Acoustic treatment

Quite right, GK. If you score some of the old Tube Traps (before ASC starting marking them) as I did (a guy advertised them in The Recyler in L.A. in the 90's---ten bucks apiece, for 13 of 'em, 9", 11", 16"!), the seam side is the absorptive side, directly across the tube the reflective. By the way, the Room Tune is just a piece of fiberglass insulation covered in grill cloth, nothing magical (unlike the ASC Tube Trap, which is a relatively highly-engineered product).

From somewhere in cyberspace,

“We subsequently purchased the lot of lightweight frames and took them home with us and used them for many years. The idea behind the Room Tune was nothing new: a reflective membrane on one side and an absorptive material on the other.”

That reflective "membrane" in the Room Tune is the foil side of the fiberglass insulation. High tech! ;-)

Pretty smart!

Pretty high profit margin!

Even better!

Interesting thread.... I just installed some helmhotz resonator improvised with long neck bottles and variable water level experiments, and I must say that it was an improvement with my sound....At no cost.... Perhaps not ideal but my ears  smiles... Thanks

About 15 years ago there was a company called Eighth Nerve that I believe duplicated the Room Tunes concept. The front of the panels were a hard surface and the back the absorption fiber glass. They were well built, not very wide, maybe 8" and about 48" tall if I recall. They were mounted at the room seams such as corners and where walls met the ceiling. Their triangles went in the upper corners. I found them to be effective, especially the triangles. I sold them off eventually and these last 4 years got rid of all room treatments in favor of a multi sub bi-amped system.

geoffkait tell me how something the size and shape of a tube trap is going to modify the dispersion of a 32 foot wavelength (20 Hz) in a 15 X 25 foot room. 

Huh? Didn’t you 🔙 post the equation last week? We already covered this last week. Does that refresh your memory?

Here’s a question for you - how can I hear a low frequency sound through ear buds if the wavelength is 32 feet?

Another question fir you - How can several tiny little bowls with diameters of 1” affect very low frequencies in the room?

Another question - How can a Schumann frequency generator affect the sound in the room when the wavelength of the Schumann frequency 7.8 Hz is 25,000 miles?

I done some long time ago with big Kotex pad ( feminine hygiene pad ) and this was the best really I tack it all around the inside and for the rest loose part I put dacron a kind of wadding or you could go like Radford speaker in is opinion he put  some real wool carded it was the best thing I use to have Radford speaker was very good in the time 1972 I gave it to my son still good redone the crossover ..........excuse my english I am french 

Shear waves in solids are what change the air molecules that come in contact with various solid materials. The acoustic wave that is generated from this interaction returns to the solid surface creating more shear and then more acoustic energy is generated off the solid surface.  This process happens all over again..not a giga buddy UFO magnetic field. . Just many many touches between shear waves and acoustic waves. Never dissipated just converted into acoustic waves..and then shear until the wave diminishes into or between 2 or more surfaces.

The material tension changes the reactivity of the surface ..This tension also changes the shape of the surface and adjusts the resonance point of the surface changing where the shear is most reactive. A strike away from  the Resonant Point will give a drum a different sound than a strike right on top of the Resonant Point. Maximum energy transmission is when a wall surface resonant point is found and when a acoustic resonator is placed on that surface point. Tension will adjust the shear wave transmission between those 2 surfaces now touching at that point. The resulting shear wave transmission will follow a shape say a tiny bowl and the air molecules that are around that shape take on those patterns and are excited ..and so you have a shape and a material and together they generate a new sound. Change anyone of those.. add a new boundary such as a piece of tonewood and then add a jewel or 3 you will have another new sound..because they are all attached they will generate multiple shear wave patterns and then new multiple acoustic waves and patterns....Tom

PS.. Eighth Nerve was Room Tune when they split to Nashville..

Mike you should look into the purchase of long hair sheeps wool. I have purchased this material in large volume from a vendor in Michigan years ago. It is a wonderful material to work with and is safe to use in your home.


 

@karl77, I use those pads to damp the high-frequency ring of my drum heads. ;-) Makes 'em sound like Levon Helm's, low and "thumpy".

Thanks to Geoff remarks about Helmhotz resonator... I completed the installation of 8 carafes and varied bottles with different aperture with different tubes of my own making inside, and different level of water to discover the right one and I must say the effects are astounding on all counts...And at no cost...All of you read about that and think,it is not necessary to pay anything, very simple to inplement if you try and trust your ears...

Let one or more contact a wall surface and hear what happens. Tom

Ok Geoffkait here we go again. Show me solid objective evidence that tube traps work. Before you start spending other peoples money you have to be full of more than BS beside not knowing how to manipulate the math behind the Helmholtz Resonator. And, don't give me manufacturers BS either. How are you going to locate standing waves in a room and exactly at what frequency? What about comb filtering? In the context of what type of loudspeaker?

IMHO the only rational for tube traps is that a lot of people make money on them.

With a constant tone or even a strike point you can find the Resonant Point of any surface of any size or dimension. Tom

Mijostyn,

You may want to  fill with some volume one of your glass objects with olive oil and then compare. Oils will conduct shear depending on their solid content. Distilled water less than salt water..Origin of olive oils will vary in shear velocity. Tom

It wasn’t misonjin but you’re very close.

Mahgister,
My most recent posts were about your method and obsevations. Tom

Thanks theaudiotweak… But my result obtained only with water are enough for the day and extraordinary... I am very pleased already, the helmhotz resonator are not snake oil,pricing sometimes is, ideas are often implemented with very low cost and sufficient good result... I will not purchase audiophile resonators, I am proud of my cheap ones and astounded... Perhaps I will try olive oil some day to comes thanks Tom for the idea... Thanks also to Geoff for his impulse and astute observations...

Just finished my bass traps and installed them. All I can say now is that I'm a believer! 

     Using large, expensive and butt-ugly bass traps always seemed analogous to opening windows in mid-winter to control the heat in your house.  Better to control it at the source, right?
      Like turning down the thermostat to reduce the heat or use a 4-sub DBA system to optimize your room's bass response and sell your bass traps.

Tim

Many older theaters were designed with a combination of bass traps,diffusers,resonators,and pillars(aka tube traps) incorporated into the structure. They have incredible acoustics.The DBA system and room treatments can work well together.

Check this out:https://www.psiaudio.swiss/avaa-c20-active-bass-trap/
It looks to me like an expensive alternative to the DBA system

jtcf:
 " Check this out:https://www.psiaudio.swiss/avaa-c20-active-bass-trap/
It looks to me like an expensive alternative to the DBA system

Hello jtcf,

     It seems to me the active bass trap and the distributed bass array (DBA) system operate on almost opposite principles.
     As I understand the active bass trap (ABT) , it uses a built in mic to identify room bass modes, that are within its limited range and up to 150 Hz,  and uses openings in its surface to somehow draw these sound waves into its inner chamber and, through an unexplained process, eliminates or attenuates these room bass modes.  I believe it's only able to identify bass modes that are peaks and not dips but I'm not certain.

     The DBA, on the other hand, takes the opposite approach of distributing 4 subs in the room in order to create many more bass modes (both peaks and dips) throughout the room and then relies on some scientifically proven and well understood psycho acoustic principles.  The following are the relevant psycho acoustic principles that the DBA concept relies upon:

1. Humans are very adept at determining the originating locations (the source) of sounds with frequencies above about 100 Hz, with this ability improving as the sound frequency increases.
2. Humans generally are unable to determine the originating locations of sounds below about 100 Hz but are adept at discerning the volume and pitch, as well as changes in volume and pitch, in these deep bass tones.
3. We need to hear the complete duty cycle of a deep bass tone frequency (the complete bass sound wave cycle from beginning to end is called a duty cycle and it needs to exist in the room) before we're consciously aware of the bass sound.  If less than a complete duty cycle exists in the room, then no bass sound is detected.  This is relevant when the length of the sound wave exceeds any of the room's dimensions; a 20 Hz tone has a total length of 56 feet, so it needs to reflect off a room surface at least once, depending on the room dimensions, before we actually discern the bass sound.
4. We need to detect multiple complete duty cycles of a bass tone frequency to determine pitch.
5. When we detect multiple bass sound waves and bass modes  (peaks and dips) at various frequencies in a room, our brains process this by summing and averaging these.  This psycho acoustic principle is the key to the DBA concept being such an effective bass solution.  

     Of course, all of these psycho acoustic dynamics described above are taking place at a subconscious level and we're just aware of how detailed, fast, dynamic, impactful, smooth, natural and perfectly blended and integrated with the main speakers the bass sounds. 
     I realize I'm seemingly constantly extolling the virtues of the DBA  concept and its only relevance to this thread is that it requires no acoustic treatments, no room correction software or hardware, minimal equalization and no DSP. 
    My main intent is really just to spread the word on how well the DBA concept actually works.  I honestly don't believe it's possible for me to overstate how well this bass solution performs in my system and room.  
     There's also no typical warning of ymmv (your mileage may vary) necessary since the DBA concept performs extremely well in virtually any room and with any pair of main speakers.  So I'll coin a new acronym exclusively for audio solutions that will work for others without qualifications: ymwnv (your mileage will not vary).

Tim

I agree with you Tim.The DBA system has my vote.

I'd never heard of an ABT before.I did a little more reading and understand better how it works.It's simple to implement,but expensive and probably a royal pain if it ever required servicing.

Hi jtcf,

     I just came up with the acronym ABT (automatic bass trap) to avoid having to use its full name on my last post.  
     I restrained from stating it didn't work because I've never tried them and, therefore, I'm not qualified to have an opinion.  
     My opinion is that good bass response is very important but one of the most difficult qualities to achieve in a home audio system.  I actually consider my system as two systems:  a bass system and a midrange/treble and stereo imaging system.
    I also prefer a system focused on producing good bass than one trying to improve bass that's already been produced in the room.

Later,
  Tim

In the case of the wretched CD there are two reason why bass response is really rather wimpy and apparently rolled off and otherwise unimpressive. It’s because of the two problems I have been pointing out of late regarding (1) scattered background laser light getting into the photodetector and (2) the fluttering, wobbly and vibratory nature of the CD itself that forces the laser servo mechanism such as it is to work overtime trying to keep the bloody laser on track. The geometry involved with how the laser reads the nanoscale data is extremely susceptible to vibration of the disc.

Geoffkait, just throw the CD's away and download all your music in MP3 files. That should be perfect for you. Your ear works just like any other microphone. It detects minute changes in pressure. In your case you might want to clean the wax out first. In the office we use a waterpick for that. 1 part hot water to 1 part  peroxide. Careful not to squirt your eye:)

Ya don’t get what I’m saying here. Look, it’s not rocket science. All you have to do, gentle readers, is compare the cassette version of almost any record with the CD version. Or the LP version. All will become clear.

@theaudiotweak , are the synergistic research acoustic art (bowls) similar to what you are talking about?  I experienced these firsthand and they definitely worked.  Crazy stuff...

@noble100 , do sba work better in treated rooms?

@noble100, Correction, does a DBA system, or a SBA too, sound better in a treated room compared to an untreated room?

And... what is a DBA?  

b_limo: "@noble100, Correction, does a DBA system, or a SBA too, sound better in a treated room compared to an untreated room?"

Hello b_limo,

     DBA is an initialism for distributed bass array.

     My 4-sub DBA system is in an untreated room and functions very well.  I can't imagine how any bass room treatments would be beneficial.  The DBA concept works best when bass soundwaves are allowed to freely reflect off room boundaries, I think any room bass treatments that would impede these bass soundwave reflections likely would also impede the effectiveness of the DBA system.

     Sorry, I don't know what an SBA is.

Tim

I now have 14 absorbers positioned throughout my listening room/ living room "not ceiling yet" and all I can say is I'm truly a believer.

They are all 4' x 2' x6". 

Lots of misinformation in this thread...

multiple subs do not magically eliminate bass decay. Bass traps are meant to absorb the bass resonance and reflections building up and coloring the initial signal. Having multiple LF source cannot address the bass decay  issue. Without enough LF absorbtion via bass traps, the bass will sound slow, lacking in attack and transient.

Multiple subwoofer will allow the user to have a flat FR easily, but it doesnt at all adress the biggest problem which is bass resonance that can be easily measured via ETC measurements.

Bass traps should be very large, made of Roxul or Owens fiberglass, ideally at least 12 inch thick, floor to ceiling, placed in as many corner possible.

mijostyn:
"Boy are you out to lunch on this one Tim. It is not what you hear. It is about what you feel. I would bet that you have never played with a system in which you can control phase and arrival times which is why you have this rather flaky opinion. This makes a major difference in the realism of the system. Just wire one sub out of phase and see what you get. I've got news for you. You have to be in phase the entire cross over region. If you are 1/2 wavelength out of time you have one sub wired backwards. This would be the kind of biased unacceptable opinion you swarm guys would come up with. If you think the bass you have now is good, you have a long way to go. "

Hello mijostyn,

     Sorry I'm so late getting back to you, we went out for lunch and we waited about 3 months for our food! So, I literally have been out to lunch.
      I feel like you have a poor understanding in general about how and why the Swarm 4-sub distributed bass array (DBA) concept works so exceptionally well.  Here's a summary of some key DBA concept info to help you grasp it:

-Phase is important and the Swarm's phase can be continuously adjusted for the 4 subs as a group on the amp/control unit. Also, during the setup process one of the final steps is to reverse the phase on each sub individually to make sure the bass doesn't sound better with one of the sub's phase reversed.  
-The fact is that the very long bass soundwaves behave very differently than the much shorter midrange and treble soundwaves in typical domestic rooms.
-This makes sense since a full-cycle 20 Hz deep bass soundwave is about 56' long while a 20,000 Hz full-cycle high treble soundwave is a fraction of an inch long.
- It's been proven that we don't even hear a deep bass frequency under 80 Hz until the full duty cycle of the frequency sound wave has been released into the room, our ears have transmitted the details of the full-cycle deep bass soundwave to the brain and our brain processes this info as the perception of a deep bass tone present in the room. 
-In other words, we cannot detect the presence of bass under 80 Hz from less than one full wavelength. 
-We also need to hear multiple full wavelengths of bass under 80 Hz before we can detect pitch and volume.  A 56 foot 20 Hz sound wave released into a normal sized room means it is going to bounce or reflect at least once before the entire duty cycle is detected and be able to be heard at the listening position. We also need to detect multiple cycles at the listening position to determine pitch and volume.
-This implies that relatively small timing differences - 'small' relative to the wavelengths in the under 80 Hz bass region - are not going to make an audible difference in and of themselves. 
-The time domain aspect, or the timing of bass sound waves reaching the listening position, is of much less importance for deep bass frequencies than it is for mid-range and treble frequencies.  We're actually not very sensitive to arrival time in the bass region.
-There's no requirement for the correct timing so that the sound from each bass driver hits the listening position at exactly the same time like there is with the midrange and treble drivers.    
-The 4-sub DBA concept works so well due to creating numerous well dispersed additional bass room modes (bass peaks and dips) at various frequencies in the room. 
-The psychoacoustics identified principle of our brains processing these numerous varied bass room modes by averaging them out results in the perception of the bass as accurate, detailed, fast, smooth and natural.
-This is properly described as controlling the speakers to correct abnormalities of the speaker/room system, not as "room control".



Tim

 
noble100 "It's been proven that we don't even hear a deep bass frequency under 80 Hz"

Proven by who and where is this proof were you part of the study that proofed this I don't have a position on this either way but you have not provided proof while others involved in this conversation have provided to you specific references, quotes, and data and if I were you I would not discount, reject, or disqualify remarks made by Vandersteen he is one of the world's preeminent creators, designers, and manufacturers of speaker systems for Music Reproduction Systems.  

Hello clearthink,

       This is from an audio consultant named Bob Pariseau and he explains adding bass via subwoofers in the article linked below from his website.  He's in the 80-100 Hz camp.

   https://bobpariseau.com/blog/2018/6/5/choosing-a-crossover-frequency-awesome-bass-begins-here

noble100" This is from an audio consultant named Bob"

Bob has no data, no studies, no scientific tests, no listening tests, no researrch, no references, hey he's just like you - you must be Bob you gave yourself away! Richard Vandersteen on the other hand has actual calculated, scientific demonstrated success in explaining, showing, and establishing that not all bass is mono now who do you think we should believe you, yourself, and Bob or someone who actually has done the study, work and science!

Hello clearthink,

     Okay, wiseguy.  There's lots of scientific White Papers on this subject from Dr. Earl Geddes, Dr. Floyd Toole and others.  These are easier to read, however.  I'd read them in order, Mehlau first and then the Dagogo interview with Geddes last.

https://mehlau.net/audio/multisub_geddes/


http://www.dagogo.com/View-Article.asp?hArticle=1047)


Later,
Tim

This is one of the weirdest fantasy land treads I've ever read on A-Gon.So much bad information that it should be deleted.  Magic thimbles as room treatment?  Shear pressures?  Electromagnetism in sound waves? 
Can't hear bass below 80hz?  That knuckle head needs to get his hearing checked.

MurphyTheCat nailed it.

OP, Read the tests on BobGold's site to get information about which materials work better at absorbing bass.  You are on the right track.  The source of the problem is the room.  Fix that. 
Ignore all the other blather about hocus pocus mystical forces at work.

noble100"Okay, wiseguy. There's lots of scientific White Papers on this subject from Dr. Earl Geddes, Dr. Floyd Toole and others. These are easier to read"

These are very nice links with lost of words and opinions but they are completely and entirely lacking any data, studies, scientific tests, listening tests, research, or references to support you're repeated claims that all bass below 100 or 80Hz is monophonic while conversely others have pointed you to such reliable, repeatable, reproducable data that is very strange that you cling to this notion and again I do not have a firm opinion on this matter but you have failed to support your claim with anything other than silly claims like "it has been shown" and "acousticians have long known" etc.

Hello clearthink,

     This is a paper by Todd Welti of Harman International, who studied under Dr. Earl Geddes.  He specifically also states that bass under 80 Hz is not directional or localized.

ttps://www.harman.com/sites/default/files/multsubs_0.pdf

clearthink,

     I'm on another thread right now posting back and forth with Duke Lejeune, Audio Kinesis owner who designed and sells the Swarm 4-sub DBA system I use.  Here's a post quote from him today:

"@noble100 wrote: "Duke... I was hoping to get your honest opinion on my thoughts on how I understand multiple sub systems function in general as well as my understanding of how bass is recorded on CDs and vinyl."  

In general I agree with what you wrote, so let me just toss out a few comments.
" We all are unable to localize deep bass frequency soundwaves..."  

My understanding is that’s generally true in a room. The figure I use is 80 Hz, rather than 100 Hz. I think Floyd Toole uses 80 Hz. This doesn’t necessarily mean that one cannot detect the location of a sub which is crossed over significantly lower, say at 40 Hz, because crossovers are not brick walls, so upper bass/lower midrange energy can give away a sub’s location if it comes through loud enough. Therefore in my opinion a steep lowpass filter on the sub helps to hide its location.  

"the bass is summed to mono on frequencies below 100 Hz on all vinyl and cd recordings."  

I wouldn’t say "all", but I would say "almost all". (If we’re talking about a Swarm/DEBRA system, a second amp can be added to give you true stereo bass).

"Our brains are able to associate the fundamental deep bass frequencies reproduced by the subs, that are not able to be localized, with the deep bass’s higher harmonic frequencies, that extend well beyond 100 Hz, which are reproduced by the main speakers that are able to be localized. This psychoacoustic association allows us to localize the deep bass in the soundstage, for example the kick drum is located in the rear center and the upright bass is located in the front to the left, which would not be otherwise possible without this psychoacoustic association our brain’s are capable of."

I agree.   

Duke"

Here's the thread link:
https://forum.audiogon.com/discussions/searching-for-matching-subwoofer-solution?page=2

Tim