The argument for/against room treatment

[Lagonda]

Because not all fields require the same amount of education and experience. I can watch a video on how to tune up my car and perform it 100% effectively, but that doesn't mean I can litigate effectively at the Supreme court via watching an episode of Law and Order.

WRT tuning one's room there are many good instructive videos on room treatment basics and of course there's a plethora of more in - depth information. Also, tools to measure are incredibly affordable and go a long way to optimal sound. Net is - a little knowledge and minimal $ go a long way in room treatment and optimal sonics. You don't need a "pro" to get quite good sound. In fact, I've heard systems in rooms designed and set up by "pros" and the result were as often as not embarrassing. As with everything in life, the more you apply yourself the more you get out of it - getting very good sound isn't brain surgery.

Let's not forget, that the "pro" makes his money from selling you products, and whatever brands he is representing at the time will be his recommendation !

 

[sbo6]

So imo it is not as simple as looking at RT60 times, because those tell us nothing about the early reflections, which are the ones most likely to be detrimental. In particular, we want to minimize lateral reflections arriving withing the first 10 milliseconds, which is feasible in most rooms, without killing off the later-arriving reflections. This is a problem which has multiple possible solutions, which I won't go into here.

There is one other thing which comes into play, and that is the spectral balance of the reflections. It is desirable for the reflections to have approximately the same spectral balance as the first-arrival sound. To a certain extent this is a function of loudspeaker radiation patterns, but room acoustic treatments can play a huge (and not always beneficial) role. In general room acoustic treatments remove more energy at short wavelengths than at long ones, so they tend to not only make the reflections quieter, but also duller, as far as spectral balance. This can do more harm than good!

And once a reflection is no longer recognizable as such by the ear/brain system, it ceases to be "signal" and becomes "noise".

This sums up well what I've experienced and employed. The key is tricking your ear / brain by minimizing the short time reflections (<10ms) and effectively attenuating / diffusing the longer time reflections. The rear wall is paramount if within this range.

 

[ddk]

If only there were more people like Elliot G! Some of us are in dire need of them!

He’s here!

david

 

[Al M.]

Because not all fields require the same amount of education and experience. I can watch a video on how to tune up my car and perform it 100% effectively, but that doesn't mean I can litigate effectively at the Supreme court via watching an episode of Law and Order.

WRT tuning one's room there are many good instructive videos on room treatment basics and of course there's a plethora of more in - depth information. Also, tools to measure are incredibly affordable and go a long way to optimal sound. Net is - a little knowledge and minimal $ go a long way in room treatment and optimal sonics. You don't need a "pro" to get quite good sound. In fact, I've heard systems in rooms designed and set up by "pros" and the result were as often as not embarrassing. As with everything in life, the more you apply yourself the more you get out of it - getting very good sound isn't brain surgery.

With respect to my room, I have found that any expert that I consulted, or took advice from, was right on some things and wrong on others. And if they were right or wrong on particular things also changed with how the set-up of my system in the room changed over the years.

It is good to listen to experts, because they have informed opinions, and you can learn from them. But in the end you have to try things in your room yourself, because it is your room and not theirs. Also, the outcome has to be to your taste, and not theirs. While their opinion may be more informed than that of non-experts, something that can be helpful, it is still just that: an opinion.

I like to gather information from diverse experts, but I have learned not to take any expert's advice as the last word on anything.

That holds not just for room acoustics, but for audio in general.

 

[Lagonda]

I can't and wont speak about acousticians and professionals however I do know that there are some very good people that can help you with getting the most from your system. This to many is not acceptable to them for various reasons which may include their own thoughts and ego.
The proper positioning of the speakers and the listening position are not matters of opinions and so when they are not set properly everything that follows will be to solve problems that are self inflicted. Understanding how different speakers work in rooms really helps get the most out of them.
As someone that has been in the business for a long time I have found that most do not want help even if offered for free. I don't understand this but it has been my findings. There are also many times that even if we go the client has set parameters that preclude really doing the job correctly. For example I can't move the furniture and the speakers must go in this space.
This is fine for acceptable results and then living with the compromises that they self inflicted. Many then are on an endless search for the "magic" device to fix what may not have been broken but caused by the set up.
I am not claiming to be the final word or the audio guru but I do read a lot of stuff here on WBF that is just wrong and that people state as facts.
I get people all the time that ask the dimensions of my room and where the speakers are placed etc. All interesting but have no valid impact in their space. I don't make anything for saying what I am about too but I am willing to say that if you use these people you will get a significant improvement in your sound without buying anything.
Jim Smith and Stirling Trayle are both terrific at set up and analyzing your room and gear. Neither to my knowledge sells anything but their expertise and time. With the huge sums of money spent by many on this site one would think that more would invest in experts to take them to their end game.
What can happen in a home should always or almost always exceed a show. There are exceptions of course ands there are really awful rooms and not so amazing gear but for the most part the gear today is great and with some expert set up it can be marvelous sounding.
I do not agree that other industries have no parallels. I play golf with people all the time that sound like audiophiles . They read this book, they watched that video, they bought this club and that ball etc. etc. yet they are not good. When asked if they ever thought about taking lessons from a good teacher they have a blank stare. My father was a simple man and certainly no genius. He had a high school education and worked with his hands most of his life. He taught me some really important things. One of which was to research from whom you buy not just what to buy.
I believe listening like many skills can be improved and can be taught how and what to listen for. I had great mentors and teachers. Just lucky perhaps and in the right place at the right time but it matters. I thank Harry Pearson, Bill Johnson, Jon Dahlquist, Arnie Nudel, Mike Kay and others all the time, I got a post graduate education in NYC. I was able to go to Lincoln Center, Carnegie Hall both before and after, the Fillmore, MSG, Academy Of Music, My Fathers Place, The Stone Pony etc. Harry was an amazing teacher and I was lucky enough to tag along for much of the journey. At Lyric in those days everyone who was anyone came through those doors both in Audio and in the real world. Designers, musicians, Rock stars, Nobel Prize winners, Musical and Theatrical directors,. It was an education one could not pay for.
I still believe there are many that know more than me and perhaps if others were to learn from the past they would get some better results.
Enjoy

You had your store on US1 not far from Sound Advice and Pure Platinum in the end 90's ? I did visit at one time when i was building a home theater, i think you had Krell, Spectral and Avalon at the time.

 

[sbo6]

With respect to my room, I have found that any expert that I consulted, or took advice from, was right on some things and wrong on others. And if they were right or wrong on particular things also changed with how the set-up of my system in the room changed over the years.

It is good to listen to experts, because they have informed opinions, and you can learn from them. But in the end you have to try things in your room yourself, because it is your room and not theirs. Also, the outcome has to be to your taste, and not theirs. While their opinion may be more informed than that of non-experts, something that can be helpful, it is still just that: an opinion.

I like to gather information from diverse experts, but I have learned not to take any expert's advice as the last word on anything.

That holds not just for room acoustics, but for audio in general.

I agree that it makes sense to keep an open mind as you never know what you can learn from who (whom?)

However, in my more than 1/2 century on this rock, one thing I've learned is - be skeptical about advice from those within fields that require no higher education or recognized certification and no experience. As such, all of us on this forum are audio /acoustic "pros".

There are few that I consider acoustic "pros"; Toole and Olive come to mind.

 

[Elliot G.]

This goes along with my theory. What is the most important audio component that is essential to great sound? ................ An understanding spouse! The second most important component is an open mind.

Elliot seems unique among dealers. Most seem to want to keep their clients in the dark and keep them on that "buy the latest Rev 2 version of component X and you will be in a state of sonic bliss" merry-go-round.

This is a side topic but goes along with the theme that setup matters to the Nth degree. I can't tell you how many dealer showrooms I have visited only to be waaay disappointed in the sound. The latest was over this past Memorial day weekend. I went to visit family and while there set up an appointment to listen to a pair of Wilson XVX. I was super excited and couldn't wait to hear them. Well, they sounded bad. And not just by a little bit. I wouldn't trade what I have now for what I heard for an even trade let alone $230K more. Do I believe the XVX really sound that bad and it is all hype -- No! They sounded bad because the dealer did not have them set up correctly. But when I asked how many pairs he had sold -- 3 was the answer. Did those three people think they sounded good or better than what they currently have? I would really like to have a conversation with them about what they heard and what they thought of the XVX's in the demo.

My Uncle is moving to Florida at the end of this year. I go to see him often and one of the first visits I am going to make a trek to Elliot's (if he will have me).

I don't know about having you lol but you are certainly welcome to come and visit !

 

[Elliot G.]

You had your store on US1 not far from Sound Advice and Pure Platinum in the end 90's ? I did visit at one time when i was building a home theater, i think you had Krell, Spectral and Avalon at the time.

We did have a place there. Never did Avalon but we did do Krell and Spectral and some others back then. I spent a lot of time at Platinum

 

[Lagonda]

We did have a place there. Never did Avalon but we did do Krell and Spectral and some others back then. I spent a lot of time at Platinum

Their lunch was spectacular ! I think i met my first wife in there !

 

[pjwd]

Sound reproduction in a "small" room is a complex problem. Most acousticians can't even agree on the target. Acousticians don't seem to be aware of the importance of speaker placement or listening position. By that I mean they think that you can just put your speakers in a "reasonable" X,Y position and match the other speaker and that there would not be any difference in moving the speakers 1/2" closer or further from the MLP. This is just not true. And of course they don't see that moving a speaker 1-2mm matters. Why? Because they see the room as a series of measurements and this movement doesn't register as a large difference in the measured output. But the human ear picks this up very easily.

It is possible to find a spot for the listening position and speaker position where everything works together to make great sound. If the room is untreated at this point then there will probably be one bump (6 dB higher) in the bass somewhere , the frequency response will look rough and the reverberation time (however you define that; REW calls this Topt) will be high-ish (0.5). Adding some treatments to the room in the right places will improve these measurements and IMHO improve the sound quality.

But, different people have different preference. I think this is well illustrated by Peter's thread on "Natural Sound". Some might like the highly reverberant sound. In this case one is listening more to the room than the speakers. But if that is what they like then who am I to say that person is wrong. I personally find that when the Topt is above 0.3 the sound is acoustically noisy but that is just my preference.

So let's say you decide you want a dedicated room (or want to "fix" your current room) and are going to hire an acoustician. Hopefully the acoustician asks "How do you want it to sound"? And hopefully you can describe what you want. But then there can be some interpretation issues and you may not get exactly there in one go. It is a bit of an iterative process.

Sorry if this is a little bit of a ramble.

I am sure if you ever hired an acoustic engineer you would pick a crackingly good one as you know all the questions to ask . Having some knowledge of the field is essential to ascertain their skill and (passion ) in listening rooms.
Most of their work is prevention of sound and vibration transmission for industry etc.
Phil

 

[Duke LeJeune]

... the basics of separating direct sound and reflected sound and ensuring that reflected sound is correlated as much as possible with direct sound is very similar...

Yes, the general principles of "what sounds good to the ear" are consistent between listening rooms and concert halls. To a reasonable first approximation, the closer we can get to what a concert hall is doing in our much smaller listening rooms, the better. This implies having weaker first refections (in particular early sidewall reflections) than home audio rooms normally do, but WITHOUT killing off the later-arriving reverberant energy. Imo the KEY is to get a worthwhile time gap in between the first-arrival sound and the strong onset of reflections. One problem I see (and hear) in many dedicated listening rooms is overuse of absorption such that the highly desirable later-arriving reflections are too weak, which has the effect of "sucking the life out of the sound". This is an issue that a good multichannel system addresses, by using dedicated channels to provide that later-arriving reverberant energy. I'm not saying multichannel is a panacea (and I neither use nor sell it), but credit where credit's due.

Let me get a bit more specific about that time gap, if you don't mind. According to Griesinger, the ear gets most of its important information from about 700 Hz to 7 kHz. Reflections which arrive before we've had time to clearly process frequencies in this region tend to degrade clarity. The amount of time the ear/brain system needs to clearly process signals all the way down to 700 Hz is 10 milliseconds, so this is why you see Geddes and his groupies (including yours truly) tossing this number around. Ten milliseconds corresponds to the amount of time it takes for sound to travel 11 feet. Not saying this is a hard target, but rather a fuzzy one, with improvement from having a reflection-free time gap which lasts for even longer.

I think it's been covered earlier in the thread, but I'm a believer in Duke's distributed bass array as the bass solution...

One advantage of a distributed multi-sub system (whether or not Duke is involved) is that it is inherently better at addressing in-room dips in the frequency response than EQ alone is. Boosting the energy going into a cancellation dip has limited effectiveness. Imo the two techniques (multiple subs + EQ) are arguably complementary. A distributed multisub system significantly reduces the spatial variance in the frequency response (how much the frequency response varies from one location to another within the room), such that EQ becomes beneficial throughout the room, rather than beneficial in one location but detrimental in others.

 

[pjwd]

Well, probably we are diverging on semantics - what are exactly your first principles? IMHO the reflecting requirements of stereo are fundamentally different from live, but surely they obey the fundamental laws of wave reflection.

Separation of direct and reflected sound, achieving a well controlled reflected sound and control of reverberation time. Large halls are more complex and the targets and scale will differ but you can use similar techniques . Sound remains faithful to physics as you say

 

[pjwd]

Yes, the general principles of "what sounds good to the ear" are consistent between listening rooms and concert halls. To a reasonable first approximation, the closer we can get to what a concert hall is doing in our much smaller listening rooms, the better. This implies having weaker first refections (in particular early sidewall reflections) than home audio rooms normally do, but WITHOUT killing off the later-arriving reverberant energy. Imo the KEY is to get a worthwhile time gap in between the first-arrival sound and the strong onset of reflections. One problem I see (and hear) in many dedicated listening rooms is overuse of absorption such that the highly desirable later-arriving reflections are too weak, which has the effect of "sucking the life out of the sound". This is an issue that a good multichannel system addresses, by using dedicated channels to provide that later-arriving reverberant energy. I'm not saying multichannel is a panacea (and I neither use nor sell it), but credit where credit's due.

Let me get a bit more specific about that time gap, if you don't mind. According to Griesinger, the ear gets most of its important information from about 700 Hz to 7 kHz. Reflections which arrive before we've had time to clearly process frequencies in this region tend to degrade clarity. The amount of time the ear/brain system needs to clearly process signals all the way down to 700 Hz is 10 milliseconds, so this is why you see Geddes and his groupies (including yours truly) tossing this number around. Ten milliseconds corresponds to the amount of time it takes for sound to travel 11 feet. Not saying this is a hard target, but rather a fuzzy one, with improvement from having a reflection-free time gap which lasts for even longer.



One advantage of a distributed multi-sub system (whether or not Duke is involved) is that it is inherently better at addressing in-room dips in the frequency response than EQ alone is. Boosting the energy going into a cancellation dip has limited effectiveness. Imo the two techniques (multiple subs + EQ) are arguably complementary. A distributed multisub system significantly reduces the spatial variance in the frequency response (how much the frequency response varies from one location to another within the room), such that EQ becomes beneficial throughout the room, rather than beneficial in one location but detrimental in others.

Duke have you followed the work of Tapio Lokki on concert halls . Its worth looking up for a deeper dive into modern acoustics thinking

 

[Duke LeJeune]

Duke have you followed the work of Tapio Lokki on concert halls . Its worth looking up for a deeper dive into modern acoustics thinking

Yes I have! I was already familiar with most of his ideas as embraced and described by David Griesinger. Far as I can tell neither are directly working with small room acoustics at this time, but imo the psychoacoustic principles are relevant.

 

[Solypsa]

I have been to the Sony studios upper west side. They were pretty dead...

A starting point imho is when the room is very comfortable to converse in. If you have problems from there by all means take care of them, but the rub is to do that without screwing a bunch of other things up. Most non-purpose built rooms have issues with symmetry that can be hard to overcome.

Most importantly to me, is that we don't hear like a microphone. The studio captures an event. The mastering engineer ( used to create a master ) checks for general qc issues and tonal balance but the listener hears it in a room just like we hear our partners voice and the alarm clock - with a sense of the room as an important way to determine 'where we are'. This is not a bad thing. Large bass nulls and tweeters reflecting off of glass is a bad thing

 

[pjwd]

Yes I have! I was already familiar with most of his ideas as embraced and described by David Griesinger. Far as I can tell neither are directly working with small room acoustics at this time, but imo the psychoacoustic principles are relevant.

Yes his " standard orchestra " being measured in a variety of halls and corellation of measurements with perception of halls quality was an epic piece of work .. I had presumed that came after Griesenger ... more reading to do

 

[Duke LeJeune]

Yes his " standard orchestra " being measured in a variety of halls and corellation of measurements with perception of halls quality was an epic piece of work .. I had presumed that came after Griesenger ... more reading to do

Geddes cites Griesinger, and then Griesinger cites Lokki, so that's the order in which I encountered their work (I started out as a disciple of Geddes about twenty years ago).

 

[alfa100]

Acoustic treatment is critical. The room itself is like musical instrument and needs tuning. Just enough and not more. I had professionals treating my room rendering it dead and bass heavy , and it was not cheap. I decided to adjust myself after a few failed follow ups. Removing all the absorbers from ceiling and walls, replacing the professional bass traps , adding 3 Heimholtz resonators and diffusers at first reflections on ceiling and side walls did the trick. Yes , just enough and no more.

 

[spiritofmusic]

For me, moving from 100% absorption at reflection points on front and side walls to effectively mainly low level diffusion w some absorption, has proved really beneficial.
My only major efforts on absorption are bass traps in corners and my unique situation of plugging a communicating hatchway to the massive volume living space below.
Treating my descending eaves the same way as walls has been an unexpected bonus, in my situation it's so easy to see why in retrospect with the eaves approximating to 1m from my spkrs at their closest point. This suggests way greater "ceiling" interaction than my old room which had 4m high ceilings, thus zero influence on direct reflected sound.

 

[Ron Resnick]

Acoustic treatment is critical. . . .

I used to agree with this statement. Now I no longer necessarily agree with this statement. Now I think that absolutist statements like this are not terribly helpful.

When I "hatch" my future stereo I will start with no room treatment at all (except for carpet on the rear two-thirds of the room). I will not automatically absorb the points of first reflections, or fill the corners with ASC Tube Traps.

The first experiment will be the points of first reflections.