So please read the whole post before commenting. The question is nuanced.
First, as you probably know I’m a huge fan of the well treated room, and a fan boy of GIK acoustics as a result, so what I am _not_ arguing is against proper room treatment. I remember many years ago, perhaps in Audio magazine (dating myself?) the concept of treating the first reflection points came up, and it seems really logical, and quickly adopted. Mirrors, flashlights and lasers and paying the neighbor’s kid (because we don’t have real friends) to come and hold them while marking the wall became common.
However!! In my experience, I have not actually been able to tell the difference between panels on and off that first reflection point. Of course, I can hear the difference between panels and not, but after all these years, I want to ask if any of you personally know that the first reflection point really matters more than other similar locations. Were we scammed? By knowing I mean, did you experiment? Did you find it the night and day difference that was uttered, or was it a subtle thing, and if those panels were moved 6" off, would you hear it?
@aj523, a good and sensible post. I use Dayton Omnimic V2 because I also need to measure the electro-acoustic and Thiele/Small speaker parameters but REW and HolmImpulse are free and do much the same.
@eric-squires, what is an "average audiophile'? You can only go so far by continual upgrading at great expense but all that extra detail and low noise floor you are paying for is being lost to strong early reflections. In fact at low frequencies where bass nulls occur that information is lost completely and you can not get it back with EQ. The more power you pump into it just cancels with the same power.
Multiple subs and bass traps are needed to smooth this problem out, a problem all domestic rooms have. If you consider the amount of time and money the 'average audiophile' spends on their system you would be better off embracing the subject than shying away from it. I am sure the cost of a mic. will be the cheapest and by far the biggest upgrade you can make. There is much on the net to help get a handle on this.
The software, apart from showing you waterfall plots which identify the most troublesome
frequencies, will also help you position your speakers and subs.
The software, apart from showing you waterfall plots which identify the most troublesome
frequencies, will also help you position your speakers and subs.
You are preaching to the choir. What I wonder about is how to be helpful with the least amount of trouble for an audiophile, or better yet, a music-phile, who just wants to get excellent results.
I wonder how many really want to learn what the software does, measure and adjust, and also, without a lot of reading and research, come to the right answers. Having the tools doesn't mean you have the skills.
And I don't want to discourage anyone from learning. What my narrow question here is, for an audiophile who is new to the idea of room acoustics, and wants excellent results, am I doing them a service by suggesting they get a mic and REW or OmniMic, or am I better off suggesting they get a consultant like GIK to help them?
Why not advising people to have fun....Trying their own ears a step at a time, with low cost materials and some creations of their own? i just do that and my room is heaven...( i just create a new form of diffusor)
It is remarkable that people trust formulas and not their ears.... Room geometry and content are acoustically complex, ready made formulas on a program will not do better at the end than your listenings playful experiments....
Be creative, free yourself, trust yourself, is my advice....
Few people know that Goethe make his point against Newton in color theory....While Newton search for a theoretical mathematical corpuscules light theory, Goethe described for the first times in history the way of colors to comes from light and dark in the world in relation to physiology....Goethe was a colossus of intelligence but in too much fields for the average people to understand him really....And to this day, Goethe reflexions seems not to go to a dead end, like a corpuscule theory of light and colors... Edwin Land was a Goethe disciple for example.... :).
In acoustic there is something similar....And Michael Green put it right by noting that sound is also pressure, not an abstract mathematical wave only, but a living wave....
We exist in a universe of waves...beginning with the subatomic, density and type variants all....
It just 'thins out' the further off we rise from what we percieve as solid ground.
And we're just another version of it, making waves of our own.
"What state do you live in?" Quantum....
"Zip code?" (Hand over a thumb drive...)
J'accuse: The number of things agreed upon = the number not. The universe is subject to the Bell Curve as much as we 'average out' in our HO about what we hear, how we hear it, and how we feel (or don't) about it ....
Flies in the fluxes of universal ambers...in the midst of all the other waves...the daily surf...
Not terribly sci about it, but it makes for my day. *S*
I were thinking about.. If we ONLY look at the side walls reflections. Then the first reflection points that the sound bouncing off.
My thoughts goes like this: First reflection point is weaker (lower dB) than the direct. And what reflects of that surface is probably more higher frequencies than lower ones (Hz).
That side point will act as a muted bass shy speaker that is delayed as it were placed further away..
Can this side walls reflection points contribute to a wider sound stage? Or some other benefits that can be a argument to not treat side walls reflections?
(And of course the our experiences will vary greatly when we have all different distances from the speaker to the side wall in our unique rooms. So I would like to know what distance is used when we tell about our experience.)
A experience I have (sidewalls 80 cm away) it is like that helps or make it possible to hear sounds/instruments somewhere between the speaker and the first reflection point.. so extreme right or left will be beyond the speaker. Yes now when I think about it the sound stage is then wider..
But it is unintended wider and nothing the artist/producer were aiming for. And when first reflection point reflect a uncontrolled frequency response/range depending on what type of surface the effect will be more or less pronounced depending on the different frequency range different instruments has..
So I think I have answered my own question somewhat.. but how are your thoughts on this?
optimize, some of your points have been addressed in previous responses.
That side point will act as a muted bass shy speaker that is delayed as it were placed further away..
Can this side walls reflection points contribute to a wider sound stage? Or some other benefits that can be a argument to not treat side walls reflections?
Because of how our brain processes reflections, how we perceive reflected sound depends on how long those reflections are delayed compared to the direct path from source to ear. If the path of the reflected sound is longer than about 6 meters longer than the direct path from the source to the ear, the reflection will add to the spaciousness of the room. Any reflection that is shorter than that will generally not be distinguished as a separate sound and will result in a spacial smear. Another consideration is that the dB level of sound decreases as the distance increases, and the dB level further decreases every time it bounces off of another surface. It has been my experience that reflections that have a path about 2-4 meters longer than the direct path are especially detrimental to precise localization of instruments and voices if those reflected signals are not at least -20 dB compared to the direct sound.
So the answer is that some reflections off of side walls are beneficial, and some are detrimental. I have left the sidewalls of my room untreated from about 0.5 meters forward from the first reflection point to the front corners. Doing so gives me better sound stage width at the expense of increased slap echo. I've devised a way to deflect the first reflection point away from the ear, which results in superb imaging in my rather narrow (~4.5 meter wide) room. My approach is different than traditional absorption or diffusion. It is more consistent with the approach described by Duke LeJuene above.
The first sidewall reflection point matters in the design of a recording studio control room. Those I have been involved in used angles which direct the reflections away from the normal listening position.
If I read your post right, your room is less than 2 M wide. I don't know how your room is laid out otherwise, but it seems likely to me that your side wall first reflection points have a delay of less than 5 milliseconds compared to the direct signal. Some say that those very short delays don't compromise imaging as much as those having a delay of 5-20 milliseconds. So you may not get much benefit from trying to treat your sidewall first reflections as others.
We can clearly say it is more than "some". More exactly half of all reflections is good and the other half is harmful for stereo image.
Experiment: Put a wall of panels from your face in sweet spot that extends right in the middle to your front wall between the speakers.
The sound stage is incredibly and will never be better than this.. ..yes it looks stupid and is impractical but just as a experiment.
In short we have one room for left and another for right and the reflections from each speaker is there BUT they are totally separated.
That shows us how "harmful" to the sound stage perception, the first reflection point from the right speaker in the left wall that reach the left ear.. that were intended for the other ear.. and vice versa.
So half of all reflections (when we can see the experiment as we have two separate rooms left and right) is not good or is just destroying the sound quality. And if you have done the experiment then you will most likely agree.
I just had my free phone consultation with Mr. Foley and after reviewing my room through photos (see link), he recommended the following:
1. No diffusion anywhere to begin with. That will worsen the problem he perceives given all the windows.
2. Treat the walls closest to the speakers first so that’s the front wall behind the speakers first and the side walls with as much absorption as possible.
3. No need to buy software to measure the room since the problems are obvious and better spent on product.
4. The treatment of corners with bass traps etc is a common fallacy and not a priority.
5. Tame from "40 cycles - 7000 cycles" as he calls it with eight (8) carbon panel CPs at $750 per panel. And since each panel weighs 150lbs, its about $1,000 for shipping. So all in $7,000.
6. He did some calculation where he said I would see 65 percent improvement. I pressed him on what that is measured against but forgot his reply.
7. Then we can talk about diffusion after a period of time of listening to the results.
" 5. Tame from "40 cycles - 7000 cycles" as he calls it with eight (8) carbon panel CPs at $750 per panel. And since each panel weighs 150lbs, its about $1,000 for shipping. So all in $7,000."
I agree with the frequency region he focuses on.
We see that serious acoustic treatment is expensive. That seven thousand dollar figure is an argument for taking loudspeaker/room interaction into account from the beginning, as imo there are more cost-effective solutions.
A dedicated audio room is way much cheaper to treat and controls....Mine with 2 windows relatively small with irregular geometry, cost peanuts and the results are astounding, superior to many upgrading of my gear...
But a living room, being a common room ask for more esthetical solutions, then costly indeed....
My own room look like the seat of an arachneid that will use his many "fingers" to connect all with his silk cables.... :)
i could not do that without divorcing in a common room....
And like usual people never speak about active room controls of acoustics, only about passive materials treatment.... I begin to think that i had invented the concept..... It seems nobody has ever hear about it all...But active controls cannot be done in a common room anyway...
Thanks Duke. Your feedback is ALWAYS appreciated. As you know I seriously took the room into consideration when make the speaker decision, turning down several planars /dipoles that i was really interested in. The Harbeths, 3 feet out from the front wall and almost 7 feet from the side walls, with their large front baffle seemed to be the best choice and quite frankly they sound absolutely amazing, BUT Foley tells me the Harbeth midrange and the speaker overall will sound like a different speaker altogether to the extreme.
Soooo... now I’m deciding on putting 1200 lbs of treatment in our main living room but save multiple x $$$$ on the cost of a wedding next June since my fiancee will surely leave me. Not an easy one indeed. 🤔
5. Tame from "40 cycles - 7000 cycles" as he calls it with eight (8) carbon panel CPs at $750 per panel. And since each panel weighs 150lbs, its about $1,000 for shipping. So all in $7,000.
@aj523
This is why I always recommend GIK acoustics. Very effective products at reasonable prices. I don’t know of any of them that weigh 150 lbs either. :)
As an alternative, consider the GIK panels with soffit traps, which are cheaper, lighter weight, and also go down to low frequencies. They also do free room consultation.
Truthfully, you may NOT need any bass treatment, so panels that go down to 40 Hz may be serious overkill. Tame the mid/treble range, and this may re-balance your room well enough. If that doesn't make your speakers sound larger and more powerful, then pull out the bass traps (GIK soffit).
Also, might want to try using excess toe-in. Have the tweeter line cross in front of your head. This may sufficiently improve reflections off the sides. Of course, heavy curtains would also help.
3. No need to buy software to measure the room since the problems are obvious and better spent on product.
What? I am not considering my self as a measurement guy. But that is the just so wrong on so many planes. It is like saying don't give someone else money but instead give it to me. On the other hand not many buy the software when it is free.. on the third hand you need only buy a calibrated microphone that cost peanuts (65-100 USD). You need to learn to use the software or get someone that can.
Nobody trust me nobody can hear what you are able to find out by measuring. (You have never heard someone say "Oh that room has a 10 dB big dip at 53 Hz" for example. But measurement will show you exactly that and much more) You can determine what effect after that you got after putting 7000 $ into your room
You should see on your measurements that your decay times is considerably lower over the whole frequency band.
Less amount of peaks and dips
How do you quantify that the sound after you spent 7000 HAS got better? Are you and Foly sitting in your sofa and subjectivity nodding to each other and saying "yes it sounds better.."
It is like emperor new clothes nobody dear to say something negative..
Plus he knows that if you don't do a measurement then you will not after the treatment say to him "Look there is still a 10 dB gain at 100 Hz (for example) after the treatment as it were before..
Plus he knows that if you get the gear and make measurements with the free software that you are halfway to be able to make a active correction.. you need "only" to take that measurement and export and then import to the DSP for it to correct your room..
To push you into that direction is only loose loose for him. When you can make demands on how much improvements you should and would expect..
But yes I am also of that opinion that we should fix the room with room treatment as far we can do THEN using active DSP.
But you NEED to measure to have and to get a baseline.. Measuring is knowing!
(On a personal plan I think you will destroy that beautiful space. With all of those windows there is not much space to put all the stuff.. and making that project very hard from a esthetic point of view.)
I love measurements. I spend my day job measuring things. I have 3 calibrated microphones right next to me, and yet, when it comes to the question of:
"How do you help the average audiophile?"
I have really come to be against measurements. I worry that those advocating for measurement software for acoustics and sub configuration (including me in the past) forget just how difficult calibrating a room is.
People think of this software like you are buying a spell checker. You just high light all the red words and check the spelling. They are nothing like that.
For this reason I’ve totally turned around. Now I advise others to find trusted acoustics consultants to help with the room, and good room correction to integrate a sub.
It may seem hypocritical, since I would never do either... but then, I have spent a lifetime learning about what I’m doing and would rather tweak it myself. If a new audiophile shows up and wants to get to done, I don’t recommend my path.
I don't want to ever discourage anyone from learning, I enjoy learning and applying tools, speakers and room acoustics a great deal, but how do I serve the audiophile asking for advice best? That's the question I have wrestled with a great deal, and no longer answer like I used to.
Now, an audiophile who wants to learn how to make speakers, or is really interested in acoustics, of course to them I answer differently.
My point is, I don't think tools and software serve everyone the same way, and I think we should be more adaptive at least.
The GIK 242s are rated from 250, and the 244s from 80. He specifically wanted to match the 35hz +/- 3db point of the Harbeth for smoother results and he thinks bass is the biggest issue in the room. But the investment is significant and the aesthetics are not great for a room that’s not a dedicated listening room. They come on rollers so the 150lb panels can be wheeled around. In the pics you can see a big plant to the left of the left speaker and a velvet sitting chair to the right of the right speaker - he said both of those have got to go! Lol. As the speakers must have unencumbered space in and around them.
You don’t match acoustic treatments to the operating range of the speakers. You match them to the reverberation of the room.
Anyone who says "well, my speakers work from x to y Hz and therefore so should my panels" is selling you bs. See practically any reference on room acoustics.
The 40.2's are so far away from the side walls that I can't believe that they are much of a problem. Vu of Deja Vu in Wash DC, a major Harbeth dealer, stated to me that they needed a *minimum* of 2 feet from outer edge to side wall, and yours have much, much more.
Frankly, it's the amount of glass in the vicinity that to me would be the major concern.
I see you have some kind of adjustable blind on most if not all of them. So simple experiment: play the same track with all blinds completely up, and then all completely down. I'd be curiously to know if you hear a difference.
The wife and I bought a distressed 3.5 story townhouse in the city of Newburgh NY for super cheap and did a top down restoration.
Except for the top attic floor.
It is there that I have my home office, studio and listening room. The room is insulated with rock wool: 6 inches in the walls and 17 inches in the ceiling. There are two dormers and a gable to break up parallel wall and ceiling reflections. Not that I have much.
My architect, who I know from college days, has designed some recording studios. He told me not to seal the rock wool behind dry wall, but instead to simply cover it with burlap. This would give me a semi-anechoic room. No panels to position etc.
The difference in the sound quality from my old New York City loft - with its tin ceiling, brick walls and huge glass windows - is night and day.
For the amount of money that I was spending anyway to insulate my home to get it to perform to near net zero performance levels, I got the equivalent of a room that is recording studio quality.
The one issue missing from this discussion is your impression of acoustic treatment at first reflection points completely depends on how wide a dispersion speaker you actually use. A speaker that narrows with frequency, say a horn, will send less info to the side walls as frequency increases. A ribbon or any planar device will also do this but it can depend on what frequency the planar portion of the speaker is working in.
So imagine a ribbon working at 3K and above. You wont get as much energy at 3K and above on first reflection points as they get fairly narrow even at 3K and get even narrower as you get to 10K and above. This is easily demonstrated by rotating the speaker until it almost faces the side walls, you'll hear bunch of splash as you get more energy on it. Also the wall material matters- glass is very different frequency emphasis than wood. There are many different types of absorbers- some work well at HF, and some work better at mids and some are built to be LF absorbers with membranes.
SO there is no universal answer to this other than to say if you have a wide dispersion speaker, the first reflection point absorption is critical to improving image. If you have a narrow dispersion speaker you may not hear much difference. Also you need to buy real absorbers like GIK, or make them, I like the 4 inch thick ones, they absorb more for the same wall space.
The one issue missing from this discussion is your impression of
acoustic treatment at first reflection points completely depends on how
wide a dispersion speaker you actually use.
For the purposes of this argument, alone, I want to argue that first reflection points don't matter, ever.
Again, I don't mean that room treatment doesn't matter. I just argue that the idea that the first reflection points are some sort of magical acupressure point for speakers seems wishful thinking to me.
What does matter, a lot, is the overall acoustic field. An even decay rate and proper balance of diffusion and absorption. But if you take a dozen panels placed around evenly in a room, I don't think you could tell that the 1st reflection points do anything more special than the rest.
And I am also _not_ making the argument that speaker to room acoustic matching doesn't matter, it does a great deal.
Some horns are symmetrical some have more width than height. That gives narrower spread up and down. And will result in less issues with ceiling and floor first reflection points. That I have experienced.
Eric I would put it like this. As we KNOW that the FIRST bounce (reflection point IS the strongest/highest in dB. Then it more energy (dB) that we can transform to friction with absorbing panels. And 2nd, 3rd reflection, and so on is, each decreasing in energy for each reflection that is done.
So if we only have 2 or 4 panels and want to absorb as much reflections from the room boundaries. Where should we places those few panels to get the most absorption as possible with those few panels? Yes at the strongest one of course.
If we wanted to preserve the side reflections but we wanted to absorb the same amount of dB but only treated the 2nd, 3rd and so on reflection points then we need much more coverage than what just 2 or 4 panels could contribute with.
So we see that first reflection points is giving us most bang per square unit of panel/treatment.
(As for me I want in general listen on what is in the recording and not get the "color" and delay of room boundaries. The "color" is defined by what material the room boundaries consist of. We know that dry walls and concrete walls reflect different amount of dB for each frequency (frequency response). So we can consider that in a concrete there inside that wall sits a mixing engineer that use litle more level on the bass faders on his console compared to the mixing engineer in the dry wall. Sorry for that dumb analogy.) :D
As my ceiling is only 6'6" high in my listening area, and it's *not* acoustic tile. It's a fairly hard surface. Speakers are not too close but it's a low ceiling. I'm sure there's a critical 1st reflection point there. Some have helped me try to troubleshoot my space a bit (thanks, brownsfan!). The side reflection points are less an issue. I can imagine I should do something with the ceiling, but I don't want to go down a room treatment rabbit hole at the moment. (I'm not a skeptic or unwilling to spend if it's worth it, but it represents a genuine investment of time I don't have right now.)
@hilde45, my pleasure. As for your ceilings, don't fix it if it ain't broken. If you are getting good imaging and vocal articulation, and you are not being troubled by slap echo, count yourself lucky and focus on things that will make a difference. We are much more sensitive to early reflections in the horizontal dimension than in the vertical dimension.
Your room is so atypical in its dimensions that general rules of thumb may not apply, as long as you stick with the long wall orientation. In your room I would still worry about front and back walls first. Treating those surfaces is likely to do more than even treating the corners in your room.
I got into room acoustics because my system sounded lousy despite the fact that I had superb gear. Treating the room was the right approach in my room, but It may well not afford you that same level of improvement. Your room and system positioning eliminates some typical problems, but affords you less opportunity for further improvement on those problems that remain. It really could be a non-productive rabbit hole for you. Cheers!
@erik_squires wrote: " For the purposes of this argument, alone, I want to argue that first reflection points don’t matter, ever."
Early lateral reflections contribute to spaciousness and expand the "apparent source width", according to Floyd Toole.
When "presence" is lacking the earliest reflections are the most responsible, according to David Griesinger.
So apparently early sidewall reflections are neither entirely beneficial nor entirely detrimental. They do some things which are desirable, and some which are undesirable.
Earl Geddes is aware of both the benefits and the detriments of early reflections, and here is his thinking on the subject:
"The earlier and the greater in level the first room reflections are, the worse they are. This aspect of sound perception is controversial. Some believe that all reflections are good because they increase the listeners’ feeling of space – they increase the spaciousness of the sound. While it is certainly true that all reflections add to spaciousness, the very early ones (< 10 ms.) do so at the sake of imaging and coloration. There is no contention that reflections > 20 ms are positive and perceived as early reverberation and acoustic spaciousness within the space. In small rooms, the first reflections from an arbitrary source, mainly omni-directional, will never occur later than 10-20 ms (basically this is the definition of a small room), hence the first reflections in small rooms must be thought of as a serious problem that causes coloration and image blurring. These reflections must be considered in the design [of the loudspeakers] and should be also be considered in the room as well."
My own investigation (controlled blind testing, but nothing peer-reviewed) leads me to believe that early reflections are strongly involved in conveying a sense of the playback room’s boundaries being nearby. The weaker the early reflections, the less "small room signature" the playback room superimposes atop the recording venue’s acoustic signature, whether it be real or engineered or both.
I have been involved in several professional recording studio projects, in which the acoustician has designed angles into the sidewalls which geometrically preclude early sidewall reflections at the mix position. This is to facilitate clearly hearing the acoustic signature which is on the recording, without the mixing room’s signature being dominant.
So imo what happens (or doesn’t happen) at the first sidewall reflection points makes a difference. Whether or not this difference "matters", and if to so what extent, is, I suppose, a judgment call.
Erik again: "if you take a dozen panels placed around evenly in a room, I don’t think you could tell that the 1st reflection points do anything more special than the rest."
This would be true in a large room, but not in a small room. In a large room the reflections paths are much longer and there are so many reflections that the reverberant energy is effectively uniform throughout the room, such that WHERE you place acoustic treatment doesn’t matter - the net effect is the same. But in our small home listening rooms, we experience discrete reflections. And the earliest and loudest of those reflections are the ones which have the strongest effects, whether their effects be beneficial or detrimental or both.
We think we know acoustic.... But acoustic is like other science full with unresolved mysteries....
I just read an article, an interesting one, where 3 specialists discuss without being able to be in total accordance about the basic acoustical treatment....And they are specialists....
Myself how can i change my room acoustic with cheap metal buckets glued together with an array of different stones on them ? The stones making a difference in the reverberation time control....
Is there a set of linear differential equation to explain that?
:)
For reflections we can use them or neutralize them..... In a small listening room it is better to use them......In a control room it is better to neutralize them.....
Myself i use them .... With success.....
« Complex waves of sound are akin to some cellular animals, they live a long life themselves but that look like milliseconds for us» -Groucho Marx
Is this discussion only limited to lateral reflections? It seems to me the floor is the largest first reflection. Is there a contention that rugs or room furniture don’t matter?
Hsw wrote: "
Is this discussion only limited to lateral reflections? It seems to me the floor is the largest first reflection.
"
The floor bounce usually is the strongest early reflection, but perceptually is is not as detrimental as its magnitude seems to imply.
The floor bounce doesn't have a strong spatial effect, as it occurs in-line with the direct sound from each speaker.
The floor bounce does result in a cancellation (comb filter) notch in the frequency response at the listening position at the frequency were the reflection arrives 1/2 wavelength behind the direct sound.
From a perceptual standpoint, the floor-bounce notch can be filled in by energy which arrives within a few milliseconds, such as by the ceiling bounce. The ceiling bounce and the floor bounce will have different notch frequencies and will tend to perceptually fill in one another's bounces.
The floor bounce notch is most audible when there are no soon-arriving reflections to fill it in. An example of this situation would be when talking with someone outdoors. There will be a lower midrange frequency response notch from the bounce off the ground or pavement, with no other reflections arriving to fill it in. Walk indoors to continue the conversation and the timbre of the person's voice noticeably warms up, and I think this is at least in part due to the floor bounce notch being filled in, perhaps largely by the ceiling bounce.
The argument has also been made that our ears are so accustomed to the floor bounce notch and other naturally-occurring comb filter effects that we largely tend to ignore them. That's NOT to say that there is no benefit from minimizing or removing them - only that they do not tend to cause colorations which draw attention to themselves.
Imo there IS benefit from reducing the magnitude of the floor and ceiling bounce notches, or otherwise breaking them up. But it is also my understanding is that they tend to be perceptually relatively benign in a home audio setting.
hsw, I'm only going to answer for myself here. My understanding is that humans are naturally more adept at localizing sources in the horizontal plane. Our outer ears are mounted on the sides of our heads and aren't especially well designed to pick up vertical clues. Presumably, our brains are similarly well suited for localization of sources in the horizontal plane. What I can tell you is that in my room, which is 14 ft wide with 8 ft ceilings, effective "treatment" of the side wall 1st reflection point is orders of magnitude more important than "treating" the ceiling and floor 1st reflection points in providing a deep and wide image with good localization of instruments and voices. My floor is not carpeted, and my ceiling is typical texture over drywall. I'm not going to say that rugs and room furniture don't matter, just that in most rooms, treating the floor and ceiling don't matter nearly as much as treating the side walls with respect to imaging. If you have a room that is atypically wide, or speakers that don't have wide dispersion, you may see something different. Also, what you do with the floor and ceiling can certainly impact other aspects of room performance. Floor to ceiling bounce can be a big contributor to slap echo, as example.
@erik_squires, have you tried what Duke is suggesting on the sidewalls? I stumbled onto this idea of redirecting the sidewall 1st reflections to the front of the room several years ago quite by accident. Every attempt on my part to reproduce the benefit of redirecting by using absorbance has failed. The image just collapses. Had I not experienced just what this technique can do myself, I might be arguing as you are.
Floors are a different thing, but we don't spot treat floors. We treat the entire area in front of a speaker. I've never seen anyone put down a 2'x2' carpet exactly in the first reflection point, and this is kind of what i mean.
Audiophiles at some point were encouraged to use a flashlight and mirror to find first reflection points and center acoustic panels there. I call that particular practice bunk.
We shouldn't spot treat surfaces. We should treat the surface. That is, putting 2'x2' panels in exactly the side, rear and even floor reflection points is practically useless. What does work is to treat the floor, side and rear.
Get a carpet to put in front of the speaker, treat the side walls and rear wall and wall behind the listener. Where the mirror points are won't matter.
Erik wrote: " We shouldn’t spot treat surfaces. We should treat the surface. That is, putting 2’x2’ panels in exactly the side, rear and even floor reflection points is practically useless. What does work is to treat the floor, side and rear. "
So if I understand correctly, you are saying that treating the relatively small area where a reflection occurs is "practically useless" - instead, we should treat the ENTIRE room surface - the entire wall, or the entire floor, and/or the entire ceiling.
Am I understanding you correctly?
And, just so we’re on the same page as much as possible, can you describe what you mean by "treat"?
So if I understand correctly, you are saying that treating the
relatively small area where a reflection occurs is "practically useless"
Yes, in that I believe most audiophiles would be unable to tell if those treatments were at the reflection points or not, and that in many cases 4 panels of 2'x2', no matter how well placed, would be unable to effect an audible improvement.
And, just so we’re on the same page as much as possible, can you describe what you mean by "treat"?
By this I mean to alter the surfaces by increasing the absorption and decreasing the ability of those surfaces to throw a coherent reflection by both absorption and diffusion.
Let me try this another way. Imagine a highly reflective room with a pair of traditional 2 way speakers and 1 listening chair in a fixed location. The room is 20’x20’x15’ tall.
There are at least six (eight if we include the ceiling) first reflection points. Being points, they are infinitely small. The audio legend is that these specific points are more important, by far, than any other place in the room. In this room we may place 1’x1’ absorptive panels.
My argument is that the legend/myth is wrong. The first six reflection points are not going to be noticeably better than any other place to put an absorber or diffusor.
Lets go through a bit of a mental exercise. We’ll consider two sides to this.
First, the very sparse case in which we treat six points and only those. At six absorbers the room remains too lively to make much of a difference.
Let’s consider the opposite situation. We have 40 panels of the same 1’x1’ dimension. Now we can make enough of a difference in the reverberant field to affect the sound quality. We put 20 or uniformly spread across the wall behind the speaker, and 10 on each side on the speaker end.
Let’s say by chance, four of these panels (2 on the rear, and 1 on each side) are exactly on the first reflection points in terms of the listening chair. In this case, removing those four panels and randomly relocating them will make a very small, if any, noticeable difference.
And this illustrates my point. Treating the initial reflection points is actually not as important as treating the room. The audiophile using a mirror to place a panel exactly on that spot is wasting his/her time. What is more important, by far, is getting a critical mass of room treatment so that the reverberant field becomes well controlled.
Floors are a different thing, but we don't spot treat floors. We treat the entire area in front of a speaker. I've never seen anyone put down a 2'x2' carpet exactly in the first reflection point, and this is kind of what i mean.
Eric, I have a dedicated room. I made 2'x4'x4" OC 703 panels that cover first reflection points on both the floor and ceiling. The rest of my floor is untreated. I realize this is not common, but I have a dedicated room and I am the only listener, so I can do what I want. Both ceiling and floor "treatments" have very little influence on imaging in comparison to my side wall "treatment." They certainly offer other benefits. which more than justify their use. I have considered modifying my ceiling panels in order to add forward facing reflection to the existing absorption, but have not done so yet.
As I recall, my measurements show that the floor and ceiling reflections are delayed about 4-8 ms, whereas the side wall reflections are more in the 6-12 ms range. Without treatment, the ceiling and floor reflections are louder than those from the side walls. With treatment, the side wall reflections are substantially reduced, whereas the ceiling and floor reflections remain relatively high. To a certain extent, I think this is indicative of how much more effective reflection is compared to absorption.
From my perspective, sidewall 1st reflection point treatment is conceptually sound, and in my room, theory has been supported empirically. Imaging and localization in my room is superb. It is the best by far that I have ever heard in a narrow room. If you have experienced something different, perhaps that is because you are attempting to "treat" your sidewalls using panels that are not up to the task. Again, I'm going to suggest that before you discount the concept, you evaluate the approach articulated at least twice by Duke and several times by me. Rip a 4x8 sheet of half inch plywood into 2 x 8 sheets and place them along the side wall behind the first reflection points angled so as to reflect sound back to the front of the room and away from the MLP. This is enough to reflect the wavelengths that are important to localization clues, and it turns early reflections into late ones. It is a cheap and easy experiment. Keep in mind that the first reflection "point" is far from a point, because the sound coming from your tweeter and midrange will spread out as it travels rather than proceed as a laser like ray. So you will need to experiment with placement and angle.
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