Graphs from REW

[Dale Doback]

One big factor for me was getting my speakers a little further from the walls and moving my subs closer together. That made some improvements by itself. Then I didn't have to do as much with the mini, which made things easier for Audyssey.

I had the same revelation with MCACC Pro.

 

[Mitchibo]

I had the same revelation with MCACC Pro.

MCACC Pro?

 

[ATLAudio]

MCACC Pro?

Pioneer's proprietary version of Audyssey

 

[Pogre]

RT not being an issue in small rooms is an incorrect inference. High RT in treble frequencies, results in overly bright rooms, while at lower frequencies, bass transients and separation are obfuscated. Getting acoustical energy, especially below transition frequency, to dissipate in small rooms needs astute design and significant commitment. If anything, high RT is a big issue in small room acoustics. A significant percentage of maladies misattributed to speakers and electronics is a direct consequence of high RT listening environment.

I didn't have time to watch the CIRMMT video. I did re-read Ch. 13 edition 2.

There two big things I noticed, all analysis is based on ideal (perfectly rectangular) rooms and use of Waterfall Plots to visualize modal ringing.

The inverse correlation of frequency resolution and time resolution in Waterfall Plots is mentioned. I read that as a caveat emptor for the nature of visualizing a plot based on frequency, amplitude and time. I suspect, it is a consequence of the Fourier Transform math. There is no mention of the inverse correlation of resolution generating incorrect filters or resulting in incorrect application of DSP filters. Consequently, I chalk that one to inexperience or overzealous EQ by the user.

I use the Waterfall Plots below transition frequency, toggling frequency resolution with time resolution. Well below transition, I prefer time resolution. Closer to transition, things get murky. Of course, well above transition, only frequency resolution matters, and life is easy completely ignoring time.

Starting with mathematical modeling of an ideal room and then correlating it to observations made in an ideal physical room make perfect sense in the pursuit of science and understanding. This approach is not feasible in the real world. At minimum, the ideal room models completely fail (exempt height, since most of us have a roof exactly parallel to floor across the whole room).

I believe our approaches overlap in that we see EQ as a tool of last resort. I will send days playing with room setup and speaker/subwoofer locations, only adjusting distance and level settings, to get the best possible coupling of source to room. If I notice a persistent peak or dip, I'll break out the room mode analysis spreadsheet to help correlate observations to idealized mathematical expectations. This helps understand which battles are not winnable on placement alone and which to focus on. Only then will I try EQ to control the worst peaks or dips.

I hear you on the topic of people considering EQ their path to audio nirvana or obsessing on speakers and electronics (or cables ) while turning a blind eye to the room or good speaker placement. To them I say, get Bose-d .

That's what I keep saying. It would be astronomically impossible to get accurate enough measurements to aggregate any meaningful information. I agree that some folks definitely get carried away, but I try to use as light a touch as possible. I put a lot of time, work and energy into experimenting with placement first to get things as best I could there before even attempting any eq. There's nothing arbitrary about it.

Everything was with purpose and I can say with utmost confidence that I have significant gains. My after is so much better now than before. Shout out to @ATLAudio for helping me with it too. Like, actual help...

 

[TheWarrior]

How is there confusion on the inferential knowledge of Reverberation Time?
"A measurement of reverberation time in a domestic-sized room yields a number. When the number is large, the room sounds live, and when the number is small, the room sounds dead"

-Why discredit your own two ears and a brain after reading that quote? That is knowledge.

"In other words, one can have high resolution in the frequency domain and sacrifice resolution in the time domain, or the reverse. All of this is most relevant at low frequencies."

-What part is not understood? To treat bass you need resolution of BOTH time and frequency, which a waterfall cannot provide. Why complain about the burden of using a tape measure, when you can save yourself the time of rendering waterfalls? And RT measurements?

I'll get around to posting my physical measurements correlated to acoustic measurements. Obviously this book flies in the face of conventional thinking about room acoustics. But it's generally advised that you try it, before you discredit it.

 

[agarwalro]

How is there confusion on the inferential knowledge of Reverberation Time?

You denounced RT.

Why discredit your own two ears and a brain after reading that quote? That is knowledge.

Because one's ears and brain are subjective and inaccurate while mics and graphs are objective and accurate.

"In other words, one can have high resolution in the frequency domain and sacrifice resolution in the time domain, or the reverse. All of this is most relevant at low frequencies."

-What part is not understood? To treat bass you need resolution of BOTH time and frequency, which a waterfall cannot provide.

And one has both. It is only the visualization that is limited, not the measurement data or math. One could have two plots, favoring time or frequency resolution.

Why complain about the burden of using a tape measure, when you can save yourself the time of rendering waterfalls? And RT measurements?

Some people are mathematical and will gravitate to the modal analysis while others are visual and prefer the plots. The end goal is elucidating sound aberrations to gain insight on corrective measures. The path to corrective measures is an individual's prerogative.

Obviously this book flies in the face of conventional thinking about room acoustics. But it's generally advised that you try it, before you discredit it.

No one's discrediting the book.

For the average person, there's no need to slog through the concepts and math. An enthusiast may read the book if desiring a deeper understanding of observations. An architect/designer of recording studios or home theaters, must firmly grasp the concepts. I would expect the last category of people to break out a tape measure and modal analysis while drawing up floor plans and room layout. I most certainly don't expect that of the first category of people.

REW didn't exist when the book was written. The trial and error approach accorded by REW is a perfectly reasonable way to go about tweaking the setup. Some prefer it to looking at tabulated numbers correlated with jargon that means nothing to them.

 

[TheWarrior]

You denounced RT.
Because one's ears and brain are subjective and inaccurate while mics and graphs are objective and accurate.
And one has both. It is only the visualization that is limited, not the measurement data or math. One could have two plots, favoring time or frequency resolution.

Some people are mathematical and will gravitate to the modal analysis while others are visual and prefer the plots. The end goal is elucidating sound aberrations to gain insight on corrective measures. The path to corrective measures is an individual's prerogative.
No one's discrediting the book.

For the average person, there's no need to slog through the concepts and math. An enthusiast may read the book if desiring a deeper understanding of observations. An architect/designer of recording studios or home theaters, must firmly grasp the concepts. I would expect the last category of people to break out a tape measure and modal analysis while drawing up floor plans and room layout. I most certainly don't expect that of the first category of people.

REW didn't exist when the book was written. The trial and error approach accorded by REW is a perfectly reasonable way to go about tweaking the setup. Some prefer it to looking at tabulated numbers correlated with jargon that means nothing to them.

This book recommends a scientific approach to dealing with rooms. It's not dogmatic, but it certainly has to be consistent and repeatable to be effective, a scientific method, if you will.

I thought everyone could benefit from trying it, and that it would yield decidedly better results than what's been recommended. I thought taking a quick inventory of parallel surfaces wasn't too much to ask. Boy, was I wrong!

The book actually discusses what it was like before laptop and mic solutions. And you'll find lots of information on how to effectively take, and interpret measurements in this book. But it also says that two ears and a brain are sufficient to understand the effects of RT in small rooms. I cited that so you could take one thing off your to-do list of room measurements. But you seem to be taking offense to the notion that it's unnecessary - "You denounced RT."

So good luck in all of your endeavors. If you feel like trying this out at some point, I think you'll enjoy the results!

 

[ATLAudio]

“How is there confusion on the inferential knowledge of Reverberation Time?”

You do this all the time. Instead of directly challenging the argument you muddy the waters insisting that the other person is somehow confused. Again, there’s no confusion point here. You dismiss RT measurements carte-blanche, and @agarwalro is giving details as to it's usefulness.

“Why discredit your own two ears and a brain after reading that quote? That is knowledge.”

This is nonsense. But, we always have ears and brains, and we also have mics and computers to assist in proving more empirical information.

“What part is not understood? To treat bass you need resolution of BOTH time and frequency, which a waterfall cannot provide.”

Your ability to logically breakdown an argument is what needs sharper understanding. It can show either or, and REW can be adjusted to show either or.

“Why complain about the burden of using a tape measure, when you can save yourself the time of rendering waterfalls? And RT measurements?”

That begs the question which is easier for the person, their tools available, and goals. Stick with measuring your room, and avoid tools in REW if that suits you. You’ve only been doing it for over a year now. However, outside a cement shoebox, you can’t argue with using sonic measurements. So far most here have found those tools much to their satisfaction.

“Obviously this book flies in the face of conventional thinking about room acoustics.”

I know, everyone else is lying, but no, this book doesn’t fly in anyone’s face that matters. It might fly in the face of lay-thinking in some respects, but that’s only much like any other text book would. That’s not to say that Dr. Toole hasn’t contributed greatly to understanding in audio, he certainly has, but he is certainly not alone. Go to Google Scholar, and type small room acoustics.

 

[ATLAudio]

This book recommends a scientific approach to dealing with rooms. It's not dogmatic, but it certainly has to be consistent and repeatable to be effective, a scientific method, if you will.

I thought everyone could benefit from trying it, and that it would yield decidedly better results than what's been recommended. I thought taking a quick inventory of parallel surfaces wasn't too much to ask. Boy, was I wrong!

The book actually discusses what it was like before laptop and mic solutions. And you'll find lots of information on how to effectively take, and interpret measurements in this book. But it also says that two ears and a brain are sufficient to understand the effects of RT in small rooms. I cited that so you could take one thing off your to-do list of room measurements. But you seem to be taking offense to the notion that it's unnecessary - "You denounced RT."

So good luck in all of your endeavors. If you feel like trying this out at some point, I think you'll enjoy the results!

“This book recommends a scientific approach to dealing with rooms.”

I’m sure it does

“It's not dogmatic,”

No, you are.

“I thought everyone could benefit from trying it, and that it would yield decidedly better results than what's been recommended. I thought taking a quick inventory of parallel surfaces wasn't too much to ask. Boy, was I wrong!”

Try what? An nice try, but no, all you’ve done is crap in folks cherrios for not doing what you do, and you still haven’t spelled that out. Or make radical assumptions, and call folks liars. Others simply questioned your approach for adequate and usable information. You yourself can’t provide more except advice to go read a whole book. Others have offered to show you said tools in REW, they are easy, and proper interpretations of the text, but you just seek to argue on your Dunning Kruger kick. Combined with your dogmatic approach to said text, discussion which should be very easy becomes incredibly hard if not impossible.

“The book actually discusses what it was like before laptop and mic solutions. And you'll find lots of information on how to effectively take, and interpret measurements in this book. But it also says that two ears and a brain are sufficient to understand the effects of RT in small rooms.”

Holding aside this inane naturalistic fallacy, then measurements should also work. We also don’t feel obligated to measure every nook and cranny of our room, we don’t have to, and there are better solutions.

“I cited that so you could take one thing off your to-do list of room measurements. But you seem to be taking offense to the notion that it's unnecessary - "You denounced RT."

No, you didn’t, and how do you, in any way, sense any offense from that statement? But, making up a different reality is nothing new for you. You belittle him as being "offended" so you don’t have to challenge the argument directly. You’ve yet to properly argue any of the caveats he said about RT.

“So good luck in all of your endeavors. If you feel like trying this out at some point, I think you'll enjoy the results!”

Good luck measuring your room for another year. You’ve never spelled out what you’re trying. We’ve for the most part have identified proper concerns and are enjoying those results.

 

[agarwalro]

I thought everyone could benefit from trying it, and that it would yield decidedly better results than what's been recommended. I thought taking a quick inventory of parallel surfaces wasn't too much to ask.

For sure, it never hurts one to consider a different approach, but...

Boy, was I wrong!

... your delivery was off putting. Specifically, creating word walls of relevant and irrelevant snippets from the book. This is why you come off as, dare I say, a fanboy.

The book actually discusses what it was like before laptop and mic solutions.

My first FR plot was on graph paper and made playing discrete test tones while measuring with the hallowed RS SPL meter. Oh! The good old days .

it also says that two ears and a brain are sufficient to understand the effects of RT in small rooms. I cited that so you could take one thing off your to-do list of room measurements.

Let's agree to disagree about the significance of RT in small room acoustics. The beauty of REW is that one measurement generates all the data needed, FR, RT, Minimum Phase, etc. related to that mic location. The host of visualizations is an added bonus.

But you seem to be taking offense to the notion that it's unnecessary - "You denounced RT."

I don't know why you get that impression. Rest assured, it is not the case. I usually PM people who offend me and try to take the acrimony off the forum.

 

[ATLAudio]

Specifically, creating word walls of relevant and irrelevant snippets from the book.

Gish Gallop

 

[William Lemmerhirt]

Wow! @agarwalro. I fondly(not) remember printing graph paper to do my first graphs too. Saving MP3’s of test tones. Those were good times lol. My next foray was using my RS meter and some 50’ long homemade cables to reach from my LR to my bedroom where the pc tower was. Wow...
Im not going to entrench myself here, but thought I’d share a layman’s perspective. As I have no degree or much too many smarts, REW is an amazing bit of software. In my situation, I have in impossibly measurable room like @Pogre. Sunken LR, vaulted ceiling, a bank of cabinets as my (partial) right wall, a hallway, foyer and two other rooms off of that. What a bitch. Even if I did measure all that, it wouldn’t matter since I (like I assume many) have exhausted my placement options and my waf with 7.3ch rig, in the LR. My LP is fixed and will not move. So knowing where my room induced modes are is only a slap in the face since I can’t move anything. That leaves EQ(since traps to reduce ringing are out. Waf limit). So my question, to the warrior, like pogres is what would I do with the known quantities of my modes? I can’t placement EQ, so what’s a guy to do?

 

[ATLAudio]

So my question, to the warrior, like pogres is what would I do with the known quantities of my modes? I can’t placement EQ, so what’s a guy to do?

Oh that's easy, the next step is you must read Toole's book cover to cover, go Clear, adopt The Secret, and take a proper blood oath.

 

[Pogre]

Oh that's easy, the next step is you must read Toole's book cover to cover, achieve The Secret, and take a proper blood oath.

That's what I keep hearing. Nothing helpful. Just pretty much keep getting told my system sounds like crap (even though I can hear with my own ears a vast Improvement) because I don't know what good sound sounds like, and "read the book". None of that is helpful and actually confuses and muddies things.

I have found in my experience that, if someone cannot explain a process in simple, concise understandable terms, they often don't know enough themselves. It becomes a regurgitation of what somebody else has written with no true understanding.

 

[agarwalro]

In my situation, I have in impossibly measurable room like @Pogre. Sunken LR, vaulted ceiling, a bank of cabinets as my (partial) right wall, a hallway, foyer and two other rooms off of that. What a bitch. Even if I did measure all that, it wouldn’t matter since I (like I assume many) have exhausted my placement options and my waf with 7.3ch rig, in the LR. My LP is fixed and will not move. So knowing where my room induced modes are is only a slap in the face since I can’t move anything. That leaves EQ(since traps to reduce ringing are out. Waf limit). So my question, to the warrior, like pogres is what would I do with the known quantities of my modes? I can’t placement EQ, so what’s a guy to do?

Live with the guilt .

 

[agarwalro]

Oh that's easy, the next step is you must read Toole's book cover to cover, go Clear, adopt The Secret, and take a proper blood oath.

Now now, no need for ad hominem attacks.

 

[agarwalro]

That's what I keep hearing. Nothing helpful. Just pretty much keep getting told my system sounds like crap (even though I can hear with my own ears a vast Improvement) because I don't know what good sound sounds like, and "read the book". None of that is helpful and actually confuses and muddies things.

No, Warrior is referring you to the book to better understand the cause of your audio aberrations. He's just more vocal and persistent than most would care to be.

I have found in my experience that, if someone cannot explain a process in simple, concise understandable terms, they often don't know enough themselves. It becomes a regurgitation of what somebody else has written with no true understanding.

Or they could be a bad teacher. Having knowledge and imparting it effectively are two wholly different skill sets that infrequently overlap.

 

[ATLAudio]

No, Warrior is referring you to the book to better understand the cause of your audio aberrations.

 

[TheWarrior]

Show don't tell. I get it and agree, and I'll get all those purdy measurements for you guys as soon as I can. Thought it would be easier to show you on your own rooms. That's truly all I've been getting at.

@William Lemmerhirt First, you need to predict your modes. Then, you need to know which ones are actually affecting your listening position with acoustic measurements. Once you've ensured levels and delays are set for all subs (after placement of course), you would then use EQ to cancel out your room modes. I've got an open living room myself, and was only limited by the 2 channels of DSP built in to my subs. Still predicted 15 modes, I think.

And that's where I've been the most vocal. The 'guesswork' that's gone in to the DSP. Room modes don't have to measure as peaks, you can be out of phase with that frequency at the listening position and simply not hear it. My mistake in telling and not showing, was that it wasn't seen by anyone, that correcting the actual modes smooths the response on it's own. My other mistake was in thinking that I could simplify an incredibly complex subject, for the masses.

@agarwalro I like your style, and appreciate the effort for actual discussion. But I think at this point there is little discussion to be had, and I've done a great job of backing myself in to a corner. So I'll keep working in order to demonstrate with pictures, how to correlate predictions to acoustic measurements. I thought it was a simple concept, that was easy to share. So hopefully you and others will be able to literally see, with pictures, what I am talking about, and how it might offer you a better solution.

@ATLAudio You've been the most vocal, and by far the only off-putting member, considering how much time I've spent with you. You called me up while I was on vacation and asked how to program a 2x4. I got your room dimensions from you and gave you the predicted modes, and I think, the DSP filters. Never saw a FR graph, or heard comments on the effectiveness. Nothing. But here you are in every thread where I advocate this procedure, slamming it. So if you want to share the progress, and what inputs you've made, then lets discuss. But you're not making me want to cook you and your family ribs again, any time soon.

 

[agarwalro]

View attachment 22381

I jest.