Does sound sounds better in a room full of furniture and stuff or without ? - Page 22 - AVS Forum
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post #631 of 871 Old 07-23-2012, 07:35 AM
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Originally Posted by amirm 

Please walk us through how...What...why....Please show an example...Please tell us how...What...How did you determine them...how do you know...tell us how...and what you are going to do...What to do next...What could be wrong...how do you disambiguate...What constitutes...Tell us...How do you solve...Please explain how...What acoustic product...Walk us through...How do you..What about...How...What other...how is it that...

Here's what you do Bigus: pretend you are confused, give him several “random tidbits”, talk about some unrelated topics for a couple of pages (real names vs. pseudonyms is always a good one), and then say you answered his questions. It's what amirm did, and you only asked him ONE question.

By the way, thank you for answering the question you originally asked amirm. You have made a valuable contribution to the forum. You have a process; amirm does not, nor is he capable of developing or articulating one.
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post #632 of 871 Old 07-23-2012, 07:57 AM
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For any passersby, here is the sum total of Amir's knowledge and the extent to which he can offer advice on your room: buy Harman speakers, put "some" thin absorption on the front wall and "some" on the rear. Where and how much doesn't matter so long as the measured RT60 @500Hz is between 0.3 and 0.5 seconds. Do this, and your room should be perfect. If you believe otherwise or want to improve it, you are mistaken. It is perfect.

Now, if you wish to pursue the best sound possible, please seek advice from someone who doesn't claim that both frequency response measurements and time domain measurements lie. Please seek advice from someone who isn't confused by these measurements and can use them to help guide you to identify problems and examine solutions. Please do not rely on advice from someone who, when presented with a room description full of potential problems so he could knock it out of the park, is instead so lost and afraid to answer that he uses every slimy trick possible to avoid directly responding.

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post #633 of 871 Old 07-23-2012, 08:02 AM
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Quote:
Originally Posted by audiophilesavant View Post

By the way, thank you for answering the question you originally asked amirm. You have made a valuable contribution to the forum. You have a process; amirm does not, nor is he capable of developing or articulating one.
I can just see it. A few weeks from now there will be people all over the place running "band limited ETC." They would be performing the magic of turning a bad speaker, the thing that produces sound, by "fixing the wall." They would know the science of how we hear despite it not being described. And know their audio preferences without being told how to do that.

Since you are such a great reader of who has said the right thing and who has not, would you opine please if Dragon is right in saying this about Bigus when he discussed the exact same topic with him:
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Yeah, and it is available where? Look bigus toolus, the qualification regarding both minimum phase systems was mentioned how many times? I'm tired of ms. congeniality constantly following me around like one other lost puppy dog some may know and trying to make points that simply do not exist had someone actually bothered to read the entire post for meaning. I am tired of this. blah blah blah. More social commentary from one who has yet to offer any contribution to the subject of acoustics. But just as with acoustics, don't let facts confuse you! ...But just keep repeating the Big Lie as you posture as Mr. Congeniality. What would be a radical change would be if you spent just one fraction of the time you spend sanctimoniously criticizing others delivery and actually attempted to pursue some of the information that has been presented that you claim to want so badly. JUST ONCE.

What do you think? Has Bigus made valuable contributions to the forum and it is Dragon that is wrong or vice versa? You are a smart man. They both talk about ETC. Are you able to determine that? You were in that thread and saw it transpire and didn't say anything. Here is your chance.

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post #634 of 871 Old 07-23-2012, 08:11 AM
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Originally Posted by amirm 

I can just see it. A few weeks from now there will be people all over the place running "band limited ETC."

If people listened to you, in a few weeks they wouldn't be doing anything except perhaps buying some random furniture.

The rest of your questions are diversionary and irrelevant, as are you.
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post #635 of 871 Old 07-23-2012, 08:19 AM
 
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Originally Posted by audiophilesavant View Post

If people listened to you, in a few weeks they wouldn't be doing anything except perhaps buying some random furniture.
No, just before they do, he will make bunch of posts in an attempt to make them believe that the real way to make the sound sounds better is to buy those overpriced audio gears he sells.
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post #636 of 871 Old 07-23-2012, 08:40 AM
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it's comical that amirm continues to resort to the quoting of bickering from other users in other threads as he frantically looks for any distraction to hide the fact that he 1) only recently even learned what the x-axis on the ETC even represents, and 2) his contradicting statements that:
Quote:
Originally Posted by amirm 
I have said and I will repeat again: ETC can have uses in the hands of someone skilled who knows how it can misfire.

^
Quote:
Originally Posted by amirm 
AVS community members who are interested in enhancing the sound in their rooms have no reason to use it. Experienced or otherwise

^
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Quote:
Originally Posted by amirm 
The money spent on such treatments should instead go toward buying a speaker that is not broken.

toole seems to think treatments are beneficial:

r9TkZ.png

it may come as a surprise to you (because you're not involved in any way-shape-form regarding acoustical treatments or modifications to an acoustical space), but DIY treatments are very cost-effective. i would know; i construct my own broadband absorbers and reflection phase gratings vs buying overpriced treatments from salesmen like yourself. modifying the room is easily the biggest 'bang for the buck' - as many others have come to realize. clearly you are ignorant of the large DIY community that exists here. no speaker in the world can cure all the inherent problems within all acoustical spaces. it's a system. and you continue to ignore the fact that SOME people PREFER more accurate and precise localization and imaging - as it is simply a "matter of taste". and thus if a user has identified such design requirements and criteria, then by all means the appropriate tools and methods can be introduced to help the user get to their final destination.

i'm still waiting to see how i can determine whether one has accurate/precise localization and imaging from viewing the frequency-response. you said psycho-acoustics is with respect to the frequency domain, so please share how one can use the frequency-response with respect to intelligibility, localization, and imaging?
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post #637 of 871 Old 07-23-2012, 08:43 AM
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Originally Posted by audiophilesavant View Post

If people listened to you, in a few weeks they wouldn't be doing anything except perhaps buying some random furniture.
.

isn't it amazing the lengths we go to to achieve good symmetry - and then as a next step, others recommend applying non-broadband, Asymmetrical "typical room furnishings"? tongue.gif
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post #638 of 871 Old 07-23-2012, 09:18 AM
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Originally Posted by localhost127 View Post

toole seems to think treatments are beneficial:
Not to fix the broken speaker. He dedicates a ton of space in his book and AES papers on why it is important to start with a good speaker. Only in an Internet forum where someone has not read such literature the message is confused that way.
Quote:
it may come as a surprise to you (because you're not involved in any way-shape-form regarding acoustical treatments or modifications to an acoustical space), but DIY treatments are very cost-effective.
It matters not in this context. You can't fix a bad speaker with slapping material on the wall. And you can make things worse. You are also forgetting the time investment to learn to build things and inability to measure their performance effectively. Above transition frequency of 200 to 400 Hz speaker *dominates* the sound you hear.
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i would know; i construct my own broadband absorbers and reflection phase gratings vs buying overpriced treatments from salesmen like yourself.
As long you then just stare at it in your condo devoid of listening tests, then you don't know anything. This is why you have confused yourself thinking you can fix bad speakers with them. I challenge you to show me how you can match a well designed speaker with a bad one with your "reflection phase grating" device. Go ahead and show us how your device fixes these problems that I asked Bigus about:

Toole-loudspeakers-and-rooms-p394.JPG

Show how your diffuser fixes the off-axis dip in speaker B. You can't of course any more than Bigus could. You need to leave the design of the speaker to the speaker designer. If he doesn't do the job right then you need to go with someone who does. Don't believe in audio alchemy of fixing bad sound after the fact.
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modifying the room is easily the biggest 'bang for the buck' - as many others have come to realize.
It could be if you know what you are doing. If you don't, it will also be the biggest waste of money and time in addition to making the sound worse. Pros routinely come into projects where they have to rip out what is put there and start over.
Quote:
[clearly you are ignorant of the large DIY community that exists here.
Not at all. As I have noted, we have built ours too. But we did it based on careful design. We didn't do it because someone said so on a forum who doesn't even own a listening space as is the case with you. And has fantastical notions of what is a broadband diffuser.

The other thing you are ignoring is that there are powerful techniques that tame the room effect which have nothing to do with a) acoustic products and b) frequencies above transition that the few of you are so fixated on. Great examples of them are outlined in my WSR Article on bass optimization, http://www.madronadigital.com/Library/BassOptimization.html, and as described by Dr. Toole. You can get seat to seat variations this good:

Sound-Field-Management-Relative-Levels.png

As you see, there is no mention of any acoustic products yet amazing amount of improvement in room response is achieved. Those techniques are not subject to psychoacousistics and therefore very reliable. Measurements tell the truth and the improvements are immediately audible and apparent. Instead of fixing 20 dB swings in your frequency response that anyone can hear and appreciate, you keep wanting to talk about the smaller problems above transition frequencies. Priorities are not there because you don't practice any of this. If you had spent time optimizing the bass, you would know the great benefit it provides and you would put things like DSPs in your vocabulary than "reflection phase grating."
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no speaker in the world can cure all the inherent problems within all acoustical spaces.
All acoustic spaces? No. But above transition frequency the selection of the right speaker is absolutely paramount. It is absurd to think that once distortion has set in due to the way the speaker works that you can cure it with stuff you stick on the wall. But maybe you show me where on RPG web site I can read that their products fix bad speakers.
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it's a system.
It is. You don't fix engine problems with transmission tuning in your car. Likewise, you better know the engine is sound and performant.
Quote:
and you continue to ignore the fact that SOME people PREFER more accurate and precise localization and imaging - as it is simply a "matter of taste".
How come despite me repeatedly asking you all what your preference is, nothing comes back but the sound of crickets? How come you are incapable of saying what your preference is and how you arrived at it? What percentage of the forum members do you think have determined that and how?
Quote:
and thus if a user has identified such design requirements and criteria,
No he has not identified that. Should I quote Bigus again saying he is confused about that? Who here is in a position to create an environment where *only* first reflections are AB tested? Remember, as soon as you put any absorption on the walls, you also impact the late reflections. You can't disambiguate this yourself. Researchers use anechoic chamber and speakers to represent the reflection. That way they can electronically add or remove such reflections. When they do, majority of people vote to have side reflections. That therefore should be the starting point and not some made up strategy of the user figuring it out when you yourself have not. If he could, he would not be reading this thread!
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then by all means the appropriate tools and methods can be introduced to help the user get to their final destination.
Yet help has not arrived after 600 posts. All we hear is run ETC and then intuit your way past that. Wrong data is added to mix to confuse things further with respect to what ETC shows.
Quote:
i'm still waiting to see how i can determine whether one has accurate/precise localization and imaging from viewing the frequency-response. you said psycho-acoustics is with respect to the frequency domain, so please share how one can use the frequency-response with respect to intelligibility, localization, and imaging?
How many times do I say that no tool is necessary in this area other than RT60 for general liveliness of the space (even that could be done without)? Why we hear what we hear depends in part on the spectrum of the signal and I have extensively covered that in explaining audibility of comb filtering, fallacy of ETC measurements, etc. Go back 3-4 pages and you see all of this. To figure out what you need to do is as simple as what I quoted from Dr. Olive. There was no talk of frequency response tools in there.

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post #639 of 871 Old 07-23-2012, 09:32 AM
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Quote:
Originally Posted by audiophilesavant View Post

If people listened to you, in a few weeks they wouldn't be doing anything except perhaps buying some random furniture.
You are not seriously that confused about what is being said, are you? First, if they do as I say, they are listening to top experts in the field instead of people going by names such as Localhost127 and Dragonfyr. Second, there are two spaces:

1. Everyday listening spaces like living room. Here, we look to normal furnishings and how they can act like acoustic products. Look at how effective they are in reducing late reflections:

i-jjWhnJp-XL.png

It is a wonderful thing that we can make such huge improvements by just furnishing our rooms properly. Solutions do not need to be ugly to work.

2. Dedicated listening spaces. As I have shown in the design of our reference home theater, since you are starting with an empty room and the target is not to make it look like a living room, you do indeed deploy acoustic products. Such rooms do not have sufficient amount of "furnishing" so additional amount needs to be provided. Even here though you have the same choices as #1. The carpet for example should be deployed in the similar manner lest you tell me you have put 8 inch absorbers on the floor as Local claims is necessary there.

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post #640 of 871 Old 07-23-2012, 09:46 AM
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It is a wonderful thing that we can make such huge improvements by just furnishing our rooms properly.
Describe the process you would go through to furnish a room "properly" and explain how you would determine whether, once so furnished, your efforts have resulted in "huge improvements".
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post #641 of 871 Old 07-23-2012, 10:08 AM
 
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...Let's see...do you prefer the early American acoustical response ... or the Danish modern acoustical response?
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post #642 of 871 Old 07-23-2012, 10:42 AM
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Quote:
Originally Posted by amirm 
As long you then just stare at it in your condo devoid of listening tests, then you don't know anything. This is why you have confused yourself thinking you can fix bad speakers with them. I challenge you to show me how you can match a well designed speaker with a bad one with your "reflection phase grating" device. Go ahead and show us how your device fixes these problems that I asked Bigus about:
Quote:
Originally Posted by amirm 
Show how your diffuser fixes the off-axis dip in speaker B. You can't of course any more than Bigus could.

this guy's entire discussion is based around operator errors. either that of the process for particular measurement tools, OR the application of 'treatment' to fix issues it is not normally used to address.

now he's attempting to discuss the user of "diffusers" to address off-axis speaker issues? good lord! completely and utterly clueless!


Quote:
Originally Posted by amirm 
It matters not in this context. You can't fix a bad speaker with slapping material on the wall. And you can make things worse.

continuing on with your 'operator error' stance.

and just where are all the AVS members who subsequently ripped down the treatments due to it "making things worse"? care to start an AVS poll? if you were confident, you would have already done this but we both know the results...

Quote:
Originally Posted by amirm 
Not at all. As I have noted, we have built ours too. But we did it based on careful design. We didn't do it because someone said so on a forum who doesn't even own a listening space as is the case with you. And has fantastical notions of what is a broadband diffuser.

i see auralex t'fusors and some RPG PRDs and some other MLS' - where are the diffusers you "built"?

fantastical notions, eh? clearly they don't teach you in CEDIA courses that sound has size and objects must be large with respect to wavelength. physics 101.

Quote:
Originally Posted by amirm 
The other thing you are ignoring is that there are powerful techniques that tame the room effect which have nothing to do with a) acoustic products and b) frequencies above transition that the few of you are so fixated on. Great examples of them are outlined in my WSR Article on bass optimization, http://www.madronadigital.com/Library/BassOptimization.html, and as described by Dr. Toole. You can get seat to seat variations this good:

lol - you fall back to LF modal region (sorry, the ROOM region rolleyes.gif ) anytime you dig yourself into a hole. what on earth does the modal region or your graph have to do with localization, imaging, intelligibility, etc. the LF modal region is your equivalent of a "security blanket". and it's laughable you spend so much time referencing rt60 times, yet never discuss or show the LF modal decay times via the waterfall/CSD. you consistently only show frequency-response, completely ignoring LF decay times. the article you keep referencing is mickey-mouse stuff. it's the equivalent of online marketing brochure. no meat in there - stop presenting it like it's of any value. stick to copy-paste parroting of others work - it's what you're good at.

Quote:
Originally Posted by amirm 
As you see, there is no mention of any acoustic products yet amazing amount of improvement in room response is achieved. Those techniques are not subject to psychoacousistics and therefore very reliable. Measurements tell the truth and the improvements are immediately audible and apparent. Instead of fixing 20 dB swings in your frequency response that anyone can hear and appreciate, you keep wanting to talk about the smaller problems above transition frequencies. Priorities are not there because you don't practice any of this. If you had spent time optimizing the bass, you would know the great benefit it provides and you would put things like DSPs in your vocabulary than "reflection phase grating."

no one ever debates the impact of addressing the modal region. in fact, it's discussed so little because there is little to debate! no one really disagrees at all on addressing the modal region. give it a rest!
and what on earth does a reflection phase grating have to do with the modal region? you don't even understand the treatments and you continue to attempt to discuss with authority. and you refer to issues above the transition region as "smaller problems" - so any issue with respect to intelligibility, localization, or imaging is considered a "small problem" to you? good to know -

im still waiting for you to show me an example frequency-response with good and bad imaging and localization. it was you that said psychoacoustics is with respect to the frequency-domain. are you going to back your statements or no? show me what i need to look for in the frequency-response to know if i have localization or imaging problems.
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post #643 of 871 Old 07-23-2012, 11:33 AM
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Originally Posted by Bigus View Post

Lol, just saw your last post. Just itching for an opportunity to post that again weren't you. Thanks for putting an exclamation point on my point for me!
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post #644 of 871 Old 07-23-2012, 11:49 AM
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And folks such as yourself have absolutely no formal training in acoustics.
Dragon: You know this statement is wrong.
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post #645 of 871 Old 07-23-2012, 11:49 AM
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Amir has detailed files on every poster.


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Originally Posted by amirm 

I don't keep them on my client system at all. There is this thing called the Internet and the cloud. I store it all on Google servers. Indexed by them so that I can use them on any device I use.
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post #646 of 871 Old 07-23-2012, 01:12 PM
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now he's attempting to discuss the user of "diffusers" to address off-axis speaker issues? good lord! completely and utterly clueless!
You quoted a reply from me to Bigus. This is what Bigus said:
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Originally Posted by Bigus View Post

You may or may not wish to exchange the speaker for many other various reasons. If not, you can modify the boundary to restore spectral balance.

See? In blue and white he says he can fix the speaker response this way. I asked him how. He would not answer. You then quoted me and said you build your own diffusers. So I asked you how that solved the problem. Now you state my position so had no business quoting my reply to him. I assume you are calling Bigus utterly clueless?

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post #647 of 871 Old 07-23-2012, 01:52 PM
 
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If the error in spectral balance is due to the superposition of a direct with a reflected signal resulting in polar lubing and derivative comb filtering, treatment can very possibly resolve this. This is a common issue routinely addressed.

This is resolved dependent upon the exact nature of the issue and the topology of the specific case.

Absorption can effectively 'remove' the superposed indirect source, hence eliminating the interference; or diffusion can be used to reduce the intensity of the indirect signal while retaining the energy (albeit in a more greatly temporally and spatially distributed manner) in the room - with any resultant polar lobing and subsequent comb filtering being rendered 'closely packed' and non-psycho-acoustically objectionable.

If however the issue is a non- uniform power response is a result of 'uneven' coverage of the various spectral passbands as a result of differing coverage of he drivers and speaker functioning as a waveguide, treatment can PARTIALLY resolve this in the form of absorbing portions of the polar dispersion that 'exceed' the coverage of the more restricted spectral components. But, while this is possible, it is a brute force attempt to solve that which would be better resolved by the design and subsequent choice of speaker. ...As while we can perhaps reduce the additional derivative coloration due to superposition in the regions of spectral polar lobing, we cannot resolve the fundamental coloration due to the uneven power response itself exhibited by the direct signal itself.

What is sad is that someone so well versed in acoustics and psycho-acoustics and simple superposition, should not be intimate with this and would waste everyone's time repeating such a fundamental question Over and over ad nauseum - something they should have learned back in physics1.

Funny, even Toole knows this..hence his advocacy of laterally placed diffusion (and ceiling placed use of 2D diffusion redirecting energy to the side walls, adequate spacing permitting). But apparently his writer of book reports failed to find such concepts effectively highlighted in his word searches.

And just to be clear, it is YOU who are "utterly clueless".

.
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post #648 of 871 Old 07-23-2012, 02:33 PM
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Amir, as dragon correctly stated, poor off axis response can be tackled by selective absorption. Yes, it is brute force. I said earlier it isn't an easy task. Addressing the speaker is certainly ideal, but as I said there may be many other factors in play that might make one consider such selective absorption as an alternative.

How? For porous absorbers, their effective bandwidth is determined by depth. Place a nonporous membrane at a specified depth and you will absorb effectively only to that depth, until you are low enough in frequency that the membrane becomes largely transpartment to sound. By creating a compound structure composed of areas of varying depth membranes and of varying materials, you can absorb peaks in off axis response and allow valleys to much less absorbed, thus the reflected energy will be much closer in spectral content to the direct signal.

How exactly to do this? Not easy. You won't find math to easily guide you to a solution. Conceptually, imagine a layered construction that has known absorption peaks over certain bandwidths. You can create many such types of layering, each best at absorbing certain bands. A composite panel would the be constructed by combining the correct amount of each type, say in 4" squares. Practically, you still won't be able to "derive" any particular construction, and the process will devolve into tedious trial and error. I said that earlier too. In any case, ETC can identify the spectral balance of the reflection before and after treatment to let you know if it is a problem and whether you have improved it if desired. You won't get a perfect solution as that specific reflection is altered to a much greater extent than the total energy spectrum in the room, but the change does address specific energy that has the strongest perceptual effect on timbre. The accuracy of the correction is largely limited by patience.

Another option is to use enough broadband absorption to push the reflection gain low enough such that it makes little perceptual contribution, and then use multichannel ambiance extraction like logic 7 as a replacement. This would also be in line with what toole has said.

You make blanket statements that such is not possible, contradicts basic math and physics, etc. As is often the case, you are flat wrong.

Please stop spreading your lies on this forum. Please stop substituting slimy behavior for a legitimate response. And if you are mad and want to insult me for exposing your ignorance, for heaven's sake be man enough to use your own words.


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post #649 of 871 Old 07-23-2012, 07:25 PM
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Quote:
Originally Posted by dragonfyr View Post

If the error in spectral balance is due to the superposition of a direct with a reflected signal resulting in polar lubing and derivative comb filtering, treatment can very possibly resolve this. This is a common issue routinely addressed.
This is resolved dependent upon the exact nature of the issue and the topology of the specific case.
Absorption can effectively 'remove' the superposed indirect source, hence eliminating the interference; or diffusion can be used to reduce the intensity of the indirect signal while retaining the energy (albeit in a more greatly temporally and spatially distributed manner) in the room - with any resultant polar lobing and subsequent comb filtering being rendered 'closely packed' and non-psycho-acoustically objectionable.
If however the issue is a non- uniform power response is a result of 'uneven' coverage of the various spectral passbands as a result of differing coverage of he drivers and speaker functioning as a waveguide, treatment can PARTIALLY resolve this in the form of absorbing portions of the polar dispersion that 'exceed' the coverage of the more restricted spectral components. But, while this is possible, it is a brute force attempt to solve that which would be better resolved by the design and subsequent choice of speaker. ...As while we can perhaps reduce the additional derivative coloration due to superposition in the regions of spectral polar lobing, we cannot resolve the fundamental coloration due to the uneven power response itself exhibited by the direct signal itself.
What is sad is that someone so well versed in acoustics and psycho-acoustics and simple superposition, should not be intimate with this and would waste everyone's time repeating such a fundamental question Over and over ad nauseum - something they should have learned back in physics1.
Funny, even Toole knows this..hence his advocacy of laterally placed diffusion (and ceiling placed use of 2D diffusion redirecting energy to the side walls, adequate spacing permitting). But apparently his writer of book reports failed to find such concepts effectively highlighted in his word searches.
And just to be clear, it is YOU who are "utterly clueless".
.
You know, as I was reading that post, I had a smile on my face as I thought we had a breakthrough. A post that was 100% technical and devoid of emotions, bickering, and insults. Then I got to the end and realized the scorpion is always a scorpion.

Anyway, as always, you are living in some parallel universe with the rules of its own. In that Universe, you get to quote Dr. Toole yet be spiteful of anything else he has to say. Additionally, your world turns on what meters and graphs tell you rather than how we hear.

I have quoted extensive research and documentation on why comb filtering is not audible and indeed, its effect can be a positive one. To run off with another post assuming otherwise in an answer to me is just silly. Just read my posts and research points where comb filtering is shown to be a positive, not negative.

You lay out a smorgasbord of speaker issues to be resolved. What is absurd is to assume anyone reading this thread and your post would have any data or insight into what ails their speaker in that manner. Speaker companies rarely release relevant data that includes off-axis response of the speaker let alone at the angles of interest. You also assume "superposition" is something that can be turned on and off. It cannot unless you create the padded cell I talked about. As otherwise, you are going to have reflections from all the surfaces including some like carpets which you are not going to want to make thick enough to absorb. So if a speaker has poor off-axis response, that is going to keep contributing to the poor output of the speaker even if you made the side walls full of fiberglass.

But let's play along and put your theory to practice. Dr. Toole outlines an experiment to evaluate what happens if you absorb poor off-axis response vs a speaker that has much less of it at the start:

"In Chapter 8, an experiment was described in which two wide-dispersion loudspeakers were compared to a loudspeaker with reduced lateral dispersion. The wide-dispersion loudspeakers were preferred, in spite of them both having irregular off-axis frequency responses. Even with this defect, the wide-dispersion loudspeakers were judged to be superior in terms of both sound quality and spatial quality. The stronger lateral reflections would generate a greater impression of ASW/image broadening, which is probably a positive attribute, and the same reflections, and those that follow them, will contribute to an enhanced sense of timbral richness, which is probably also beneficial."

And this is the main issue with trying to fix the speaker's off-axis response with acoustic material assuming it fixable (i.e. it is NOT a dip as the common case I presented which cannot be resolved as you concede). That as humans we have such strong preference for existence of side reflections, that fixing the speaker with removing them, is a net negative. The cure is worse than the disease it seems. What made sense on paper and a meter/graph, doesn’t make sense to a real human experiencing the same.

Then there is the issue of practicality. Few people will tolerate an absorber in their living room. In that regard you absolutely want a good speaker to give you maximum flexibility. And it is not like speakers with smooth off-axis response are expense. Some cost just a few hundred dollars or hardly more than what you would spend on absorption panels.

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post #650 of 871 Old 07-23-2012, 07:41 PM
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Originally Posted by Bigus View Post

Amir, as dragon correctly stated, poor off axis response can be tackled by selective absorption. Yes, it is brute force. I said earlier it isn't an easy task. Addressing the speaker is certainly ideal, but as I said there may be many other factors in play that might make one consider such selective absorption as an alternative.
How? For porous absorbers, their effective bandwidth is determined by depth. Place a nonporous membrane at a specified depth and you will absorb effectively only to that depth, until you are low enough in frequency that the membrane becomes largely transpartment to sound. By creating a compound structure composed of areas of varying depth membranes and of varying materials, you can absorb peaks in off axis response and allow valleys to much less absorbed, thus the reflected energy will be much closer in spectral content to the direct signal.
How exactly to do this? Not easy. You won't find math to easily guide you to a solution. Conceptually, imagine a layered construction that has known absorption peaks over certain bandwidths. You can create many such types of layering, each best at absorbing certain bands. A composite panel would the be constructed by combining the correct amount of each type, say in 4" squares. Practically, you still won't be able to "derive" any particular construction, and the process will devolve into tedious trial and error. I said that earlier too. In any case, ETC can identify the spectral balance of the reflection before and after treatment to let you know if it is a problem and whether you have improved it if desired. You won't get a perfect solution as that specific reflection is altered to a much greater extent than the total energy spectrum in the room, but the change does address specific energy that has the strongest perceptual effect on timbre. The accuracy of the correction is largely limited by patience.
Another option is to use enough broadband absorption to push the reflection gain low enough such that it makes little perceptual contribution, and then use multichannel ambiance extraction like logic 7 as a replacement. This would also be in line with what toole has said.
You make blanket statements that such is not possible, contradicts basic math and physics, etc. As is often the case, you are flat wrong.
Do you read what you post? Do they make sense to you? Read them again and pay attention to the sections in blue.

Now think between the lines. I have a $2000 pair of speakers. You just proposed what for me to do to fix them? BuilD this contraption you can't even properly describe with all of the hand waving? And if doesn't work I am supposed to keep iterating? And even then it won't be a perfect solution? Pray tell, how imperfect will it be? Can you even quantify it? How many membrane panels of this type have you built? Can you share pictures and measurements?

You are a fan of dipole speakers. Speaker M below is such a design:

Toole-loudspeakers-and-rooms-p394.JPG

Quantify for us what type of acoustic product solves the myriad of problems that ails that speaker. I will take anything.
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Please stop spreading your lies on this forum. Please stop substituting slimy behavior for a legitimate response. And if you are mad and want to insult me for exposing your ignorance, for heaven's sake be man enough to use your own words.
I back everything I say with references and data. If they are lies, then the experts are lying. Your posts on the other hand are devoid of references and personal data. It is fine to state an opinion. Just don't ask me to believe them when they appear to be paper napkin thoughts from someone who apparently doesn't even have a measurement mic let alone be a higher authority than the experts I look to in this area. So there. I was direct smile.gif.

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post #651 of 871 Old 07-23-2012, 07:52 PM
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And round and round your arguments go.

'ETC can't be used when surfaces are not broadband.'

Except that it can, in fact can be particularly useful investigating this situation.

'But it doesn't matter because you can't improve a reflection's spectrum to better match the direct signal.'

Except that you can.

'But that is still bad because more sidewall reflections are good. People like them.'

Except that some don't. And except that in dedicated multichannel setups, per toole, any such benefit dissolves.

'But padded cells are bad.'

Except that we aren't advocating a padded cell. Indeed, instead of bothering to optimize treatments for the conditions, he posts suggested schematics from toole that show quite a bit of absorption, more than is likely needed, as in the padded cell variety. And you can use ETC to help preserve energy in the room.

'But ETC lies...'

And round and round you go.


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post #652 of 871 Old 07-23-2012, 08:07 PM
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Originally Posted by amirm 
Do you read what you post? Do they make sense to you? Read them again and pay attention to the sections in blue.
I can't see colored text on the tapatalk app.

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I have a $2000 pair of speakers. You just proposed what for me to do to fix them?
Replace them if they are poor speakers. If for some reason or another you can't or won't, you can however improve the situation.

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You are a fan of dipole speakers. Speaker M below is such a design:
Speaker M is a poor excuse for a dipole. Arguably doesn't even fit the description. And I wouldn't have it. That being said, I stated that you can't derive a solution in a straightforward way. The easiest way to proceed down that path is through trial and error. You read that, and still made your predictable demands to calculate this, do that...

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Quantify for us what type of acoustic product solves the myriad of problems that ails that speaker. I will take anything.
You will take anything as more potential targets to attack, more ways to divert attention from your ineptitude, more food for the troll. Make no mistake amir, you are the worst type of forum troll.

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I back everything I say with references and data.
Data you often don't understand, misinterpret, and still regurgitate ad nauseum.

Tell you what, find a reference that supports your assertion that ETC can't examine the frequency dependent filtering a boundary may impose on incident energy.

Find a reference that says absorbers can't be constructed to target specific frequency bands.

Find a reference that supports your most amusing use of a sample in the context of statistics as being a single value from the curve.

Find a reference that supports your insistance that you can correct opinions. biggrin.gif

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It is fine to state an opinion. Just don't ask me to believe them when they appear to be paper napkin thoughts from someone who apparently doesn't even have a measurement mic let alone be a higher authority than the experts I look to in this area.
I dont care if you believe me or agree with my opinion, I just want you to cease spreading misinformation and misinterpretations and thus doing damage to this forum. Go do that to your own forum. Sad that all it often takes is napkin thoughts to expose your ignorance. And I never claimed to be an expert... just smarter than you.



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post #653 of 871 Old 07-24-2012, 05:48 AM
 
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I have quoted extensive research and documentation on why comb filtering is not audible and indeed, its effect can be a positive one. To run off with another post assuming otherwise in an answer to me is just silly. Just read my posts and research points where comb filtering is shown to be a positive, not negative.


And this is the main issue with trying to fix the speaker's off-axis response with acoustic material assuming it fixable (i.e. it is NOT a dip as the common case I presented which cannot be resolved as you concede).

LMAO!!!


First, such carte blanche statements as the first is utterly and completely BS. "Comb filtering is not audible". Not some comb filtering depending upon the width of the notch, or even the spacing (density) of the notches is not audible...or indeed, seeing as how comb filtering does NOT even exist in nature but instead refers to the spacing of spatial polar lobing on the distribution of a signal - a FUNDAMENTAL concept about which you still have no grasp as you continue to think that a pattern on a frequency response MEASUREMENT is REAL!!!!!

Nope, instead we get "comb filtering is not audible".

Your assertion is WRONG. The effects of polar lobing - what you think actually exists as comb filtering in nature - can INDEED be VERY audible! If the polar lobing is sufficiently dense and depending upon the bandwidth of the effected lobe, is it necessarily objectionable? No. But if the lobing is not dense and/or if the bandwidth is not narrow? Yes, it absolutely can be VERY audible.

But keep reading your book, whose conclusion has morphed all over the spectrum, ranging from telling us how we NEED to treat a room to now where no treatment is necessary except for a trip to IKEA.. But hey, since we all become used to a sound and adapt, and seeing as how many grew up listening to rock and popular music on mono AM car radios, why bother at all, as we all grew accustomed to it and we all survived.

Seeing as how you lack any formal training in actual acoustical physics, one can only imagine what will happen when you read a second book. My guess is schizophrenia as you tear yourself apart trying desperately to reconcile the differences, having no foundation of physics upon which to evaluate and qualify the various physical behaviors described.. As we already see the signs of simple delusion as you simply are lead about by logical descriptions without the benefit of any actual understanding of the actual physical behavior.

And yet we are treated to your admonitions against measurements insisting as you do on the primacy of experience - yet you fall victim to an even worse malady of following a book around without any conception of the actual behavior it describes - unable to evaluate claims as both your first hand knowledge and experience in acoustics. If word searches and cut and paste were sufficient, you would be a world class acoustician. But unfortunately they are not.

It is seriously past the point where all of us on this forum should avoid you like the plague you represent. At this point you offer nothing constructive. You are unable to apply practical knowledge to empirically solve ANY acoustical problem. And with your HUGE latest revelation that "comb filtering is not audible" you conclusively demonstrate that you do not have a clue.

And we haven't even gotten to your audacious claims about fixing an anomaly in a speakers response of which we are provided no information as to the baseline response, crossover information, and as such cannot easily separate what is a driver-driver speaker sourced anomaly and what is speaker-room based as you sling your crap about without qualification, effectively dumping a child's toy box onto the floor and demanding to know which toy hit the floor first.

And then you assert that " it is NOT a dip as the common case I presented which cannot be resolved as you concede" "I concede", huh? Really? What I concede is that you are utterly unable to construct a coherent case for ANYONE to evaluate - keeping far too many variables hidden as you falsely posit cases that no one is able to properly ascertain any more than one can conclusively solve (ab x cd x ef) = 75.

My suggestion is for one to read Toole yourself. What he proposes is not really radically new. Many of he ideas have been around for many years, without having gained substantial traction. Some ideas are quite interesting. And some, depending upon one's preference may actually be something that one may want to incorporate. But as to whether he has reinvented acoustics, the answer is a definitive "No". And as far as the asinine interpretation that his approach is the ONLY legitimate approach, that a zealot book report writer has interpreted as a license to demand that all others must capitulate - well, words do not convey the sense of nausea that that notion generates.

After all, whatever happened to Toole's assertion hat folks can adapt and become accustomed to just about any environment or response? After all, people here have become accustomed, however uncomfortably, to the crap that is routinely presented by someone whose claim to fame is to have written a very poor book report and who personally lacks the acoustical knowledge to adequately ascertain just what is real and what is hype.

And as I said previously, its time for responsible people who DO seek to actually learn more about acoustics and who hope to apply the concepts - and who also want to be able to objectively and subjectively verify the effects of such behavior, to ignore you and your one trick dictatorial BS pony.
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post #654 of 871 Old 07-24-2012, 07:59 AM
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Originally Posted by dragonfyr View Post

LMAO!!! First, such carte blanche statements as the first is utterly and completely BS. "Comb filtering is not audible". Not some comb filtering depending upon the width of the notch, or even the spacing (density) of the notches is not audible...or indeed, seeing as how comb filtering does NOT even exist in nature but instead refers to the spacing of spatial polar lobing on the distribution of a signal - a FUNDAMENTAL concept about which you still have no grasp as you continue to think that a pattern on a frequency response MEASUREMENT is REAL!!!!!
In the context we are talking about, comb filtering caused by side reflections, study after study shows it to be a beneficial effect. Both frequency and time domain measurements lie relative to what we hear. Don’t be a slave to a dumb meter lest you want to be the same place it is.
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Your assertion is WRONG.
It is not my position. It is the position of top experts in the industry. I assume you know that clearly but use this as a debating tactic as you know you can’t set yourself up to be superior to them (although you do try – see the end of my post below). As I said to Bigus, if there is something wrong, you need a) establish you know more than these experts, b) show your own data and experiment results, c) your own references. You do none of this other than come back with another emotional response insisting that these top experts are wrong. That doesn’t amount to anything nor does it add any information to the thread. Your intimidation tactic seems to have worked with Bigus and I assume others but it has no effect on me. The fact that you keep trying demonstrates lack of commonsense.
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But keep reading your book, whose conclusion has morphed all over the spectrum, ranging from telling us how we NEED to treat a room to now where no treatment is necessary except for a trip to IKEA..
Another tired, repeated attempt at misstating Dr. Toole’s position. Just yesterday I explained how we face two situations: 1) a multi-use room such as a living room or 2) dedicated space. The former does not call for filling it with acoustic devices especially the extreme versions you all recommend. If you are single, and don't care about what the room looks like, sure, go and fill it with acoustic products. No one will stop you. What I and Dr. Toole are trying to stop is people pretending that unless you do that, you can't get good sound. You absolutely can. Furniture will help tremendously with reducing late reflections. Carpets for example, if you understand psychoacoustics and are not slave to a dumb meter, help with first reflection there just the same. Talking about that, what is your excuse for ignoring my question to you in that area multiple times? How did you make the carpet broadband?

I have also asked repeatedly to see how your camp has treated their living room with such products. None of you produce any pictures. Turns out Localhost doesn't even have a listening space -- living room or otherwise. So we know his recommendations to others which he himself does not follow doesn’t count. What is your excuse for not posting pictures of your living room showing us that you shop at RPG for decoration instead of IKEA?

When you have a dedicated space where the look can be that of a listening space, then sure, you use acoustic products as we have. One has to be aware of customer requirements. A 70 year old who just wants a reliable car to go to the store cannot be told to buy a sports car because it handles better than the Camry he is trying to buy. Telling him otherwise shows that you don't live in the real world taking in full requirements of the customer. I have to live in one. We have real customers we have to serve. And I assume when someone in this forum posts questions, it is a real situation too and not a made up world where absorbers can be put on windows instead of curtains. Note the title of the thread. Can furniture improve the sound of a room? Of course it can. Compare an empty room with one having furniture in it. If you have never done that comparison, then you have missed the ABCs of this business.

Another thirty rounds will go by but at the end the facts are as I stated. You dispute the work of top experts in this industry which unlike you, have to earn a living this way. Unlike you they published their work in respected journals and books. Unlike you they have access to test environments such as anechoic chamber so that they can test single effects such as reflections. Unlike you they write under their real name so if they are wrong, it soils their reputation and prospect for making a living. Unlike you, they stick with facts rather than thinking we get scared of insults and buzzwords. Unlike you, they are honest brokers. They don't say Bigus knows nothing about acoustics, lies about what is being said, then come here and try to defend his fantastical views of fixing speakers with what goes on the wall. (You honestly bought his version of building a car to drive to work with tootpicks with his membrane idea?) And then fail just like him to answer two specific speakers put forward with more detail than anyone usually has and comes back instead with this kind of diatribe.

As Dr. Toole says, what is presented is a biased view. The view is not commercially motivated but is rooted in real science. That science is explained in hundreds of pages of documentation. Heaven knows Dr. Toole could say what it is and call folks like you who disagree stupid with a "LMAO" and move on. He certainly has gained enough respect to do that. But instead, his book goes on for many, many chapters in full detail documenting and proving his point of view. Even if you don't agree at the end, you learn a ton about audio and it heavily puts doubt if not downright dispel the myths people throw around in these threads, believing their dumb meters instead of how we hear. If I told people here that two CD players have frequency response that varies by 0.1db and hence they would sound different, they would go nuts, demanding listening tests. And their position would be that listening tests trump measurements. Yet the same people in this thread, in post after post, and in agitated mood no less, argue that we should keep chasing measurements like ETC over how we hear. They seem completely oblivious to how inconsistent they are being. It has fallen on my shoulders and my shoulders alone to justify that we should care about what we hear. And what we hear is different than what we measure and sometimes by a mile.
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Seeing as how you lack any formal training in actual acoustical physics, one can only imagine what will happen when you read a second book.
Formal training? I have formal training. You are the one who lacks it. I am trained by the top experts that I quote here. I am trained in the latest understanding of this science. Your training on the other hand seems to be from Navy work on light as if that is the same as how our two ears and a brain hear sound. Outside of that, you have been in some ancient seminars on how to use tools like ETC. That's cool. You have done more than others. And you can spell more words. But in no way does that approach the work and knowledge of the experts I quote who have been my teachers. Or make your understanding of science more accurate when you have been completely sleep when the science of how we hear was taught. That is why you talk about "actual *physics*" as the important bit, rather than science of psychoacoustics. Instead of that, you need to study how our hearing system works. How its bandwidth is variable and hence can’t hear comb filtering due to notches being too small as soon as its frequency starts to go up above 500 Hz. This is the science that I know and not from any seminar but work experience and managing 20+ PhDs whose job was to advance this area for more than a decade. While not big on putting my name on patents, if you look me up you will see my name in such area (http://www.patentmaps.com/inventor/Amir_H_Majidimehr_1.html).

I also have three decades of experience in audio and signal processing. Again, my job required it as did my degree program. So what you know I can know in fine detail. There is a reason I have explained more about how ETC works than you have by a mile.

None of this makes me a better or smarter person than you. It simply means I am more up to date and have read and understood more relevant research than the few of you have. I have also had the pleasure of spending considerable amount of time with the experts who are leading this area of research. Again, my job, in this case the company I founded, Madrona Digital, gives me that privilege. You keep quoting Dr. Toole where convenient. But of course you have not spend any time with Dr. Toole or you would immediately know that he would not tolerate one second with you talking the way you do. His expertise like mine started with psychoacoustics. He has no patience for anyone who throws out that science at the starting point as you do.
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My guess is schizophrenia as you tear yourself apart trying desperately to reconcile the differences, having no foundation of physics upon which to evaluate and qualify the various physical behaviors described.
That is your dilemma, not mine. You are the one that has to explain why what we hear is not what we measure when you are so slaved to dumb meters. I used to be that way relying on forums for my net knowledge. The reason is that little of what Dr. Toole makes it into these discussions and what does gets stomped on by people like you. What I like about Dr. Toole’s teachings is that it all “hangs together.” He discusses everything, your point of view and his. He then connects it all in a comprehensive and authoritative way. Best of all, he shows you how to move forward without having to understand much of the complexity. Those are all proof points. The final job is dead easy. No need to go and brush up on band limiting of ETC I am afraid. That is the sign of a good teacher. He is able to distill the knowledge to where it is useful. I quoted Dr. Olive’s summary earlier. Wasn’t that dead easy to follow? If you have to obfuscate your solution so much with fancy words, maybe there is a problem with your approach.
Quote:
And we haven't even gotten to your audacious claims about fixing an anomaly in a speakers response of which we are provided no information as to the baseline response, crossover information, and as such cannot easily separate what is a driver-driver speaker sourced anomaly and what is speaker-room based as you sling your crap about without qualification, effectively dumping a child's toy box onto the floor and demanding to know which toy hit the floor first.
Here is the other thing you do. You don’t read the posts. My position is what you just stated. That you cannot know any of this, so therefore you can’t even begin to claim you can fix speakers with acoustic products. Yet Mr. Bigus says you do exactly that in his post with wall treatments. I say he cannot, and even in my response to you say the same thing about lack of off-axis data. Yet here you come pretending my position the opposite after I had the identical interchange with Localhost where I clarified the same.

So put please aside your angst long enough for the blood to clear from your eyes and read what is written. You waste my time and that of the forum with these information free emotional outbursts.
Quote:
My suggestion is for one to read Toole yourself. What he proposes is not really radically new. Many of he ideas have been around for many years, without having gained substantial traction.
Says who? A guy who is not in the industry and is stuck with a 1970s measurement? You are in that room by yourself. There is not one top industry acoustician who doesn’t quote Dr. Toole from time to time. Their research into using multiple subs is universally accepted for managing low frequency response. You yourself quote him left and right. But boy, quote him one bit after that and he is not a guy anyone follows? Why not say the sun comes out west while you are at it.

Didn’t I quote Dr. D’Antonio’s slides talking about his work and finishing his presentation on your case study of blackbird studio that he looks up to his teachings? Here is the slide again since you have forgotten about it again:

i-XFHWr3v-X2.png

Where does he park your ideas of LEDE, etc? Here:
i-tXbpPn6-X2.png
He recognizes Dr. Toole’s work as the most modern instantiation of what we know. You advocate in 1970s school of thinking and claim everyone stuck in your wagon wheel era still? Please give us some credit for intelligence to see through debating tactics devoid of proof points.
Quote:
And as I said previously, its time for responsible people who DO seek to actually learn more about acoustics and who hope to apply the concepts - and who also want to be able to objectively and subjectively verify the effects of such behavior, to ignore you and your one trick dictatorial BS pony.
It is a shame we have no evidence of you two practicing any of this seeing how you have shared no data, no list of equipment, no list of acoustic products, no measurements, and no pictures of anything you do that has to do with audio or this topic. Real shame….

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post #655 of 871 Old 07-24-2012, 08:44 AM
 
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I am not even going to bother to read the crap.

All "comb filtering" is not the same.

He reads the word "lateral" and all thinking ceases.

Let's look at some COMB FILTERING.

And this time you tell us how the causal factors are equivalent and NOT discernible in LISTENING TESTS!

So comb filters are comb filters, huh?

And not audible? Really?






In the first we have comb filters induced by the arrival and superposition of a very early arriving 3ms sparse signal well within the Haas interval.
You will NOT hear the reflection as a discreet event - rather it will be smeared and combined with the direct signal.
But the effects of the polar lobing and derivative 'comb filtering' pattern is VERY audible in the frequency domain!






In this we see a sparse signal that arrives VERY late at ~185ms after traveling ~209 FEET further than the direct signal.
The irony is that this is not discernible in the frequency domain. Rather it is perceived in the TIME DOMAIN as a VERY distinct SLAP ECHO!

But, but, but...."comb filters are not audible", and the frequency response is all one needs to fully ascertain acoustical behavior. Yeah, right. And I think we can say that merely reading one book is absolutely not sufficient to claim to understand acoustics.

Its a shame clown school does not qualify one as an acoustician.

But this is what you get from folks who only conduct word searches but who have NO functional understanding of what they read.rolleyes.gifrolleyes.gifrolleyes.gif

And since live sound and modelling are not an issue here, we will leave out SysTune and Smaart and EASE...




And nitwit, the presentation of the CHRONOLOGY of ideas does not indicate their level of sophistication or correctness as is readily apparent in your IGNORANCE of them. If anything, you can follow the development of the tools that resulted DIRECTLY as a result of the various proposals...But then except for that PDF, you have absolutely NO ideas as to what was developed and why? Do You??? I can cite a myriad SPECIFIC developments both in theory as well as in hardware that resulted SPECIFICALLY from the efforts of Don and Carolyn Davis.

And as far as this bit of rotten tripe: "None of this makes me a better or smarter person than you. It simply means I am more up to date and have read and understood more relevant research than the few of you have" It in fact, makes you NEITHER. I have read Toole, and was aware of his work LONG before you since back in the late 1980s. Unfortunately you are aware of only one book - and with it you cease to study acoustics and simply become a uncritical follower of a personality - "but Tooles says..."..... And not very much of that. And you know next to nothing of the larger context of acoustics - a fact readily apparent with your last substantial gaff.

Get a clue...


Now, we can all hold our breaths in weighty anticipation of which of the same sections he will again cut and paste, seeing as how he is incapable of independently expressing the ideas without mere paraphrasing.rolleyes.gifrolleyes.gifrolleyes.gif

...that is if he even realizes that we just demonstrated a case where the frequency domain did not provide sufficient information regarding the subjective effects/perception of physical cause, but where we had to rely on the time domain. But, but, but....
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post #656 of 871 Old 07-24-2012, 09:07 AM
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But the effects of the polar lobing and derivative 'comb filtering' pattern is VERY audible in the frequency domain!
I am not going to repeat for you why this is wrong just because you want to rehash it and stay in denial about the science of how we hear. Here is my reply again: http://www.avsforum.com/t/1413173/does-sound-sounds-better-in-a-room-full-of-furniture-and-stuff-or-without/390#post_22198248

I will copy it again here in the small hope that you will read it this time. Note how it includes personal data from me rather than graphs you duplicated that said not to:
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There is no frequency information in that [ETC] graph. We have amplitude vs time. Much of what we know in psychoacoustics comes from the frequency domain. Let's go back to mother of such research with Fletcher-Munson equal loudness graphs (circa 1930s):
400px-Lindos4.svg.png
The graph shows the ear’s sensitivity to level and how it varies substantially based on frequency. Each one of those lines represents the same perceived volume. This concept is used in audio compression for example where we can increase the distortion/noise level of low and high frequencies and still have the distortion be inaudible (or relatively so compared to the most sensitive mid-frequencies). An amplitude measurement is devoid of frequency components so you can't perform such analysis and take action appropriately. The FHG graph for example showed an impulse reflection from the carpet prior to addition of the absorber. The carpet clearly filtered the sound before reflecting what was left back. A reflection that was not filtered would have had a different audible impact when combined with the direct sound.
The above is the reason perceptual (psychoacoustic based) audio codecs are almost always "transform based." The audio samples are converted into the frequency domain using an overlapped transform (so that we can invert it fully) and then we perform the analysis there. Once done, we transform back to time domain to get our original time varying audio samples. We would not bother with any of this if we could perform the same analysis in time domain using the music amplitude as our source of insight.

sorry, but the above graph in the frequency-domain has zero relevancy to the psycho-acoustics of intelligibility, localization, and imaging.
OK, I think answering this will take care of my backlog of questions. BTW, I added in the rest of the context in my quote which Local had taken out.

The reason I brought out the Clark experiment was to set the stage for this answer. There we noticed that reflections despite creating pretty nasty looking notches in the frequency response were not only not noticed as such in listening tests but actually praised! How can the ear not hear those dips? The instrument did. The answer has to do with psychoacoustics and how we hear.

Let’s review the problem again. The comb filter occurs because a signal is delayed and then mixed with itself. Let’s simulate that in the computer as I have done here:

i-PxrCt7C-X2.png
The display is logarithmic so it shows the dips bunching more and more together as frequencies go up. This is to properly represent them based on psychoacoustics which I will soon explain. If we had looked at linear scale we would see what Clark showed which is a series of regular notches whose frequency is the delay of the signal. Let’s park that for now.

We see that above that the signal is clearly distorted. That is what the meter sees which is highly linear device unlike our hearing system per Fletcher-Munson graph. So we need to map one to the other. A few years later, in 1941, Fletcher performed further analysis of our hearing system and came up with what is called “critical bands.” This is what they look like:

threashold_4.gif
In essence the ear works like a bank of filters each tuned to a different frequency. These are called auditory filters. As the critical bands show, there is peak sensitivity or resonance if you want to call it, and then the response drops off on each shoulder of the center frequency. While the filter bandwidth appears to be equal on that graph, they are not. Notice how the horizontal scale is logarithmic, doubling with each band. Look at the right tail of the 250 Hz. It extends to about 1 Khz for 750 Hz of bandwidth. The 4 Khz one on the other hand ends well past the 8 Khz point so it is much, much wider than the filter for 250 Hz. This means that our hearing discrimination for frequencies drops rapidly as frequencies increase.

A more refined modern instantiation of this is from Moore and Glasberg called “equivalent rectangular bandwidth” or ERB for short. It is very close to critical bands and likewise shows how as frequencies go up, the bandwidth of the filters increases. Here they are overlaid together:

img156.png
Hang in there. We are getting close smile.gif. As I noted, the frequency of comb filter is proportional to its time delay. If the time delay (i.e. extra distance from reflector) is say, 10 milliseconds, the frequency of notches will be 100 Hz ( f = 1/time). If we look at the Y axis for 100 Hz (10^2), we see that the critical bandwidth has been achieved at almost all frequencies! This means that the notches are not detected by the ear because they are too low in frequency width. The ERB however says that this won’t happen until the source frequencies get up to 500 Hz. By that measure, any notches shown above 500 Hz in our frequency simply are not detectable or detectably by much when a human listens to them. Putting it all together, we cannot stare at those frequency response measurements and decide there is a distortion. The ear is “blind” to those notches above 500 Hz in this instance.

As I noted in my last response, the right frequency response graph would take this into account and start to smooth the graph proportional to ERB as frequencies go up. We can perform a crude version in our audio workstation software by changing the FFT analysis resolution way down. The original chart had a resolution of just 0.3 Hertz! Clearly well below what we can hear. Let’s dial this down to 44 Hz by dialing down the FFT points to 512:

i-S7CTtnG-X2.png

We see a sharp drop in the notches. Sadly when folks want to talk you into buying acoustic product, none of this is taken into account and people put up the first chart and ask, “Doesn’t it look bad? Please buy an absorber to get rid of them.” Equiv. of that happens with spikes shown on ETC relative to where those reflections are. Well the absorber will do that but it is taking away a problem that does not exist in the first place – at least above 500 Hz as shown in the above analysis.

So what about below 500 Hz? Well that answer was given in the Clark analysis I post. In a real room, there are more than one reflective surface. Those reflections will tend to fill in the gaps so their amplitude is not what it seems. Importantly, as I showed there just the same, the two ears hear two different signals. Here they are again:

i-vrLJBM9.png

Look at the left ear vs the right ear. Remember comb filtering frequency is a function of distance. Since your left ear is farther way from the reflection from the right than your right ear, it picks up a different comb filter. Further, your head is a fairly effective filter at middle to higher frequencies. See this graph I provided to Bigus:

hrtf.gif

See how at the very low frequencies the two ears kind of track the same thing. But as frequencies go up, the two deviate and the ear that is in the shadow of the head, picks up much less signal. You would go nuts if the brain simply presented these signals as is. It would be like walking around with double vision and double tint! Fortunately reflections are a fact of life so the brain has learned to search for what is common between the two signals. In this case, it sees two different frequencies so it throws that aspect out and gives you a sort of an averaged function of the two. Such filtering and change (called HRTF) does not occur for very low frequencies and hence the reason psychoacoustics is not a concern there.

Now think of a real room where we not only have the one reflection arriving at the two ears differently but countless others which also arrive, likewise different in each ear. Once the brain applies this “central summation” to it, it mostly averages out. This is the reason why in Clark’s test even a huge 2 foot by 3 foot reflector that caused reflections as strong as the signal itself yet it was “barely noticed.”

You ask how we can tell all of this from psychoacoustics represented in that graph? Now you know. Your meter showing linear response in either time or frequency domain is woefully inadequate in capturing such effects. Yet that is what we want them to do: tell us what we are hearing. Unfortunately they cannot in the raw form.

As you see, it takes a lot of work to dig into topics like this. So the constant complaining about me not answering and childish positioning it as no answer exists was quite silly. ALL of this is explained and then some in Dr. Toole’s book. Only a person who has not read that work and related research would think there is no answer here. There are absolutely answers here. And they explain results of listening tests by large extent. The heart of which was the knowledge of how the hearing system works as it relates to frequencies and its non-linear nature.

Watch you come back with another measurement and claim what is there must be audible....

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post #657 of 871 Old 07-24-2012, 09:26 AM
 
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What? So now you just copy and paste everything you have all as a result of your looking like an idiot after your last bogus claim?

And you even toss in Fletcher Munson curves????rolleyes.gifeek.gifbiggrin.gif

Yup folks, it is only a "claim" that slap echo is audible. Yet our clown friend places diffusors only effective against flutter echo on his otherwise 'absorbent'(sic) walls!

And when we do bother to post a real measurement illustrating this, watch him play the crab as he illustrates his ignorance.

I still want to see an "ETC Meter"! And have you discovered what those 'partition things' are in studios? rolleyes.gif

You are not even worthwhile responding too....
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post #658 of 871 Old 07-24-2012, 09:54 AM
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I also have three decades of experience in audio and signal processing. Again, my job required it as did my degree program. So what you know I can know in fine detail. There is a reason I have explained more about how ETC works than you have by a mile.

good lord - you only just learned what the x-axis on the ETC represents a mere week or two ago! and this is AFTER you have been attempting to discuss the tool with authority for months! sad fact is, you outed yourself on your lack of understanding on the ETC...self inflicted wound.

and look at this: http://www.avsforum.com/t/1413173/does-sound-sounds-better-in-a-room-full-of-furniture-and-stuff-or-without/630#post_22245767

i ask him what the frequency-response tells him with respect to intelligibility, localization, and imaging. what does he do? he goes on a tirade of what he calls an "explanation", without even using the words intelligibility, localization, and imaging!

laughable.
Quote:
Originally Posted by amirm 
We have amplitude vs time. Much of what we know in psychoacoustics comes from the frequency domain. Let's go back to mother of such research with Fletcher-Munson equal loudness graphs (circa 1930s):

wow, what does the flethcer-munsor curve tell me about the psycho-acoustics of intelligibility, localization, and imaging? nothing you say?
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Originally Posted by amirm 
You ask how we can tell all of this from psychoacoustics represented in that graph? Now you know.

nope - you still haven't provided a frequency-response and are able to tell me how you are able to determine localization and imaging from the frequency-domain.

and you still can't admit what domain that the "Gain vs Time" olive/toole graph and research is in - what did you revert to calling it yesterday, the "audio domain"? rolleyes.gif

how many auralex t'fusors do i need slapped on my wall before it looks like im an expert? it's laughable the condo dweller has no problems constructing his own reflection phase gratings, but a professional and dedicated showroom has to rely on auralex t'fusors to impress clients. LOL.

you're a salesman - own up to it.
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post #659 of 871 Old 07-24-2012, 10:17 AM
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Formal training? I have formal training. You are the one who lacks it. I am trained by the top experts that I quote here

the only thing you're formally trained to do is copy-paste parrot. "top experts" - lol.
you have a religious "my way or the highway" approach to acoustics, and im starting to believe you have serious father-figure issues with dr. toole. does toole fill a gap from your early childhood?
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post #660 of 871 Old 07-24-2012, 10:29 AM
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You are not even worthwhile responding too....
Yet you keep responding. More stomping the feet as evidence. More emotions substituting for data. More snickering as proof of something not being right. More measurements confused with our hearing system and listening tests. More absence of personal data. More acting like higher authority than top experts in the industry. More of your evidence damning your own cause such as Dr. D'Antonio presentation. More of my enemy's enemy is my friend (rather than the truth about audio).

Mind you, it is a great role you play, saying things that allow me to bring in the real research and science. So please don't stop on my account smile.gif. But if you go away, I shed no tear. There are others who are very comfortable acting the same way as you do....

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