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post #2911 of 9577
Quote:
Originally Posted by AustinJerry View Post

Markus, do you mean the actual REW measurement file uploaded to DropBox?

Yes, the .mdat please!

Gear mentioned in this thread:

post #2912 of 9577
Quote:
Originally Posted by AustinJerry View Post

I actually think I have too much absorption of the mid to high frequencies, and will be removing some rather ineffective ATS Acoustics panels from my side walls.  They will be replaced with a single GIK panel at the primary reflection point.  I ordered the GIK panels with a "scatter plate", which is a new enhancement they have recently added, just to get an idea of what the plate does.  On the side with the fireplace, I will be placing a panel on a stand in front of the fireplace mantle so that I have matching treatments on each side of the room at the FRP.  My understanding is that reflection symmetry is also important.  I'll report back my findings.

absorption is a band-aid for attenuating first-order signals and this is why you generally see splayed walls (or large (with respect to wavelength) flat reflector panels) to redirect the first-order reflections away from the listening position and towards the rear wall/rear sidewalls where that energy can be diffused and reintroduced to the listening position as a laterally arriving dense diffused sound-field. in home theater, you have active speakers to provide the rear returns (vs the passive lateral diffused returns in this 2ch model for envelopment). it can still be extremely beneficial to make all indirect later arriving energy diffused and this can be accomplished with binary amplitude diffusers (BAD) which spatially disperse the energy without the distance/size/seating limitations as you have with reflection phase gratings (QRD/PRDs) - albeit at the expense of losing temporal dispersion. this is why BAD panels can be extremely effective in home theater environments (with multiple rows/seating positions and real estate limitations).

the splayed walls/reflector panels attenuate the destructive signal while still maintaining the energy within the room - energy that can be managed and reintroduced to the listening position via a diffused later-arriving sound-field. absorption at first reflection points removes this energy and any subsequent later-arriving (multi-order) "bounces" from those same absorbers. again, it depends on the room response requirements and how you wish to manage how energy is induced to the listening position.
post #2913 of 9577
Quote:
Originally Posted by jim19611961 View Post

Jerry, those ceiling panels really helped. Lookin' good!

Once you deal with that 5ms reflection, you may be able to call it a day.

 

Hi Jim.  Yes, REW shows that reflection to be at 5.7ft.  I need to do some detective work to find out what is causing it.  With all the guidance I have received, for which I am very grateful, I am getting a little better at finding the source of the problems.

post #2914 of 9577
Quote:
Originally Posted by AustinJerry View Post

Hi Jim.  Yes, REW shows that reflection to be at 5.7ft.  I need to do some detective work to find out what is causing it.  With all the guidance I have received, for which I am very grateful, I am getting a little better at finding the source of the problems.

Id put my bets on the first reflection points on the untreated walls to the left and right? of the speakers. I.E. about where the fireplace is for the left (cant see the right wall in the pic).
Edited by jim19611961 - 5/23/13 at 9:22am
post #2915 of 9577
Quote:
Originally Posted by jim19611961 View Post


Id put my bets on the first reflection points on the untreated walls to the left and right? of the speakers. I.E. about where the fireplace is for the left (cant see the right wall in the pic).

 

That is my theory as well, and will be tested when the new panels arrive next week.  To date, I have not tried any treatments where the fireplace is, but as I mentioned earlier, I am going to try a 2'x4' panel on a stand.  If I want to use the fireplace (which is not that often in a hot climate), I can simply move the stand out of the way temporarily.

post #2916 of 9577
Quote:
Originally Posted by AustinJerry View Post

That is my theory as well, and will be tested when the new panels arrive next week.  To date, I have not tried any treatments where the fireplace is, but as I mentioned earlier, I am going to try a 2'x4' panel on a stand.  If I want to use the fireplace (which is not that often in a hot climate), I can simply move the stand out of the way temporarily.

just hold a broadband absorber in the direction/vector that you think the reflection is ingress from and remeasure to see if diminished (eg, the "blocking method"). rinse / repeat.

remember, since you are not utilizing hardware loopback (eg, direct signal arriving at T=0), the total flight path of the indirect energy will not be accurate (although the delta between direct and indirect will be).
post #2917 of 9577
Quote:
Originally Posted by localhost127 View Post


just hold a broadband absorber in the direction/vector that you think the reflection is ingress from and remeasure to see if diminished (eg, the "blocking method"). rinse / repeat.

remember, since you are not utilizing hardware loopback (eg, direct signal arriving at T=0), the total flight path of the indirect energy will not be accurate (although the delta between direct and indirect will be).

 

Got it, thanks!

post #2918 of 9577

Just re-checking my noise floor after I had new windows installed several weeks ago.  These are triple-pane glass, with pretty good sound isolation from outdoor noises.  Here are two methods of measurement.  I used my EMM-6 calibrated mic, since its S/N ratio seems to be significantly better than the UMM-6.

 

 

 

 

My question is, which of these two methods is more acceptable to measure the noise floor, and why?  Or is there yet a better way?

post #2919 of 9577
Quote:
Originally Posted by AustinJerry View Post

 

As far as your recommendation for picking a small room acoustic model, I have done some reading of white papers, and browsed some of the discussion threads, but I'm not sure I am any closer to making a decision.  I'm familiar with the terms now, and the high level objectives.  However, since I don't have a dedicated room, and since the back of the room is open to the rest of the ground floor, I'm not sure any of the models will fit.  Reading the "Small room acoustic models" here on AVS was a bit of a chore.  Too bad there isn't an "ignore the bickering" button. 

 

+1 on the highlighted/bolded sections.  I realize there is a lot of controversy (to say the least) with respect to which model to follow, but would it be worth documenting some of the pros and cons of each in this thread to help others like myself with their selection?  As I mentioned previously, I've received some excellent advice in this thread on improving my overall SQ but it seems I'm at a cross-roads of sorts wrt types of room treatments and where they should be applied?!  TBH, at this point I'd almost rather explore two different models just to compare the differences realizing the requirements to implement said models might be exactly opposite one another.

 

In any case, I've read just about all the "theory" I can take on this and would like to pick a path and start experimenting.  Unlike Keith, I don't have a dedicated 2-ch listening room but my preference is heavily weighted towards movies (90:10 or even 95:5 movies:music). HST, it's not like I want that 5 or 10% to sound like crap just because I picked one model over the other...HELP!

post #2920 of 9577
Quote:
Originally Posted by jkasanic View Post

+1 on the highlighted/bolded sections.  I realize there is a lot of controversy (to say the least) with respect to which model to follow, but would it be worth documenting some of the pros and cons of each in this thread to help others like myself with their selection?  As I mentioned previously, I've received some excellent advice in this thread on improving my overall SQ but it seems I'm at a cross-roads of sorts wrt types of room treatments and where they should be applied?!  TBH, at this point I'd almost rather explore two different models just to compare the differences realizing the requirements to implement said models might be exactly opposite one another.

In any case, I've read just about all the "theory" I can take on this and would like to pick a path and start experimenting.  Unlike Keith, I don't have a dedicated 2-ch listening room but my preference is heavily weighted towards movies (90:10 or even 95:5 movies:music). HST, it's not like I want that 5 or 10% to sound like crap just because I picked one model over the other...HELP!

+ 5 on this - I understand the paradigm of starting with an acoustic model as a baseline. But right now I don't see any reason to do more than LEDE, since the other alternative that I've seen mentioned (a purely non-environmental room model) won't be suitable if I'm interested in music as my primary interest: call it 60/40 music over movies. And while I know there aren't simple issues involved (and it's going to require considerable reading and time above and beyond the work I've done with Audyssey), at least a simple FAQ for pros/cons of the leading models - and what other models than NE and LEDE are worth considering for HT use in multipurpose living spaces - would be very helpful to know where to start, before reading books.

Or maybe that's backward, and you've got to have solid acoustic training even before thinking of models and treatments. In which case this really is the "graduate-level" class for those of us that appreciate what AJ, Keith, and people like Sanjay have done to turn this into an interactive thread while Jason's been "waiting" us out..
Edited by sdrucker - 5/23/13 at 1:22pm
post #2921 of 9577

Actually, I'm just the opposite (from Jkasanic).  I would prefer to optimize my listening room for music, both stereo and multi-channel.  My thoughts are that if it sounds great for music, it is likely to be "good enough" for me for movies and television.

post #2922 of 9577
Quote:
Originally Posted by AustinJerry View Post

Actually, I'm just the opposite (from Jkasanic).  I would prefer to optimize my listening room for music, both stereo and multi-channel.  My thoughts are that if it sounds great for music, it is likely to be "good enough" for me for movies and television.

 

Jerry, I wouldn't necessarily say that we're opposite in this regard.  I was merely indicating my listening preference.  To your point, if optimizing for music results in a better combined response than optimizing for movies, then we're on the same page.  As I mentioned, I don't want my 2-ch and multi-ch music to suffer extraordinarily because I chose one model over the other.  As Keith points out from time to time, should there be any reason the two should be in conflict with one another (i.e. do the speakers/room really care if they're reproducing music or movies)?

post #2923 of 9577
I am 0/100 movie/music, so take this into account as per my response.

LEDE / RFZ implies not only a ISD-gap, but a terminator. A REAL LEDE / RFZ calls for a dense diffused termination no less than -12db. Now, if your going to use a reflector (specular) for the termination instead of a diffuse terminator, you have already deviated from the model. If you are to have no terminator at all, then you cant even call it quasi-LEDE / RFZ anymore. Not saying LEDE / RFZ achieves the only good sound in a room, but if your going to call it that, then certain criteria must be in place.

Mitigating / treating first reflection points and thus creating a ISD gap of some kind is a good thing IMO. Early high energy reflections are undesirable IMO. BUT, by the time you have the first 20ms at -20db, or better still -25 or -30db, if you havent done things carefully, you have a dead space. Alas the terminator to reintroduce delayed energy. Although its a short cut, its often a necessary one to replace the dense diffuse return for a specular one in a small rectangular room to get the terminator strength to -12db or better. In small rectangular rooms, achieving the prescribed terminator strength via defuse returns is nearly impossible, especially if you follow the LEDE / RFZ model all the way and have these returns only arrive from 110 degrees or so.
post #2924 of 9577
Quote:
Originally Posted by jim19611961 View Post

Although its a short cut, its often a necessary one to replace the dense diffuse return for a specular one in a small rectangular room to get the terminator strength to -12db or better..

time to tear out the rear wall of your living room, jim - lol:

HSZ9nOs.png
post #2925 of 9577


I found this ^^^^ the limits of my room and patience eek.gif

Thanks for the recommendation though rolleyes.gif

smile.gif
post #2926 of 9577
biggrin.gif
post #2927 of 9577
Quote:
Originally Posted by AustinJerry View Post

Just re-checking my noise floor after I had new windows installed several weeks ago.  These are triple-pane glass, with pretty good sound isolation from outdoor noises.  Here are two methods of measurement.  I used my EMM-6 calibrated mic, since its S/N ratio seems to be significantly better than the UMM-6.

My question is, which of these two methods is more acceptable to measure the noise floor, and why?  Or is there yet a better way?

Jerry,

Use the RTA and switch "Mode" to "Spectrum", not "RTA", otherwiese your graph will be skewed. Examine pink noise and white noise with both modes and you'll see the difference.

Noise floor within a room is one of the most important things to look at, especially for beginners. Often people look at data that is nothing more but noise. They change sub location, bass trapping, etc. and wonder why the waterfall graph doesn't reflect those changes.

The "logger" is good for long term SPL observation. It is (more or less) blind to frequency.
post #2928 of 9577
Quote:
Originally Posted by jevansoh View Post


In Keith's case, he's stated he doesn't listen to music in his room and doesn't want to add any livliness/spaciousness and only wants whatever ambiance is recorded on the track, IE: From surround speakers, since he listens to movies only.

Keith would want to suppress all reflections with a gain higher than -20db and not terminate his ITD to achieve this. This method is based on the NE design (Non-Environment).
 

 

Yeah!  I am a NE Dude :)  It is certainly much simpler if one decides to use the HT solely for movies I think. HST, I have not really fully achieved a NE room (yet) and there are still some reflections which show up on my ETC. But I am happy with the sound in the room and am not sure if I really want to add even more treatments. I am reading more and hopefully may come to a conclusion at some point! But I am definitely in the camp of wishing to hear just the speakers and getting any and all the ambience required from the mix and the discrete channels.

post #2929 of 9577
Quote:
Originally Posted by AustinJerry View Post

Here is a picture of the ceiling treatments.  Thanks to Keith for suggesting the use of cable-ties to secure the panels to the hooks in the ceiling.

 

 

Neat job, Jerry. I continue to admire your endless energy and dedication to the pursuit of better sound. You really are an inspiration to us!

post #2930 of 9577
Quote:
Originally Posted by jkasanic View Post

Quote:
Originally Posted by AustinJerry View Post

 

As far as your recommendation for picking a small room acoustic model, I have done some reading of white papers, and browsed some of the discussion threads, but I'm not sure I am any closer to making a decision.  I'm familiar with the terms now, and the high level objectives.  However, since I don't have a dedicated room, and since the back of the room is open to the rest of the ground floor, I'm not sure any of the models will fit.  Reading the "Small room acoustic models" here on AVS was a bit of a chore.  Too bad there isn't an "ignore the bickering" button. 

 

+1 on the highlighted/bolded sections.  I realize there is a lot of controversy (to say the least) with respect to which model to follow, but would it be worth documenting some of the pros and cons of each in this thread to help others like myself with their selection?  As I mentioned previously, I've received some excellent advice in this thread on improving my overall SQ but it seems I'm at a cross-roads of sorts wrt types of room treatments and where they should be applied?!  TBH, at this point I'd almost rather explore two different models just to compare the differences realizing the requirements to implement said models might be exactly opposite one another.

 

In any case, I've read just about all the "theory" I can take on this and would like to pick a path and start experimenting.  Unlike Keith, I don't have a dedicated 2-ch listening room but my preference is heavily weighted towards movies (90:10 or even 95:5 movies:music). HST, it's not like I want that 5 or 10% to sound like crap just because I picked one model over the other...HELP!

 

It's not that I have a dedicated 2-ch space, Joe -- although I’d love that -- my stereo system is in a normal living room space, furnished as normal, with carpets, drapes, large sofas etc. But the HT is dedicated to movies and this does make the job much easier I reckon. A lot of the difficulties seem to stem from trying to get a space that sounds good for 2ch and also good for m/ch.

post #2931 of 9577
Quote:
Originally Posted by jkasanic View Post

Quote:
Originally Posted by AustinJerry View Post

Actually, I'm just the opposite (from Jkasanic).  I would prefer to optimize my listening room for music, both stereo and multi-channel.  My thoughts are that if it sounds great for music, it is likely to be "good enough" for me for movies and television.

 

Jerry, I wouldn't necessarily say that we're opposite in this regard.  I was merely indicating my listening preference.  To your point, if optimizing for music results in a better combined response than optimizing for movies, then we're on the same page.  As I mentioned, I don't want my 2-ch and multi-ch music to suffer extraordinarily because I chose one model over the other.  As Keith points out from time to time, should there be any reason the two should be in conflict with one another (i.e. do the speakers/room really care if they're reproducing music or movies)?

 

I don't think they do - it's all 'noise' to the speakers and room. The conflict seems to arise from the need for reflections to add spaciousness for 2ch music reproduction whereas my own belief is that all the 'spaciousness' or ambience is already recorded into a m/ch HT track so I don't believe I need any added reflectivity in the room - all I require is already in the disc itself.  This seems to be borne out when I visit an actual movie theatre - these seem to be effectively 'dead' or 'inert' spaces, unlike concert halls for example. Of course, compared with others here, I am a rank amateur in this regard, so feel free to add a very large grain of sodium chloride to this :)

post #2932 of 9577
Quote:
Originally Posted by markus767 View Post

Jerry,

Use the RTA and switch "Mode" to "Spectrum", not "RTA", otherwiese your graph will be skewed. Examine pink noise and white noise with both modes and you'll see the difference.

Noise floor within a room is one of the most important things to look at, especially for beginners. Often people look at data that is nothing more but noise. They change sub location, bass trapping, etc. and wonder why the waterfall graph doesn't reflect those changes.

The "logger" is good for long term SPL observation. It is (more or less) blind to frequency.

Markus,

It was my understanding that to measure the noise floor, the REW RTA was used without at test signal, but you mentioned examining both pink and white noise, so I am confused. What am I missing here?

Thanks.

Mark
post #2933 of 9577
Quote:
Originally Posted by kbarnes701 View Post

HST, I have not really fully achieved a NE room (yet) and there are still some reflections which show up on my ETC. But I am happy with the sound in the room and am not sure if I really want to add even more treatments. I am reading more and hopefully may come to a conclusion at some point! But I am definitely in the camp of wishing to hear just the speakers and getting any and all the ambience required from the mix and the discrete channels.

Keith, WRT reflections, I am learning that there are good reflections, and bad reflections. Early seems to be bad, and beyond a certain time interval seems to be good. I am in the process taking down some of my treatments that were installed before I really had any understanding of what was going on, and moving some other treatments to better locations. Now that I have had a taste of "spaciousness", I want more.
post #2934 of 9577
Quote:
Originally Posted by giomania View Post

Markus,

It was my understanding that to measure the noise floor, the REW RTA was used without at test signal, but you mentioned examining both pink and white noise, so I am confused. What am I missing here?

Thanks.

Mark

Sure, if you want to measure the noise floor then the test signal is silence smile.gif
But, REW has two different RTA modes modes, "Spectrum" and "RTA". For noise floor measurements always use "Spectrum", not "RTA".

When you examine a pink noise signal in RTA mode you'll get a flat response. In spectrum mode you'll get a falling response curve:




White noise in RTA mode results in a rising curve whereas in spectrum mode the curve is flat:




Why is that?
Pink noise has falling power density whereas white noise has constant power density.
post #2935 of 9577
Quote:
Originally Posted by AustinJerry View Post

Now that I have had a taste of "spaciousness", I want more.

Audyssey DSX? smile.gif
Unfortunately the whole topic is very complex and not well understood because our hearing isn't well understood. State of the art is still trial and error - LEDE, RFZ, RRZ, Moulton, non-environment, ambechoic, you name it. So keep on experimenting.
post #2936 of 9577
Quote:
Originally Posted by jim19611961 View Post


Id put my bets on the first reflection points on the untreated walls to the left and right? of the speakers. I.E. about where the fireplace is for the left (cant see the right wall in the pic).

 

Jim, I thought you might be on to something here.  Here is the "before" picture, showing the bare wall on each side of the flat panel.  WRT the MLP, the angle of incidence/reflection makes this wall a potential for that reflection.

 

 

So, I tried using two ATS Acoustics panels, but no change in the reflection as per the ETC measurement.

 

 

Thinking that the ATS panels might not be effective, I tried two GIK 242 panels.  Still no reduction in the reflection.  Perhaps the front wall is not the issue.

 

 

Quote:
Originally Posted by localhost127 View Post


just hold a broadband absorber in the direction/vector that you think the reflection is ingress from and remeasure to see if diminished (eg, the "blocking method"). rinse / repeat.

 

So, following the recommendation by Localhost, I tried this.  (Panel on left, right, top, bottom, and behind).  BTW, the panel on top is referred to as the "Markus position".  wink.gif

 

 

 

 

 

 

 

Here is the "Before" measurement.  There are two reflections, one at 5ft, and one at 5.9ft, at -11dB and -14dB, respectively.

 

 

Results of the test:

 

Panel on the left:  no change

Panel on the right:  no change

Panel on the floor:  no change

Panel behind:  no change

Panel in the Markus position:  change!

 

 

The reflection at 5ft is now -20dB.  The reflection at 5.9 feet is still unchanged.

 

So, I have several questions for the experts:

 

1.  I just installed absorption panels on the ceiling, which significantly reduced a reflection at ~7ft.  Why is this test showing me that something vertically is still causing a reflection?  And at a distance shorter than the ceiling FRP at 7ft?

 

2.  Why didn't one of the five panel positions reduce the reflection at 5.9ft?

 

Side question:  My two front subs, which are at the 1/4 and 3/4 points on the front wall, ar partially behind the left and right speakers.  Would this cause any audio issues?  Both the subs and the mains are in the sweet spots for my listening room.

post #2937 of 9577
There are often loud 2nd order reflections, they bounce off from two boundaries. Sometimes multiple reflections add at one point in time, which makes it look like there's only one.

Didn't I mention at one point to cover the whole back wall? smile.gif
Edited by markus767 - 5/24/13 at 3:22pm
post #2938 of 9577
Jerry, the technique you used putting an absorber on different sides of the speaker can be used at the mic also wink.gif
post #2939 of 9577
Quote:
Originally Posted by jim19611961 View Post

Jerry, the technique you used putting an absorber on different sides of the speaker can be used at the mic also wink.gif

OK, Jim, I will try that tomorrow, thanks.
post #2940 of 9577
Quote:
Originally Posted by markus767 View Post

There are often loud 2nd order reflections, they bounce off from two boundaries. Sometimes multiple reflections add at one point in time, which makes it look like there's only one.

Didn't I mention at one point to cover the whole back wall? smile.gif

I did cover the whole back wall.
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