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Thread: Real speakers in real rooms - what to expect especially in the lower frequencies

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    Lightbulb Real speakers in real rooms - what to expect especially in the lower frequencies

    When loudspeakers are being developed, they are usually designed and optimised (and subjectively evaluated e.g. critically listened to by the designer) under conditions whereby the listening environment plays as small a part in their performance as possible. Taken to a ridiculous (and subjectively ill-advised) extreme, a loudspeaker could even be entirely designed and approved in an anechoic chamber thereby completely removing the listening environment from the design equation.

    Loudspeakers tend to radiate sound in all directions at the lowest frequencies and as frequency increases they generally become more beamy - i.e. they concentrate their sound in an ever narrower sonic pencil beam and logically, there is less sound spraying sideways. That's deemed to be a 'good thing', because with less sound sploshing around the listening room away from the essential axis to the listener's ears, the contribution of the room to the overall subjective experience should diminish. At least, that's the working hypothesis.

    From time to time, with real-world speakers in real-world rooms there will be an unfortunate coincidence of dimensions, distances and surface absorption such that no matter how much effort is expended on stands, cables, pucks, spikes and the like the lower registers are unnatural. Rarely do listeners comment about excessive leanness in the bass even though the test equipment can readily reveal it. The problems that draw attention are due to subjectively excessive bass. Now some common sense. To be able to detect a difference in loudness, the human ear needs to detect a marked increase or decrease in sound pressure. That difference is measured generally in decibels, and as an approximation we can say that 2 or 3dB is barely detectable under optimum conditions in the middle frequencies where are ear is at its most sensitive. At lower frequencies, where our ears have poor sensitivity, perhaps 6dB or even 10dB is barely audible. That's a really good thing because it allows us to use real-world speakers in real-world home listening rooms and not be excessively concerned by the lumpiness in the bass register. It also means that, if we are honest, the introduction of gizmos and gadgets that make, if best, 0.01dB measurable difference to the sound simply cannot make the improvement they are claimed to make. Any benefit they could have is swamped by the lumps and bumps in the room's response.

    So, is it likely that if you have a room issue at low frequencies that this can be solved with fancy cable? No. Not unless the amplifier is so poorly designed that its feedback control can't adjust to whatever cable load is connected to it and no audiophile should use such an amplifier for fear of damaging his speakers. How about different types of stands? Many say this can make a difference. Or what about isolating disks or the like between speaker and stands? Again, some swear by it and as it's unlikely do do any harm, why not have a flutter with them.

    What are we left with as remedies if we discount these first, inexpensive and reversible steps? This is where we have to draw a dividing line between subjective DIY tweaks and acoustic science, a line none of use are really qualified in experience or resources to tackle to a perfect solution. Whatever we dream up has to strike a balance between what's practicable - and cosmetically acceptable. This is where we have to accept in our hearts that real speakers in real rooms cannot ever fully reproduce the concert hall experience. That's because the concert hall or recording studio is a box with its own acoustic character (esp. in the low frequencies which are difficult to treat), replayed over a loudspeaker (another box, same issues) in the listening room - yet another box. And if the recorded musical instrument itself is a box (cello, guitar etc.) then that's yet another box with its own acoustic character. So, recording a cello and replaying it at home is a box recorded in a box replayed through a box in a box room. And the only 'box' we have any influence over is, of course, the listening room itself, unless we want to delve inside the speakers and redesign them.

    So what acoustic issues can we encounter when we put real-world speaker (like Harbeths) in a real world typical listening room at home? Continued ....
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

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    Default Isolating disks between speakers and stands

    Quote Originally Posted by A.S. View Post
    Or what about isolating disks or the like between speaker and stands? Again, some swear by it and as it's unlikely to do any harm, why not have a flutter with them.
    Alan, there is a live thread running on this subject, and I would be glad to hear your view.

    A digression - some years ago, I had heavy floor standers at home, a lot heavier than my C7s, ones with an electrostatic panel for the high end. They were placed on solid marble floors. When they were mounted on spikes on the same floor, I remember that the sound tightened up for the better, for the lack of a better word.

    To the subject of 4 isolating discs on stands - with respect to Harbeths - would you be surprised to hear a marked difference in the sound with/without these in place? If so, why do you think this might happen?
    Personally, I have them in place to only protect the speaker veneer.

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    Default [1] Bass, whichever way you turn ....

    Quote Originally Posted by A.S. View Post
    ...So what acoustic issues can we encounter when we put real-world speaker (like Harbeths) in a real world typical listening room at home? Continued ....
    Let's look at some of the the measurable phenomena that we're sure to find in most or even all listing rooms, other than perhaps those $$$ rooms in millionaire's homes.

    The position of the speaker is critical to the sound we hear. That's because the speaker is nothing more or less than an air pump; think of it as a fast-triggered repeating exploding bomb sending out shock waves thousands of times every second. As we know from shock waves, the low frequencies can be heard far from the source and equally loud regardless of direction. The higher the frequency the more directional, and as a general rule, the less energy their shock wave transmits. So it's the low frequency 'boom' that does the damage. The same in the listening room: no matter where you listen in the room, the bass is generally the issue: emphasised at this point, but a few cms either way and that note is completely missing. So, we have to be realistic about solving bass issues: if just moving our head this way and that can make bass notes come and go, then logically there cannot be one universal fix that damps the entire room - other that filling the entire room with cotton wool and placing the speaker slap bang in the centre. In other words, we are going to have to accept compromises both sonically and cosmetically and then we are simply going to have to admit defeat and settle down to 'listen through' the issues and to enjoying the music.

    The starting point has to be an acceptance that low frequencies really are omnidirectional. They reach out and touch every surface in the room like an invisible gas: no object in the room can hide from them. No object can hide in the shadow of another and escape the all-pervasive low frequency pressure wave and more than you can sit indoors on a rainy day watching your barometer believing that your home is hermetically sealed from the humidity outside.

    When we build an anechoic chamber we have to line all the surfaces: walls, ceiling and floor. We place a grid half way between the true floor and the ceiling and that way, regardless of the direction that the sound emanates from the source, it is equally absorbed. See PDF of the recently demolished BBC anechoic chamber attached.

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    Alan A. Shaw
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    Harbeth Audio UK

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    Default

    I think I've already answered your question about expectation of audibility of the interface under the speaker cabinet in post #1 and many times elsewhere. I believe that there is a fundamental misunderstanding about the transmission of energy from the drive units to the cabinet, the cabinet to the 'isolators' and the isolators to the stand and the stand to the floor. Has anyone actually bothered to glue an accelerometer onto the stand and take some readings? No? Well unless they do, it's a subject that will never make any genuine technical progress. Relying on ears alone in the total absence of test equipment makes no sense to me at all.

    I'd like to continue with observations about gross many-dB issues that can be measured all too easily.
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

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    Default [2] A loudspeaker in a real room ... pumping action

    So what actually happens when you put a real loudspeaker (or two, three, five seven) in a real room and start playing music?

    The first issue is that the room is swamped with energy - pressure waves from the speakers. If we had a super-dooper highly sensitive barometer in the room (the type that tells you if rain is expected) with an ink-pen that was extremely light weight, the nib would actually move in time with the music. So all the speaker is doing is 'inflating' and 'deflating' the air in the room according to the music, thousands of times every second. In fact, if we had Superman's muscles and lightning-fast reactions, we could achieve the same pressure-pumping effect as (a small speaker) by operating a bicycle pump really fast in time with the music.

    So that's all the speaker does - wafts the atmospheric pressure at some point of measurement or listening up and down around the stasis pressure (so many millibars) just as if you were waving a large sheet or towel. And because the forward or upward going pressure can only create music in our ears if it is immediately followed by a reverse of direction giving a push-pull effect on our ear drums, the total volume of air in the room remains constant. So we'd hear music even if we hermetically sealed the room and guaranteed that none of the air escaped, and no new air entered. For example, we know from the Apollo missions that thousands of miles from earth in the airtight sealed command module, without helmets the astronauts could talk and play music. And our vocal chords are merely another way of locally modulating air pressure, and that push/pull pressure leaves our mouths and radiates away from us - detected by an ear (or microphone) as it passes them.

    The essential point I want to make here is that the transmission of sound requires air to be pumped, and that pumping action both needs energy and radiates energy as a sound wave. Now consider this: we start playing music and we charge the room with sonic energy. We measure that sonic energy (with great difficulty) in acoustic watts by placing an infinite number of probe microphones in the room and adding together how much energy each one detects. Clearly, that's not practicable, so we conveniently sidestep that technical nightmare, and forget all about acoustic watts and think about power amplifier watts going into the speakers and their efficiency and directionality: a backwards but expedient way of imagining all those sound waves sloshing about like water in a fish tank.

    Statement: as sound waves radiate from the speakers, they will hit surfaces. Depending upon the angle they impinge on the surface or object, the frequency, the absorptive characteristics of the object or surface, they will be reflected. Not even the anechoic chamber with 2m wedges is perfectly absorptive. Only a vacuum would neutralise the sound waves: if an astronaut removed his helmet, stepped outside the spaceship and attempted to speak, there would be total silence.

    Observation 1
    : It follows that at best, there will be a maximum amount of sound wave energy pumped into the room by the speakers commensurate with the room's ability to fairly rapidly absorb that sound (by repeated bouncing of the sound between the objects in the room). Beyond the critical Room Maximum Sound Input (Rmsi) the room will be driven into acoustic overload, and the following notes will wrap-around into the unabsorbed reflections from the earlier notes.

    Observation 2:
    It must be true that for every room, for a given set of loudspeakers and music, there will be a certain amplifier power needed to drive the room up to its Rmsi and that regardless of how many additional watts, or hundreds of watts are available from the amplifier, these simply cannot ever be drawn without the room's acoustic overload becoming chronic, and the sound a muddy mush. For most speakers in most rooms, probably no more than 100W is ever needed under any circumstances with any music if the room is to be driven up to but not beyond its Rmsi.

    Observation 3: It must follow then that we can say, as a general rule, that a certain dB loudness as measured with a sound level meter can be used to estimated the Rmsi considering that most people listen in approximately the same size room with approximately the same absorption to approximately the same music. The critical loudness which just avoids room overload is probably about 80-90dB (a guestimate at this time) - but far lower than most audiophiles would think.

    Observation 4: The WHO recommends that the public are not exposed to persistent loud sounds and that 85dB or so should be considered a relatively safe long-term listening level.

    Observation 5: The speaker designer should use every design trick available to him to ensure that the speaker sound as natural as real-life even though the listener should be playing the speakers at home below Rmsi hence at a loudness far below that of the music, heard live.

    Observation 6: We have to understand how the room corrupts (especially) the low frequency output from the loudspeakers, how audible that is, what can be done about it and whether it is worth the effort.
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

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    Default Lower is definitely not better in my experience

    I am really interested in this topic.

    Currently i have speakers that are bass reflex, have woofer of 4.5 inch, and have tech specs they go to 40hz. Oh boy, i wish so much they dont go so low. Why? Well IMHO they make them go so low, but they do it so bad. I have room resonance at 46hz, and it kinda reacts with this bass reflex design so much it just makes unbearable resonance, so i get HUGE 46hz boost in my room. So high that only fix i managed to make up, is hook up subwoofer, and adjust phase so it cancel that 46hz boost. Its not so bad like that, but still i can hear its somehow still wrong sometimes during music play. I tried some small speakers, sealed design, that go to 80hz, and if i pair them with sub i get pretty good bass response.

    That's why i am interested in p3esr, sealed box, dont go to deep, wont mess to much with my 46hz resonance.

    Moral of the story? In my experience with problems with bass in rooms, is i was fooled with low specs of my speakers, and always thought lower is better. Before i laughed at specs like 75hz, and now i realise its nice compromise between bass extension and lack of problems that low bass can make in rooms.

    During hifi shows i heard, 80% of speakers actually had bass problems, to muddy, to many resonances, i cant imagine how bad would that sounded in my 2 times smaller room, rest 20% were ofc smaller speakers, who didnt shake room with fullness, but had way better frequency linearity in lower registers.

    Looking forward buying p3esr, will take a couple of months cause they are expensive for me in my country, but will write my impressions how to behave in my room, mostly bass related.

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    Default [3] The cheapest, simplest room-bass fix .... guaranteed!

    Now we can look at the challenges of reproducing low frequencies in normal, lightly-damped domestic rooms.

    First, it is a fact that unless you listen in a free-field room (like the BBC anechoic chamber) you must accept that the room will mess-up the bass response of even the finest loudspeaker. You cannot escape this. That's the physics of long wavelength low frequencies 'folding back' on themselves in domestic listening rooms. That means all we can do is play around with alternative solutions to arrive at some sort of compromise that you and your family can live with. Both cosmetically, financially and practically. You cannot completely 'cure' room problems, especially in the lower frequencies.

    But as I explained in my previous post [2] the best, cheapest, easiest and quickest way to reduce bass problems is .....TURN DOWN THE VOLUME. Pump less acoustic energy into the room! Then there is less to bounce around! Sit closer!
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

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    Default [4] The simplest and most useful room-test equipment ..... your hands

    Absolutely true. We can use the hands in two ways - clapping together to make a load but brief 'crack' (i.e. a sonic impulse) and that will reveal useful information about the room's upper frequency behaviour. We can also form our hand into a tight fist and strike the walls, floor, doors, even ceiling if we can safely reach. Have you ever tried that? Every surface has its own natural resonant frequency.

    Many UK homes like ours have thin decorative internal doors made of lightweight plywood panels lightly pinned onto a frame. They may look like solid objects but they're highly resonant. Attached picture of me banging one such open door with my first. I've trapped the door between foot and knee.

    Then I walked around the house banging other doors and walls and recorded their sonic signature on a high quality portable sound recorder in CD format. I imported the recording into an audio editor that could simultaneously display the waveform and more importantly for us this time, diplay the frequency response of the surface being thumped.

    What do you think I found? All the doors and all the non-brick walls in this 1960s house have their own sonic 'twang' which you can hear for yourself on the recording. In reality, these seemingly solid surfaces are themselves acoustic instruments - once the critical note in the music is played by the loudspeakers, the sound wave (i.e. the bang from the first) will set them into motion at their natural frequency. And those surfaces will play 'their note' or notes as a continuous drone to accompany the music, but delayed in time and lingering long after the musicians note has ceased. That's what I call 'room bloom' or in a really bad combination of speakers, speaker placement, room construction, door construction and negligible soft furnishings 'room boom'. As I've shown on this quick example just walking around my home, we must consider that what we hear is always a combination of the speaker's latent abilities plus the sonic character of the room. The room's influence cannot ever be completely removed from the home listening experience. Not ever.

    By the way, even the window glass has a characteristic low frequency sound and, being a very hard surface, is highly reflective in the middle and upper frequencies too. But for safety reasons, I don't suggest that you go around banging your windows, just in case they break.

    Now tell me - considering the chronic effect that the room's surfaces have on low frequencies, is it really credible that a few mm of 'isolation material' between the speakers and their stands is likely to influence the sound?

    Here is the video of the spectral analysis of the bang testing.

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    Alan A. Shaw
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    Harbeth Audio UK

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    Default USA room construction

    This explanation of the resonance of the walls, doors, windows, etc. is clear and makes sense.

    Here in the US, the wall in a modern house is often a sheet of "drywall" or "sheetrock" or "gypsum board" nailed to vertical wooden "studs". Between the vertical studs, there are cavities which resonate when you thump on the wall in front of them. In exterior walls these cavities are sometimes filled with fiberglass insulation.

    Is there any reason to believe that filing these cavities with fiberglass insulation could reduce the resonance of the walls at the low frequencies we are discussing?

    Update: The "Master Handbook of Acoustics" (Everest and Pohlman, Fifth Ed.) indicates the answer may be "yes."

    The book discusses the absorption of low frequencies by plywood panels attached to studs and states that "Absorbtion is increased when the cavity is filled with a porous material such as glass fiber insulation. This is because the material increases damping. The material may be stuffed loosely inside the cavity or attached to the back of the panel."

    It goes on to say about drywall: "Drywall or gypsum board plays an important role in the construction of homes, studios, control rooms, and other spaces. Drywall absorbs sound by a flexural, diaphragmatic action, working as a resonant system. Drywall is particularly important in the absorption of low-frequency sound. Usually, such low-frequency absorption is welcome . . . . Drywall of 1/2-in thickness on studs spaced at 16 in offers an absorption coefficient of 0.29 at 125 Hz and even higher at 63 Hz (which would be of interest in music recording studios)." (This is in Chapter 12, near Figure 12-23.)

    This may be off the topic of speaker isolation, but it could be of interest to people who are thinking of remodeling (or constructing) a listening room.
    Last edited by Nahtanoj; 27-11-2011 at 02:57 PM. Reason: Update

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    Default Applying an eraser to the door changes the sound

    I think so and here's why. I tried the door test sans test equipment as I too have hollow core interior doors. If I tap the door with my knuckle it resonates or reverberates. If I press a pencil eraser against the other side of the door and tap that same spot again, it resonates for a shorter time duration. If I apply pressure on the eraser, even less time. If I press my palm against the other side of the door and tap again, it resonates for a shorter time duration than it did with the eraser. If I hold the door in place with my foot, press my palm against the other side of the door and apply pressure, it resonates less than the pencil eraser with applied pressure.

    This leads me to believe that surface area and applied pressure (weight of speaker) will make a difference in the sound of the speaker. For my personal taste, I like my C7's to resonate as much as possible so I want as little contact with the bottom of the speaker. That's why when I removed the 25 mm rubber pucks from between the speaker and stand and left the speakers sitting on the 7mm rubber nubs the sound opened back up. Please tell me I'm out of my mind but be gentle.

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    Default [5] Your room and its panelling - free but over-enthusiastic 'musicians'

    I demonstrated in the previous step that when we play loudspeakers in a normal domestic room we will certainly excite seemingly solid surfaces in the room into sympathetic vibration with (low frequency) notes in the music. That wouldn't be too much of a problem if those flapping surfaces started and stopped vibrating sympathetically very quickly: if that was the case, then we could consider the walls and doors to be adding extra 'weight' as they augmented the speaker's output: it could even be argued that the surfaces were acting like unpaid but welcome musicians who played along with the recording. We might even agree that with the total surface of the room harmonically 'humming along' the overall effect would be more like being immersed in the full sonic experience of the concert hall.

    Unfortunately, the flapping panels in our room are not under the control of the conductor. They have their own agenda, and due to their mass and stiffness, they need a little time to work themselves up into resonance - that's not a problem - and then once they've started to sing, they are reluctant to stop. And that's a big problem as I'll show.

    Another experiment: have you noticed that when you blow across an empty beer or wine bottle, that once you're blowing at exactly the right rate, the note will sustain itself and you hardly need to blow at all i.e. you only need apply a tiny amount of regular energy input to sustain the note = to maintain the system resonance? Have you also noticed that there is a small pause once you're up to steam between the note building-up to it's maximum loudness, and conversely, when you stop blowing, the not continues with diminishing loudness for some time after? We need to look at that phenomena and see how it relates to bass frequencies in real rooms. The loudspeaker(s) are the energy source, the notes in the music are the energy input and the panels in the room (doors, ceiling, walls, windows) are tuned, just like the beer bottle to sing at their own natural frequency.

    So, here is what happens in your untreated listening room when the seemingly solid wall/floor/ceiling/door panels are set into motion by low notes in the music ....

    Video ...... video of using a beer bottle as a tuned resonator to simulate a panel's natural resonant frequency
    Alan A. Shaw
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    Harbeth Audio UK

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    Default Unsupported structures (doors, walls) and supported structures (speaker cabinets, stands)

    Quote Originally Posted by Don Jr View Post
    ... If I tap the door with my knuckle it resonates. If I press a pencil eraser against the other side of the door and tap that same spot again, it resonates for a shorter time duration ... this leads me to believe that surface area and applied pressure (weight of speaker) will make a difference in the sound of the speaker....
    Ah ha! With the greatest respect and much appreciation for you taking the trouble to correspond, you have connected two completely unrelated observation and leapt to a wholly unjustified conclusion!

    There is absolutely no comparison in physics between a large unsupported structure such as a door hanging on it's hinges and free to wobbly about when impacted and the bottom of a speaker cabinet which is fully supported (or else it would fall to pieces when moved) sitting atop a stand. The door is secured to the door frame using hinges along just one of its four sides: the other three sides are free to flex and bow. But which part of the speaker cabinet (or the stand) is free to flex? Every joint of the cabinet (and stand) is rigidly glued, and the stiffness in the corners of the cabinet is at a maximum because of the close proximity to the nearby seam-joints. So much so that even if you take a sledge hammer you are going to have to hit the corners really hard to break open those seams; hit the door with a hammer and it will either swing wildly from the blow or the hammer will pass through the door.

    On this basis, if you are one who believes in the magic of 'isolators', the least effective place to position them is surely in the corners of the speaker cabinet where the cabinet flexure must logically be at a minimum; the most effective position (if there is one) would be far from the corners. That's the converse of the neat cosmetic arrangement isolator protagonists recommend.
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

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    Default Isolators and their magic

    Hi Alan,

    I am one who believes in "the job of isolators" and "YES" I find myself that if you place far from corners they do it the "magic". That's why don't believe in those stands like "Something Solid or Foundation" are good enough...

    Cheers

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    Default Instantaneous differences due to isolators

    On this basis, if you are one who believes in the magic of 'isolators', the least effective place to position them is surely in the corners of the speaker cabinet where the cabinet flexure must logically be at a minimum; the most effective position (if there is one) would be far from the corners. That's the converse of the neat cosmetic arrangement isolator protagonists recommend.
    I can only rely on my ears. I do not believe in anything that isn't instantaneous as in burn in time. I also do not believe that there's a difference in speaker cables or interconnects or at least I cannot decipher it. Cable elevators, weights on top of CD players, cryoed wall receptacles.......I've heard it all. Not even the slightest difference captured on my radar with any of these deceptive marketing practices.

    However, with every speaker I've ever owned including the C7, I can instantaneously hear differences in what the speaker is sitting on. It's been my greatest challenge which thankfully I'm not currently challenged with. Is it possible that I'm the only person who can hear these differences?

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    Default Caution about stand recommendations

    Quote Originally Posted by micron View Post
    ... I am one who believes in "the job of isolators" ... that's why don't believe in those stands like "Something Solid or Foundation" are good enough...

    Cheers
    I don't believe you have tried the excellent Something Solid stands, because if you had, you wouldn't dismiss them. I

    I have been using and selling Something Solid stands for 25 years and they are about as good as it gets and especially with Harbeth. A marriage made in heaven.

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    Default [6] Acoustic damping - vital to tame room resonances

    In the video in my post #11, I used a beer bottle as a handy resonator. I showed how this bottle had its own natural resonant frequency and with just a little energy input from me (lightly blowing across the open neck) it was set into vigorous resonance. And that's exactly how the seemingly solid surfaces in your room behave when they are excited by a little energy radiating from the loudspeakers.

    As I mentioned in post #7 ...

    ... the best, cheapest, easiest and quickest way to reduce bass problems is .....TURN DOWN THE VOLUME. Pump less acoustic energy into the room! Then there is less to bounce around! Sit closer! ...
    and that must be true because with both the air in the bottle and the walls in the listening room, there is a certain minimum 'huff' that's needed to overcome their inertia and set them into motion. And motion is an essential prerequisite to them generating sound, even though it may not be apparent to the human eye or even to the touch. But a vibration detector would readily measure their sonic contribution.

    In the current version of the Harbeth User Guide here we mention the efficacy of (thick) curtains and drapes in the listening room. They need not be permanently drawn across walls - they could be drawn for listening and then withdrawn - and they should be spaced away from the wall as this magnifies their acoustic benefits. Alternatively, although more visually intrusively, the wall/door/surfaces could have acoustic tiles permanently attached. Or the existing panels could be removed and re-hung on energy absorbing joists. Whatever method we chose, the end game is to increase the amount of acoustic damping in the room because that is sure to eliminate or at least ameliorate resonances. And resonances in the listening room can never bring us closer to the music; they will always color the recorded sound by introducing tonality that just wasn't present at the recording venue. The more minimalist, bare and unfurnished the room the less the absorption, and inevitably the more the walls/ceiling/floor/door/windows will contribute to the sound.

    So, back to the beer bottle and its simplistic analogy with a room surface in resonance. How can we damp its propensity to sing-out at its natural frequency? Can we apply damping to tame it and how much do we need? Do we need sophisticated materials or techniques? Will damping the air in this bottle demonstrate the importance of damping in the listening room as a general concept?

    Watch my demonstration video .... here. I was surprised myself.

    We have to accept that in the real world, few if any of use can build a $$$ listening room engaging world-class acousticians. But if we can get the idea of acoustic damping firmly in our mind then we just may be able to turn even the most challenging lively room into one that is good enough to enjoy great sound in without spending a fortune. As I've shown with the bottle, we need only the minimum amount of damping optimally positioned. We need no more than that.
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

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    Default Summary of videos about room resonances thus far

    Pulling together Alan's videos in this thread concerning resonances in the listening room >>>>>>. You can read the full posts by referring back to his subject [No.] previously.

    Note: the video will play after adequete buffering (hopefuly).

    ================================================== ================================================

    [4] Here is the video of the spectral analysis of the door bang testing.

    [5] Video of using a beer bottle as a tuned resonator to simulate a panel's natural resonant frequency

    [6] The meaning of damping when applied to resonances

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    Default Some people like coloration

    Quote Originally Posted by A.S. View Post
    ?.... And resonances in the listening room can never bring us closer to the music; they will always color the recorded sound by introducing tonality that just wasn't present at the recording venue. ......
    But I know there are many people who cannot bring themselves closer to music in a damped room (need not necessarily be over damped).*

    Recently, I attended a live performance and had a chance to talk about the venue's acoustics to the pianist *who happens to be an accomplished musician. In his opinion the acoustics was excellent. However, to my ears, even though the music was good but it was not without coloration and smearing.*

    The room itself wasn't big. Maybe, about 20ft x 60ft. The ceiling was at least 20 ft high.* A single mic for the piano and one for the pianist (both mics were on all the time) the double bass came with its own amplifier and speaker and the drums with two mics. *The piano and the drum sound were played thru a pair of Bose Speakers hung about 10 ft above them. Even without the speakers, you could hear the unamplified sound clearly at where I was sitting . So imagine how much smearing that we were hearing from the sound directly from the speakers and from the instruments and from the room itself which wasn't treated at all!

    To my friends that's *how their system should sound like. They call it "the sound got the energy". *IMO, most of us experienced music with reverberations. *We were exposed to guitar or piano sound played in our living room or in our classroom which adds much colouration to the original sound. And that, we have accepted as natural to us.*


    ST*

  19. #19
    Join Date
    Dec 2010
    Location
    Canada
    Posts
    147

    Default Can't play

    For some reason on my iPad i can only get the image of Alan looking like an air traffic controller, however cannot get it to play, the timer shows, but has 0:00. Will try it later on my computer...

  20. #20
    Join Date
    Dec 2007
    Location
    United Kingdom
    Posts
    9

    Default All play on Mac

    All three play fine on Mac with Flash v 11.1.102.55 plugin.

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