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I’ve been a huge proponent of acoustic treatments and use them in my reference room too much success, however it hasn’t always been the case. For years I understood the importance of acoustic treatments and room acoustics but like many audiophiles and enthusiasts I wasted my time, money and energy on new equipment, cables and/or speakers thinking that they would lead me to the promise land. Well they led me to a promise-the promise that I, like many before me, would become a broke-ass audiophile.
When I finally wised up and said enough was enough I still didn’t give room acoustics and treatments their proper due. Instead I thought I knew better and began scouring the Internet in search of quick fixes and tweaks that would cost me a fraction of what acoustic treatment companies were charging for solutions that WORKED.
Below is a list of the five most commonly used “acoustic treatments” that actually DON’T work.
Egg Cartons as Diffusers
This one has to come from the pro world for we’ve all seen pyramid like panels and/or wedges plastered across the walls of countless recording studios leading many to think that their unused egg cartons would work in a similar fashion. Truth is they don’t, instead they’re actually more absorptive than anything and even from an absorptive standpoint egg cartons are weak sauce.
Foam Wedges, Pyramids, Panels etc.
Foam is cheap and readily available just about everywhere, especially online which is why so many flock to it as the go-to solution for addressing room acoustics. The truth of the matter is foam does treat some aspects of a room’s acoustics, think super high frequencies, but does very little elsewhere and is pretty much useless if you’re trying for diffusion.
Albums and Books as Diffusers
A lot of people will tell you that if you want diffusion but don’t like the look of acoustic treatments you should get a couple of large bookcases and fill them with LPs and/or books to achieve the same effect. Truth be told, bookcases filled with books can be a somewhat useful acoustic tool in their own subtle way-they just tend to be far more absorptive than anything else. For what it costs to buy a few bookcases and fill them with books you’ll never read though will display proudly to your friends you can buy far more effective products from reputable acoustic treatment manufacturers.
Hanging Rugs and/or Heavy Drapes on Your Walls
I’ve been guilty of this one more than once and the conversation is always an interesting one when your guests inquire as to why there is a rug on your floor and your wall. Hanging a rug on your wall does little to no good in taming any problem nodes outside of uber high frequencies associated with slap or clap echo, which are easily dealt with using simple treatments that will attract far less attention to themselves than an area rug hanging overhead or on a wall.
Using Foam Core, Foam, Plastic, Pennies and/or Anything Else You Can Get Your Hands On Solution, Solution
This one might seem a bit strange but we’ve all seen it, some whack-a-doodle claiming that by cutting the corners of your room with foam core, or by suspending pennies from your ceiling (this is real) or even placing various shipping tubes behind your speakers you’ll achieve sonic bliss. Well this is all BS too, for while their inception may be grounded in some form of reality their application, especially the pennies, doesn’t achieve… you know what. They claim that because your walls are no longer parallel or that they consist and or are obstructed by uneven or non-parallel surfaces your sound is going to be better when in reality all you’ve accomplished is minimal (emphasis on minimal) scatter and maximum what the hell were you thinking effect.
So before you go off and attempt to out-smart the professionals who do this sort of thing for a living by suspending 500 yards of hamster cage from your living room ceiling-do yourself, your family and your wallet a favor and call one of the many acoustic treatment manufactures first.
I personally recommend both ASC, makers of the famed Tube Trap, and GIK Acoustics for both companies are highly reputable, ethical and will consult with you about your room and its acoustic needs free of charge.
So, what to do about slap echo (ringing when clapping hands) with 4-7 dbC increase in frequencies above 4KhZ? Tried this on both your companies and apparently they have no affordable solutions or not giving them out if so. Realizing this is opposite problem to classical acoustics where the bass is really uneven.
Hello Rojoy,
Art Noxon of ASC TubeTraps here. I’m sorry that I took so long to notice this thread…..and especially because we didn’t help get the ring out of your room. I suggest that if it’s still there, please send photos and a floor plan and them call and ask for me directly. We never fail to fix room acoustics.
Your observations about high frequency ringing are very interesting and I’d like to take some time to discuss some basics. The word “slap echo” is formally reserved to describe a single echo, which is a reflection that is about 60 ms time delayed or more. Usually this only occurs in big rooms or outdoors, where we are about 30’ from the nearest wall and other walls are farther away, a lot farther….. Usually most audiophiles don’t have rooms that big.
Now a great way to stimulate a “ringing” in a room is to clap your hands together, or to slap a book on the table or floor, hence the misuse use of the word slap echo or slap tone. The question the audiophile wants to know is not so much how much ringing comes from a hand clap, but how much ringing comes from the loudspeaker as it plays the room. High performance rooms are deliberately left bright in certain areas. Clapping your hands and listening in those areas will cause a ringing sound, but normal use of the room does not ever see the creation of sound in that location.
What is normal use of the room is to listen to loudspeakers in the room. The concern is if there is a ringing tone left over in the room after the tweeter shuts off. There is an “art” to clapping and stimulating room acoustics. Let’s go over the basics.
First of all, imagine that the clap is like a light bulb. If you stand up and clap your
hands overhear, it’s as if you illuminated the room by holding the light bulb over your head. The whole room is illuminated at one time, except for the shadow area cast on the floor by your body. Next, imagine you stand tall but now clap your hands close to your body, in front, at stomach level… This is the same as holding the light bulb in
front of you, at your stomach level….Your body again casts a shadow but this time
the shadow covers the whole back 1/3rd of the room. When you do a hand clap test, always track what part of the room is being illuminated. The relative position of your body with respect to the hand clap is a good tool, but it can give you bad results if you don’t remember what you are doing.
What we usually want to know is if the speaker is throwing a high frequency ringer. The way to check that with the hand clap is to clap your hands directly in front of and close to the tweeter and at the same time, listen to what you are hearing in your listener’s chair. Unless you are plastic man, one person can’t do this test. You need a clapper assistant, someone who knows how to keep their body in the right and
not the wrong shadow casting position.
However, when you clap your hands, and listen, you do hear something and the listener seated some distance away will hear something like what you hear, so if you have to work alone, all is not lost. So we want to clap near the tweeter and we don’t want our body to block the expansion of the sound wave, unless we are mimicking how the front baffle of the speaker blocks the expansion of the upper treble. Often we have to scrunch down in front of the speaker to position ourselves for the good clap.
In any case there is a second kind of clap sound effect. It is called a flutter echo. This is not a circulating reverb kind of sound, but a completely different sound effect. Often time it is heard between the floor and the ceiling if the floor and ceiling have hard surfaces, no carpet. It also occurs between the side walls, as long as they are parallel, have no sound panels and are hard surfaces. What we hear is what is called a pseudotone. It’s the same kind of sound effect we hear when we put a playing card in the spokes of a bicycle. Each time the spoke snaps the card we hear a snap but what we think we hear is a bass tone whose frequency is equal to the number of snaps per second we hear.
And so it is in the listening room…..If we stimulate a side to side flutter echo, in a room that is 15’ wide we probably will hear a slap reflection every 15 ms, which corresponds to a frequency of 1000/15 = 70 Hz, a bass tone. There once was a snake oil bass trap company that sold very low cost bass traps, essentially a crumpled sheet of tin foil, in a fabric covered frame. The demo artist would stand in the front of the room with his back to the front wall and give a strong hand clap which created a flutter toe of 70 Hs. A-hah, there’s the bass tone….Then he would hang the disguised high frequency diffuser sheet up and clap again, and the bass tone would go away, because the high frequency energy had been side-scattered. But because the bass-pseudotone disappeared he claimed he had created a very small and low cost bass trap. May people believed the guru and bought his budget
“bass traps”. Last I saw him his business was closed down and he was driving a brand new Mercedes in NYC…..
Actually, ASC has a product called “FlutterStix” which is a very small sound panel that with a thump pins itself into the sheetrock wall. We took them to some hifi show and handed them out pretty much for free. We got a big bill at the end of the show for all the thumb tack damage……and that’s the last time we made that product.
Here’s another flutter echo story…..The Wilson speaker just didn’t sound right at a prestigious show room on the east coast. I had stopped by for a visit and they played
the speaker…..sure enough a top end blur and a midrange pseudotone was ruining
the otherwise “perfectly setup” showroom. You know, the better the room sounds, the smaller the defect it is that a person can hear. After much clapping and exploring, I realized to my amazement that we have a vertical ring tone, right in front of the cabinet, between the floor and ceiling.
It couldn’t be. It was a brand new expensive carpet. But over and over we could prove it was a vertical flutter echo. I laid down on the floor and said into the carpet “check, check, testing one two….” And sure enough this expensive carpet was very reflective, like a sheet of plastic. I went to the corner of the room and pealed back
some carpet off the nailer strip and tried to blow through it, and no air flow…the
carpet was air tight. Closer inspection revealed that sure enough, the back of the carpet was sealed water tight with plastic. No liquid could get through that carpet, ever….and sound couldn’t get through it either. And the pile on the face of the carpet wasn’t thick or dense enough to absorb the hand clap energy. We tossed a small, high quality Persian carpet down in front of each speaker and presto, the Wilson’s sounded perfect, the way they were made to sound….
OK, one final story….I stopped by an ultra high end showroom on the west coast, with a full on ASC acoustic compliment and running Avalon, MIT and Spectral. The owner kept complaining about a ringer tone. I clapped and sure enough I heard it….After much searching I found a thin brass leaf attached to a decorative metal vine on a lamp, hanging out from the lamp and twanging away.
Anyway, if you ever have a problem, give us a call….
Art Noxon,
President of ASC-TubeTrap
Wow! Thanks, Art! What an amazing read! Ton’s of info / knowledge and great stories. Can’t thank you enough! Aneek
you just said all these do not work so pls write out what you know that works that would be a better way to it.
I concur with dboss…what DOES work? WHY do you recommend ASC and GIK? I can’t stand people who think they understand what DOESN’T work but have NO idea about what DOES work! If you don’t understand what works, your recommendation is not valid. In your own words, “many audiophiles and enthusiasts” have “wasted” their “time”, and all you can say about your ASC and GIK is that “both companies are highly reputable, ethical and will consult with you about your room and its acoustic needs free of charge.”
Big deal. A free consultation from someone who doesn’t have the right stuff is a waste of my time. They may be reputable and ethical, but that doesn’t necessarily mean they have a good product.
Any scientists out there wiling to post some real decibel data so we can see what’s really going on?
GIK makes amazing products that are very effective.
People who think like you are in horrendously short supply. The vast majority of people just accept what sales people tell them as gospel. They ask no questions themselves but shut down anybody else who does. It’s amazing just how easy it is for snake oil salesmen these days. Anyway, read a textbook if you want to find useful data. The internet is full of absolute rubbish such as this promotional article.
I bet you’re getting paid by the acoustic treatment manufactures to write egg cartons etc don’t work because they lose money over it. Using rockwool and egg cartons does work…..it might not be perfect but it helps..it’s noticable. Who’s gonna pay $ 1000,00 for a piece of basstrap. No need for that at a homestudio.
Egg cartons do work if you want to make wrong decisions when mixing. I learned the hard way. You get what you pay for, or at least spend a lot of time building yourself. I’ve had 3 different studios: one with egg cartons, another one with pyramid shaped foam (1″, 2″ and 4″) and the last one with proper bass traps and diffusers. Only the last one sounded good.
Of course, if you are happy with demo-level recordings, then none of this matters.
traps are cute
in fact , the 5 Acoustic Treatments Works, but the problem is the same , people don’t now how to use it.
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I work as a substitute teacher at various schools near Ferguson Missouri. One of the schools has HORRIFIC echo problems in most rooms. So,.,.. I’m not trying to build a sound studio…. just want some idea of something that could be done for about ZERO DOLLARS that would make normal conversations possible in those rooms. The rooms have very tall ceilings like 12 feet at least. The walls are concrete blocks. I have a roll of carpet pad made with various small pieces of foam formed into the pad. If these were cut up into 2 ft squares and a hundred of them placed on the walls, would that help or do nothing? The kids could paint the front surfaces of them and make them look like art pieces. Remember, I just want to get the room so people could have normal conversations without YELLING at each other!!! The school has zero money and I am poorer than they are. My email address is framistan@sbcglobal.net Thanks for any ideas or comments, as I am an ex-electronics technician with experience working in tv studios, but am not an audio expert.
“all you’ve accomplished is minimal (emphasis on minimal) scatter and maximum what the hell were you thinking effect.” Well said. There is a wealth of data available from practically every acoustic materials company about absorptivity, but it takes some work to find it. Then, you have to learn how to read it. I’m with you on GIK and ASC. Their datasheets are very complete and their products are very predictable. Homemade stuff just gives the “installer” the satisfaction of feeling like “I did something,” without knowing how little was done. Lots of audiophile equipment relies on the same unfounded hopeful thinking.
Good Points, but regarding treating a wall with a thick tapestry or heavy curtain etc.,this can make a HUGE difference when you are recording an instrument next to that wall. The tapestry/curtain knocks down the high freq slap being recorded. Of course, that same tapestry does nothing/very little for the sound of the whole room or any problematic nodes. Sometimes we are dealing with two different objectives; recording a small portion of a room, or prepping a whole room sound for mixing/recording.
I don’t generally disagree with the article, except…
Many sound treatments aren’t about “making the room sound better,” but about eliminating the room sound through absorption. That’s a reasonable approach for a home studio that doesn’t have enough noise isolation to have mics far away: Take away as much reflection as possible, close-mic to reduce outside sound, then put the “room sound” back with a good reverb plugin.
Egg cartons and carpet, by the way, are great for that. That’s what people use them for—not to improve the room sound.