The "Official" xtz Room Analyzer Thread - Page 7

so is someone here going to validate the use of RTxx in our residential spaces or not?

you guys are measuring well past Dc, yes?

LOL!

ANYTHING to avoid addressing ACOUSTICS!
And for you acoustics is based upon "opinion"???????

And OBVIOUSLY you know ALL about acoustic measurement platforms.....
Get a clue.
The fact is that folks can spend significantly less and get significantly greater capability. But even after doing that, they, unfortunately are still limited by their knowledge of both acoustics and as to how measurements are applicable to the actual behavior. And simply having a button that can be pressed that says it will generate a result in the hands of someone who lacks any appreciable understanding of acoustics is the recipe for error - as is the case with applying statistical RTxx calculations in a small acoustical space.

And Arny talking about being banned - well few have the experience he does! http://groups.google.com/group/rec.audio.opinion/browse_thread/thread/43ec27377a679fed/adff443eb4435d25


It is also interesting to note that XTZ maintains, incorrectly, that "The spectrogram is a 2D waterfall diagram which shows the room reverberation time to easily find problematic areas in the low frequency band."

Modal activity is NOT "reverberation"! It is a resonance reinforced by the dimensions of the space. Funny how this 'exhaustive' tool shows the same frequency response in multiple displays which appears to some to be an increase in fundamental capability. But a spectrograph is essentially identical to a waterfall, the primary difference being that one is vied from the side and the other from above and intensity/gain is displayed in terms of color rather than by relative elevation on a Y intensity scale..

And then it goes on to address modes as being somehow indicative of a reverberant sound field and them jumps to the use of statistically based calculations that are dependent upon the ACTUAL existence of a statistically reverberant sound field about which folks from Schroeder to Shultz to Davis and many more have established does not exist to any appreciable level in a small acoustical space! But there is a dearth of tools that specifically allow one to examine the precise behavior of specular energy in a bounded space that are basically ignored, some of whose capabilities are present in the alternative free, or less expensive, downloadable tools, and which are totally eschewed in XTZ.

But hey, it has a button marked "RT60", which when pressed displays a result which therefore MUST be accurate! Even if a statistically reverberant soundfield does not exist in the space. Now THAT'S sophistication! And the debate moves to one of how to attribute the error - to mechanical ignorance on the part of the machine for not verifying a few pre-requisite conditions, or to operator error for not being aware of what a reverberant soundfield entails and how to know if it even exists in a space - in other words - acoustics. You can buy a set of tools, however extensive or limited, but that does not make one a competent mechanic.

But if all you are interested in is a tool that will display room modes and help determine filters for use in the EQ for modes, its an expensive option limited to that application. And then when you decide to evaluate large acoustical spaces where reverberant sound fields may actually exist (but where modes are typically not an issue), and where an RT60 calculation may prove beneficial, you will be ready. ...Kinda...


Folks would do well to download and read the ARTA and EASERA (and even SysTune) user guides in order to get a better grasp on what some of the measurements actually indicate and to a degree, how they are obtained and generated.
Edited by dragonfyr - 7/31/12 at 9:15am

Dragonfyr are you a Acoustic Engineer professional?

Yes, I have those credentials and more...

It sure would be nice if some around here chose to focus on the acoustical principles and less on unfounded opinions and other unrelated issues.

Yes, and I have a bridge I need to sell you. You have professionals who act professional and you have the self-enlightened fruitcakes who deliberately act obtuse and lecture others with carefully constructed word salad and colourful prose. Of course, anyone claiming frequency response changes cannot influence our subjective impressions of bass should not be accepted as a credible source of information by default. Being temperamental, belligerent of others opinions, self-righteous etc etc does wonders for your personality.

I can claim to have credentials in the field too. There. Now just copy and paste acoustic theory from some book or website, act obtuse, wrap it up in word salad and you are good to go.

Poor baby...

And then add to your vast list of accomplishments the need to learn acoustics. And then to learn the meaning of the words used to describe acoustical behavior that actually have meaning. As well as imagining that statistical calculations are appropriate in a space that does not support an appreciable reverberant soundfield.

I know, I know...but the machine has a button labelled.....
Edited by dragonfyr - 7/31/12 at 4:27pm

oh, this explains it:
http://www.avsforum.com/t/1419740/bass-speed

ah, human nature...

it's a shame that some here do indeed need to be "lectured" on the satisfying criteria and requirements for RTxx calculations.

ACOUSTICS. not ACUOSTICS.

Fortunately dragon did not prove anything in that thread except that he can juggle words together. Oh and he is correct, I am wrong because he claimed I am wrong which is evidence that I am wrong. Great argument. Oh yes, modal activity etc etc ..YAWN. .I'll rather have a second opinion, or two, or three than listen to his drivel.

Which Acoustics based company (name) do you own?

I never knew you had a lisp.

...not too surprising considering the myriad other topics in that long list of things that you don't know...

...But do let us know if you ever decide to actually engage in a topic having something to do with actual acoustical concepts.

Myriad of other topics? I sit here with clenched teeth. I suppose your opinion has more weight because you are this well respected, world renowned acoustician. Oh but wait, no you're not. Here, let me use the rolling eyes emoticon now. For added spice let me go one step further. Remind me again why you were banned from the Shack?

goneten, was REW + mic + pre-amp simply too difficult for you to configure?

Gee i thought this was a XTZ ROOM ANALYZER thread?

So Goneten is simply overwhelmed by the mention that the use of the RTxx function is inappropriate in a small acoustical space, despite its being included in a tool that does little more than provide the basic frequency domain tools suitable for modal analysis.

At this point it does not concern me that owners are precluded from employing a large number of additional valuable analytical tools. Instead the concern was primarily over the misapplication of a feature (RTxx) that was included that is rather nun-sequitur to the context of the other tools and to the space in which the other tools would be most useful and to the fact that such a measure requires a significantly different method for acquisition in so far as a non directional source (such as a dodec) is optimally used as a stimulus and the mic must be placed in the far field welt beyond the critical distance (Dc). And I am sorry if those proper acoustical terms used precisely because they have meaning are confusing. If you would like further clarification, ask - don't whine.

And to the degree that the calculation is employed, if it is not in a space that actually supports a reverberant soundfield, and if the method used to actually generate and to record the stimulus are not properly performed, the results are complete nonsense. You see, that is the larger issue at play at this point. And it really doesn't matter what anyone feels about it. Physics is funny that way.

And thus part of the proper utilization of the tool is to implement that which it can do properly, and to understand the necessary limitations this presents in order to insure the reliability of the measurements that it is capable of generating - while avoiding mistakes resulting from trying to make do that which it cannot..

How about you telling us why anyone should care what you think as you have repeatedly demonstrated that you do not understand many concepts and sit here largely ignorant of the measurement process and what the various measurements mean and how they are properly interpreted.

And we already stated the reason. Or do you need help understanding that as well?

One should easily see how, having the application installed, that opening a file by simply clicking upon it would be such an 'oh so difficult'(sic) task! Especially when it allows for the quick and easy re-windowing of the display as we may use it to further convolve the data into yet additional perspectives allowing for still more data to be ascertained - compared to others insisting that only a jpeg of a generally incorrectly windowed plot be posted rendering any manipulation by the program moot. That would be great if those posting were intimate with exactly what they were looking for and if they were able to properly windows the data - but seeing as they were the ones asking for help, it was a foregone conclusion that they were not aware or capable or presenting or perhaps even capable of identifying the data in an optimal manner.

But then hey, in all fairness to the folks at the HTShack, all they have heretofore used the program for has been for the identification of modes and for its limited use in the manner of its name - namely room EQ for modal analysis - as well as the inappropriate attempts to EQ frequency anomalies resulting from the superposition of non-minimum phase specular signals. Oh, but wait, I used a few fancy words that in acoustics have very specific and appropriate meanings, didn't I? Sorry, next time i will try to dumb down the response sufficient for you to understand it, as apparently asking for clarification of terms about which you might be unaware is above you, as you would rather whine and complain.

So apparently Goneten is confused as to why the RTxx calculations are not appropriate for use in a small acoustical space where no appreciable reverberant sound field exists. If you would bother to actually learn what the various terms and corresponding behaviors refer, one would think that the problems with the misapplication of the concepts would become readily apparent. But hey, you are welcome to persist in your willful ignorance as long as you would like. And we can point this fact out whenever it may be apropos as well.

And I am sorry if you are upset at the fact that both XTZ and OmniMic present a very limited feature set that is far less than even the two cheaper alternatives, one (REW) of which offers substantially more capabilities while the other (ARTA), a two channel FFT, rather dramatically trumps even that for yet a fraction of the price of either XTZ or OmniMic.

My concern in this regard is more with those who are interested but who have not yet made an investment, in order to direct them to more capable alternatives that offer greater and more useful capabilities for substantially less cost. And if they still have questions about how the measurements can be properly used, both pointing them to additional resources that can help provide additional information as well as helping if they simply ask - as there are those of us who would be glad to try to explain concepts and there application. But I really have neither the time nor interest in responding to those who lack both and understanding but who would rather debate something about which they know little instead of asking, listening and, perhaps, learning.

And if your concern is due to being told that you spent more money than necessary for a platform that offers significantly less capabilities for a greater price, I am sorry. Live and learn. Hopefully others, if they wish greater future oriented capabilities, will avoid such misgivings.

Do you have ANY acoustical topic(s) which you wish to address, aside from the fact that you are simply part of the noise floor?
Edited by dragonfyr - 7/31/12 at 6:46pm

Dragonfly you haven't answered my question post 189.

Also if you had taken any notice, the original post was for a friend that has XTZ and i have REW and Omnimic.

So this will be the last we hear from you on this thread, hopefully.

See a specialist in anger management urgently.

I have already answered that in other threads. And I am not here like some trolling for business.
And apparently you are not very familiar with additional applications of physics and acoustics beyond simple listening rooms.
We are here only to discuss the various concepts and to dispel a few of the various urban myths that pervade such forums and to explore the acoustical ideas. And yes, i will admit that it would be much more enjoyable if more actually had sufficient understanding to allow for a more advanced exploration of concepts instead of he perennial misuse of terms and basic concepts that dominate such forums. And yes, a few actually DO have extensive experience in applied measurements and data acquisition and analysis at many levels - most at levels far higher than simple LF medal analysis extending not only to applied acoustics in terms of system design, various types and applications of 'room' analysis and design, but also to advanced imaging systems, mechanical vibration analysis/control, seismology, various sonar and radar technologies, and other associated technologies. You just might be surprised at the degree physics scales.

And as we pointed out, the use of the RTxx calculations in small acoustical spaces, is not an appropriate use of the tool - and it WILL necessarily vary as does the nature of he energy distribution in the small acoustical space, as opposed to a large acoustical space that exhibits a reverberant soundfield and the associated statistically homogeneous soundfield.. So if you really want to help your fiends, please try to learn enough to ask good questions that will help your frond avoid mistakes, and not simply reinforce your feelings.Noting as well that YOUR question does not define the scope of the thread...The fumy thing is that your question was answered.
Edited by dragonfyr - 7/31/12 at 7:08pm

Edited by Phillips751 - 7/31/12 at 7:11pm

Why don't you explain to us how you can remain so ignorant of the what defines a statistically reverberant soundfield and how those necessary conditions for the use of statistical calculations such as an RTxx calculation vary from the locally variable soundfield in a small acoustical space?

After all, you have REW and OmniMic....I am a bit surprised you are not teaching everyone in the thread and forum.

You still haven't answered the question.

I have not commented on your what you are saying, other than products used (opinions).

Hopefully you have made the appointment for the specialist, you really really need help, for your sake.
Edited by Phillips751 - 7/31/12 at 8:14pm

shhh, they have products to sell here!

nevermind the acoustics!

Local trying to get in on the action. Hilarious.

My goodness, resorting to strawmen to bolster your position now. A failed tactic but it had to happen at some stage.

Shame, you just have this incessant need to argue, even about topics I don't recall bringing up nor caring about. You are welcome to waste more bandwidth on this if it suits you, though. I do recall bringing up frequency response aberrations as a variable affecting our subjective impressions of bass. Sorry Phillips, I know, wrong thread and I apologise for that.

Dragonfyr, you should start a new thread on why frequency response can't affect our subjective impressions of bass .. at all. Compose a long essay on it and then we can discuss it in depth. The longer it is, the better. You are welcome to throw in RT60 being irrelevant in small spaces if you wish, but it's not a requirement.

Oh geese. I respond to an issue another presented and you complain that everything is not oriented solely around YOU.

Which isn't really surprising as it indeed does not - well, except to YOU.

And a strawman? LOL! ANOTHER person specifically complained of RTxx calcs that were inconsistent - as of course they will be, seeing as they are not based upon a homogeneous reverberant soundfield!!! A fact that should actually be rather obvious if one understood either the actual behavior in a small acoustical space or the pre-requisite conditions upon which such statistical calculations are based - and thus rendered inappropriate for a small acoustical space.

And yes, I should worry myself about constructing a thesis and a "new thread" in order to address a problem imagined by someone else who is concerned with the effect of frequency and gain on "fast" or "slow" bass - above and beyond the fact that if one stops for a moment and thinks about it, frequency is ALREADY defined specifically in terms of "how fast" changes are already taking place, and any variation would result in a change in frequency. Duh.

Personally I find the entire concept fascinatingly absurd, and the terms patently incorrect. So yes, i will devote all of my time to the imagined issue.

And a I am NOT here soliciting business and am instead here with the desire to only address acoustical concepts - in fact on quite a few occasions refusing offers for pay in exchange for assistance - if anyone wants to know more about what I have done professionally or desires more assistance, one is welcome to contact me by PM and arrange to talk by voice. I know this concept confuses more than a few, but hey, some are easily confused...a concept to which one respondent is (or should be if they were only cognizant of their own folly) very familiar. But then its always ironic and humorous when the person who does not understand the issues demands to assume the role of someone who does - so, by all means, continue to expand on the process of testing.... humor is always welcome...
Edited by dragonfyr - 8/1/12 at 8:15am

After reading through this thread, maybe this is at play here:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2789942/?tool=pmcentrez

Maybe Bigus, who is in the medical field could comment. I know this seems off-topic but frankly most of these recent posts have nothing to do with the subject matter either.

Oh but I thought transient response was frequency response. Oh well. You are the world class acoustician here, but I am certain there is more to you than meets the word salad. If you have a hump over a particular frequency range that coincides with a musical note then it will sound bloated, muddy etc etc etc "insert a term that fits the mood" vs a flat response. Common sense would tell you that if you remove that hump by flattening it there will be more even octave to octave balance of energy. Duh. For the purposes of this discussion and all of our exchanges I have to assume you don't own a HT system and also, you don't own a parametric EQ or have ever dabbled with it.

For the record I was hoping you would take me up on my offer. Oh well.
Edited by goneten - 8/1/12 at 9:23am

What does what he owns have anything to do with anything? Has he argued that he is the "best shopper"? Are we discussing who has the biggest wallet? Do you only believe in cosmologists who actually own a rocket? If a particle physicist does not own a collider, does it mean he doesn't know about particle physics? Do people who fund Cern know more about particle physics than physicists?

No. But why bother buying all those parts .. hoping everything is compatible (not all components work out of the box, more fiddling around etc etc etc etc), updating this or that driver, calibrating levels, the added clutter of everything and then hoping beyond hope that the graph you see onscreen is an accurate display of reality when in actual fact there are 100 reasons why your graph is not. An all-in-one acoustical package like XTZ and/or Omnimic takes most of the fiddling out of the equation and saves time. Time is money as they say.

"Oh but I thought transient response was frequency response."

I think that pretty much sums up the problem.

Yes, I don't even know what a PEQ or a HT system are. But considering your additional insights, such conclusions are completely to be expected. In fact, one would be mightily disappointed if your convoluted reasoning can to any other conclusion. And unfortunately what is too often referred to as "common" sense is all too "uncommon".

And all of this points to yet one more reason that someone should have the additional access to time domain analysis offered by such free tools as REW and for the best bang for the buck in the industry, the dual channel FFT engine called ARTA - which is also optimized for binaural and IACC measurements, for those so inclined, as well....And then folks can invest a little time and perform their due diligence in learning to what the PROPERLY and APPROPRIATELY administered measurements actually apply and what the results of a PROPERLY administered test actually indicate.

And I am sorry that simply asking and following a few SIMPLE suggestions is SO difficult where all the guesswork has been removed. But what IS painful at the HTS is watching as SO many who have NO clue persist in traveling off script and attempting to assemble and configure some if the most hilarious assemblages of gear rather than simply benefiting from others experience and just following the suggested basic entry configurations that ARE relatively simple to configure. But again, its always fun to watch those who do NOT know, ignore the advice of those who do as they run off to redefine the application before they even know what it is - and then to listen to them thereafter whine about the complexities of attaching ~3 interconnects and in selecting the appropriate input and outputs (possibly in their computer's OS) and in the application itself.

Considering just how simple this actually is and how readily available help is form any number of sources, it is always hilarious to what those who do not know ignore assistance and proceed to reinvent the wheel. And even funnier when they then blame everyone and thing aside from themselves when their schemes fail. Yup, its all everyone else's fault!
Edited by dragonfyr - 8/1/12 at 9:46am

Because you have practical experience and then you have theory ... and then you have cookie cutter theory. It appears he is relying solely on his theory. Anyone at home can test out the practical stuff. Move your subwoofer around, measure it .. move your speakers around... apply EQ curves .... etc etc etc etc etc.. Not rocket science but we sure can make it sound like rocket science.