Room acoustics

How about a thread on room acoustics and ways to improve the in-room performance of your system and its speakers? Subjects covered could be the physics of room response, measurement of response in your own room, and how to deal with imperfections, above and below the Schroeder frequency, like damping, bass traps, speaker positioning, (multiple) subwoofers, and dsp equalization. Other subjects could be how to create a room with lower background noise for greater dynamic range, building construction, or what to do in small rooms.
I am a bit busy just now, but as soon as I have time I will try to kick off with some posts and links.
OK, for a kick off: measurement. To measure and interpret in-room response, you need a measurement microphone and a system to generate test signals, to record the response, and visualize those data in a graph. These days, that can all be done with a free software package: Room Equalization Wizard (REW), for Windows, OS or Linux. All you need in addition to a computer and this software is a calibrated measurement microphone. Personally I use the microphone that came with my Antimode 8033 room eq (plus its MicAmp), but for most people the calibrated UMIK-1 usb microphone is their best bet, at $75.
The result is likely to horrify you, and serves to underscore the importance of speakers and of optimizing their in-room response. It is not unusual to measure in-room peaks and dips of +/- 10 dB. Compare that to the peaks and dips of good electronics - usally +/- 0.2 dB over much or all of the audible frequency range. That 0.2 dB limit is important because it represents about the smallest level difference that humans can recognize. So the peaks and dips in listening rooms are many times larger than that. A significant part of those unwanted deviations from a flat frequency response originates in the room itself, and not in the speakers. Good speakers are not nearly as flat as good electronics, but usually manage to stay within +/- 3 dB for much of the full range of human hearing. Usually only the bass region is much lower. Compared to good electronics, +/- 3 dB is still not very good, but far better than their real life performance in an actual listening room. So the challenge is to get them as close as possible to their best performance in an anechoic room, or free field outside in the open air.
Your big problem will be that the measurements will be way off in the bass, and considered by the measurement formulas/methods to be impossible to navigate and thus.... not relevant. Even your measurement systems, a weighting, c weighting, ...they all ignore the bass. Bass is not looked at in professional environments and professional scenarios.

"Since the ear is insensitive to 500hz on down, we’re not going to measure it!"

Yet your bass to midbass will be the the source of the vast majority of your room issues. As in: the heart of the matter.

the mid-high parts they talk about dealing with, anyone can fix those with a small bit of internet research. the odd throw rug, some simple diffusion, common knowledge stuff.

Bass traps, the vast majority of them, barely do much of anything at all. We hear the small bits they do and we take what we can get from them, happy for any minor improvement.

Going into a commercial box or Imax theater and listening to the surround systems in them is a horror show. Awful sound and awful acoustics. These are supposedly professionally done systems. It illustrates how little even the pros know about bass and midbass and how to tame it. Ultimately, billions of dollars involved in getting it right, and they can’t get it done.
On Mac OS you can use Fuzzmeazure to measure speaker and room response. Audyssey XT32 is or was an excellent automated system on Onkyo devices
The discussion about weighting is how much different frequencies should be weighted to measure total sound level. That is a different issue and not relevant here.
Thanks for pointing this out: indeed there are other systems as well. REW is what I use and, I think, most people. Of course, there are also other automated measurement and equalization systems (I use one myself). My plan was to leave those for later.
It is 100% germane to the scenario in your room. It has to be mentioned, noted/corrected and then--deal with the entire package. which has now been done.

Good luck fixing it. (bass-midbass)

You don't seem to understand what can be done with a microphone, a pc, software and frequency sweeps or chirp signals and a little mathematics (convolution and fourier analysis).
There is no need to convince me of the importance of room in the hierarchy of 2 channel stereo sound quality. I’ve been pondering this room mode problem for several weeks now reading authors like Floyd Toole, Todd Welti, S. Linkwitz, and Nyal Mellor in addition to reviewing various forum discussions. I have also talked briefly with one acoustic consultant. My take away is as follows:

- In a mixed use room environment, acoustic treatment is a very limited option. Changing/ replacing furniture and adding baffles/ diffusors to the walls is a non-starter with my wife and I would guess that I’m not alone in this constraint.
- Multiple subwoofers looks to be the most promising solution for dealing with room modes although integrating these subwoofers is a legitimate challenge. My concern is that I’ll spend $2.5K and have a very fussy system that needs to be tweaked with every CD played.
- Equilization. A simple and relatively inexpensive way to go (depending on equalizer) but the results are limited to a very small listening area. Moreover, I’m concerned about potential degradation in sound quality with an additional A/D - D/A conversion. Many have said that the improvement in room modes outweighs the small to negligible degradation in signal quality.

In other on-line forums, a few contributors questioned the sonic benefits of a very flat bass response claiming the sound to be anemic. Likewise, Floyd Toole’s experiments at Harman showed trained listeners preferred a modest rise in bass response compared to ruler flat. My quandary is whether to give up a very simple system for the promise of better bass at the cost of complexity and $ without knowing if I’ll like the result (enough).
A quote from Franco Serblin, Sonus Faber founder and speaker designer -

He found the search for perfect bass futile. "When you want more bass, you miss it; when you have it, it disturbs you."
I bit of bass lift is not quite the same as a bass peak. These peaks generate one note bass.
As a practical solution in real life where you want to maintain an elegant decor, I think the combination of two smallish subwoofers plus an automatic equalization system like the Antimode 8033 is quite realistic. It does not involve ugly bass traps or huge subwoofers, is not a great hassle to set up at all, and is relatively affordable. Depending on room size and desired levels of bass extension and loudness, two small subs and an Antimode 8033 would cost from about $1300 (more if you want the subs to go lower and louder to fill a bigger room). Push the subs into two adjacent corners of the room, do the Antimode measurement ritual (half an hour’s work, including reading the manual), set the level and crossover (that is the hardest bit), perhaps with a measurement microphone, and you are done. With my B&W PV1d you get precise instructions for slope, phase and crossover settings for the specifications of your main speakers. They turned out to be spot on.
In my case I am still using only one sub, and even then the equalization is a big improvement. The Antimode allows you to optimize for a wider area, and that has worked pretty well. Even so, a second PV1d sub is the first item on my shopping list.
As for the additional analogue to digital to analogue conversion, with the Antimode 8033 this only happens in the bass region reproduced by the sub(s). The main speakers receive the same signal as before.
a larger number of subs can give xlnt results

Great topic and posts willemj - room equalization is an important issue, much more so than most of the threads on here

... mre tidbits follow
The very best reference book and how to that I know of is:
Master Handbook of Acoustics. by F. Alton Everest, and‎ Ken Pohlmann.

As an audio cheapskate, I save $20 and checked it out from my local library.

I have an open floor plan so this will not work for me, but if you have an enclosed listening room you can use an online calculator to get the room modes (freq.s where the sound amplitude "stacks up" i.e. wave superposition).

I've actually just started using REW and was pleasantly surprised at the measurements. I do need to tame my frequencies below 200Hz, but there don't seem to be any consistent peaks now that I've brought my orange tree in the room for the winter. The very large pot of moist soil seems to have done a beautiful job as a bass absorber. Before that, I had a few peaks that wouldn't decay..
My question is this: how do I know where to put bass traps when I make them? My guess is to generate bass tones at the problem frequencies, then walk around with an SPL meter looking for areas with the highest measurements. I'd love other ideas..
Indeed Randy (I have an open plan as well), but real life rooms are almost invariably more complex than simple models. Therefore, rather than measure dimensions, I prefer to measure (and adress) the response.
Oh, @willemj  , we can't post pics directly in a thread on this forum. You'll have to post pics on your systems page or on any image hosting site, then put links in your posts on this thread. Not optimal, but..
And I completely agree, great thread. It seems this is more technical than most want to deal with around here, since it involves more than purchasing an item and installing it.. but we do have many members who like to dig in and who are incredibly knowledgeable, so hopefully this thread will bring that knowledge out.
OK, maybe we need to look into that then, because graphs are very illustrative of potential problems. Most telling are waterfall graphs, as these show that peaks also linger on. If people talk about slow bass performance of a speaker/sub they are wrong to blame the speaker. It is the room that makes the sound linger on. And that is very audible.
I have to sign off now (it is evening where I live) because I am expected at a birthday party. Please continue.
a couple of tidbits from an Email exchange with ASC (Tube-Traps):

1. ona hardwood floor, put a rug down, which should extend all the way underneath the speakers, sticking out for at least a foot in all directions from under each speaker. The rug should also extend all the way beneath the listening chair. This can have a large effect, softening the perceived hardness and brightness of the sound.

2. for glass windows, use the heaviest-available theater drapes from -- even these are acoustically transparent below 1,000 Hz -- but the main components of stereo image formation occur above 1,000 Hz
I have a basement listening room with low ceilings.. two things I've done that have helped reduce peaks, resonance and echos: suspended ceiling with Armstrong tiles and fully carpeted. I'll check which model of ceiling tiles I have, they weren't cheap but they do a great job of sound absorption in the mid to high frequencies
To answer the original question without having to use in room measurements yes acoustic treatments on side walls for early reflections, in corners and on ceilings for slap echo and also diffusers on back wall do make a huge improvement for reducing brightmpness and increasing imaging and overall clarity. You can hear everything way more clearly and focused just using side wall early reflection absorption. I can tell you from experience in my 12 x 13 basement theatre / listening room it was one of the best improvements to sound and coherency I've done. After treating my room I heard instruments, nuances and background vocals I never heard before, everything sounds just more tightened up, better bass and just much better. 
You ears tell your more than anything. 

Hmm, your ears can tell you a lot, but sometimes there are some specific issues that are audible but not easily remedied. These peaks and nulls, which seem to be persistent once the easy room treatments are done, are so specific in their frequency band, that I think you'd be hard pressed to identify and fix them by ear. At least that's my experience. A little bit of data can be useful.
But your mind is still the ultimate decision maker on sonic performance. So it does have to sound good, whatever it measures
My secret methodology for treating room anomalies. You need to find and map out all the sound pressure peaks in the room, incluing the 3 dimension space of the room. The most effective way to do this is using a test tone (s) and SPL meter. I select test tone(s) around 315 Hz or thereabouts since that frequency is very revealing, and effective, but you can use other frequencies, too. This will allow you to find all sound pressure peaks that are say, 6 dB (i.e., 4 times higher!) above the average sound pressure in the room. Generally speaking, these peaks will be found in room corners, at first reflection points and on the wall between the speakers, on the wall behind the listener but also at random and unexpected locations around the room, including in the 3D SPACE of the room. Sometimes right where the listening chair is located! 😧 All of those peaks 6 dB or higher act as "speakers" that interfere with the primary sound produced by the speakers. The objective is to reduce those peaks as much as possible - without producing side effects. But trying to treat the room by ear is a fool’s errand. It’s like trying to solve n simultaneous equations in n + x unknowns. Sure, you can do better than nothing but you will only find a local maximum, not the real maximum.

There are a great number of devices that can be employed to defeat the peaks once you’ve located them. I can vouch for Traps, Hemlholtz resonators, tiny little bowl acoustic resonators, crystals, Mpingo discs, Room Tunes Echo Tunes, Golden Sound’s Acoustic Discs, Skyline diffuser, but not (rpt not) SONEX.

This may be the moment to introduce the so-called Schroeder frequency, named after the German physicist Manfred Schroeder. The Schroeder frequency denotes the crossover frequency between the chaotic behaviour of sound waves above it and the discreetly spaced peaks and dips/nulls below it. Above the Schroeder frequency sound waves bounce around the room, producing many small spikes that are closely packed along the frequency range. Below the Schroeder frequency the peaks occur at the resonant frequency of the room's dimensions, and create big peaks at particular frequencies and again at their upper harmonics. These so-called room modes are large and pretty far apart, so they are quite obvious to the listener, with a boomy bass that often lingers on at particular frequencies. See here for more explanation:
The Schroeder frequency can be calculated approximately, and depends on a room's dimensions. The larger the room, the lower the Schroeder frequency, from about 200 Hz in smallish rooms down to about 100 Hz for a large room. See here for a calculator:
Knowing the Schroeder frequency of your room is important, because treatment above it has to be quite different from treatment below it. See here for more discussion:
To put it simply, treating the frequencies above the Schroeder frequency is a matter of adding damping material like rugs, bookcases etc. It can often be achieved without too much intrusion into the style of your home decor, although there are also more visually imposing solutions from the world of studio design. The exception to the idea that dealing with these higher frequencies would be quite easy is if like me you prefer a modern minimalist interior. Such rooms have a hard acoustic and softening the acoustic without changing the style of the interior is a challenge.
Conversely, adding rugs and the like to reduce peaks below the Schroeder frequency is pointless. What you are dealing with here is big resonant peaks that can be tamed in only three ways. The first is so-called bass traps. Unfortunately at the frequencies we are talking about these bass traps are necessarily large and ugly. The second is multiple subwoofers. Main speakers have to be located for best mid range response and imaging, and that is not necessarily best for bass reponse. So separating bass response from the main speakers allows you to locate the bass speakers at the best spot for them. Traditionally HT subwoofers were used alone, but it is now increasingly understood that using multiples smoothens their response because their response peaks and dips do not coincide. See here for some explanation: You get twice as many peaks, but of much smaller amplitude, and that sounds a lot better. To be sure, this is still not an argument in favour of stereo subs. It remains true that at these low frequencies sound is not directional, so dual subs are mostly still connected as mono subs for a somewhat smoother response compared  to stereo subs.
Finally, remaining peaks may be equalized by dsp eq units like the Antimode 8033 for subwoofers. The results can be quite stunning with a far tighter and more tuneful bass. The limitation of room eq is that it works best in only one listening position. The smaller the room and the higher the frequency that has to be equalized, the more localized the good result. Using two or more subwoofers gives a good result over a much larger listening area than with a single sub.
It should also be obvious that a larger listening room is highly beneficial. Its Schroeder frequency will be much lower. And the lower the room mode frequency, the less obtrusive it feels. Moreover, equalizing a lower fequency works over a much larger listening area than equalizing a higher frequency.
So, to be honest, good bass reproduction in a small listening room of, say, 10x14 feet is not really feasible. There is no space for bass traps, room modes are at too high frequencies (and their upper harmonics even more so), and equalizing them only works for a very small listening position. In my view, the simplest solution for small rooms is to just use little monitor speakers without too much bass output. The brain is pretty good at imagining there is bass when there really isn't much of it.
(It seems I had nothing else worthwhile to do today, so I decided to submit this novel I had originally written for publication. I haven’t proof read it yet, it’s just too damn long for me. ;>)

I can understand why no one here might fully have reason to understand the nature of the original problem given the unique perspective that I’ve been able to glimpse at it over the last several years. I don’t pretend to know everything on the topic, but I’ve been seeing it from a different angle somewhat.

First, the underlying problem, as I see it, is really bandwidth.

We may pay for our equipment and speakers and we tend to think of them as they’re spec’ed. But their frequency response measurements are usually not measured in-room. Speakers may seem to us to be something of an exception since they’re measured with a mic, but the frequency measurements are usually anechoic. IOW, those measurements most closely reflect only what the gear is capable of, in mathematical terms, under the best of conditions, frequency-wise, and those particular measurements certainly are not taking your room into account.

But, none of these specs in the real world will end up having much of a direct correlation to what we hear and what we measure in-room...the measurements are typically way off from what is spec’d. This tends to cause us audiophiles to sort of go off in all directions and start looking for anything and everything that may influence the problem. Room treatments of countless flavors, EQ/auto correction, speaker placement, vibration control, etc...

At this point anyone who may be only half seeing what I usually post about will likely be annoyed and thoroughly unsurprised when I mention Alan Maher Designs, whose electronic noise reduction devices I’ve been buying for the last 7 yrs the tune of, now, about $10k. That’s $10k’s worth being thrown at a $6k system...(yes, I know, I’m certifiable, but all that is another novel I will bore you with some other time).

But, in the course of steadily improving the sound and presentation (in all regards) in-room over that time, I began to notice that, yes, the frequency response in-room was becoming more extended at both ends and all that, but what made me pay attention was that it was Flattening the overall response as well. This is one of the things AMD gear is touted to do, but until I’d seen it in action under my own roof, it hadn’t fully dawned on me yet what this actually represented.

Alan’s claim all along was that if you flatten in-room response with this approach, then you’re reducing frequency peaks and actually filling in the nulls...without EQ...just by getting rid of noise. IOW, room effects can (to a very large degree - surprisingly large) be thought of in terms of the audible effects of electrical noise. To restate it: what we’ve been audibly attributing to room effects all along (what we are hearing and measuring in our rooms) may actually be more correctly thought of as the audible impact on our systems of ordinary amounts of electrical noise (yes, everybody has it, so don’t think that it somehow won’t apply to you). To put another way: by assuming that in-room bandwidth irregularities are directly resolved by the whole room-treatments/EQ/placement concept only, and that there was no other real factor involved, then we all may have been barking up the wrong tree. Not that room modes don’t exist, they do. It’s just that the majority of what we are hearing may actually be a rather extreme exacerbation of that problem due to nothing more than electrical noise. Remove enough noise and maybe 90% of the audible effects of the room mode problem go away - IF you go far enough to take the AMD approach to a logical conclusion that is, as I have already.

But, as I became more and more convinced that this approach actually works well in the real world (through adding purchases, primarily for other sound improvements, though they all contribute to an overall improvement to the sound), I steadily realized how much less and less dependent I was becoming on EQ and room treatments...these days, a modest EQ boost of no more than 3.5 dB in the low bass (15" woofers), another, more narrow, 3.5 dB boost at 13 kHz and no EQ at all in between...despite OB speakers that are 5ft out from the front wall in an open room...yet I get perfectly sounding lower mids (and, with the EQ’d extremes, everything else so far). (I haven’t measured yet, but I must say that currently I’ve no audibly discernible reason to at the moment).

But, then I realized that that meant there were now a multitude of methods that could be brought to bear on the problem - room treatments, EQ, and now electrical noise reduction (like conditioning here, but without adding any sonic ill effects). But, when I considered all that, I began to see that starting from the room itself first and trying to work backward to the electronics was possibly getting the cart in front of the horse. It all seemed to make more sense to do all the electrical noise reduction first, then whatever minimal EQ was necessary and, lastly, whatever room treatments would then be called for...also, by that point, presumably minimal.

Room treatments are a great thing, but I think its application presumes that all your system ducks are in a row before you start. Change anything: your gear, placement, EQ, noise levels, and theoretically you’re potentially calling for a revised room treatment that may even have you starting over from scratch with it if you were to do it right. But, the directional approach starting from ENR, to EQ and then to (hopefully) a less involved room treatment array might make the whole thing a little more doable than if we start with the room first and then try to head upstream.

The takeaway here is that, fundamentally, the best way to resolve the bandwidth problem is to try and resolve it Before it reaches the speakers. Once it becomes audible, then technically it becomes much harder to correct with accuracy.

Buying equipment with better specs is not the answer. The specs only show us what the gear would be capable of IF it were operating at spec. Unfortunately for anyone concerned, I’ve discovered that that is Never the case and that it can’t be without solid ENR - there’s just too much of it in our everyday lives, no matter what our circumstance. I have AMD for all that and it works really well, but, along these lines and many others with AMD performance, it did not begin to start sinking in just How well all the AMD pieces were working together until I was into it for at least a couple thousand bucks or so. But, at the $10k level, my gear is now all operating at several times above spec and the audible improvements have continued to be dramatic in every respect.

EQ is great, too, but the only problem with it is that it can be compromised from normal amounts of electrical noise, as I have discovered. The 2 biggest problem areas for it are the colorations in the lower mids within the "mud" frequencies and the grit/grain/glare in the upper "hash" frequencies. With the noise removal here, I’ve been able to squelch the effects of both, so in my case there are no more ’best compromise’ settings between tone and noise.

Hopefully at some point more audiophiles will discover the relevance of the link between electrical noise, measured in-room response and room modes...and, by discovering AMD, or something like it, will realize that something effective can be actually done about it.

Regards, John

And, yep (you guessed it), all that’s yet one more reason why I like AMD...(this was reason #4217). My apologies once again for the long post. Carry on.

Great thread! Another ++ for Room EQ Wizard, great software. I don't focus so much initially on the frequency response charts. I begin with the waterfall or spectrogram looking for base that is hanging in the room too long. Even a few 6" base traps from GIK start to help this. 
REW is indeed very good. And to see what is going on the waterfall graphs are most instructive. They show that peaks are not just peaks but are also an issue in the time domain, by lingering on and giving you that feeling of ’slow’ bass.
For those of you who only use a computer as a source (as I do in my home office), equalization is very easy. Just ask REW to create an equalization graph of the range below about 200 Hz and download that file into the Equalizer Apo software on your computer (aided by the Peace interface). Make sure that you turn off the default shelf filter that boosts the bass, if you want a flat reponse.
In my case I was using my Harbeth P3ESR mini monitors as desktop speakers (with the tweeters raised to ear height by IsoAcoustics desk stands). Unfortunately the proximity of the desktop still created a little bass hump that I could equalize easily for a rather tighter and cleaner sound. If you use more sources than just your computer, you will have to download the equalization file into e.g. a miniDSP and fit that somewhere in the signal chain.
Post removed 
I agree it regards to treating the room, not the signal. But I'd imagine both are valid solutions with their own particular compromises. 

The waterfall graph is exactly what I've been looking at.. a very useful data visualization. What is considered an acceptable decay time for bass? I've also discovered a dip at 2k.. hmm
I’ve yet to build one, but for bass absorption, the limp membrane trap seems ideal. A member on here also recommended it to me, without me having mentioned that's what I was considering.
All right y'all, I've posted some interesting waterfall plots on my systems page.  Check them out.  There are three measurements:
: The first is my room without any extra bass treatment, other than the bass panels behind my speakers and the acoustic panel stuck in the corner.  You can see the bass is a mess and there is a nasty frequency around 120 that lasts forever.  That would be the one-note bass i've started noticing.
: The second is with a big, potted orange tree in the corner behind and to the left of my left speaker.  There is a three panel glass sliding door on the left wall. You can see the bass is much cleaner, the bass that didn't want to die is now dead and the whole graph is much cleaner.
: The third is with a quick limp membrane bass trap I whipped up last night.  I used some dynamat i had from a car install to cover the top of a 5 gallon bucket, with a blanket thrown in to stop it all rattling on the tile floor. As you can see, it's not as clean as the orange tree, but the one note bass isn't there either.  The midrange region is definitely a bit dirtier than with the orange tree, but it's better overall than having no extra bass treatment. 

The orange tree is, oddly, the best sound treatment for my current issues. Ha! The problem is that it is sitting outside right now so it gets more sunlight so the oranges can ripen and in the summer it's outside all the time.  This means I'll need something that can either be a permanent part of the room or that i can move in when i move the tree out.  I thought I was just dealing with bass decay problems, but it looks like that corner gets a lot of midrange reverb, probably from the large amount of glass right there.  Curtains aren't an option. We have a clean look and blinds would make it feel cluttered and small, a problem in a basement with 7 foot suspended ceilings..
Thanks very much. This is interesting. You can clearly see that things get dirtier below the Schroeder frequency, even with your orange tree (wish I could have them in our climate). If and when you use a computer as a source, you could use it to equalize the low frequency response. If you like that, you could get a miniDSP to do the same with other sources.
I also like the clean decor, but yes hard surfaces like glass windows also make for a dirtier response. No equalization will help you there, only soft surfaces etc. There are some minimalist looking slotted panels etc that apparently dampen mid and high frequencies (often used in modern meeting rooms).
What I find particularly interesting are all the frequencies below 20 Hz.. I start my sweep at 20, so where is everything what coming from?
now you know why some guys bring big leafy plants to shows...and put them in the corners and the hotspots of their room...
@toddverrone are you able to set some limits in your waterfall plots? Maybe just the first chart to begin with. Set frequency 10-500HZ, 30-90 dbs, and time to 500ms. Then we can read the data better.
Yes, Room acoustics play an invaluable role in listening pleasure. I bought a pair of used speakers listening to them in a acoustically professionally treated room, took them home and wasn't even close. They are good speakers but not as good as what I had heard. I was buying them on what I had heard their in their room.  So you have to be aware of that when buying equipment. When it comes to room acoustics just read and learn on how to make room sound better. Unless you have 20 or so grand and get it done professionally. Enjoy the music!!! 

Yes, Room acoustics play an invaluable role in listening pleasure. I bought a pair of used speakers listening to them in a acoustically professionally treated room, took them home and wasn’t even close. They are good speakers but not as good as what I had heard. I was buying them on what I had heard their in their room. So you have to be aware of that when buying equipment. When it comes to room acoustics just read and learn on how to make room sound better. Unless you have 20 or so grand and get it done professionally. Enjoy the music!!!

>>>>One can’t help wondering what other goodies the system you heard had going for it, lurking about, besides visible acoustic treatments. Perhaps things you couldn’t see. Super expensive cables, perhaps. Blue Fuses? Some quantum thingies. Things the OP would undoubtedly call oil of the snake. 🐍After all, they ARE trying to sell you something. Speakers or amps, or whatever. So it would behoove them to get the sound in the room as good as possible, you know to maximize the chance of a sale. On the other hand, there is a specialty audio store in this area that use to have a policy of no room treatments and no tweaks. The idea being they wanted to present the pure sound of the various components in the system. Which kind of doesn’t make any sense either.

Surprised no one has mentioned the room build itself, or as a core component of the acoustic environment. If one has an oportunity, building a room with acoustic design forethought, aids a lot to improve the overall acoustical environment. Of course, if one does not have this opportunity, then all of these other suggested methods, which help to tune the room, are also great. 

My room was built with acoustics in mind from the onset. 31’x19’ is the core, resil channel all walls, dual wall construction on back wall, (2x4 studs each, 5/8 inch quiet rock each layer (530), Roxul safe and sound each wall assembly)), sidewalls and one back walll (surrounded by concrete (5/8 quiet rock 2x4 construction with roxul safe and sound), ceiling (5 inch acoustic spray foam insulation, roxul safe and sound, double layer quiet rock 5/8 inch 530). Room measured with Phonic and Rives Audio measuring tools, in addition to Velodyne Sub EQ for low frequency measurements. After all that, the room still needs some spot treatments. I have natural stone columns, and partial natural stone front wall, to aid in natural diffusion. The result, one of the best complements was from a fellow audio friend, who dabbles in the extreme exotic who said that my system sounded the best compared to other extremely expensive systems. It’s the room to blame👍😀
Great thread so far with a lot of information. When taking FR measurements, what kind of smoothing needs to be applied? IOW, what is the minimum Q of a mode that should or needs to be dealt with?
geoffkait, Yes you might be right because the guy was telling me that since he got his room done professionally his systems didn't sound as good. He has had hundreds of speakers and components and even 100,000 system. It definitely helped sales. I probably wouldn't of bought them. You have to watch out when buying equipment. But back to room acoustics I have read many articles on room acoustics and to get it done right you need somebody to come in and measure all the room nodes and so forth. You can probably buy a few acoustic panels and reflective panels. It probably would help to a certain degree. But as I pointed out before get somebody that knows what their doing if that is important to whoever really wants to put that kind of money into a room. Audiophiles can be obsessive to a large degree. I just want to be happy and listen to the music on a nice system. Yes that guys  100,00 system sounded phenomenal especially in that room. But like I said he wasn't happy until he got that done. That just goes to tell people how important Room Acoustics really are. Laterr