Elk
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Wes Phillip's review of RealTraps, February 2010 issue
tom collins
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i look forward to getting my copy. i am very interested in this area and have taken a few treatment steps in my room, but am still on the lookout for improvement.

Elk
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It is astounding what room treatment can do.

It isn't sexy and is no where as fun as shopping for a new preamp. But it will make a bigger difference.

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Quote:
It is astounding what room treatment can do.

It isn't sexy and is no where as fun as shopping for a new preamp. But it will make a bigger difference.

If a room has too much energy storage, there is NOTHING you can do electronically, NOTHING, that will take care of this hangover, which is often quite audible.

First rule of acoustics is "don't put energy into a room unless you want it there".

So when a room stores energy at some frequency it means not one, but at least three things.

1) Some parts of the room will have pressure peaks
2) Some parts of the room will have pressure nulls
3) The entire room will have "hang over" at that frequency.

No matter how much you reduce the input at that frequency, those problems will continue.

Add absorbtion, that's the key.

Orb
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Quote:
It is astounding what room treatment can do.

It isn't sexy and is no where as fun as shopping for a new preamp. But it will make a bigger difference.

Also a fun side effect is that I swear it helps to train the ear/listening, from my experience anyway.
Instead of purchasing a new preamp, move the acoustic panels and then re-tweak by ear for satisfaction.
I appreciate this is a nonononono but more for if bored or curious, it is interesting to see how over time you slowly migrate the acoustic panels to certain points or use a certain type of panel at a spot.

One thing though, while I appreciate there is much talk about improvements they provide, I have noticed it is possible to ruin the sound stage/tonal vibrancy-life with incorrect placement.
These do not necessarily always follow the rules exactly as for a small room I have noticed moving panels just 6 inches can be enough to cause changes that are not preferred long term (bit like the subtlety of speaker positioning/toeing IMO).
Definitely not a plonk it in and it will always be better, which some may expect.

Cheers
Orb

cyclebrain
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Room treatment is not very cool to talk about with your surround-sound video co-workers but is a major factor in sound quality. Saying that absorption is the answer can be misleading. First reflection Absorption will make a major improvement in clearity by reducing early reflections that confuse the brain by providing multiple signals that are too close together in time for the brain to seperate resulting in a smeared sound. To much room absorbtion will cause the removal of later reflections that cause the brain to sense spaciousness (i.e. sounds dead). As always, to much, to little is bad.

Orb
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Agreed, definitely interesting if you got the time and the room where you can freely place them without WAF issues.
Still, my point stands in my experience even when using the right amount of panels and then move the placement by 6-inches (small room).
This example is not 1st reflection but wall behind the speakers, where careful placement can help with balance-bass/reverb/etc but can also be detrimental from my own experience just with subtle movement of a few panels.
Similar way speaker positioning/toe-in can affect the sound (maybe bad comparison but ah well).

Cheers
Orb

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Quote:

Quote:
It is astounding what room treatment can do.

It isn't sexy and is no where as fun as shopping for a new preamp. But it will make a bigger difference.

If a room has too much energy storage, there is NOTHING you can do electronically, NOTHING, that will take care of this hangover, which is often quite audible.

First rule of acoustics is "don't put energy into a room unless you want it there".

So when a room stores energy at some frequency it means not one, but at least three things.

1) Some parts of the room will have pressure peaks
2) Some parts of the room will have pressure nulls
3) The entire room will have "hang over" at that frequency.

No matter how much you reduce the input at that frequency, those problems will continue.

Add absorption, that's the key.

I'm not at all fond of the idea of active room control, as you might imagine. Specifically the idea of measuring and then correcting at the output of the given system to attempt to fix the 'sound'. That is a real case of the sound being compromised to deal with room issues, yet the original problems remain uncorrected and the original notes are now compromised. Looks like a bad deal on all sides, to me.

We've been using (basic analog) eq in these situations for just about forever, and I've not so much of a qualm or issue with that..but I, myself, can and do hear how such corrections compromise fidelity and most specifically, if these systems have to digitize the original signal first.

To me, this is fundamentally wrong. IMO, it can be used to fix public address systems or live events, even bars, but not for home audio, and high fidelity? To me, it is the exact wrong direction for high fidelity. And, for me, I can hear how it affects the presentation in a deleterious way.

When we do a room, acoustically and mechanically...we do it so no eq of any kind is necessary. Even in the bass range. When we were still doing bars..the given band would come in..and many a time, half way through the night or even far sooner... the given sound engineer would slowly but surely work his way down to almost no eq of any kind and sometimes....even remove his EQ from the presentation-entirely.

Then they would come over, and say - with a confused look on their face, "You know..this is the ONLY room I've EVER been/worked in..that no eq is required."

What I'm trying say..is that.. to me, mechanistically treating the room first is the only way to go and electronic correction should be secondary or an (wholly secondary) adjunct to that given mechanistic correction.

Since we cannot 'see' sound waves, this can give us grief when the average dude attempts to figure out what is going on and how it works. With the advent of some more 'interesting' acoustic devices in the recent past, it seems as if the area of acoustics (and mechanical noise control of said room)is heating up a bit.

While Ethan and I have our disagreements I think that we can both agree that acoustical/mechanical correction of a room comes in as a 'first principle' issue.

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Elk: I have a 12x13 listening room and I cannot imagine how you can put 11 2x4 panels in their and still have much room for anything else!

Orb
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Helps if you have a dedicated seperate room and you will not be nagged by the wife

Wall behind speaker; Bass in corners 2, on wall 2 symmetrical placed panels and another panel centre = 5
1st reflection; 1 each side = 2
Behind wall,Bass in corners 2, on wall 1 to 3 (lets say 2) = 4
Total 11.
This ignores the ceiling reflection (not sure importance in small room) or floor to ceiling covering for some panel points that would double amount of panels there.

My room is a similar size to Elk, 11 minimum does seem pretty good and noticable when you move out of position / remove any panel or symmetrical placed panels for an ideal speaker and listening position setup.

Cheers
Orb

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Quote:
Elk: I have a 12x13 listening room and I cannot imagine how you can put 11 2x4 panels in their and still have much room for anything else!

It is not as bad as it might seem, but it is a dedicated room.

I have two panels in each front corner at 45 degrees, one on top of the other.

There are two on each side wall (wide first reflection area).

There is one on the ceiling (first reflection).

One directly behind me on the rear wall.

Finally one at the corner intersection between the back wall and ceiling.

As a WAF suggestion:

The ones in the corners people like as they appear almost architectural. One on each side wall would be acceptable to most and the ceiling panel most don't even notice.

Orb is right, moving a panel is noticeable. One very interesting experiment is to take a thick 2'x4' broadrange bass panel and have someone move it around while behind you. It is astounding how much this changes the sound.

A single good panel on the back wall can make the performers come toward you and increase front to back perception of depth.

My main room is roughly 25'x30' with a 32' ceiling and a wall of glass on one side. It has very good acoustics due to its size, lots of wood (a little less reflective than drywall), only two parallel walls and a sloping ceiling.

I have played with panels in this space. I am now planning to get a bunch of bass panels and stack them up in two of the corners (to 12' high). They would both look interesting and help a lot.

I keep wondering how much a TV screen between the main pair hurts in a home theater setup.

Orb
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Personally I feel it may hurt a lot (I guess affect also has to take room considerations as well).
I am forced to use a quality thickish (6-inches) acoustic panel at the centre between my speakers to assist with bass and tonal balance/subtle reverb-reflection.

It makes a noticable difference to sound quality; experimented with different types of panels and angles/placement as well but seems for my room/setup a flat acoutstic panel with that depth is best (no tv as dedicated room for my stereo setup).
Imagine it replaced with a flat screen tv that usually is in line with the speakers and can be at an angle (left-right/up-down or combination).

Still I guess if in room with a TV then the listener is probably using a processor/AVR with some kind of audio correction.

But can Audyssey and the other solutions correct problems caused by a flat screen between the speakers?

Interesting to know
Orb

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Orb,

Is your panel centered between the speakers at about ear height or placed otherwise?

I've wondered what panels behind the speakers and between them would do.

I don't think you can have too much bass absorption. You probably can have too much high frequency absorption however.

Orb
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Bit too busy to respond just now, interesting why do you say that?
Will explain a bit later but very curious on your thoughts.
Note I did say different panels and that placement by ear is a nononono unless bored or curious

Cheers
Orb

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Yeah I would love for someone who is technical to explain what the panels behind and between speakers do as well.
Nudge nudge anyone

But I can say in a small room they are noticable, I guess my setup is a combination of a GIK and RealTraps suggested setup (seems to work best for me).
I do wonder if the speaker behind and between panels make more of a difference the closer the speakers are to the wall, which is much more probable with a small room to say a medium and large where the speakers can be brought into the room much more.

Regarding the height of the centre panel in my room; it starts around 2ft off the ground and is vertical to ceiling (2ft wide).
I have tried horizontal but this just damages the soundstage and some other aspects of the sound too much.
Also I have tried thinner panels but this as you suggest then absorb more of the high FR than the bass so are not good, also tried depth up to 8inches depth and also diffusion or various positioning of 3 or more panels on wall behind speaker (excluding corner bass from this count).
Ok I was surprised that the diffusion improved some aspects of the sound quality but quite amusingly had a negative effect on the soundstage (could say it was perceived as not natural).
I say amusingly because I just could not resist moving my head around most of the time.
In the end the best result was from using a quality 5inch absorption panel.

BTW your last sentence touches on a subject that has been in the back of my mind for some time.
I have heard it said many times you cannot have too much bass absorption, however correct me if I am wrong but every panel absorbs medium and high FR.
So by adding more absorption you are still absorping the high FR that you thought may had been a potential problem for me.

I can say quite happily though for my setup there is a good balance between bass and high FR absorption (which is what you may had been suggesting as a possible issue ), but as I mentioned before adding anymore panels or moving the existing ones just subtly is detrimental in my experience.
Even if those panels are able to absorb a high ratio of low FR.
I would say I am reaching the conclusion now that maybe the ideal setup is a certain number of panels combined with electronic EQ if wanting to go a further step than I am at currently, but this is based on my experience of various panels in a small room, and possibly larger rooms do not share same behaviour.

Cheers
Orb

Elk
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Your experiences mirror mine as far as experimentation goes.


Quote:
BTW your last sentence touches on a subject that has been in the back of my mind for some time.
I have heard it said many times you cannot have too much bass absorption, however correct me if I am wrong but every panel absorbs medium and high FR.
So by adding more absorption you are still absorbing the high FR that you thought may had been a potential problem for me.

I suspect that this is exactly why some argue that too much bass absorption can be bad.

I find it odd that an anechoic room does not sound good for sound reproduction. It should be perfect as all you hear is what comes out of the speakers. Perhaps what would work is mixing and mastering in an anechoic space to sound good in such a space.

OTOH, too much bass absorption and not enough diffusion can be a problem in a recording space. When recording we want the room to sound good. When listening we want the room to get out of the way.

Orb
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Yeah good points, and you could be right with some stating about too much bass (although I must admit the trend mostly seems the opposite).
I guess it needs others to spend possibly more cash than they need to for the various types of panels and play around with it as I did to see if their experience is similar to mine.
For medium to large rooms this could be an eye watering price so probably a no go, hey a benefit of a small room for once

Still, the curiosity of it did cost me as much as what some spend on a system
Do I really want to continue my experience with expensive balanced electronic solution when I am happy with my results so far, think I need to be much more bored

If you have a play with the wall behind the speaker would be interested to know how you get on, appreciate you may have to compromise sound by using currently placed panels.
Its fun honest!!!
Ok just curious to what your experience would be trying a combination/each of say GIK and RealTraps suggestion and trying to add more or move them along wall behind speaker:
http://www.gikacoustics.com/room_setup.php
http://www.realtraps.com/placing_mt.htm

Cheers
Orb

KBK
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Bass is always the more difficult to remove and many of the acoustical correction devices out there will do too much (removal/alteration) to the upper midbass and up...and then the tilt to over-emphasized bottom frequencies will be worse. It would be like taking an eq and removing even more mid to high..and then boosting the bass. It can make you feel like you've got cotton in your ears and if the material/devices are of a poor quality nature and type, even worse--a slight pressurized underwater feeling, as the bass/mud issue remains. A simple difference is not always a good thing.

Orb
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Which is why from my experience you can only use so many panels for room acoustics before it becomes detrimental (even ignoring liveliness/deadness issues), even with the right number of panels and correct types/depths moving them to a less than ideal position is still detrimental (and my experience we are talking inches here for a small room).

Maybe there should be a caveat for those saying you can never have too much bass absorption (not directed at you Elk but many others who seem to be making an assumption IMO).
Thanks
Orb

Elk
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Good thinking.

Bass absorption probably needs to be proportional to the problems presented.

OTOH, I doubt completely removing a problem in one are, while only diminishing it elsewhere is necessarily bad.

I think most would benefit a great deal with just a couple of bass corner traps and a panel to address first order side reflections. Affordable, not too disturbing appearance-wise and a great cost/benefit ratio.

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Quote:
Which is why from my experience you can only use so many panels for room acoustics before it becomes detrimental (even ignoring liveliness/deadness issues), even with the right number of panels and correct types/depths moving them to a less than ideal position is still detrimental (and my experience we are talking inches here for a small room).

Maybe there should be a caveat for those saying you can never have too much bass absorption (not directed at you Elk but many others who seem to be making an assumption IMO).
Thanks
Orb

Well, it is true, though.

You can never have too much bass absorption.

But, in the vast majority of case it comes with too much mid-high absorption. Theoretically, it is a nice idea. I've heard it practically, as in 'reality' ..the odd time. It is a great thing to hear.

Orb
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Yes indeed that may be true, but as I said most take that statement too generally to mean using more and more panels is always better as it absorbs bass.
As it stands "you cannot have too much bass absorption" is one of the most loose statements doing the rounds on many audio boards when someone asks about room improvements and the discussion then focuses specifically on panels and associated materials put into walls/etc.

Hence the need for a caveat or a better/more complete phrase, if only to break the assumptions.

I wonder how many use tuned products for specific low frequencies problems (do not affect mid to high FR) to deal with "you cannot have too much bass absorption".

Curious, anyone know of materials that say are NRC 1 (or close to) up to say 250Hz or lower and then quickly drop low on the absorption above this FR and could be used for room acoustics?

Cheers
Orb

Elk
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GIK's monsterbass trap does not do this, but from what I have seen has the quickest fall off of absorption with rise in frequency. absorption data

However few manufacturers post any real data. Real Traps and GIK are some of these few. Real Traps appears to have a bit broader range of absorption.

I understand however that there are such differences in testing methods that direct comparison of tests - even from competent labs - is iffy at best.

I have not experienced a problem with too much higher frequency absorption, either in my own spaces or in places I have visited, but I appreciate it could be a problem.

This I think of this as more of an academic problem than practical, especially for listening to reproduced sound.

I see it is a bigger potential problem for a recording space however, particularly when recording a drum set where one wants a certain amount of room reinforcement and ambiance.

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It is interesting to note that when it comes to actual bass absorption in a room, or 'in situ', so to speak, it is, for the vaster part, impossible for us to measure such phenomenon. We can get 'numbers' but what their relevance is, that is the question. We have pressure development and modulation issues to deal with that have variables that need a type of resolution where we have not quite figured out the full nature of the problem. Hence the difficulty in measuring what we have not fleshed out enough, as of yet. This is why the different weighting systems have a marked roll off, as our measuring capacity down there with regard to accuracy in any form is basically -non existent. The way they got around our lack of capacity in those frequency ranges is to make those frequency ranges not relevant in/to data collection.

Imagine yourself down near the beach, out about a few hundred feet into the full surf...in the body of some mid sized waves, with your tiny measuring device, trying to asses the power of the wave. You will get some general data but assessing the wave, with repeatable accuracy in all locations and ways? Not going to happen. You can create a standard, and you can make people use it the same way every time, but you can't make the wave be the same every time and the same on every beach. So you don't have a hope in hell of getting any idea of true wave power or true wave data.

Elk
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It is indeed tricky to measure low bass.

I have good room measurement software. It is repeatably consistent and gives me a good idea of the changes, but I wouldn't claim it is giving me an absolute reading. It is satisfying to see the big peaks and dips decreasing in size as the room acoustics improve.

Ethan is right when it comes to ear placement. Move the mic an inch or two and everything changes, especially when you are not rounding off to 1/3 octave resolution and start digging in at higher resolution.

j_j
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Quote:
Yeah I would love for someone who is technical to explain what the panels behind and between speakers do as well.
Nudge nudge anyone

Oh, come on. At low frequencies, speakers are omnidirectional, and you'll get at least some absorbtion there. If you have dipoles or bipoles, you'll also have radiation from the back of the speaker at higher frequencies, and you want to have roughly equal absorbtion across frequency (well, not quite, but that depends on a lot of other things, too).

In a small room, reflections off the other walls will hit the front wall and there is certainly an advantage in not having 20 millisecond delayed (figure 22 foot path length) reflections from next to the speaker.

There are a lot of reasons, but it all boils down to hearing what the speaker is putting out, or hearing what the room is bouncing off the wall next to it.

For a given room and loudspeaker, the answer may be different.

One thing that is often ignored in loudspeakers is the total power response vs. the direct response. Another is the directivity of the power and direct radiation.

This is one of the two reasons that "make it flat" room correction fails miserably.

The first is that most rooms store a lot more low freqency energy, and an omni mike in room correction systems will capture it (as long as you have a multiposition sampling, at least, there are other issues with a pressure microphone as well) and turn up the treble relative to the bass. The result? Feeling like you're on the wrong end of a dentist's drill in your ear.

Add to that that many speakers are not even close to flat integrated power response, and you get even more direct high frequency preemphasis. More ouchies.

There are ways to deal with this. The talk on the MicroSoft room correction (deck at www.aes.org/sections/pnw/ppt.htm) shows one way. There are better ways, but they require more complexity in capture and rendering. Can't say more about that presently.

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Quote:
It is interesting to note that when it comes to actual bass absorption in a room, or 'in situ', so to speak, it is, for the vaster part, impossible for us to measure such phenomenon.

Well, true, if you're using a pressure microphone.

KBK
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Unless you are beginning to come close to capturing an entire rarefaction-compression cycle and specifically, the whole envelope of energy..then it is just a calculated inference, is it not?

As an example, I was just reading about, over at physorg.com, that we can't even understand how a drop of water works. it has acoustical phenomena and air phenomena that we cannot replicate and have no model for.

As the drop hits the surface and then slams below..the tunnel or channel of air drilled into the water..as that collapses, it can and does create a supersonic jet of air moving at over 4,000 fps. We have no acoustic or air flow analogy that fits that phenomena. One lousy drop of water.

Now, how goes that acoustic 'science', again?

"Under construction", would be the answer and very likely will be for quite some time yet.

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Quote:
As an example, I was just reading about, over at physorg.com, that we can't even understand how a drop of water works. it has acoustical phenomena and air phenomena that we cannot replicate and have no model for.

And that's something with which we are all familiar. I am still trying to come to grips with the prediction from String Theory that all of what we perceive as reality comprises the interactions of three-dimensional projections from two-dimensional Planck-length holograms that tile the Universe's "event horizon" (ie, a sphere with a radius equal to the distance where the Hubble Velocity equals the speed of light.) And they say audiophiles are crazy? Physicists are _really_ out there!!!

John Atkinson
Editor, Stereophile

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Quote:

Quote:
As an example, I was just reading about, over at physorg.com, that we can't even understand how a drop of water works. it has acoustical phenomena and air phenomena that we cannot replicate and have no model for.

And that's something with which we are all familiar. I am still trying to come to grips with the prediction from String Theory that all of what we perceive as reality comprises the interactions of three-dimensional projections from two-dimensional Planck-length holograms that tile the Universe's "event horizon" (ie, a sphere with a radius equal to the distance where the Hubble Velocity equals the speed of light.) And they say audiophiles are crazy? Physicists are _really_ out there!!!

John Atkinson
Editor, Stereophile

Took me a few seconds to figure it out but I have the answer and the model, on the air phenomena, concerning the drop of water.

As for the holographic part, many psychics that have visions (in broad daylight, or whatever and wherever)..DO report that the things seen, are one of a flat 2-d nature.

ie the vision is there... but it is flat and one sided, no matter the viewpoint. Exactly as physics predicts.

Time, as we like to call it, is a interactive phenomena and does not exist outside the interaction of the separate quantum components as they cascade into bulk groups into 3-d mass as we see it in the Newtonian (gross aggregate) sense.

Time, like gravity and mass, exist purely as a quantum to quantum interactive. The perfect flow and perfect rejection of a superconductor immersed in a magnetic field show this very clearly. We have, in the scientific sense failed to realize this, as we cannot measure what is going on in the superconductor without a difference or differential reading. Differential - being the essence of 3-d reality, the only constant being the interactive..but the interactive is always changing and thus time, energy, mass, gravitation and space...Voltage is potential is differential is polarization differential, and current is flow across differential..and perfect current flow requires no polarization differential but still having flow ...and within perfect current flow..no time exists. We can only infer that, as we need the differential to conduct a test or to measure, so when attempting to measure or grok this perfect flow ---we tear it down.

When we have a large or powerful spark occur then we encounter Kosyrev's 'superluminal' as we, at the very least, have a minor aspect of perfect current flow..and this disturbance that is partially perfect..causes a disturbance in the regular flow, like a rock suddenly appearing in a river and then disappearing..and thus waves cascade off that point in it's superluminal way...and with the right sort of similarly designed detector..we can then detect this superfast wave or disturbance in the superfast wave. Then we have information flow that is FTL. Simple.

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Quote:
I am still trying to come to grips with the prediction from String Theory that all of what we perceive as reality comprises the interactions of three-dimensional projections from two-dimensional Planck-length holograms that tile the Universe's "event horizon" (ie, a sphere with a radius equal to the distance where the Hubble Velocity equals the speed of light.)

This is discussed at length in Leonard Susskind's "The Cosmic Landscape: String Theory and the Illusion of Intelligent Design" (2006, Little, Brown & Company).

John Atkinson
Editor, Stereophile

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Quote:

Took me a few seconds to figure it out but I have the answer and the model, on the air phenomena, concerning the drop of water.

As for the holographic part, many psychics that have visions (in broad daylight, or whatever and wherever)..DO report that the things seen, are one of a flat 2-d nature.

ie the vision is there... but it is flat and one sided, no matter the viewpoint. Exactly as physics predicts.

Time, as we like to call it, is a interactive phenomena and does not exist outside the interaction of the separate quantum components as they cascade into bulk groups into 3-d mass as we see it in the Newtonian (gross aggregate) sense.

Time, like gravity and mass, exist purely as a quantum to quantum interactive. The perfect flow and perfect rejection of a superconductor immersed in a magnetic field show this very clearly. We have, in the scientific sense failed to realize this, as we cannot measure what is going on in the superconductor without a difference or differential reading. Differential - being the essence of 3-d reality, the only constant being the interactive..but the interactive is always changing and thus time, energy, mass, gravitation and space...Voltage is potential is differential is polarization differential, and current is flow across differential..and perfect current flow requires no polarization differential but still having flow ...and within perfect current flow..no time exists. We can only infer that, as we need the differential to conduct a test or to measure, so when attempting to measure or grok this perfect flow ---we tear it down.

When we have a large or powerful spark occur then we encounter Kosyrev's 'superluminal' as we, at the very least, have a minor aspect of perfect current flow..and this disturbance that is partially perfect..causes a disturbance in the regular flow, like a rock suddenly appearing in a river and then disappearing..and thus waves cascade off that point in it's superluminal way...and with the right sort of similarly designed detector..we can then detect this superfast wave or disturbance in the superfast wave. Then we have information flow that is FTL. Simple.

Thanks for clearing THAT up. I'm still working on the snap, crackle, pop in Rice Krispies.

Orb
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Oh, come on. At low frequencies, speakers are omnidirectional, and you'll get at least some absorbtion there. If you have dipoles or bipoles, you'll also have radiation from the back of the speaker at higher frequencies, and you want to have roughly equal absorbtion across frequency (well, not quite, but that depends on a lot of other things, too).

Thanks for the advice, although what you shared I could pretty well say most of us here already understood that much
Would love to have more technical info though if you have it, although I guess the only way to get more info is to read some of the books on the subject, which tbh I really do not want to do and I guess nor do a few others.

Thanks anyway
Orb

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I am still trying to come to grips with the prediction from String Theory that all of what we perceive as reality comprises the interactions of three-dimensional projections from two-dimensional Planck-length holograms that tile the Universe's "event horizon" (ie, a sphere with a radius equal to the distance where the Hubble Velocity equals the speed of light.)

This is discussed at length in Leonard Susskind's "The Cosmic Landscape: String Theory and the Illusion of Intelligent Design" (2006, Little, Brown & Company).

John Atkinson
Editor, Stereophile

Ah if you enjoy theoritical physics you should consider the Heim theory and also extended Heim theory presented by Dr

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GIK's monsterbass trap does not do this, but from what I have seen has the quickest fall off of absorption with rise in frequency. absorption data

However few manufacturers post any real data. Real Traps and GIK are some of these few. Real Traps appears to have a bit broader range of absorption.

I understand however that there are such differences in testing methods that direct comparison of tests - even from competent labs - is iffy at best.

I have not experienced a problem with too much higher frequency absorption, either in my own spaces or in places I have visited, but I appreciate it could be a problem.

This I think of this as more of an academic problem than practical, especially for listening to reproduced sound.

I see it is a bigger potential problem for a recording space however, particularly when recording a drum set where one wants a certain amount of room reinforcement and ambiance.

Heh why I am a bit reluctant to comment on the NRC rating of the panels I own, sadly not all seem to follow same processes that then makes it unfair for those (in this case possibly anyway) with accurate measurements.
One comment with the GIK values is that they are providing ideal measurements for different scenarios (positions)
If taking wall mounted the absorption coefficient is same at 100Hz and 1.5Khz onwards.

So looks like they are behaving like other panels, I guess we just put panels in corners is the answer

Cheers
Orb

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Corner placement is indeed incredibly effective. The loss of space is minimal and the panels look good in the corners also.

Ceiling panels(s) to absorb first reflections is often forgotten but effective. These panels visually disappear as well.

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Thanks for the advice, although what you shared I could pretty well say most of us here already understood that much
Would love to have more technical info though if you have it, although I guess the only way to get more info is to read some of the books on the subject, which tbh I really do not want to do and I guess nor do a few others.

Thanks anyway
Orb

Well, that's about what I'd expect from you. I notice you extracted half of the article for your thinly-veiled, intellectually lazy and dishonest personal attack.

Selective quoting is just another mark of somebody who is trying, but what they are trying I won't say.

It's funny, someone like you, who goes on and on about being civil, etc, manners, etc, consistantly reacts in such a mannerless, insulting fashion.

You know, if in fact you know anything, that the answer to your question depends on many particulars of any given room, if we are to address the psychoacoustic issues at all, ergo some more information from you might get you a useful answer.

But instead of some information, look what we get.

Figures.

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Err,
I really think you need to re-read my post as it was deliberately done to be neutral, you see provocation where there is none.
In fact I edited the post to try and ensure this.

The fact is you expressed "oh come on" and then went on to explain what we already know.
I mentioned the books because in most cases it always comes back to books for reference on such subjects as these, due to the web not having enough technical detail on the mechanics myself and Elk were discussing and interested in.

Specifically, the wall behind speakers (lets say traditional box speaker) and more precisely the radiation pattern combined with different absorption/diffusors/reflection (such as flat screen tv).
I can look at linwitz for detail but it does not cover the mechanics more precisely when considering the good and bad of acoustic panels behind speakers or reflections caused by items in line with the speakers,etc.

I did not include the rest of your quote as it was not necessary.

Elk you may know of the Linkwitz site as it has plenty of info regarding speaker design, useful link partially discussing this subject.
http://www.linkwitzlab.com/rooms.htm#Loudspeaker directivity

JJ, I appreciate all the parameters are not known, and as I said any information you can share on these specific mechanics (solely wall behind speaker as mentioned above) that would be great.

Cheers
Orb

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Thanks for the link, Orb.

Linkwitz "The best remedy is to move the speaker away from the wall, or to make the wall as sound absorptive or diffusive as possible."

Also see his FAQ #31.

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He has a lot of interesting info scattered around, btw it looks to me faq31 is specific to open baffle/dipole speakers, the acoustic page shows how each speaker type has different radiation patterns.
Would be nice to see more detail (distance and lower FR) with regards to box speaker radiation pattern, even though it does show how low frequency radiates in a much wider circular footprint all around the speaker.
Also curious how much different box speakers designs and materials affect the radiation pattern, if it all.

Cheers
Orb

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As I understand it, we can affect the radiation of higher frequencies by recessing the drivers, lining the recess with felt, designing a driver that is more "beamy, avoid cabinet diffraction effects, etc.

The lower the frequency the less we can do about it. Low tones zip around just about anything, and go right through a lot as well.

His is an interesting site. Definitely gets one thinking.

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As I understand it, we can affect the radiation of higher frequencies by recessing the drivers, lining the recess with felt, designing a driver that is more "beamy, avoid cabinet diffraction effects, etc.

The lower the frequency the less we can do about it. Low tones zip around just about anything, and go right through a lot as well.

His is an interesting site. Definitely gets one thinking.

More specifically, you can start to get pattern control when the radiation area of the driver(s) (arrays included) gets to about a half-wavelength.

This is, for instance, why tweeters can beam horridly if they aren't designed properly, or if the designer paid no attention to radiation pattern. Nothing new here, but a lot of people haven't been careful this way, as a listen to any of a lot of speakers will show.

This leads into the whole direct vs. power response issue, but that's for another thread, I think.

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This leads into the whole direct vs. power response issue, but that's for another thread, I think.

Nuts with this!

Go for it!

We like learning.

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