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Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How... - Page 292

post #8731 of 9619
Quote:
Originally Posted by pepar View Post

I am certain that I got all of the points on why technique and precision is important when measuring. And, for the most part, I understand what measurements reveal about our systems/rooms and possibly what can be done to improve them (rooms/systems) ... improve them ... for the listener(s). But I am stuck on this L&R measurement and how anything that could show would correlate to room/system changes that would improve the listening experience.

Jeff

The relevancy of some measurement techniques or types is debatable, I agree. I pointed out their value to me, but they might not be to someone else. Some people don't run sliced ETC's. I do. Many do not. Some find waterfalls more useful than decays. Some use spectrograms, some do not. There are some I don't find useful such as RT-60.

They are simply tools.

Hopefully, we can agree that if your going to use a tool, you have to learn how to use it properly. In the case of L+R full range, it just so happens that it requires very precise mic placement to be useful.

Gear mentioned in this thread:

post #8732 of 9619
Quote:
Originally Posted by jim19611961 View Post

The relevancy of some measurement techniques or types is debatable, I agree. I pointed out their value to me, but they might not be to someone else. Some people don't run sliced ETC's. I do. Many do not. Some find waterfalls more useful than decays. Some use spectrograms, some do not. There are some I don't find useful such as RT-60.

They are simply tools.

Hopefully, we can agree that if your going to use a tool, you have to learn how to use it properly. In the case of L+R full range, it just so happens that it requires very precise mic placement to be useful.

I would be interested in what some of the more esoteric (to me at least) measurements have told you about your room/system, e.g. the sliced ETCs and the much-discussed smile.gif L+R?

I suppose I am looking for a "rosetta stone" that ties the measurements to the listening experience.
post #8733 of 9619
The point of a consistent measurement method for L and R is to enable a full range eq that is aiming at a consistent target across l and r. This doesn't mean your head has to be in a vice to be useful as frequency dependent windowing is really about (as I currently understand it at least) taking reflections out of the equation. Basically it is attempting to linearise the speaker at the listening position (which for me seems the only way to do it given that I have a 2 way passive speaker with multiple drivers on each way).

Other people, who are employing different methods, may have different reasons/goals of course.
post #8734 of 9619
Quote:
Originally Posted by AustinJerry View Post

For those of you who were involved in the discussion of the importance of mic placement when conducting a left+right measurement, and who have suggested that the Guide provide the appropriate caution regarding signal interaction when measuring in this fashion, please refer to dot-point 5 under the section "Additional Measurement Guidelines (courtesy of Jevansoh)".  J clearly emphasizes the importance of proper mic placement when taking this measurement.

Here is the relevant section referenced in Jerry's note:

If you decide to view a full range measurement with L+R+Sub(s) you will most likely be
disappointed above about 1khz or so (most of the time and unless you are VERY careful and
have very exact speaker and mic placement between the speakers) as the wavelengths start to
become so small the slightest movement of the mic will cause phase interactions, comb filtering,
and a very poor and inaccurate measurement in the higher frequencies. There really isn't any
reason for this. Again, the only measurement necessary for L+R+Sub(s) - combined - should be
to look at the overall bass response, below 300Hz, unsmoothed.
post #8735 of 9619
Quote:
Originally Posted by pepar View Post

I would be interested in what some of the more esoteric (to me at least) measurements have told you about your room/system, e.g. the sliced ETCs and the much-discussed smile.gif L+R?

I suppose I am looking for a "rosetta stone" that ties the measurements to the listening experience.

IMO, there is no Rosetta Stone. The correlation of measurement to listening is a tricky one. This is particularly true when you bring psycho-acoustics into the fold. Additionally and perhaps most relevant is what your listening room is used for (multi-channel HT or 2ch audio) and what room interaction you desire to have. Some people want to virtually take the room out of the equation and others want the room to play a major part.

That said, many of the different room measurements are about data organization. That is, there are many ways to look at the data. In my view, how you want to look at the data depends on what you are trying to do in the first place. This leads to room criteria and models.

I think I have said what i have to say about L+R. Others may add here. ETC slicing and the ETC in general is one of the two most important tools I use. The other being frequency response. Slicing the ETC is basically taking the full range ETC and limiting it to a band of frequencies. By looking at say 500hz, 1K, 2K and 4K 1 octave slices of the ETC, one gets a sense of the frequency make up of your reflections. Most agree that reflections, when purposely implemented as part of ones room criteria and design that they be as broadband as possible. When you factor in psycho-acoustics, you find that down to 300-500hz is fine. So without getting into a full blown discussion, the frequency content of reflections is important to know and they have obvious implications to the listening experience.
post #8736 of 9619
Just a quick post to mention that I managed to do a 'right plus sub' measurement last night. I still had that poor response between 100 and 400Hz, but it occurred to me that my old subwoofer (a bulky ported sub) could be moved out of the way from being pretty close to my right speaker. I could only slide it 3' away and there was a noticeable improvement in the response with it moved, so I hope it'll be even better when I can get some help to remove it from the room completely. It's become such a part of the room's furniture (literally as well since it has a lamp on it) that I've almost stopped noticing it.

It just shows how even small changes can effect things positively (even if the speakers themselves can't be moved from where they are).



I've set up a nice EQ for the sub so that I can run without Audyssey on for music and my ankle is sore because I sit there foot tapping away to the music now. smile.gif
post #8737 of 9619
Thanks, Jim. Any further questioning on my part would be OT for the thread's purpose.

Jeff
post #8738 of 9619
Quote:
Originally Posted by pepar View Post

Thanks, Jim. Any further questioning on my part would be OT for the thread's purpose.

Jeff

Your welcome.

It is well within the thread topic to discuss measurements and what they mean.
post #8739 of 9619
Quote:
Originally Posted by jim19611961 View Post

Your welcome.

It is well within the thread topic to discuss measurements and what they mean.

Alrighty, have your octave-banded ETC measurements caused you to change anything about your room or system? I am specifically thinking about the design and/or position(ing) of acoustical treatments.

Jeff
post #8740 of 9619
Quote:
Originally Posted by pepar View Post

Alrighty, have your octave-banded ETC measurements caused you to change anything about your room or system? I am specifically thinking about the design and/or position(ing) of acoustical treatments.

Jeff



Black = 500hz
Orange = 1K
Green = 2K
Blue = 4K

As you can see, I have an intentional reflection at just under 25ms. I have had to adjust the size and arrangement of my reflection panels several times to get a reasonably good and equal bounce at these frequencies. The 500hz bounce is still a bit low and I would like to improve upon it. But when I started, the 1K band was about where the 500hz band is now. And the 500hz band was near -20db.

I also had a goal to get all the bands <-20db up to that peak. I am close.

If you click on the "My Room" link in my signature and go to the later pages. You will see the current arrangement.
post #8741 of 9619
JIm,

Have you perceived any changes/improvements in the sound as you brought the 1k termination reflection in line with 2k and 4k? You mentioned psycho-acoustics; this falls into that category, does it not?

Jeff
post #8742 of 9619
Quote:
Originally Posted by pepar View Post

JIm,

Have you perceived any changes/improvements in the sound as you brought the 1k termination reflection in line with 2k and 4k? You mentioned psycho-acoustics; this falls into that category, does it not?

Jeff

As the reflection more resembles the source in frequency content, the illusion of spaciousness is more convincing.
post #8743 of 9619
Quote:
Originally Posted by jim19611961 View Post

As the reflection more resembles the source in frequency content, the illusion of spaciousness is more convincing.

That's something that speaks to me ... anchors the theoretical to the practical. Is this something more applicable to 2-ch systems than home theater/surround systems?

Jeff
post #8744 of 9619
Quote:
Originally Posted by jim19611961 View Post

As the reflection more resembles the source in frequency content, the illusion of spaciousness is more convincing.

Does that make the image bigger? Or rather offers the sense of spaciousness within the recording (more space between instruments, say)?
post #8745 of 9619
Quote:
Originally Posted by pepar View Post

That's something that speaks to me ... anchors the theoretical to the practical. Is this something more applicable to 2-ch systems than home theater/surround systems?

Jeff

I am not sure about its HT application. I will say that some, in this thread even, feel the ambiance/spaciousness that I seek in 2 ch is more than provided for by the surround channels in HT.

Even in 2 ch, my use of a Haas kicker (big spike at 25ms) is not standard doctrine although it is part of the LEDE/RFZ model in one of its variations. I would say this line of thought is applicable in most 2 ch except those going for a near anechoic room response, in which case the reflections are far too subdued for their frequency content to matter.
Edited by jim19611961 - 2/11/14 at 7:36pm
post #8746 of 9619
Quote:
Originally Posted by artur9 View Post

Does that make the image bigger? Or rather offers the sense of spaciousness within the recording (more space between instruments, say)?

Depends on the gain and timing of the reflection(s). The term "image broadening" applies directly to what your asking wrt to "bigger". Perhaps this may help.



The space between instruments I would say is more related to soundstage width and depth which constitutes many factors of which reflections is only a part.
Edited by jim19611961 - 2/11/14 at 7:34pm
post #8747 of 9619
Quote:
Originally Posted by jim19611961 View Post

Depends on the gain and timing of the reflection(s). The term "image broadening" applies directly to what your asking wrt to "bigger". Perhaps this may help.



The space between instruments I would say is more related to soundstage width and depth which constitutes many factors of which reflections is only a part.

The red and green zones are pretty much .. lol .. black and white. But the yellow zone, IME, is psycho-acoustical territory and, also, the land of preference. For my MCH theater, I initially favored an adaption of LEDE. But after a lot of use, I have noticed (and can no longer NOT notice) that the front lobes of the dipole surrounds are collapsed causing a hole between the L&R and their respective surrounds. And, with carpeted walls up to seated ear level (along with the completely absorbent front wall), I "feel" the room is over-damped in general.

And this is what brought me to REW in the first place. I wanted to measure before and after I swapped the rear FRP absorber for skylines, and see if that fixed my concern. I am also prepared to swap front L&R FRP absorbers for skylines as well. But I bumped into one obstacle; what should my target decay be? A helpful chap from THX once told me that they design for a midband decay of 300ms. OK, one "data point." but in all of my questioning on the Acoustical theory thread, none of the resident acousticians would ever divulge what they used as a target ... as if it were knowledge reserved for the gurus.

So, I know how to build and deploy acoustical treatments and measure, and I certainly know how to listen, but I am missing some sort of guide rail. The Q&A of the last few days and, especially, the graph you just posted has helped me. And convinced me that I need to do more research.

Jeff
post #8748 of 9619
Quote:
Originally Posted by pepar View Post

The red and green zones are pretty much .. lol .. black and white. But the yellow zone, IME, is psycho-acoustical territory and, also, the land of preference. For my MCH theater, I initially favored an adaption of LEDE. But after a lot of use, I have noticed (and can no longer NOT notice) that the front lobes of the dipole surrounds are collapsed causing a hole between the L&R and their respective surrounds. And, with carpeted walls up to seated ear level (along with the completely absorbent front wall), I "feel" the room is over-damped in general.

Agree about the yellow zone. It is also mitigated by the type of source material and the direction the reflection(s) is coming from. Carpet, as you probably know, only dampens higher frequencies. This leads to an unevenness in reflection spectra.
Quote:
Originally Posted by pepar View Post

And this is what brought me to REW in the first place. I wanted to measure before and after I swapped the rear FRP absorber for skylines, and see if that fixed my concern. I am also prepared to swap front L&R FRP absorbers for skylines as well. But I bumped into one obstacle; what should my target decay be? A helpful chap from THX once told me that they design for a midband decay of 300ms. OK, one "data point." but in all of my questioning on the Acoustical theory thread, none of the resident acousticians would ever divulge what they used as a target ... as if it were knowledge reserved for the gurus.

Target curves needs LOTS of context to be useful. I.E. one "data point" isnt that useful, agreed.
Quote:
Originally Posted by pepar View Post

So, I know how to build and deploy acoustical treatments and measure, and I certainly know how to listen, but I am missing some sort of guide rail. The Q&A of the last few days and, especially, the graph you just posted has helped me. And convinced me that I need to do more research.

I am still researching a lot myself. Its common for folks to get stuck in trying to implement one piece of the puzzle without knowing how all the important pieces fit and interact together. For the better or worse, most folks seem to bottom out in how much time and effort they are willing to put into the research side and settle on the modest gains they have made and call it a day. We all stop at some point.
post #8749 of 9619
Quote:
Originally Posted by jim19611961 View Post

We all stop at some point.

haha, I think some are, with REW, in the "cold, dead hands" category. wink.gif
post #8750 of 9619
Quote:
Originally Posted by jim19611961 View Post

We all stop at some point.

Stop? There's a way to stop?

:eek:

post #8751 of 9619
You know it's time to stop when you find yourself in your car whistling a 20-20000Hz sweep like it's the latest catchy tune. biggrin.gif

Maybe I'm not as OCD as I thought though since after my recent adjustments (and a very large deep rug), I'm just enjoying listening to old CDs and concert BluRays.

I know it could be frowned upon, but I promise to beat myself with a UMC-1 mic if I don't run REW again in another week or so once I've finished my subs properly. biggrin.gif
post #8752 of 9619
Quote:
Originally Posted by Kelvin1965S View Post

You know it's time to stop when you find yourself in your car whistling a 20-20000Hz sweep like it's the latest catchy tune. biggrin.gif

Maybe I'm not as OCD as I thought though since after my recent adjustments (and a very large deep rug), I'm just enjoying listening to old CDs and concert BluRays.

I know it could be frowned upon, but I promise to beat myself with a UMC-1 mic if I don't run REW again in another week or so once I've finished my subs properly. biggrin.gif

lol, My cellphone ring is the Audyssey sweep. I never fail to hear it and never confuse it with anyone else's ringtone.
post #8753 of 9619
Quote:
Originally Posted by pepar View Post

lol, My cellphone ring is the Audyssey sweep. I never fail to hear it and never confuse it with anyone else's ringtone.

hahaha brilliant
post #8754 of 9619
post #8755 of 9619
Quote:
Originally Posted by pepar View Post

lol, My cellphone ring is the Audyssey sweep. I never fail to hear it and never confuse it with anyone else's ringtone.

How do others react when it goes off? (those that obviously don't know what it is)
post #8756 of 9619
Quote:
Originally Posted by jim19611961 View Post

How do others react when it goes off? (those that obviously don't know what it is)

Lots of strange looks. In public places, I reduce the volume a bit. Restaurants, of course, it is off.
post #8757 of 9619
Quote:
Originally Posted by Kelvin1965S View Post

You know it's time to stop when you find yourself in your car whistling a 20-20000Hz sweep like it's the latest catchy tune

My kids can whistle that sweep. Do you think I should stop? Maybe I've gone a bit too far...
post #8758 of 9619
Quote:
Originally Posted by Kelvin1965S View Post

You know it's time to stop when you find yourself in your car whistling a 20-20000Hz sweep like it's the latest catchy tune. biggrin.gif

 

 

In my case, I know that I reached the edge when I tried to use REW to measure the audio response in my car....

post #8759 of 9619
Quote:
Originally Posted by AustinJerry View Post

In my case, I know that I reached the edge when I tried to use REW to measure the audio response in my car....

Do you know I was thinking the other day that I wonder if I could do this? biggrin.gif

Not so I could try to improve the response, but to try to find out what it is I like about the response (it's 2011 BMW 3 series and I spend a lot of my working day in it listening to music). However, by sitting with a long USB cable from my sub amp to my laptop I've been able to switch between different EQ settings and I've worked out what I like (it's not quite flat either, but the 'bump' I like pleases my ears for music anyway, yet to try a whole film).
post #8760 of 9619
Quote:
Originally Posted by Kelvin1965S View Post

Do you know I was thinking the other day that I wonder if I could do this? biggrin.gif

Not so I could try to improve the response, but to try to find out what it is I like about the response (it's 2011 BMW 3 series and I spend a lot of my working day in it listening to music). However, by sitting with a long USB cable from my sub amp to my laptop I've been able to switch between different EQ settings and I've worked out what I like (it's not quite flat either, but the 'bump' I like pleases my ears for music anyway, yet to try a whole film).

I bet an ETC/Waterfall in a car cabin would look horrendous eek.gif
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