Above the Schroeder Frequency. Diffraction.

[DanDan]

Clearly he hasn't looked up the world Irony yet.

Another couple of illustrative examples-

Sabine (all bow and face Boston) used balloons, a starter pistol, as stopwatch, and lots of pillows.

The Titanic was built by Professionals, the Ark by Amateurs......

DD

[SAC]

Irony is useful and has meaning once one knows of that which one speaks. And an ETC is what again? You previously proved that you thought it was the impulse response.

But then it was Wittgenstein who said:
About that which one does not know, one must remain silent.

Take the hint.

And the real irony is that the folks to whom I refer were more advanced than you in this current technique even before you discovered acoustics as you still persist in living in the age of the tools that dominated the world of Sabine. Now THAT'S irony!

gee....aren't trolls fun?

[dykesh]

I'm sure not trying to cause any problems with my earlier post asking about the graphs, I'm just trying to learn a little. I appreciate everyones help. I guess I was assuming that the peaks on the graph would need to be addressed with absorption or difusion, or something else. I just wanted to see if I was thinking about this correctly and wanted to know if tracking down the first 50 msec or so in my room would be worthwhile. thanks

[DanDan]

Aha, the Peacock's true colours are revealed! Again.

Irony needs to be funny to work Mark. You are not quite there yet.
Also, trolls are just boring.

dykesh, you will get answers to questions here in these fora. Not from SAC though. Do a search of his posts, also under his other name foxfyr. I guarantee you will find no answers or helpful information whatsoever. Don't be fooled by the often incomprehensible, seeming random, or insane, trotting out extracts from well known scientists. It is merely ignorance. The accompanying layer of arrogance and aggression should also be clearly visible now.

DD

[Seamus TM]

Oy.

I think the difference is in what the intent of the original post is. This is, obviously, different for every new thread, even if it doesn't seem like it to the guys here that read ever single thread that is started here.

I will agree that there are a lot of common denominators, but they are all a little different.

Now, within these differences, there is intent. I would say that most people want their room to sound better and get back to making music. They don't necessarily care about the why. There is nothing wrong with this. I could care less what value resistor is where inside a limiter that makes it do one thing instead of another. I care even less about what the actual electrons DO when they get to that resistor.
I just want the limiter to work.

I draw this analogy of acoustics to electronics for a reason.
Electronic components : Types of treatments.
Electrons : Sound.

I, personally, want to know as much as possible about this. I want to know about the different kinds of treatments and what they do. I want to know what happens in the room when different things are done. I want to know on the electron level. I don't want to blindly do X,Y and Z because it will most likely work because it mostly works in most peoples' bedrooms or whatever. I'm looking for more.

I can understand how other people on, say, an electronics forum, would be annoyed if someone simply asked, "My mic pre buzzes. How can I get it fixed", and someone goes into the physical properties of what electrons do to make something buzz. I get that.
However, for this particular thread, I am asking for it. I want it.
I don't want to simply swallow the fiberglass pill and go about my business. I want to know that by putting superchunks in my front and rear ceiling wall corners will help my 1,0,1 mode. I want to know why.
I haven't been as excited about anything as I am with acoustics since I got into recording about 12 years ago. I feel the same way about it.
I have books. Everest and Rod G. Books are good. First hand experience is better.

Now, I'm not saying this to prove or disprove anyone about anything. I am simply making an observation.
As to what's happening in this thread, I found SAC's post very helpful. I understand that his posts can be perceived as hammering a finishing nail with a bulldozer, but in my case, it was welcome.

I hope that makes sense and I hope I didn't ruffle anyone's panties.

Seamus

[DanDan]

mumblesound. With respect, the text books are out there. I recommend that you go to the source. You will find them carefully written, unambiguous, and without insult and arrogance. SAC, foxfyr, has a repeating pattern here. He uses seemingly sophisticated references and language to suggest that there is another better way to achieve sonic nirvana. When asked about such a way, or how to get there, there is never an answer, never. How exactly would you use that haircut to identify reflections and treatment spots? And if you went to all that trouble, in what way is it better or even as good as the visuals, mirror, handclaps, approach?
Take 15, do a search of posts by foxfyr SAC. All the posts are virtually identical:- Famous names and text books, how ETC cures baldness Everyone but SAC is wrong, ignorant, unaware of research from 30 years ago, and unaware or too poor to buy arcane superseded software. He has never taken the time to read the FM or REW manuals. He has no interest in communication or providing answers or help. Just the same old diatribe over and over. When he gets banned or too boring, he changes his name.
Four of the long term regular helpful posters here have noticed my picking at SAC/foxfyr nonsense lately. The four have PM'd me. All thanked me for speaking up. All agree that SAC's posts cause and contribute greatly to confusion. All would like to see them and him gone. If you think I might be coming across as unnecessarily harsh here, do the search. Here's one at random, which perfectly demonstrates actual communication vs technoturets.
First Fuzzmeasure Graph. Any opinions?
DD

[Seamus TM]

That's cool, DanDan.
Like I said, I'm not judging anyone here. All I'm saying is that I found post #21 of this thread helpful in a big picture kind of way.

I have MHoA and a couple of other texts. They are helpful, but I do find them a bit vague, sometimes, as they deal more with generalities, as most texts do.

As far as all the forum politics stuff, well, it is people's responsibility to educate themselves. I would never take one source's word as gospel.
Like I said before, the Studiotips site and Sayers site has been great in areas of expertise that I can't find here at Gearslutz... and vice versa.

Just as I would never take one persons word as gospel, I am constantly cross checking things from one site to another and also to the texts that I own, as well as all the great information available on the BBC site.

Again, I'm not condoning or condemning anyone.
I couldn't care less if everyone thinks that SAC is a freak and you meet him after school in the park and kick the crap out of him. Whatever. I'm just looking for information. By the same token, I couldn't care less if SAC actually IS a freak and he has just enough knowledge to confuse people on purpose because he got picked too much in the 9th grade. Whatever.

Now, if I'M sounding too harsh, I apologize. I don't mean to sound combative. It's just that, well, it's my thread. I just want to know where my 60Hz, 115Hz, 150Hz and 325Hz nulls are coming from and why they are there and basically everything there is to know about them... so I can kill them.... because I hate them.

Respectfully,
Seamus

[Seamus TM]

As an aside, I remember the name foxfyr, and remember thinking that he was kind of a D-bag.

That doesn't change the fact that on THIS thread, I found post #21 helpful.

[Seamus TM]

Oh, and I forgot to address the whole reflection analysis thing.
I think both ways of finding reflections is fine.
Since I don't have any fancy software, I use a mirror.
Cool.

Though I wonder if that mirror is finding reflections from the ceiling to the wall to my face.

I need more mirrors.

[SAC]

LOL!

Let's see. All of this because poor Dan can't figure out how to read an ETC (after he had to have it explained that it was not the impulse response - a fact) when the axes are gain and time???
And calculating the distance of travel from the time of travel is complex? LOL!

And assuming that someone is able to help him do the above steps,
DanDan wants a quick answer. What to do...1., 2., 3. ...A one size fits all, 2 hand claps and apply absorption solution as is his mantra. But unfortunately what exists is a process, based upon a foundation of related topics.

Or for that matter, has he explained how to use the ETC response for anything at all? After all, as I am so negligent, yet he offers nothing except his trolling.

Of course, has DanDan discussed and explained the various acoustical room models? Of course not! As he doesn't even have one, let alone distinguish between the various models.

And without being familiar with them, and choosing one, the specific goal for which he expects a 1., 2., 3. procedure is what? As he is too busy running about clapping, he provides no answers, as after all, he and PaulP claim that after all is said and done, that none of the models apply in such a small room!

Which is absolutely incorrect. But then DanDan also claims that Russ Berger's use of the collimating phase grating is questionable as well.

The fact is , the ETC is a basic tool.

But you then use it as a tool in conjunction with a chosen acoustic room model to accomplish the tuning of the space in acordance to acoustic and pyscho-acoustic best practices in order to accomplish establishing a response consistent with the chosen acoustic model.

Well, some do. But not DanDan. He wanders about clapping and simply installing absorption.

And for the rest of the folks, they are not responsible for learning how to install their software, nor to referring to the support sites. Heavens no. That's my fault as well.

SO, I am supposed to learn software I do not use, but yet those who have it are not supposed to take the time or effort to read the manual or to consult the specific support sites designed to help them.

Of course if I refer to the tools I routinely use to generate the responses in question, well that's elitist.

The only thing he has not yet faulted is that I do not actively go to their house and do it for them. Heck, the folks selling stuff for whom the various web forums are their primary marketing tools don't even do that!

Heck DanDan doesn't even complain when the author of REW who also posts here doesn't help walk each user step by step through the installation, configuration and making each measurement for the folks who wait for others to read the manual and tell them how to do it (as it should not be his responsibility either to do the basic due diligence that any user should do!). But I should!?

Sorry DanDan, if they want help interpreting the measurements, I have offered to help. But I have NEVER volunteered to configure and take the measurements for them.

[DanDan]

Seamus, good points, regarding your original question, here's how I would find those modes which are causing the nulls.
Use a Room Mode Calculator.
bobgolds.com has a detailed one.
This one is more pictorial and shows graphically where the bass hangs out.
hunecke.de | Room Eigenmodes Calculator
Next, use a sine generator. A hardware one with a pot is best but DAW ones are workable. Signalsuite is nice.
Sweep around the predicted first order modes. The exact frequency is usually slightly different from the predicted. When you hit the spot, the room will make it obvious.
Then simply survey the room, including the ceiling and floor to find the hotspots. An SLM is useful here, it shows up the really loud ones from the just loud. However ears and a brain will work also.
This process will show you where and how strong your modes are, and where to treat them.
Sometimes a false wall/trap which changes one dimension can be of great benefit.
If you would like a simple visual indication of how changing dimensions can help try these John Sayers' Recording Studio Design Forum • View topic - Roomtune spreadsheet download


DD

[DanDan]

Another irritating waste of time, causing confusion to the unfortunate original poster.
New Recording Room for Acoustic Guitar and Vocals
Mark, Mac, SAC, where did foxfyr go and why? Would you be so kind as to follow him?
DD

[SAC]

Poor DanDan.

Note his answer above as to how identify room modes.

But that was NEVER the express topic of this thread. Ooops!

Helpful, isn't he?

LOL! Yeah, go back and read the thread! That was the guy who expected us to install and configure the software for him, and who then told us that the frequency response and RT times are adequate but would not generate an ETC or even a log-squared response.

...After he was told several times what responses were needed and which he failed to do.

So tell us DanDan, what ETC did he produce that I failed to analyze?

Thanks for your clarification! We're all clapping now after that display!

[DanDan]

I just want to know where my 60Hz, 115Hz, 150Hz and 325Hz nulls are coming from and why they are there and basically everything there is to know about them... so I can kill them.... because I hate them.

Seamus, have I misunderstood the topic of the thread?

Mark, SAC, foxfyr, Mac, if you persist I will have to ask the various long term posters who have contacted me to send requests to Jay to put your multiple personalities together and beyond use.

DD

[SAC]

Originally Posted by Mumblesound

Anyway, can anyone explain to me what the "Diffraction and Diffusion Dominate" portion of this room analysis means, and how I would go about addressing that range? As it so happens, I have a few nasty dips in the 100Hz-400Hz area.

Frequency Regions:
- No modal boost: 1hz to 27hz
- Room Modes dominate: 27hz to 101hz
- Diffraction and Diffusion dominate: 101hz to 404hz
- Specular reflections and ray accoustics prevail: 404hz to 20000hz

Read.

[DanDan]

11th July 2009, 07:03 PM
foxfyr
This message has been deleted by jayfrigo. Reason: repeated insults, bickering, and unnecessary escalation.

Typical foxfyr SAC, Mac, Mark, result.

DD

[PaulP]

Originally Posted by Mumblesound

I just want to know where my 60Hz, 115Hz, 150Hz and 325Hz nulls are coming from and why they are there and basically everything there is to know about them... so I can kill them.... because I hate them.

If you go over everything that has been said in this thread I think you'll have
to come to the conclusion that none of it will help you with your nulls. SAC
does provide some interesting ideas for upper frequencies but what to do about
modes is always sidestepped. On his recommendation I bought the book
Sound System Engineering expecting it to provide everything that SAC wasn't.
Well, he could have written the book because it does the exact same
thing. Here is, in its entirety, what the book has to say about treating
modes :

Small Room Resonances
(just the one page 179, there isn't anything else in the book).

The book does talk about modes in further detail but nothing is mentioned
about what you might do about them other than the cursory mention of
a diaphagmatic absorber (notice that in figure 8-3 the caption says
"helmholtz resonator", undoubtedly left over from a previous version).
The index has no entries for helmholtz resonators nor diaphragmatic
resonators.

The book has other redeeming features but treating small rooms is not one
of them.

I can understand your thirst for knowledge, I share it, but you'll have to
come up with your own solutions because there is no practical help available
(other than absorption). This can only be because either there is no 'surgical'
solution or those in the know aren't sharing (to protect their incomes ? to be
seen as high priests ?).

Paul P

[johndykstra]

Well, this is a shame.

I too have had my run in with SAC, I actually lost sleep over it. I started searching for posts of his, just to confirm I wasn't the only one in his sites. Clearly I wasn't.

Then I found this thread, and you know what... it made some sense. And he wasn't attacking anyone. It was the first time I saw him take a deep breath and start from the beginning of his thought process so all of us could follow along. Mirrors or software, don't care... we have learned how the information collection is achieved.

I feel like I was watching a movie and someone cut the power right at the climax! We were just about to learn how to evaluate the data and make intelligent decisions on what reflections should be absorbed, and how, and which ones should be diffused by what type and depth.

I beg of you Dan, let this thread continue of it's own course... if it turns out just the same as the others, I'll eat my words.

Thanks,

John

[Brainchild]

For real. It's not a race to the bottom to see who has the ugliest personality.

[Seamus TM]

SAC, this is helpful:

Originally Posted by SAC

You see, as the dimensions support differing modal ranges, and as the wavelengths become shorter, modes are supported less and less by different surfaces, until the wavelengths are smaller than all of the room surfaces and you then have a region above which all behavior is specular in nature.

[Seamus TM]

This is not:

Originally Posted by SAC

Poor DanDan.

Note his answer above as to how identify room modes.

But that was NEVER the topic of this thread. Ooops!

Helpful, isn't he?

It's less than helpful.
It's destructive and childish.

[Seamus TM]

DanDan,
No, you had not misunderstood the purpose of the thread.
It started out by me being curious about the "grey area" between modal behavior and specular behavior.
It got more specific later on when trying to apply it to my room.

I have yet to try hunting them down with sine waves and an spl meter.
I should try that.

Thanks,
Seamus

[DanDan]

Hi John,

We were just about to learn how to evaluate the data and make intelligent decisions on what reflections should be absorbed, and how, and which ones should be diffused by what type and depth.

Don't we wish.
The first couple of times I came across SAC posts I had the same reaction as most.
I was impressed by the references to respected textbooks and so on. I was intrigued by the possibility that there was ' another way'. i.e. a more sophisticated way of treating small rooms. That's his trick, most people take the bait. When asked to proceed, e.g. I (and many others) have asked him to please show us how to use an ETC to deal with reflections etc. I was genuinely interested. Not a sausage. He vanishes at that stage, always.
The same pattern repeats over and over. Do a search and you will quickly come to the same conclusions as I have. To save you some time, here is a perfect example of SAC hooking Chris, teasing a little with some numbers, then as usual, delivering nothing.
Measuring and Treating a Home Studio Using FuzzMeasure Pro
Nothing of course, except for the nasty little barbs, the arrogant presumption of superior knowledge, the name dropping, and all sorts of toxic ingenuity.

I believe his presence diminishes this forum. I am not at all alone in that conclusion. I am guessing that his previous incarnation here, foxfyr, was probably banned from Gearslutz. Either that or too many people had copped on to his singular trick.
I don't think I need include the obvious next sentence.


DD

[johndykstra]

SAC, please, don't allow personal feelings towards me... or anyone else for that matter distract from the discussion.


Can we continue?

[johndykstra]

Dan I agree, and I have done the searches. But it was Foxfyr who initiated a discussion on space couplers that started terry j on his experiment:

SPACE COUPLERS. Theory, construction and effectiveness on traps.

that thread has died for whatever reason, but the results looked promising in the infant stages.

I suspect that SAC or what ever he chooses to go by doesn't respond well to being cornered... much like an acoustic leprechaun. I submit to feel free to flame away on threads he deserves it in...

[SAC]

The procedure for evaluating the ETC has been presented multiple times.

What is lacking is an evaluation of various room models used as templates for adjusting the room response as well as a greater understanding of the various ways the available tools can be used to accomplish said response as well as a base understanding of the psycho acoustics that place their stamp upon the purely physical behavior of the acoustical energy within the room.

The other part that is lacking is the understanding that there is not a cookbook solution where one approach or treatment solves all problems in all cases. And that confounds folks like your colleague who laments the fact over and over as he decries process.

On the other hand, the process does address just about all situations. But you see, that involves exploring different situations and exploring the various available options and making decisions based upon the methods relative to the goal. And this seems to utterly confound and offend those who are looking for a static answer good for all situations and who are confronted with the possibility that they may have to analyze, evaluate and make decisions where various combination may suffice dependent upon the given situation.

And I love how you object when the origination sources of said process are mentioned in response to folks like you who attempt to denigrate the process as simply my product. Those lofty names are the very sources of the process.

But go back in this thread and see just what DanDan has contributed, beginning with his posts simply aimed at me personally. And then ask him to distinguish between an impulse response and an ETC. As perhaps something has been accomplished in these posts, as just maybe he has learned the difference between the impulse response and ETC after his initial announcement that he already knew how to interpret that which he could not even recognize - and now complains was never explained.

[johndykstra]

Is it possible then, to combine the information given by an ETC reading, and transpose that time based information with frequency waterfall plot and determine from the given reflection points that the spectrum arriving at the listening position is bad (absorption) or needs augmenting (diffusion)?

[Victor_Stoian]

Originally Posted by DanDan

Four of the long term regular helpful posters here have noticed my picking at SAC/foxfyr nonsense lately. The four have PM'd me. All thanked me for speaking up. All agree that SAC's posts cause and contribute greatly to confusion. All would like to see them and him gone.

to be honest, i'm not confused by SAC posts and for sure it is not nonsens!
But that put aside, simply thinking different than "the four" and yourself is reason enough to get banned? Is the inquisition back to town? Are we here to learn or do we have to "follow" to still remain part of the GS community?

sorry for the OT

[SAC]

The two categories of measurements (frequency response/CSD/waterfall and ETC) address two regions with differing models of behavior.

And the nature of how the LF treatment is applied has a great potential to adversely effect the region beyond the modal region.

The frequency response and cumulative spectral decay/waterfalls (they are not the same) are appropriate for the modal region. The ETC is appropriate for the region dominated by spectral reflections - and has uses such as signal alignment that go far beyond.

Earlier in the thread we again explained a simple way how anyone here can identify the reflections and how to identify the focused reflection incidence points - allowing one to treat specific points and to subsequently verify the effectiveness of such treatment without removing more energy than is absolutely necessary.

Typically (but not necessarily), absorption is used to treat the early arriving first order reflections. But only enough to remove and define a particular response, a we want to retain and 'reshape' the remaining energy in more productive ways.

We also must address the perception by many that reflections are to be eliminated with absorption or diffused, with little understanding of where, when or why. And the answer to this is dependent upon a number of things. It is not a simple cook book answer. It is a process dependent upon a number of factors. First of which is a determination of the room's use and the desired response.

In a primary acoustical response model, we also want to establish a method by which we create an essentially anechoic short duration response followed by a stimulus to trigger the Haas effect - a psycho-acoustic response affecting how we perceive the signal. To do this in a small room, this may involve the use of a reflecting source - often a LF QRD that acts as a reflector to the mid-HF energy that is reflected back in a controlled manner of sufficient intensity and optimal orientation sufficient to trigger the Haas effect.

To cite a few points from several definitive sources; several factors, each requiring further analysis, are:

1. The direct path between source and listener must be effectively anechoic.
2. This anechoic Initial Signal Delay Gap should be sufficiently long (the longer this ISD, the larger the perceived space will be) and
3. The initial energy return from the reflected sound field to the listening position must be of sufficient level to ensure an effective Haas effect, and that this stimulus be followed by a high density exponentially decaying sound field. The greater the level of this return energy, the livelier the room will be perceived to be. This stimulus effective removes the directional information from the remainder of the later arriving sound field while allowing us to hear their level and tonal contribution.(The nature and design of this stimulus can be explored later.) Similarly, the more diffuse the exponentially decaying sound field is determines the tonality of the sounds heard.

[johndykstra]

So do we use the frequency transition regions of our room to determine at what frequency we should build/buy or diffusion? And is there a formula to determine an approximate amount of diffusion coverage to obtain a semi-diffuse sound-field based on volume?