OC 703 faced? - Page 5

The comment was directly aimed at the millwork in a room that I designed and built (as a Certified THX Screening room). More to the point, someone sitting in their arm chair at home makes a suggestion that something likely doesn't work when they have never been in the room, never measured the room, and likely can count the number of rooms they've designed and built on one hand. In essence ... a lot of talking about something of which they have no first hand (or even second hand) knowledge. But, on the other hand, why not? They can hide behind a handle and never be placed into a position where their expertise can be vetted or they have to take personal responsibility for their actions. Just annoying. Plain annoying. It is very easy, while hiding from scutiny, to be critical and argumentative. Not so easy to invent, build, develop, or actually do something original.

Nonsense!

I made the comment in response to the physics of the Sketchup rendering - as you falsely posit my remarks to that which you fantasize I was responding.

And we had NO specs of any kind - not even scale!

And after more than 20 years dealing 1st hand with TEF and Easera, I can definitely perform specular 'ray tracing' napkin analysis on a general drawing.

If you want to make claims that folks can discuss, then substantiate them with something more objective that alleged testimonials used in ads very specifically for the fact that they have absolutely no legal standing. Words are indeed cheap.

And I know of NO reputable acoustician who fails to provide some minimum objective proof of performance standards.

But you also seem to forget - I am not here selling anything.

So, why is it you are so defensive about a statement you didn't make. Odd. What hit home? The fact that you want us to take you at face value with no objective proof you have the creds, experience, expertise and 20 years of playing with neat toys? It don't know what "legal standing" has to do with anything; but, it seems you just aimed that gun at your own foot. Where's your objective proof? And, btw, third party objective proof for that specific room does exist.

Gotcha. I wasn't thinking that the splayed portion would be attenuating, just thinking that maybe the early reflected energy could be delayed outside the magic 20ms time frame by redirecting it. What I didn't fully consider is the amount of possible vectors/paths involved from the source, which local and dragon pointed out. So, not a good solution although there's obviously some merit to the concept or Dennis wouldn't have incorporated into the room linked.

Perhaps his approach was due to the millwork/overall design and addresses speaker-carpet-wood path of sound (since wood isn't such a great absorber)

Lol at this thread.

If you guys keep bashing my sketchup rendering.....well, I'm just going to quit "drawring".

Subscribed.

Lol.

False allegations made by someone a bit too paranoid to note what other already have! And I don't like false allegations made by anyone about anyone. And that includes your nonsensical fantasies and false allegations.

And You are the run running about making claims while offering no objective proof using industry standard "toys"....Seems to me that you are the that "doest protest too much".

BTW, Fotto, your Sketchup drawing was fine, as it was more than adequate for the points we were trying to make! But its quite entertaining to watch another run around frantically thrashing out at just about everyone all because we had the unmitigated audacity to comment on the various possible general behaviors of the structure defined in your drawing.

Oh, and "legal standing" in that context means : they are worthless.

And combining this with the fact that mostly speakers that are used are cone/dome forward radiating types(with an awful off-axis response), sidewalls are hit with proportionally less high freq. energy. So only high frequency absorption is kinda useless. One reason why diffsorbers/perforated absorbers (with correct amount of material to absorb low-midrange) are nice tools to have.

Outside of the current debate over "who said what" (and quite frankly, I'm a bit disappointed not to hear even ONE "Well, I oughta"), I've stepped back a bit to try to comprehend the big picture of your contribution on this forum.

First off, Draganfyr, I have come to the conclusion that you actually ARE a carbon based life form and not a supercomputer surfing the web in some back room in San Jose. You recognized my "pain" over my perceived rendering inadequacy, which has to be "proof of life". So, "drawring boycott" avoided.

Now, having been hanging around here for 3 years or so (not long compared to others), I have yet to see the detailed elaboration on actual theory you, localhost etc. have presented. Your description on measurements etc. in my opinion is very refreshing, even with my (and others) negative observation on your delivery. Might even go as far to say a "paradigm shift or two" (I frickin hate that phrase). Now is all that theory correct? If subject matter experts here are not disputing it, then I take it as such.

I've been following the mtbdudex thread here http://www.avsforum.com/avs-vb/showthread.php?t=1351247 with great interest, as I am getting into the ETC measurement phase myself. The exchange of information there seems so much more cordial.....why so much conflict here?

Not sure what the current argument is really about at this point, but my personal interest is that you will continue posting here as I don't see anyone else offering this level of advice on actual measurement techniques and interpretation. Traditionally, you have to go elsewhere for that info.

So, until if/when you guys are proven as the "great deceivers", I'm content to soak things up and "Enjoy the Show" (or what's left of it, as I shove another handful of popcorn in my pie hole)

Fotto, this type of information has been posted and discussed previously on avs. I and others have many times offered the advice that the first step forward in any treatment plan is properly measuring the space.

It just hasn't previously been, well, as visible.

I'd be curious to see a post on process of taking and interpreting an ETC reading (not just suggesting that one do it). The concept of measuring isn't new to me either, but I haven't found it detailed to the extent I have recently. Not trying to be difficult or defending anyone, just don't recall ever seeing it described in detail.

Convoluted thread here.

Discussion of a "White paper" on 2ch goals, including ETC, here.

Fotto, the larger question is that TEF/TDS and the ETC response has technically been available since 1967 thanks to Dick Heyser, and licenses for its use available since ~1977. If you were not a pioneer willing to manually assemble the the ~$40,000 in assorted HP & GenRad gear (as were folks such as the esteemed Russ Berger) back in 1977, then you had the opportunity starting in the early 1980's to acquire a Techron TEF10 or 20 in the mid 1980's, albeit for a tidy sum of ~$10,000 and $12,000 each, followed by the TEF20 available for ~$6,000 (sans software) from about 1990-1 as some of the heavy lifting began to be transferred to the accompanying PC.

Considering that the ETC has been fundamental since the 1970s, the question is not when it was first presented, but why the concepts which it illustrates and its use are not ubiquitous in such discussions here and elsewhere.

Ironically, the only place where I know such to be true has been in the association of the folks from SynAudCon, due in large measure to the insight and efforts of such special folks as Don & Carolyn Davis, whom all of us owe a great debt of gratitude whether one is aware of them or not, for which the response has become both a fundamental and necessary asset.




Oh, and if you will research the issue at GS, you will find that the function and use of the ETC was presented significantly prior to the reference in that paper! Complete with doubt, derision and the admonition from at least one participant that it not be made available to the mere lay person and that it should remain available "only for professional use".

And just who is that SAC fellow who had the audacity to try to present a concept that it only seemed reasonable that the rest of the world should finally be familiar a mere 30+ years after its introduction...some nerve...

Anyone have a summary of the different standards for two channel listening rooms compared to multi row theaters with 7 discrete channels of surround sound and multiple sub-woofers?

Odeon and my BEM model indicated there could be some potential issues in some areas along that portion of the wall. The potential cost of ripping out all that solid mahogany in a "do over" was out of the question. All of the fabric panels can be easily removed allowing a very easy "do over" of the speaker placements and acoustic treatments. Fortunately, after I and two independent third parties measured the room, "do overs" were not required. (Odeon, btw, isn't exactly the tool of choice for small rooms.) That idea, btw, was not my own ... many, many years ago, the acousticians at Sky Walker Sound faced a similar issue when building a screening room for George Lucas and that was their solution.

It is taught in every HAA class.

The first link is the one I already noted in post 131, but appreciate the second link...looks like a good read.

The spirit of my post was not that I was recently enlightened that the concept of measurement/ETC has just arrived on the planet. Technology has marched on and now the average Joe can have an acceptable method to measure their room for well under $100. Why wouldn't everyone here building a room that's costing easily $10K plus plop down another $100 and measure?

What us average Joe's (who don't plan on making audio theory a second career) need, is guidance and instruction on use and interpretation of these easily available tools.

Tricky to do, because you have to have acoustic knowledge to interpret measurments. No - it's the other way, through knowledge in (psycho)acoustics you can start to identify problems, measure them and solve them. No other way around it, sorry.
If you have all these 'general recommendations' it gets you somewhere, maybe its good for starters? Problem is that these recommendations gets to be blindly applied everywhere, even when not appropriate. Asking to interpret measurments in forums like this is the next best thing I suppose.
Somewhere mentioned ARTA manual is a place to start.

I hear what you're saying dannut. The level of understanding and self education of acoustics is obviously going to vary by individual. Personally, I don't have the interest to get to the level of Dennis, draganfyr, localhost etc. That being said, take my experience here as an example of what some others may be going through.....

I decided to construct a HT over two years ago with no pre-existing education on audio theory, sound isolation etc. Only construction and electrical background. My last receiver was bought in the 80's!
As I started digesting more here, I came to the conclusion that sound isolation was important in my situation, and of course I wanted a good audio experience as well, but certainly no intent to have a THX certified theater.

As natural progression over the course of 2+ years, I began soaking up what "general" and more specific information is offered here. I would think that anyone investing in such a project will be reading and absorbing this information as much as their time and level of interest permits them, to hopefully achieve a goal that THEY are happy with.

In my case, as example of "general concepts" surrounding bass trapping, I constructed front and rear corner traps, as well as doing what I could with my riser. The results of that turned out pretty good (in my opinion, black line) as measured following (actually, most recent Audyssey is even better);



My room currently sounds "good" to me. I have good bass response, I don't detect a muddy sound field, comb filtering etc. but I am under the impression that with some simple measurements I will most likely find some sources needing treated which may further enhance my audio.

Now on to first reflections, which is where I'm currently at. The opinions on treatment methods, materials etc. seem to go on and on and quite frankly I'm not sure that I want to further investigate the merits of using QRD vs. diffusion vs. absorption etc. What I want to do is measure, determine any issues via ETC. and either someone will comment with a recommended solution, or I will eventually figure it out on my own. My current plan is to just absorb it away.

So what's the point of all this?
1) I believe there are indeed general guidelines which can be applied "generally" and there are some which cannot.
2) Certainly, knowledge is power, but there will always be varying degrees presented here.
3) A person CAN measure without being a subject matter expert, interpretation and correct resolution can be another matter entirely.
4) I APPRECIATE the feedback that the "more audio astute" here provide to those of us who are not in a similar position.

No need to be overly defensive Dennis. I simply said that I didn't know what reflection was being addressed and that with the slight angle I had my doubts as to the effect generated. In the context of the ongoing discussion, its a valid observation as I don't think whatever you were doing there applies to the specific question being asked here.

If the room sounds great, then great. I'm among those who have been saying that this is what in the end is important.

Just a quick note as I am already running late (but for that matter, when am I not?)

Over and over I keep hearing the notion that we can make the measurements (here referring in particular to the ETC response), but interpreting is so difficult if not impossible.

In point of fact, they are NOT!
And my goal is to prove that!

Somehow this notion that they are exotic and oh so difficult has become ingrained as fact, and many are discouraged to even try, and this is simply NOT the case.

Let me backtrack just a bit. Many talk of having had REW for 5 years or 2 years or other periods and that they still have yet to figure out what to do with all the tools. This drives me crazy, as such is not, and SHOULD NOT, be a necessary condition!

The irony is that much more can be realized if folks would simply read the 76 pages of chapters 4-8 of Sound System Engineering by Davis and Patronis. Now don't run away!!!!! Let me explain!

Yes, they do list math formulas for reference purposes. But one does NOT have to understand ANY math to understand the concepts (so drop that tired objection!!!), which are adequately described in English and with pictures - many of which you will probably recognize as Everest and D’Antonio also sourced them from the various SynAudCon workshops, etc., of which they were also a part (gee, what a coincidence!).

...And why is this important and 'unavoidable' if one desires to discuss the topic?

Chapters 4-8 provide a good overview of: speaker dispersion and Q as well as spatial loading, the pertinent environmental concepts of acoustics, how they are modified for large room behavior, and how they are further refined for small acoustical spaces. This is critical, as most of what folks know from a basic physics class apply only to unbounded spaces or they have heard of measurements applicable only to large acoustical spaces - but which do not apply at all to small bounded spaces. So a simple understanding of these differences will greatly help you to make greater sense of the behaviors we talk about here. There simply is no getting around such important basic information. And don't be afraid of this, as you only have to be familiar with the general concepts and terminology!

Not only that, but you will have a good grasp of almost all the pertinent concepts – maybe not a ‘subject matter expert’, but at least you will be functionally conversant with the terms and have a basic idea of the concepts and how they apply – and from that point is becomes EASY to elaborate in as much detail as one desires. ...And I think we all know the difficulty encountered when trying to explain concepts if we don't understand the language!

Much of the text is available online via Google Books! And if someone STILL has problems, PM me and I will see what we can do…………

What is frustrating is the degree that many still will go to avoid simply reading chapters 4-8 of Sound System Engineering and asking for clarification regarding any of the ideas presented – as trust me – the text is actually like a Cliff’s Notes version of the subject. It is basically a shorthand version of the subject, where if anyone wants more detail on any topic, it is readily available upon a PM or voice discussion over the phone to more easily focus in on the precise issue of interest or the precise aspect that may be acting as a stumbling block. But perhaps most of all, having some figures and diagrams to look at is perhaps the most useful tool of all –as trust me, as difficult as it may be to understand some of the concepts, it is even more difficult to explain a complex multi-variant issue in words without the use of a reference diagram that makes the various relationships pretty obvious!

So, if one is simply conversant with the terms (that are a shorthand in themselves that carry with them a few additional paragraphs of assumptions and qualifications - which they save repeating each time the term is used!), that will go a long way toward achieving a functional understanding of what is going on.

So, if we can get past just the ‘definition’ stage, I think we can pretty quickly get folks up to speed with a basic understanding and ability to interpret the ETC. It’s NOT hard!!!

But back to the ETC.
Without trying to go into exactly how it works and how its interpreted here, please be aware that it is NOT difficult to:

1. Identify early arriving sparse high gain indirect energy arrivals.(these are the indirect signals that are destructive - the rest you can safely ignore/enjoy. In other words, not all reflections are evil as many have come to think... Hopefully this alone will clarify many debates about various models that one may commonly hear...)
2. Identify the specular vector path such high gain sparse energy signals traverse
3. From these determined pathways, to determine the point/region of boundary incidence where the approximate treatment should be placed.
4. And from the ETC display, you can determine the character of the indirect energy - whether it is sparse or diffuse - and also how various treatments appear in the ETC, and how the appropriate treatment option can be chosen to modify the behavior in a room - and how this behavior is reflected (sorry for the unintended pun) in the display.

Now, we can save an examination of the various acoustic response models for later. The fact is, once you understand the basic response models and how they appear in terms of the ETC response, it is not difficult to either interpret the majority of the response of a room, and it is fairly easy to modify the response and achieve a ‘hybrid’ response appropriate to a small acoustical space that is both practical to achieve, as well as that correlates to ones desired response preference.


So if we can achieve a basic conversant comfort level with the various terms, and achieve a basic understanding of how to interpret the ETC response, we can then introduce you to the various ‘major’ acoustical room models (which are generally presented by the display of their characteristic ETC responses), and we can explain what the features are for each and how they can be recognized in terms of the ETC, and from there, you can get an idea of what the basic behavior of your room is, identify the destructive anomalies and address them.

And THEN, if one is interested in further chasing the goal around, once you have a functional understanding of the various acoustical room response models, you can begin to tailor the total response of YOUR room to further refine it to incorporate the various psycho-acoustical responses that you desire – be it a greater diffuse ambience, a drier more analytic response, or something else of your own preference. But you will understand how this can be done and how to ‘recognize’ it. And then you can explore the various tricks of the trade that can be employed to achieve the various responses, be they absorption, redirection, or diffusion – as well as some pretty neat tricks that can be used to overcome some of the fundamental limitations of many small spaces.


So, the bottomline is that it IS possible to achieve a good functional understanding of the tools and the models. If you want to go further, that is your option. If not, fine – but cool it with the notion that it requires 10 years of dedicated study to obtain the basics - it DOES NOT! It’s time for that nonsensical notion to die!

And as I have offered before, once one has become comfortable with the basic terminology and what it means, one is free to PM me and I will be glad to clarify concepts or to help you interpret your measurements. But the real goal will be to get YOU up to speed so that YOU will be able to recognize what is happening and for YOU to be able to do this!

After all, the ETC is simply arrival time and gain, and from that you can determine the precise path of travel and incidence – as well as the sparse or diffuse character of the reflections that can be modified by various treatments! And it’s pretty cool how so much information can be derived from this one tool!

And then, IF you want to know from where all this all comes, and to delve more deeply into what all the measurements (and the time and frequency domains) really mean and how they relate (and they DO!!!), we can explore that too, when folks are conversant enough to address the topic…

Rur;
Thx for posting the white paper - wish that was available August-2011.

Sorry if my ETC thread comes off as "Convoluted" to you.
My overall goal is to summarize my lessons learned in that ETC thread upon its conclusion and post into the 1st post.


btw, after reading all 5 pages here, I subscribed to this thread titled "OC 703 faced? " - if it could be re-titled what would be appropriate title for it?

Wasn't meant as a pejorative, Mike. Most threads which go more than a couple of pages begin to fit that descriptor.

As I said in the thread, I do appreciate you being the guinea pig, as it were, for the exercise.

/Ken

understood Ken - can I share here?

I've printed my waterfall charts and ETC charts and shown them to family/friends who've come over to the HT room, and then tried to give a "elevator" speech on acoustics in 1-2 minutes, showing them the treatments and what each has done with measurement data.

Everyone looks at me like ....silence......silence, then "ok mike thx for sharing, now turn on the HT, load that demo blu-ray, and really show us what you are talking about"

Has anyone here had same?

Yeah, in the vast majority of threads on this forum.
And you don't even have to trot out the actual responses, just mention the terms.


...But I guess you were referring to places Other than 'audio' forums....

compared to the motor-head explaining the turbos, active diffs, geometry setup of the suspension, etc - and the user says: "just hit the gas, already"

Just keep in mind that it seems every time you get to a good part, the next page or so is blocked... So be ready for that unless you buy it.

However, what is there and what you can read, is fantastic and will leave you wanting more.

Test,

How much value is there in the 3rd vs. the 2nd edition? The price difference is substantial.