous material can reduce sound energy at frequencies that have wavelengths greater than 4 times its thickness. That is, if we are talking about excess at 100Hz (which has a length of approximately 11.3 feet) we'll need something an absorber close to 33.85" in thickness. Somewhat too thick to lose in a room and it will not absorb frequencies below 100Hz, just above (if the problematic frequency is low as an open E, wich rings in 41Hz, it would require an absorber more than 70" thick!). So, any porous absorber isn't really helping. * For calculating the wavelengths, we have the following formula: f = v / L - where "f" is the frequency - "V" is the speed of sound (about 1130 feet per second, since the velocity varies with environmental conditions, specially temperature) - and "L" stands for waveLengh ** a simple formula to porous absorber is: f = 1/4 d - where "f" is the low frequency above which our absorber will be effective - and "d"is de thikness of it | ||
| sonicus
Senior Member Username: sonicus Post Number: 2723 Registered: 5-2009 |
If you really want to know what going on in a room ; first of all I would do a few "Pink Noise Shots " with an "RTA" (real time analyzer) to get an idea of what you have in front of you. Other wise it's almost like trying to grab a fish in a 12 foot deep barrel with muddy water with no visibility. Don't fall in the water ___ LOL ! | ||
| edwin
Senior Member Username: edwin Post Number: 1366 Registered: 5-2002 |
If we are trying tame very specific room modes, then broadband absorption is the wrong tool. Tuned diaphragmatic bass traps work much better for this. However, they are much more involved to make well. I'm curious about the simple rule of absorption of wavelengths 4 times greater than the thickness. I wonder if this is a rule across all types of absorptive materials or a generalization or an average. My anecdotal evidence is that even 6" is very effective at tightening up the low end in a room that is roughly 12x20x7 (low ceiling-grrrrr). Counterintuitively, bass traps actually improve the perception of bass response rather than attenuate it. I went through a bunch of different monitors trying to find some with good bass response before I added the bass traps. As soon as I did, it became obvious that any of the monitors I had chosen would have been fine. | ||
| mario_farufyno
Senior Member Username: mario_farufyno Post Number: 848 Registered: 9-2008 |
However, to our joy, we can create membrane absorbers that use the mass of the material to lower its frequency of operation without requiring an increase in thickness as large as would be required with porous materials. Thus, with a wooden plate (or even fiberwood) just a few inches away from the wall, can act in these severe. And it's good to know that this type of absorber acts only on Lows. While a porous aborvedor acts as a hi-cut (or Low Pass Filter), attenuating sounds above its cutoff frequency, a membrane absorber acts as a lo-cut (High Pass Filter). That's why they are called Bass Traps. The operating principle is that bass can easily pass through a plate due diffraction. Whenever the wavelength of a sound is greater than an obstacle, he can overtake him as if it didn't exist. Thus, the bass pass through the plate and flap against the wall. Upon returning to the room, they meet with the board by behind. At this time the board will tend to vibrate, consuming the sound energy from air converting it into plate motion (transforming acoustic energy into mechanical energy). If we associate some kind of cushioning to damp this vibration, we can dissipate excessive energy in a bass resonating room. It's like what happens when you put your fingertips on a vibrating string. Bass Traps doesn't act over Highs because their smaller wavelenght makes them "bounce" at the plate and they reflect back to the room. That's why we combine different absorbers to treat a room. In fact, we have to calculate Standing Waves and Reverberation Time to know exactly how much area of each we'll need on any specific room (because we don't want it sounding too dead, too). But you can spread Bass Traps to improve how your room sounds and make further adjustments ahead, anyway. The advantage is that you can tune your bass trap just puting it closer or far way from a fixed wall, because cutoff frequency depends on its mass and distance to the wall. *This is the formula: f = 1900 / √(m x d) - where "f" is the cut off frequency, below what our bass trap will be effective - 1900 is simply a constant related to metric measures (sorry, being brazilian I don't know the constant to imperial measurements) - and this constant is divided by the square root of "m" (surface mass in Kilograms per square meter - Kg/m2 - weigh divided by area) multiplied by "d" the distance to wall (in milimeters, mm) | ||
| mario_farufyno
Senior Member Username: mario_farufyno Post Number: 849 Registered: 9-2008 |
Sonicus is right, an RTA can show you wich frequency is offendant Edwin, that 1/4 rule is probably an generalization, for sure. And it is clearly better to control just the specific problematic frequency than start to kill all animals in a forest just to catch a single rabbit. Hope that membrane Bass Trap formula helps somehow That "√" in the formula was an attempt to write down Mac's square root symbol that went wrong... | ||
| mario_farufyno
Senior Member Username: mario_farufyno Post Number: 850 Registered: 9-2008 |
ofensive or problematic frequency would be better (sorry, I suffer to express myself in english) | ||
| mario_farufyno
Senior Member Username: mario_farufyno Post Number: 851 Registered: 9-2008 |
Important is that membrane is meant to vibrate freely, so hold it by its corners. You can use any material other than plywood, as glass sheets, fabric or even some foam sheet. It can act as broadband absorber if you put it on a corner, since distance to wall will vary. Don't forget the damping behind the plate, it can increase its "strenght". You can weigh plywoods in a scale and divide by its dimensions to know its "surface mass". If you wll use Imperial measurements, you must change the constant. If you measure in meters, you must change constant to 19. If using centimeters the constant will be 190 (1900 works just with milimeters). Metric measurements are based on decimal divisions... | ||
| edwin
Senior Member Username: edwin Post Number: 1367 Registered: 5-2002 |
Obrigado muito para toda a informação, seu inglês é muito melhor do que meu português! | ||
| mario_farufyno
Senior Member Username: mario_farufyno Post Number: 854 Registered: 9-2008 |
This is an easy and cheap way to control Lows in a room. If we simply use porous absorbers (like foams or rockwool/fiberglass) we'll end in a very dead room - no high end, very little reverberation - a totally unnatural enviroment since we're used to glue sounds with reverberation and realize our position in space by hearing sound reflections oposing to direct sound. Our brain needs those subtle data to feel inside a place, to feel that there are walls, floor and ceiling around us. This is why we use reverbs and delays in a mixing process. This is the secret behind obtaining an soundscape with depth and dimensions beyond simply Left/Right paning. This is true when recording - that's why we combine distant and ambient miking with close miking techniques - as is true in mixing. But we need or enjoy being in live rooms, too. Specially when playing, since each musical style uses longer or shorter reverb times (as Gregorian Choirs in a Cathedral or a Punk Band in a garage or small club). We should adjust reverb time to match the music we're playing combining different materials to control each tone band (sub-bass, lows, low-mids, mids, hi-mids and so on). But in Javelinemd's room the issue seems to be standing waves reinforcing lows. In this scenario is better to kill just the specific frequencys that are exagerated. Avoid using foams to not make things worst. They will mess with your high end and let Lows prevail compared to such damped Highs. Since thin sheets of porous absorbers can't affect lows (just highs above cut off frequency), using them without Bass Traps creates boomy rooms. ps.: Love your effort in portuguese, Edwin! (Message edited by mario farufyno on November 28, 2012) |
