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post #7621 of 9491
Quote:
Originally Posted by Audionut11 View Post
 
 
With Keiths example above.


Without all of the noise clouding the measurement, we can see more clearly a better representation of what Keith hears. We also can see more clearly the areas of interest.

Keith, I am confident that if you have EQ capability and use it to match a FR as such.


You would gain some audible benefits. Firstly, a flatter FR is always welcomed, including a peak in response @20hz, rather then 54hz with the roll-off. Also, reduction in source signal translates to a reduction in the time domain. So by reducing that peak @54hz 6dB and flattening the FR, you reduce the room mode by 6dB also. With less energy triggering the room mode I would expect to see a reduced bump from the room mode in the time domain.



In others words, not only would the area circled above be further down towards the ambient noise floor, it would be less pronounced. In other words, instead of the tail of that resonance continuing out to 300ms as it does, the EQ might reduce the tail below graph 50-100ms earlier, and flatten it so that it more resembles the rest of the FR.


Make no mistake, further treatment of the room would be preferred, but considering the amount of work already undertaken, and hence, the amount of work that would be required to further reduce the influence of the room, EQ is probably a cheaper, easier option at this point.

I get the low end result of this.



From this (same 50dB bottom scale and measurement level).



With EQ, and EQ alone wink.gif

 

A fabulously informative post. Thanks for the analysis of my waterfall above. Much food for thought there. That problem at around 50Hz has been with me for a long time and, while I am not consciously aware of any audible problem, I know there really must be one, so at some point I am going to have tackle this. Thanks again.

Gear mentioned in this thread:

post #7622 of 9491
Quote:
Originally Posted by kbarnes701 View Post

A fabulously informative post. Thanks for the analysis of my waterfall above. Much food for thought there. That problem at around 50Hz has been with me for a long time and, while I am not consciously aware of any audible problem, I know there really must be one, so at some point I am going to have tackle this. Thanks again.

For what its worth, I view your 50hz problem as minor (perhaps that is why its not discernibly audible) smile.gif
post #7623 of 9491
I agree with Jim. And my apologies Keith, I did mean to make mention that I thought your waterfall would represent a nice sounding system. Gotta love that low end response. wink.gifbiggrin.gif

Your (mine or anyone else's) inability to discern it is actually a good thing. I made note of a few advantages of narrowing down the (one of mine) waterfalls, one of which.
Quote:
My listening experience is not affected by a measurement graph I took moments before

We want to make changes to our system that increase the enjoyment our listening experience. We do not want to measure our systems to the point where we find things in the measurement data that distract us from this listening experience.

Think of it as something to look at the next time you are looking for something to do biggrin.gif

Thanks for the praise guys. It's good to know that others can understand and benefit from the post.
Edited by Audionut11 - 12/27/13 at 6:51pm
post #7624 of 9491
Quote:
Originally Posted by jim19611961 View Post

I thought I would elaborate on my take of the waterfall in an interpretational way.

The top slice represents your FR basically. Each slice below that equates to the "echo" of that response in the time domain modified by the room response.

In a perfect world, the FR would be a strait horizontal line representing the same sound pressure for every frequency. Each additional slice would also be a flat horizontal line as you move further in time from the direct response. So in a perfect world, 100ms (for instance) after the direct response, the sound pressure level for each frequency would still be constant, but some measure of -X db down. Such a scenario would imply a room that is perfectly flat across the frequency domain as you move further from the direct response in the time domain. This is the ideal.

Now, what we see in our waterfalls is a asymmetrical FR followed by a asymmetrical room response. This represents itself as the direct response (FR) in the top or first slice that has asymmetries (not perfectly flat), followed (in time) by a room response that treats the decay of frequencies differently as you move in the time domain.

Thanks Jim. I tried to explain how things should (ideally) be even through the time domain, but the above quote explains this better.

Here is a graph that shows what is being described.




Shamelessly stolen from here. <<<< Good read!

Quote:
Originally Posted by cfraser View Post

And I do agree that treatments that may only show small changes in the graphs can have a much larger audible effect. Those more experienced would recognize this though, but most of us here only have one room to "practice" on.

For instance, the old DIY bass traps I mentioned before, compromisingly installed in this room, do not show "large" changes in the LF waterfalls. In fact, in some areas they show what to a newbie looks worse in some ways. But it sounds a lot better and clearer because they're doing something up at the higher end of the bass region, and into the vocal area/mids. Actually, they make a very large diff to me, beyond what the graphs would suggest. i.e. if somebody tried to sell me the traps "on paper", I'd have said no thanks...going to be more careful now. Fun!

Some (most actually) things only come with experience. Measurement graphs can be difficult to read. For the simple fact that a measurement graph might be weighting an area with greater or lesser emphasis then what our auditory system does.

I personally prefer to make changes and then listen to those changes first. After listening to the system, I then take a measurement of the system. This way, if the measurement does not translate to what I am expecting, I have not clouded my listening experience. In this way I feel I can more clearly interpret the measurement based on my listening experience, rather then trying to interpret my listening experience based on a measurement graph that I might not be understanding completely.

Quote:
Originally Posted by djbluemax1 View Post

It strikes me that some of the waterfall anomalies can be more easily seen depending on the rotated angle of view (and I've seen people with different viewing angles with different waterfalls), but I've never figured out how to do that

Indeed. I don't want to take away from the importance of having a base line set of standards that people follow when posting their results, but it's important to understand that some things might be better represented with different settings.

I have a tendency to always be playing around with waterfall settings, and I should include a standard waterfall with my custom waterfalls to make it easier for people to see how I am displaying my results.
Edited by Audionut11 - 12/27/13 at 8:56pm
post #7625 of 9491
I've done everything right. But I'm stuck right at REW>>PREFERENCES>>SOUNDCARD. On the input side it's showing 1: UMM-6 1 which is my mic. But the Output shows not connected. There's no selection for 1: HD Audio HDMI out #0 1. I've done everything right in windows audio Playback devices. Windows is showing my AVR. I'm on the right HDMI output because sound and display is coming out of the AVR. And all 8 channels on my AVR are lit. AVR is displaying PCM. Did I miss something?
post #7626 of 9491
Quote:
Originally Posted by jim19611961 View Post
 
Quote:
Originally Posted by kbarnes701 View Post

A fabulously informative post. Thanks for the analysis of my waterfall above. Much food for thought there. That problem at around 50Hz has been with me for a long time and, while I am not consciously aware of any audible problem, I know there really must be one, so at some point I am going to have tackle this. Thanks again.

For what its worth, I view your 50hz problem as minor (perhaps that is why its not discernibly audible) smile.gif

 

Well, your opinion is worth quite a lot, Jim and I thank you for it. Like I said, I am not consciously aware of a problem in that region, but it would be satisfying to remove the 'anomaly' from the graph.  It isn’t at the top of my priorities though, I agree. One day....

post #7627 of 9491
Quote:
Originally Posted by Audionut11 View Post

I agree with Jim. And my apologies Keith, I did mean to make mention that I thought your waterfall would represent a nice sounding system. Gotta love that low end response. wink.gifbiggrin.gif

Your (mine or anyone else's) inability to discern it is actually a good thing. I made note of a few advantages of narrowing down the (one of mine) waterfalls, one of which.
Quote:
My listening experience is not affected by a measurement graph I took moments before

 

Hey, no need to apologise. All constructive criticism or comment is welcome here!  Even though I believe I cannot consciously hear a problem, there's no doubt that the graph shows that some sort of, let's call it an 'anomaly' exists and it would be good to track it down and fix it. But things that don't spoil my audible pleasure go onto the list, but near the bottom :)

 

 

Quote:

 We want to make changes to our system that increase the enjoyment our listening experience. We do not want to measure our systems to the point where we find things in the measurement data that distract us from this listening experience.

Think of it as something to look at the next time you are looking for something to do biggrin.gif
Thanks for the praise guys. It's good to know that others can understand and benefit from the post.
 
I totally agree that one can get too hung up chasing graph perfection - what Bill Fitzmaurice called, aptly, 'graphitis nervosa'.  Believe me, I am not one of them!
 
Praise fulsomely deserved IMO!
post #7628 of 9491
Quote:
Originally Posted by rhed View Post

I've done everything right. But I'm stuck right at REW>>PREFERENCES>>SOUNDCARD. On the input side it's showing 1: UMM-6 1 which is my mic. But the Output shows not connected. There's no selection for 1: HD Audio HDMI out #0 1. I've done everything right in windows audio Playback devices. Windows is showing my AVR. I'm on the right HDMI output because sound and display is coming out of the AVR. And all 8 channels on my AVR are lit. AVR is displaying PCM. Did I miss something?

Don't know what hardware you're running REW on, but if you're running ASIO4ALL, try using the *exact* beta version shown in Jerry's guide. Not the latest beta version of ASIO4ALL from the site, that didn't work at all for me on my "recent" Win7/64 laptop. Can you record (via mike...) and play back a test audio file just via Windows utilities? This latter won't tell you anything re REW & ASIO4ALL, but is a basic test step.
post #7629 of 9491

Also, after installing the ASIO4ALL software, select it as the driver in the REW Preferences screen, then exit and re-start REW.  If this doesn't work, re-boot the laptop and re-start REW.  ASIO4ALL can be a bit picky to get properly configured the first time.  I guess that's why they call it beta software, but it is all we have for now.  Keep trying!

post #7630 of 9491
^ Yes, I forgot to mention that: my laptop required a reboot after ASIO4ALL installation to work reliably.

Been very good ever since, though ASIO4ALL does require a bit of a kick here to get it going again when the laptop comes out of hibernation.
post #7631 of 9491
ok..Thanks guys appreciate all the help. My first time with REW. Got the mic from cross spectrum. And I bought a cheap HP LT from BB.
post #7632 of 9491
Quote:
Originally Posted by Digione View Post

Spent my whole day taking measurements with different methods of trying to reduce my primary floor reflection. Will post later when I get my head together. smile.gif

Posted in a separate thread...by accident. eek.gif

http://www.avsforum.com/t/1508194/floor-reflections
post #7633 of 9491
Quote:
Originally Posted by kbarnes701 View Post

I totally agree that one can get too hung up chasing graph perfection - what Bill Fitzmaurice called, aptly, 'graphitis nervosa'. Believe me, I am not one of them!

I'm glad you can say that without irony biggrin.gif
post #7634 of 9491



My first measurement. Man, after hours of working out the quirks on the intel HDMI drivers. Finally got it to work. Anyway, looks like REW picked up my small house curve that I did with the Antimode Dual Core 2.0. Im still learning but this fun. Thanks guys.. And let me know what you guys think of this graph.
post #7635 of 9491
Quote:
Originally Posted by Audionut11 View Post

Onto the specifics of your question, run a measurement with no source signal.

I am not targeting a reduction in noise floor and don't currently have the means (to reduce the noise floor) even though I would like to, so all of this noise is just that, noise. I personally don't want my observations being effected by noise, so I'll adjust my waterfall parameters from now to filter this noise out.

 

 

Interesting post.  Can you be more specific WRT how you run a measurement in REW with no source signal, and how you take the results of this measurement, combine it with a full measurement to "filter out the noise"?  I would like to duplicate your results, but I am unclear about how you actually did it.

post #7636 of 9491
Quote:
Originally Posted by rhed View Post

My first measurement.

I assume the room is untreated? Use 1/48th measurement smoothing to remove the comb filtering and see more clearly your FR in the top end.
If the room is untreated, the low end response is pretty damn good. Follow AustinJerrys guide to posting a waterfall graph. There is a link to his guide in his signature above.
Quote:
Originally Posted by AustinJerry View Post

Interesting post.  Can you be more specific WRT how you run a measurement in REW with no source signal, and how you take the results of this measurement, combine it with a full measurement to "filter out the noise"?  I would like to duplicate your results, but I am unclear about how you actually did it.

Unplug the speakers, unplug the amp, mute the source signal. Whatever is easiest. All we want to do is have REW think it's measuring signal without any actual source signal being present. I like to ensure I have measurement length set to 1M in REW to capture as much noise as possible in each measurement run.
Quote:
Originally Posted by Audionut11 View Post

This noise is around 53dB, so filtering this out of the equation we are left with this (I'll scale the bottom end of the graph to 50dB just to be on the safe side, and be considerate that some noise is still present at the low end of the graph).

Ambient noise varies in amplitude and frequency depending on which way the wind is blowing. Run a few measurements yourself to find the average peak of noise in your environment.

Then simply set the bottom end of the waterfall scale to some level at or above your average level previously measured.

There is no way for REW to filter out the noise automatically. As mentioned above, it varies everytime you dip your pinky in water.
post #7637 of 9491
How does this differ from using the RTA function to determine the noise floor, and then simply setting the lower limit of the waterfall to that value? I believe this is what most of us have been doing.

I'll try your method tomorrow.
post #7638 of 9491
They are different functions providing data in different ways.
Quote:
Originally Posted by Audionut11 View Post

Onto the specifics of your question, run a measurement with no source signal.



There is no source signal present, so everything in this waterfall MUST be noise.

We are interested in the noise as seen by the waterfall graphs, not whatever noise reading is being displayed by the RTA.
AFAIK, the RTA is making noise readings that more closely resemble human hearing based on the window setting. If you were telling someone what the ambient noise floor was of your room, you would use the RTA. The waterfall isn't using any averaging or weighting, it's showing direct amplitude of the signal/noise in the time domain. We need to measure the noise as seen via the waterfall and subtract that from our graphs.
Edited by Audionut11 - 12/28/13 at 11:05pm
post #7639 of 9491
Quote:
Originally Posted by sdrucker View Post
 
Quote:
Originally Posted by kbarnes701 View Post

I totally agree that one can get too hung up chasing graph perfection - what Bill Fitzmaurice called, aptly, 'graphitis nervosa'. Believe me, I am not one of them!

I'm glad you can say that without irony biggrin.gif

 

LOL. I do like a nice looking graph - but I really do try to remain interested only in elements of the graph which can actually be heard via my ears :)

post #7640 of 9491
I have this ETC for my right speaker. If I understand correctly there's a strong reflection at about 7ms which equates to about 7-7.5 feet.

Now, that's the signal path so that's in addition to the direct path from the speaker to the MLP. Since my speaker is about 14' from the MLP the total path is 21-21.5 feet.

Please let me know if my understanding is incorrect.

To find that reflective surface, what are some methods other than the string method?


post #7641 of 9491
Quote:
Originally Posted by artur9 View Post

I have this ETC for my right speaker. If I understand correctly there's a strong reflection at about 7ms which equates to about 7-7.5 feet.

Now, that's the signal path so that's in addition to the direct path from the speaker to the MLP. Since my speaker is about 14' from the MLP the total path is 21-21.5 feet.

Please let me know if my understanding is incorrect.

To find that reflective surface, what are some methods other than the string method?



14' = 12.4ms

7ms = 7.78 feet

My first question is how is it your 14' from the speakers? How far apart are your speakers? Can you provide a pic or link to your room layout?

The reason I am asking is because the reflections magnitude is directly proportional to the direct energy. That is, the closer to the speaker you are, the lower the reflections will be all other things being equal.
post #7642 of 9491
Quote:
Originally Posted by jim19611961 View Post

14' = 12.4ms

7ms = 7.78 feet

My first question is how is it your 14' from the speakers? How far apart are your speakers? Can you provide a pic or link to your room layout?

The reason I am asking is because the reflections magnitude is directly proportional to the direct energy. That is, the closer to the speaker you are, the lower the reflections will be all other things being equal.

Sorry, Jim, I misremembered. By tape measure my speakers are 4'10" apart, mid-grill to mid-grill. I thought they were farther apart than that. I'm going to have to figure some way to get them farther apart.

The MLP is 11'10 from the right speaker.

Room layout

View towards screen & speakers .
Only change since that picture was taken is that I've added a black fabric behind the TV. Really makes the screen pop!
post #7643 of 9491
Quote:
Originally Posted by artur9 View Post

I have this ETC for my right speaker.

I think the reflection must be coming off the ceiling as there's nothing else anywhere near the speakers that could be causing a reflection with that distance measure.
post #7644 of 9491
Is this the latest version? Thanks

Link to REW 101 v3.12.pdf

Also, is there a prefer mic to use with REW? Or is it just up to personal taste?

Umik-1 or UMM-6? Looks like they are about the same price
Edited by smokarz - 12/29/13 at 2:48pm
post #7645 of 9491
Can someone address or point me to a source that will help me correlate what I see on an REW graph and what I hear? Beyond that, how do subtle improvements in sound quality, specifically improved integration of surrounds and LCR, manifest themselves in REW graphs? And just how would one measure a 7.1/5.1 system to check for better integration.

I am able to interpret improvements in decay time and mode reduction. But the integration thingy is elusive.

Thanks,

Jeff
post #7646 of 9491
Quote:
Originally Posted by pepar View Post

Can someone address or point me to a source that will help me correlate what I see on an REW graph and what I hear? Beyond that, how do subtle improvements in sound quality, specifically improved integration of surrounds and LCR, manifest themselves in REW graphs? And just how would one measure a 7.1/5.1 system to check for better integration.

I am able to interpret improvements in decay time and mode reduction. But the integration thingy is elusive.

Thanks,

Jeff

Really, Jeff? This sounds like a not-so-subtle response to Keith's claim that if he can't measure it, then it doesn't exist (or something to that effect). Personally, I would prefer that the debate that has been going on in the Pro thread stay in that thread, and not spill over into this thread. Would that be too much to ask?
post #7647 of 9491
Quote:
Originally Posted by AustinJerry View Post

Really, Jeff? This sounds like a not-so-subtle response to Keith's claim that if he can't measure it, then it doesn't exist (or something to that effect). Personally, I would prefer that the debate that has been going on in the Pro thread stay in that thread, and not spill over into this thread. Would that be too much to ask?

I thought I asked a simple and seemingly pretty basic question in the thread that is filled with users.

Is there a way to correlate the measurements with what is heard?

Jeff
post #7648 of 9491
Quote:
Originally Posted by pepar View Post

Can someone address or point me to a source that will help me correlate what I see on an REW graph and what I hear? Beyond that, how do subtle improvements in sound quality, specifically improved integration of surrounds and LCR, manifest themselves in REW graphs? And just how would one measure a 7.1/5.1 system to check for better integration.

I am able to interpret improvements in decay time and mode reduction. But the integration thingy is elusive.

Thanks,

Jeff

I think the first thing is what graph do you want interpreted?
post #7649 of 9491
Quote:
Originally Posted by pepar View Post


Can someone address or point me to a source that will help me correlate what I see on an REW graph and what I hear?

REW graphs are based on amplitude and frequency presented as numbers. Relating amplitude and frequency presented as numbers is a mental skill that is often learned by people who do recording and production.

If you search goggle using the following words you will find many alternatives for ear training

ear training frequency amplitude
post #7650 of 9491
Quote:
Originally Posted by arnyk View Post

REW graphs are based on amplitude and frequency presented as numbers. Relating amplitude and frequency presented as numbers is a mental skill that is often learned by people who do recording and production.

If you search goggle using the following words you will find many alternatives for ear training

ear training frequency amplitude

So, REW measurements can be used to confirm an improvement in sound quality, but not to even loosely quantify, categorize or characterize them as being a little better, a lot better or holy cow?

Is this mostly a tool for assessing room treatments? I initially used it ten years ago for determining the amount of SSC traps I needed as well as decay time tuning

Jeff
Edited by pepar - 12/29/13 at 4:53pm
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