Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 157 - AVS Forum
Forum Jump: 
 185Likes
Reply
 
Thread Tools
post #4681 of 12042 Old 09-23-2013, 03:07 AM
AVS Addicted Member
 
kbarnes701's Avatar
 
Join Date: Jan 2008
Location: Main Listening Positon
Posts: 18,691
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 1901 Post(s)
Liked: 1988
Quote:
Originally Posted by sdrucker View Post
 
Quote:
Originally Posted by kbarnes701 View Post

Yes, but for your experiments, the mic presumably won’t be moved between measurements?

Well, no, but I also like reproducible results.....Not just for Sunday evening at 9 PM when the Maltese is chewing on his Donald Duck toy, if you follow....biggrin.gif

 

True - but if you left the mic in the same spot for every measurement, I think you would get reproducible results - even if you compared measurements from weeks ago. How could you not - 

it's a computer?  I am sure that the small variations in mic position are what cause these variations usually (when nothing else has been changed). I know in my own case that moving the mic 1 inch makes a visible difference to the graph - and I have no way to be sure that I get the mic positioned with a 1 inch degree of accuracy when I make subsequent measurements.  One way would be to tie a small lead weight to some fishing line and then suspend the weight from the ceiling with the tip right at the mic tip - then leave the weight there for ever. But that would be absurd IMO :)

kbarnes701 is offline  
Sponsored Links
Advertisement
 
post #4682 of 12042 Old 09-23-2013, 03:09 AM
AVS Addicted Member
 
kbarnes701's Avatar
 
Join Date: Jan 2008
Location: Main Listening Positon
Posts: 18,691
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 1901 Post(s)
Liked: 1988
Quote:
Originally Posted by ggsantafe View Post

^^^^ Just throwing this out - but I wonder if changes in temperature & humidity have any impact on measurements - thus producing different results when microphone measurements are carefully replicated? Or does the Gremlin theory prevail?

 

Changes in humidity will affect the speed of sound through the air I'd imagine. If the change in humidity was significant, I'd bet it could make results vary. IDK about temperature.

kbarnes701 is offline  
post #4683 of 12042 Old 09-23-2013, 06:40 AM
AVS Special Member
 
jim19611961's Avatar
 
Join Date: Mar 2011
Location: Texas
Posts: 1,397
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 126 Post(s)
Liked: 85
Quote:
Originally Posted by kbarnes701 View Post

Changes in humidity will affect the speed of sound through the air I'd imagine. If the change in humidity was significant, I'd bet it could make results vary. IDK about temperature.

http://www.sengpielaudio.com/calculator-soundpath.htm

Sound moves faster through warmer air than colder. I.E. On a ETC, your reflections will be slightly more delayed in a colder room than a warmer one.

Using the link above, you can plug in different temps and see how the delay times change accordingly.

My Room
My Music
Rega - Apollo, Rega - DAC, Goldpoint Passive, (2) Classe CA-100 bridged power amps (350w)
Jenzen Next
jim19611961 is offline  
post #4684 of 12042 Old 09-23-2013, 06:43 AM
AVS Special Member
 
AustinJerry's Avatar
 
Join Date: Jan 2003
Location: Austin, Texas
Posts: 7,555
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 754 Post(s)
Liked: 792
Quote:
Originally Posted by kbarnes701 View Post

True - but if you left the mic in the same spot for every measurement, I think you would get reproducible results - even if you compared measurements from weeks ago. How could you not - 
it's a computer?  I am sure that the small variations in mic position are what cause these variations usually (when nothing else has been changed). I know in my own case that moving the mic 1 inch makes a visible difference to the graph - and I have no way to be sure that I get the mic positioned with a 1 inch degree of accuracy when I make subsequent measurements.  One way would be to tie a small lead weight to some fishing line and then suspend the weight from the ceiling with the tip right at the mic tip - then leave the weight there for ever. But that would be absurd IMO smile.gif

Hanging a weight from the ceiling would be absurd, something like what I might do, but I don't. I rely on a tape measure, knowing that my MLP is 118" from the side wall, and 46" from the back wall. Placing the Audyssey mic at this spot produces the same calibration distance calculations each time. Assuming Audyssey is correct, and then placing the REW mic at the same spot, this is a reasonable way to ensure measurement consistency.
AustinJerry is offline  
post #4685 of 12042 Old 09-23-2013, 07:05 AM
Advanced Member
 
artur9's Avatar
 
Join Date: Mar 2013
Location: near philly
Posts: 756
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 65 Post(s)
Liked: 44
Quote:
Originally Posted by AustinJerry View Post

Hanging a weight from the ceiling would be absurd, something like what I might do, but I don't.

If you had a drop ceiling you could tuck the weight in there when not in use. wink.gif
artur9 is offline  
post #4686 of 12042 Old 09-23-2013, 07:31 AM
AVS Club Gold
 
sdrucker's Avatar
 
Join Date: Feb 2006
Location: Chicago, IL
Posts: 2,211
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 140 Post(s)
Liked: 145
Quote:
Originally Posted by AustinJerry View Post

Hanging a weight from the ceiling would be absurd, something like what I might do, but I don't. I rely on a tape measure, knowing that my MLP is 118" from the side wall, and 46" from the back wall. Placing the Audyssey mic at this spot produces the same calibration distance calculations each time. Assuming Audyssey is correct, and then placing the REW mic at the same spot, this is a reasonable way to ensure measurement consistency.

That's a perfect solution for consistent length, width and height, and IMO should go into the REW guide as best practice. Much less subjective than a picture on my iPhone.

What has it done for REW plot consistency?

Stuart

 

Denon 4311 with XT32 and Audyssey Pro

Oppo 93 and 103

Panasonic VT50

Sherwood R-972 with its version of the Trinnov Optimizer

MiniDSP 10x10 HD

PSB Imagine T2, Center, and Surrounds (as of 5/2014); HSU ULS-15 subs (2)

 

The Audyssey FAQ Guide can be found here:

http://www.avsforum.com/...

sdrucker is offline  
post #4687 of 12042 Old 09-23-2013, 07:53 AM
AVS Special Member
 
AustinJerry's Avatar
 
Join Date: Jan 2003
Location: Austin, Texas
Posts: 7,555
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 754 Post(s)
Liked: 792
Quote:
Originally Posted by sdrucker View Post


That's a perfect solution for consistent length, width and height, and IMO should go into the REW guide as best practice. Much less subjective than a picture on my iPhone.

What has it done for REW plot consistency?

 

 

Reasonable consistency.  There is still an imperfect human being taking the measurements and lining things up.

AustinJerry is offline  
post #4688 of 12042 Old 09-23-2013, 08:27 AM
AVS Addicted Member
 
kbarnes701's Avatar
 
Join Date: Jan 2008
Location: Main Listening Positon
Posts: 18,691
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 1901 Post(s)
Liked: 1988
Quote:
Originally Posted by jim19611961 View Post
 
Quote:
Originally Posted by kbarnes701 View Post

Changes in humidity will affect the speed of sound through the air I'd imagine. If the change in humidity was significant, I'd bet it could make results vary. IDK about temperature.

http://www.sengpielaudio.com/calculator-soundpath.htm

Sound moves faster through warmer air than colder. I.E. On a ETC, your reflections will be slightly more delayed in a colder room than a warmer one.

Using the link above, you can plug in different temps and see how the delay times change accordingly.

 

Excellent - thanks for the link.

kbarnes701 is offline  
post #4689 of 12042 Old 09-23-2013, 08:29 AM
AVS Addicted Member
 
kbarnes701's Avatar
 
Join Date: Jan 2008
Location: Main Listening Positon
Posts: 18,691
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 1901 Post(s)
Liked: 1988
Quote:
Originally Posted by AustinJerry View Post
 
Quote:
Originally Posted by kbarnes701 View Post

True - but if you left the mic in the same spot for every measurement, I think you would get reproducible results - even if you compared measurements from weeks ago. How could you not - 
it's a computer?  I am sure that the small variations in mic position are what cause these variations usually (when nothing else has been changed). I know in my own case that moving the mic 1 inch makes a visible difference to the graph - and I have no way to be sure that I get the mic positioned with a 1 inch degree of accuracy when I make subsequent measurements.  One way would be to tie a small lead weight to some fishing line and then suspend the weight from the ceiling with the tip right at the mic tip - then leave the weight there for ever. But that would be absurd IMO smile.gif

Hanging a weight from the ceiling would be absurd, something like what I might do, but I don't. I rely on a tape measure, knowing that my MLP is 118" from the side wall, and 46" from the back wall. Placing the Audyssey mic at this spot produces the same calibration distance calculations each time. Assuming Audyssey is correct, and then placing the REW mic at the same spot, this is a reasonable way to ensure measurement consistency.

 

:) Yes, it is clearly possible. Personally I don't measure though - I just put the mic in more or less the same place each time. I don't sweat it because I know my head is only more or less in the same place each time too :)

kbarnes701 is offline  
post #4690 of 12042 Old 09-23-2013, 08:30 AM
AVS Addicted Member
 
kbarnes701's Avatar
 
Join Date: Jan 2008
Location: Main Listening Positon
Posts: 18,691
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 1901 Post(s)
Liked: 1988
Quote:
Originally Posted by AustinJerry View Post
 
Quote:
Originally Posted by sdrucker View Post


That's a perfect solution for consistent length, width and height, and IMO should go into the REW guide as best practice. Much less subjective than a picture on my iPhone.

What has it done for REW plot consistency?

 

 

Reasonable consistency.  There is still an imperfect human being taking the measurements and lining things up.

 

And different room temperatures and humidities too - another thing to worry about now LOL.

kbarnes701 is offline  
post #4691 of 12042 Old 09-23-2013, 08:39 AM
AVS Special Member
 
markus767's Avatar
 
Join Date: Apr 2009
Posts: 5,272
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 768 Post(s)
Liked: 309
Hi guys,

Total OCD heaven (or hell?) is coming: REW will support the Emotiva UMC-200 in a future release smile.gif

Markus

"In science, contrary evidence causes one to question a theory. In religion, contrary evidence causes one to question the evidence." - Floyd Toole
markus767 is online now  
post #4692 of 12042 Old 09-23-2013, 09:13 AM
AVS Club Gold
 
sdrucker's Avatar
 
Join Date: Feb 2006
Location: Chicago, IL
Posts: 2,211
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 140 Post(s)
Liked: 145
Quote:
Originally Posted by markus767 View Post

Hi guys,

Total OCD heaven (or hell?) is coming: REW will support the Emotiva UMC-200 in a future release smile.gif

That actually wouldn't be a bad idea for Pioneer to consider LOL for their Elite AVRs....as many of you know, Pioneer is at a serious disadvantage with REQ because their MCACC doesn't EQ the subwoofer channel, and with speakers run as Small, starts EQing at 125 Hz eek.gif. All you would need for us enthusiast types is REW, a calibrated mic, and voila you could download REW's filters to a Pioneer Elite with sub EQ data at the very least, and possibly other speakers, if their parametric EQ supported it. It might well be better than anything they can come up with independently, and their Elite AVRs already have USB inputs.

Of course, they'd probably charge several hundred dollars more for this feature...biggrin.gif

Stuart

 

Denon 4311 with XT32 and Audyssey Pro

Oppo 93 and 103

Panasonic VT50

Sherwood R-972 with its version of the Trinnov Optimizer

MiniDSP 10x10 HD

PSB Imagine T2, Center, and Surrounds (as of 5/2014); HSU ULS-15 subs (2)

 

The Audyssey FAQ Guide can be found here:

http://www.avsforum.com/...

sdrucker is offline  
post #4693 of 12042 Old 09-23-2013, 09:30 AM
AVS Club Gold
 
sdrucker's Avatar
 
Join Date: Feb 2006
Location: Chicago, IL
Posts: 2,211
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 140 Post(s)
Liked: 145
Quote:
Originally Posted by kbarnes701 View Post

smile.gif Yes, it is clearly possible. Personally I don't measure though - I just put the mic in more or less the same place each time. I don't sweat it because I know my head is only more or less in the same place each time too smile.gif
Quote:
Originally Posted by kbarnes701 View Post

And different room temperatures and humidities too - another thing to worry about now LOL.

I took a look at the chart - in practical terms, unless you live in a climate with extreme conditions and no heat or air conditioning, how much will this matter in practice, is the ambient temperature is roughly 60 to 80 degrees Fahrenheit (roughly 16 to 27 Celsius)? Seasonal calibration is the path to madness...

HST, say what you will, Keith, but I intend to start over measuring my pre/post Audyssey comparisons with Jerry's tape measure approach before I do anything else. As REW doesn't have a means of spatial averaging as such, I'd prefer to have a sweet spot that I at least know isn't creating more variation by how much subtlety there is in the mic position.

I've never had much problems with Audyssey getting stable results, but since REW represents a higher standard of assessment, and I'm doing A/B/X tests, I'd prefer not to have to redo all my measurements every time I make a change to see what's happening, or wonder if it's random variance causing the results. Obviously we can't do that with anything like certainty, but having the same measurement +/- an inch is a start.

Call it OCD, but it's a more practical solution than sharing the MLP with a mic, or getting out the fishing reel and weight...and certainly less outer space than the impossible wish to run a Monte Carlo simulation of our rooms.

Stuart

 

Denon 4311 with XT32 and Audyssey Pro

Oppo 93 and 103

Panasonic VT50

Sherwood R-972 with its version of the Trinnov Optimizer

MiniDSP 10x10 HD

PSB Imagine T2, Center, and Surrounds (as of 5/2014); HSU ULS-15 subs (2)

 

The Audyssey FAQ Guide can be found here:

http://www.avsforum.com/...

sdrucker is offline  
post #4694 of 12042 Old 09-23-2013, 11:50 AM
AVS Special Member
 
AustinJerry's Avatar
 
Join Date: Jan 2003
Location: Austin, Texas
Posts: 7,555
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 754 Post(s)
Liked: 792
Quote:
Originally Posted by kbarnes701 View Post

smile.gif Yes, it is clearly possible. Personally I don't measure though - I just put the mic in more or less the same place each time. I don't sweat it because I know my head is only more or less in the same place each time too smile.gif

Keith, since you already know I am totally OCD, I have to ask. Does your method of placing the mic in the MLP always yield identical distances to the left and right speakers? If I don't get exactly the same distance, I re-do the calibration.
AustinJerry is offline  
post #4695 of 12042 Old 09-23-2013, 12:49 PM
AVS Special Member
 
markus767's Avatar
 
Join Date: Apr 2009
Posts: 5,272
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 768 Post(s)
Liked: 309
Quote:
Originally Posted by sdrucker View Post

That actually wouldn't be a bad idea for Pioneer to consider LOL for their Elite AVRs....as many of you know, Pioneer is at a serious disadvantage with REQ because their MCACC doesn't EQ the subwoofer channel, and with speakers run as Small, starts EQing at 125 Hz eek.gif. All you would need for us enthusiast types is REW, a calibrated mic, and voila you could download REW's filters to a Pioneer Elite with sub EQ data at the very least, and possibly other speakers, if their parametric EQ supported it. It might well be better than anything they can come up with independently, and their Elite AVRs already have USB inputs.

Of course, they'd probably charge several hundred dollars more for this feature...biggrin.gif

I've stopped thinking about why these companies build useless products with useless features. The UMC-200 on the other hand is a rare exception from the norm. Not that it couldn't have been done 10 years ago but the on-board PEQs are a unique (at that price point) and useful feature one doesn't find in (m)any other devices.
The problem with current room correction products is that they don't offer much insight into what they are doing nor why. That's outright unacceptable to me.

Markus

"In science, contrary evidence causes one to question a theory. In religion, contrary evidence causes one to question the evidence." - Floyd Toole
markus767 is online now  
post #4696 of 12042 Old 09-23-2013, 01:54 PM
AVS Addicted Member
 
kbarnes701's Avatar
 
Join Date: Jan 2008
Location: Main Listening Positon
Posts: 18,691
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 1901 Post(s)
Liked: 1988
Quote:
Originally Posted by AustinJerry View Post
 
Quote:
Originally Posted by kbarnes701 View Post

smile.gif Yes, it is clearly possible. Personally I don't measure though - I just put the mic in more or less the same place each time. I don't sweat it because I know my head is only more or less in the same place each time too smile.gif

Keith, since you already know I am totally OCD, I have to ask. Does your method of placing the mic in the MLP always yield identical distances to the left and right speakers? If I don't get exactly the same distance, I re-do the calibration.

 

My listening position isn't quite central between the L&R speakers, Jerry, due to the awkwardness of a small room. So Audyssey doesn't come up with the same distances for both - but what it does do is a very, very good job of giving me a superb front soundstage with terrific imaging. Obviously, I put the mic where my head is when listening and the delays and levels Audyssey sets are always perfect in the sense that they create this terrific imaging. By offsetting the delays and levels appropriately, the centre channel is bang on the visual centre of the screen. What I mean by that is that if someone is talking dead centre of the screen, that is where their voice comes from - just as it would if I was in your living room with you and you were speaking to me from a slightly off-centre position (in relation to my seat). It's one of the things that has impressed me most about Audyssey - it seems to set the delays and levels to perfection. In the old days, pre-Audyssey I would try to compensate for an off-centre seating position by adjusting the levels between the R & L channel, but adding in the additional factor of adjusted delays seems to make a big difference. Also, of course, having a physical centre channel roots the sound to that spot. Obviously, I would prefer to sit dead-centre, but it just isn't possible in this room.

 
Your next question might be, 'does Audyssey always set the same distances for the R, C and L speakers?' and the answer is no, it doesn't - but that is because I am not especially careful to put the mic in the exact same spot each time. I am sure it would if I took sufficient care with the mic placement - and the distances never vary by more than a tiny amount anyway. I'd estimate that the mic is always put in the same spot, with a possible 3 inch diameter circle that it might fall anywhere within. I'm not especially OCD about this because I know that my head will move around by more than this during a movie. Given that, it seems futile to aim for an ultimately precise mic location for each and every measurement run. 
kbarnes701 is offline  
post #4697 of 12042 Old 09-23-2013, 01:56 PM
AVS Addicted Member
 
kbarnes701's Avatar
 
Join Date: Jan 2008
Location: Main Listening Positon
Posts: 18,691
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 1901 Post(s)
Liked: 1988
Quote:
Originally Posted by sdrucker View Post
 
Quote:
Originally Posted by kbarnes701 View Post

smile.gif Yes, it is clearly possible. Personally I don't measure though - I just put the mic in more or less the same place each time. I don't sweat it because I know my head is only more or less in the same place each time too smile.gif
Quote:
Originally Posted by kbarnes701 View Post

And different room temperatures and humidities too - another thing to worry about now LOL.

I took a look at the chart - in practical terms, unless you live in a climate with extreme conditions and no heat or air conditioning, how much will this matter in practice, is the ambient temperature is roughly 60 to 80 degrees Fahrenheit (roughly 16 to 27 Celsius)? Seasonal calibration is the path to madness...

HST, say what you will, Keith, but I intend to start over measuring my pre/post Audyssey comparisons with Jerry's tape measure approach before I do anything else. As REW doesn't have a means of spatial averaging as such, I'd prefer to have a sweet spot that I at least know isn't creating more variation by how much subtlety there is in the mic position.

I've never had much problems with Audyssey getting stable results, but since REW represents a higher standard of assessment, and I'm doing A/B/X tests, I'd prefer not to have to redo all my measurements every time I make a change to see what's happening, or wonder if it's random variance causing the results. Obviously we can't do that with anything like certainty, but having the same measurement +/- an inch is a start.

Call it OCD, but it's a more practical solution than sharing the MLP with a mic, or getting out the fishing reel and weight...and certainly less outer space than the impossible wish to run a Monte Carlo simulation of our rooms.

 

I too have a sweet spot. But the 'spot' has a diameter of about 3 inches (at a guess). Clearly, I can't fault Jerry's approach with the tape measure - but I personally don't feel the need to be more precise than I am. Like I say, my head will move way more than that as I fidget about in my seat during the 2 hours the movie is running.

kbarnes701 is offline  
post #4698 of 12042 Old 09-23-2013, 02:58 PM
AVS Special Member
 
AustinJerry's Avatar
 
Join Date: Jan 2003
Location: Austin, Texas
Posts: 7,555
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 754 Post(s)
Liked: 792

Sorry, Keith, I must have been having a senior moment.  Of course I know that you have a two-seat layout, and the MLP isn't exactly in the center.  But speaking from the perspective of one who has a centered MLP, I find that the stereo imaging is most precise when I make sure the distances to the left and right speakers are spot-on.  And yes, I know you don't use your room for listening to music, but I am simply stating that a simple measurement process ensures an exact center, and thus more consistency between REW measurements, FWIW.

AustinJerry is offline  
post #4699 of 12042 Old 09-23-2013, 03:18 PM
AVS Special Member
 
markus767's Avatar
 
Join Date: Apr 2009
Posts: 5,272
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 768 Post(s)
Liked: 309
Quote:
Originally Posted by AustinJerry View Post

But speaking from the perspective of one who has a centered MLP, I find that the stereo imaging is most precise when I make sure the distances to the left and right speakers are spot-on.

Yes, that's how stereo works. It is a single seat solution and works best when you're sitting in the center. Blumlein's "stereo patent" from 1931 (!) is a good read. We haven't come far in the last 80 years.

Markus

"In science, contrary evidence causes one to question a theory. In religion, contrary evidence causes one to question the evidence." - Floyd Toole
markus767 is online now  
post #4700 of 12042 Old 09-23-2013, 03:53 PM
AVS Special Member
 
jim19611961's Avatar
 
Join Date: Mar 2011
Location: Texas
Posts: 1,397
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 126 Post(s)
Liked: 85
I don't fault anyone for their approach or technique. But to add my own experience, I would have to say that even moving my head 1/2" to one side or the other makes detectable changes to the soundstage. And at 1" or 2", some soundstage info is lost completely. Simply put, a delay from one speaker or the other caused by unequal distances shifts image locations and causes SPL inequity.

Now, you guys using processor room correction devices where a speakers timing and amplitude can be changed may compensate somewhat for asymmetries of these kinds. I don't know how well they do at this. So I am not explicitly saying these same asymmetries cant be dealt with. I do know that not having them in the first place is preferable. But I am a 2ch audio only guy, so take that into account in reading my response smile.gif

My Room
My Music
Rega - Apollo, Rega - DAC, Goldpoint Passive, (2) Classe CA-100 bridged power amps (350w)
Jenzen Next
jim19611961 is offline  
post #4701 of 12042 Old 09-23-2013, 04:04 PM
AVS Club Gold
 
sdrucker's Avatar
 
Join Date: Feb 2006
Location: Chicago, IL
Posts: 2,211
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 140 Post(s)
Liked: 145
Quote:
Originally Posted by jim19611961 View Post

I don't fault anyone for their approach or technique. But to add my own experience, I would have to say that even moving my head 1/2" to one side or the other makes detectable changes to the soundstage. And at 1" or 2", some soundstage info is lost completely. Simply put, a delay from one speaker or the other caused by unequal distances shifts image locations and causes SPL inequity.

Now, you guys using processor room correction devices where a speakers timing and amplitude can be changed may compensate somewhat for asymmetries of these kinds. I don't know how well they do at this. So I am not explicitly saying these same asymmetries cant be dealt with. I do know that not having them in the first place is preferable. But I am a 2ch audio only guy, so take that into account in reading my response smile.gif

Well, what caught my attention was a center channel response that was nicely flat looking like it had a chunk of sound bitten out of it on the upper bass, between 100 and 200 Hz. I'll remeasure tonight to see if I've somehow "fixed" it by a position more in line of where I tend to sit, but the difference in what I documented as my March measurement in the MLP and the one I did on Friday night couldn't have been more than about 2-3" if that (i.e. a shifting in the seat, for those of us that aren't immobile in how we sit). We have a leather sofa where MLP is the center cushion, so how you sit or lean forward matters.

If the sweet spot being measured and tweaked has that little tolerance, it brings into question just what "optimal" means. I've been using the Target Pro Curve Editor to iteratively tweak my basic frequency response, based on REW, and regenerating the calibration. But if the results are _that_ sensitive, and nothing else is off in how I conducted the measurement, it makes me wonder what use a so-called optimization really has with the Pro editor. However, I will add that Pro helped me tame a peak in my surrounds, as I noted previously. And for whatever reason, that's more stable LOL smile.gif.

YMMV with treatments, though. Any thoughts about the stability of measuring impact of room treatments with the same variance in the < 300 Hz area, and above Shroeder or the crossover point?

Stuart

 

Denon 4311 with XT32 and Audyssey Pro

Oppo 93 and 103

Panasonic VT50

Sherwood R-972 with its version of the Trinnov Optimizer

MiniDSP 10x10 HD

PSB Imagine T2, Center, and Surrounds (as of 5/2014); HSU ULS-15 subs (2)

 

The Audyssey FAQ Guide can be found here:

http://www.avsforum.com/...

sdrucker is offline  
post #4702 of 12042 Old 09-23-2013, 05:07 PM
AVS Special Member
 
jim19611961's Avatar
 
Join Date: Mar 2011
Location: Texas
Posts: 1,397
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 126 Post(s)
Liked: 85
Quote:
Originally Posted by sdrucker View Post

Well, what caught my attention was a center channel response that was nicely flat looking like it had a chunk of sound bitten out of it on the upper bass, between 100 and 200 Hz. I'll remeasure tonight to see if I've somehow "fixed" it by a position more in line of where I tend to sit, but the difference in what I documented as my March measurement in the MLP and the one I did on Friday night couldn't have been more than about 2-3" if that (i.e. a shifting in the seat, for those of us that aren't immobile in how we sit).

If the sweet spot being measured and tweaked has that little tolerance, it brings into question just what "optimal" means. I've been using the Target Pro Curve Editor to iteratively tweak my basic frequency response, based on REW, and regenerating the calibration. But if the results are _that_ sensitive, and nothing else is off in how I conducted the measurement, it makes me wonder what use a so-called optimization really has with the Pro editor. However, I will add that Pro helped me tame a peak in my surrounds, as I noted previously. And for whatever reason, that's more stable LOL smile.gif.

YMMV with treatments, though. Any thoughts about the stability of measuring impact of room treatments with the same variance in the < 300 Hz area, and above Shroeder or the crossover point?

We set our own room goals so what is or is not within tolerance is our own parameter also. When your going all out and your scrounging to fix 1 and 2db peaks and valleys, then your measurement methods have to be very good. Simply moving the mic 1/4" - 1/2" can make these kinds of measured differences, so your chasing your tail if you cant reproduce yesterdays readings within 0.5db - 0.8db across the FR.

IMO, this kind of precision can best be achieved in the time span where the mic is not moved at all. Where you make room changes, take a measurement and repeat without the mic ever moving. When I tear down the mic for listening for instance, and then must set it up again, I dont worry too much if things have changed slightly (knowing the room is the same and the mic must be in a slightly different position). I just lay down a new base measurement and work from there.

While looking at old measurements (weeks or months ago) and comparing them to the present is interesting. There isnt much way to say the two measurements are completely comparable (for purposes of analyzing your room treatment effectiveness), especially if you have moved speakers, moved the listening spot, changed room treatment and so on. One can make broad comparisons in this setting, but that is all. I say this because whatever treatment you have works in a certain fashion based on the specific geometry of your speakers, listening position and such when that measurement was taken. Some specific treatment in some part of the room will function differently when you change the geometry. The mere angle that sound approaches an absorber determines its acoustic characteristics. Change the angle of incidence and you have changed how that absorber performs. Diffusers also change what they do based on incidence angled both approaching and ones angle to it.

My Room
My Music
Rega - Apollo, Rega - DAC, Goldpoint Passive, (2) Classe CA-100 bridged power amps (350w)
Jenzen Next
jim19611961 is offline  
post #4703 of 12042 Old 09-23-2013, 05:37 PM
AVS Club Gold
 
sdrucker's Avatar
 
Join Date: Feb 2006
Location: Chicago, IL
Posts: 2,211
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 140 Post(s)
Liked: 145
Quote:
Originally Posted by jim19611961 View Post

We set our own room goals so what is or is not within tolerance is our own parameter also. When your going all out and your scrounging to fix 1 and 2db peaks and valleys, then your measurement methods have to be very good. Simply moving the mic 1/4" - 1/2" can make these kinds of measured differences, so your chasing your tail if you cant reproduce yesterdays readings within 0.5db - 0.8db across the FR.

IMO, this kind of precision can best be achieved in the time span where the mic is not moved at all. Where you make room changes, take a measurement and repeat without the mic ever moving. When I tear down the mic for listening for instance, and then must set it up again, I dont worry too much if things have changed slightly (knowing the room is the same and the mic must be in a slightly different position). I just lay down a new base measurement and work from there.

While looking at old measurements (weeks or months ago) and comparing them to the present is interesting. There isnt much way to say the two measurements are completely comparable (for purposes of analyzing your room treatment effectiveness), especially if you have moved speakers, moved the listening spot, changed room treatment and so on. One can make broad comparisons in this setting, but that is all. I say this because whatever treatment you have works in a certain fashion based on the specific geometry of your speakers, listening position and such when that measurement was taken. Some specific treatment in some part of the room will function differently when you change the geometry. The mere angle that sound approaches an absorber determines its acoustic characteristics. Change the angle of incidence and you have changed how that absorber performs. Diffusers also change what they do based on incidence angled both approaching and ones angle to it.

I'm not _that_ obsessive: I'd be perfectly happy with +/- 5 db if I can't get 3 db. tongue.gif And in my comparison, literally nothing with speaker positions, general listening spot, or treatments had changed. Hence my surprise after measurement 'hiatus'.

If you have a multipurpose room, there are some things that are hard to avoid, like which magazines are on your sofa's table or objects on a desk or countertop that for all I know cause subtle angle/reflection changes. It's also impractical to have a mic in permanent measuring position...

However, I would like to know that today's tweak has a shelf life of some efficacy beyond the way I ran my measurement that day. The difference was well outside of my tolerance, so I'm looking into the 'how' if I can before I move on, at least over the next couple of days.

Stuart

 

Denon 4311 with XT32 and Audyssey Pro

Oppo 93 and 103

Panasonic VT50

Sherwood R-972 with its version of the Trinnov Optimizer

MiniDSP 10x10 HD

PSB Imagine T2, Center, and Surrounds (as of 5/2014); HSU ULS-15 subs (2)

 

The Audyssey FAQ Guide can be found here:

http://www.avsforum.com/...

sdrucker is offline  
post #4704 of 12042 Old 09-23-2013, 06:03 PM
AVS Special Member
 
jim19611961's Avatar
 
Join Date: Mar 2011
Location: Texas
Posts: 1,397
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 126 Post(s)
Liked: 85
Quote:
Originally Posted by sdrucker View Post

I'm not _that_ obsessive: I'd be perfectly happy with +/- 5 db if I can't get 3 db. tongue.gif And in my comparison, literally nothing with speaker positions, general listening spot, or treatments had changed. Hence my surprise after measurement 'hiatus'.

If you have a multipurpose room, there are some things that are hard to avoid, like which magazines are on your sofa's table or objects on a desk or countertop that for all I know cause subtle angle/reflection changes. It's also impractical to have a mic in permanent measuring position...

However, I would like to know that today's tweak has a shelf life of some efficacy beyond the way I ran my measurement that day. The difference was well outside of my tolerance, so I'm looking into the 'how' if I can before I move on, at least over the next couple of days.

+/- 5db (at 1/24th oct smoothing) is a pretty lofty goal actually smile.gif

Personally, I put more emphasis on the ETC.

My Room
My Music
Rega - Apollo, Rega - DAC, Goldpoint Passive, (2) Classe CA-100 bridged power amps (350w)
Jenzen Next
jim19611961 is offline  
post #4705 of 12042 Old 09-23-2013, 06:53 PM
AVS Club Gold
 
sdrucker's Avatar
 
Join Date: Feb 2006
Location: Chicago, IL
Posts: 2,211
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 140 Post(s)
Liked: 145
Quote:
Originally Posted by jim19611961 View Post

+/- 5db (at 1/24th oct smoothing) is a pretty lofty goal actually smile.gif

Personally, I put more emphasis on the ETC.

+/- 5 db at 1/6th smoothing on a full-range (15 Hz to 20,000 Hz) FR plot isn't...

Edit: The great mystery has been solved. And it's a bit ridiculous....

First, I did the AustinJerry approach of tape measuring exactly where I measured where I sit: 42" from both the left and right end arms of our sofa, 23" from the back end of our sofa, and 24" from the top of the bottom cushion to ear height while sitting on the cushion tongue.gif.

Then, I measured and lo and behold, my 100 to 200 Hz center channel trough shrank to closer to 5 db. I then realized that I'd forgotten that I'd had my Oppo 103 HDMI cable box on the table. It was smack dead center, and just high enough that with the tape measure it could angle to my center channel..

I then removed the box and my measurement is now +/- 5 db of my 75 db offset target for both my 3-13 and 9-23 center plots, except for 400 Hz...which is close enough for me that I could "fix" this in the Target Curve Editor if I truly want.

There's a lesson here, possibly....but I finally feel I've gotten somewhere! Cue the trumpets...the R/C experiment will move forward!

center subs 3-13 vs. 9-23.jpg 199k .jpg file
Attached Images
File Type: jpg center subs 3-13 vs. 9-23.jpg (198.6 KB, 11 views)

Stuart

 

Denon 4311 with XT32 and Audyssey Pro

Oppo 93 and 103

Panasonic VT50

Sherwood R-972 with its version of the Trinnov Optimizer

MiniDSP 10x10 HD

PSB Imagine T2, Center, and Surrounds (as of 5/2014); HSU ULS-15 subs (2)

 

The Audyssey FAQ Guide can be found here:

http://www.avsforum.com/...

sdrucker is offline  
post #4706 of 12042 Old 09-24-2013, 05:28 AM
AVS Addicted Member
 
kbarnes701's Avatar
 
Join Date: Jan 2008
Location: Main Listening Positon
Posts: 18,691
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 1901 Post(s)
Liked: 1988
Quote:
Originally Posted by AustinJerry View Post
 

Sorry, Keith, I must have been having a senior moment.  Of course I know that you have a two-seat layout, and the MLP isn't exactly in the center.  But speaking from the perspective of one who has a centered MLP, I find that the stereo imaging is most precise when I make sure the distances to the left and right speakers are spot-on.  And yes, I know you don't use your room for listening to music, but I am simply stating that a simple measurement process ensures an exact center, and thus more consistency between REW measurements, FWIW.

 

Oh I agree entirely, Jerry. Your method is simple to implement and gives a reliable result; as such I would commend it to anyone.  I find that with the settings for delay and level that Audyssey gives me, I do get a central image with stereo sources, as I said before. When I initially placed the mic dead centre, the image was skewed off to the right (the MLP is slightly to the right of centre). Now, when I place the mic at the MLP the imaging is perfect. I think Audyssey does a really good job with delays and levels.

kbarnes701 is offline  
post #4707 of 12042 Old 09-24-2013, 05:36 AM
AVS Addicted Member
 
kbarnes701's Avatar
 
Join Date: Jan 2008
Location: Main Listening Positon
Posts: 18,691
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 1901 Post(s)
Liked: 1988
Quote:
Originally Posted by sdrucker View Post
 
Quote:
Originally Posted by jim19611961 View Post

We set our own room goals so what is or is not within tolerance is our own parameter also. When your going all out and your scrounging to fix 1 and 2db peaks and valleys, then your measurement methods have to be very good. Simply moving the mic 1/4" - 1/2" can make these kinds of measured differences, so your chasing your tail if you cant reproduce yesterdays readings within 0.5db - 0.8db across the FR.

IMO, this kind of precision can best be achieved in the time span where the mic is not moved at all. Where you make room changes, take a measurement and repeat without the mic ever moving. When I tear down the mic for listening for instance, and then must set it up again, I dont worry too much if things have changed slightly (knowing the room is the same and the mic must be in a slightly different position). I just lay down a new base measurement and work from there.

While looking at old measurements (weeks or months ago) and comparing them to the present is interesting. There isnt much way to say the two measurements are completely comparable (for purposes of analyzing your room treatment effectiveness), especially if you have moved speakers, moved the listening spot, changed room treatment and so on. One can make broad comparisons in this setting, but that is all. I say this because whatever treatment you have works in a certain fashion based on the specific geometry of your speakers, listening position and such when that measurement was taken. Some specific treatment in some part of the room will function differently when you change the geometry. The mere angle that sound approaches an absorber determines its acoustic characteristics. Change the angle of incidence and you have changed how that absorber performs. Diffusers also change what they do based on incidence angled both approaching and ones angle to it.

I'm not _that_ obsessive: I'd be perfectly happy with +/- 5 db if I can't get 3 db. tongue.gif And in my comparison, literally nothing with speaker positions, general listening spot, or treatments had changed. Hence my surprise after measurement 'hiatus'.

If you have a multipurpose room, there are some things that are hard to avoid, like which magazines are on your sofa's table or objects on a desk or countertop that for all I know cause subtle angle/reflection changes. It's also impractical to have a mic in permanent measuring position...

However, I would like to know that today's tweak has a shelf life of some efficacy beyond the way I ran my measurement that day. The difference was well outside of my tolerance, so I'm looking into the 'how' if I can before I move on, at least over the next couple of days.

 

Given that we all agree that moving the mic by even one inch or less will have a visible impact on the graphs, it seems to me, Stuart, that the only way to ensure repeatability from one month to another is to never move the mic in between times. But this is not practical, so - in my case - I live with the small variations I see when comparing a current graph with an older one where nothing has changed in the room. I know it has to be the mic that has moved.  But, as I have said many times, I also know that I move my head way more than one inch in any direction during the course of a movie, so why worry about the mic having been moved a little bit anyway?  The only way to be sure to hear what the mic measured is to clamp your head in a vise at the exact mic position - and even Jerry has rejected that as an idea!!  LOL.

kbarnes701 is offline  
post #4708 of 12042 Old 09-24-2013, 06:02 AM
AVS Club Gold
 
sdrucker's Avatar
 
Join Date: Feb 2006
Location: Chicago, IL
Posts: 2,211
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 140 Post(s)
Liked: 145
Quote:
Originally Posted by kbarnes701 View Post

Given that we all agree that moving the mic by even one inch or less will have a visible impact on the graphs, it seems to me, Stuart, that the only way to ensure repeatability from one month to another is to never move the mic in between times. But this is not practical, so - in my case - I live with the small variations I see when comparing a current graph with an older one where nothing has changed in the room. I know it has to be the mic that has moved.  But, as I have said many times, I also know that I move my head way more than one inch in any direction during the course of a movie, so why worry about the mic having been moved a little bit anyway?  The only way to be sure to hear what the mic measured is to clamp your head in a vise at the exact mic position - and even Jerry has rejected that as an idea!!  LOL.

See my last post on the 23rd: I've declared victory by getting 'close enough'. And no vise for me either....

BTW I don't know if anyone's noticed, but there's a newer ASIO4ALL beta (2.11 Beta 2) than the one many of us download last winter. The beta supposedly:

Make an effort to take back control over blocked ("unavailable") audio devices.

Fix minor resource leak.

Fix regression in 2.11 Beta 1: Function of the "Always Resample" checkbox was inverted.

Remove excess outputlatency under the followingconditions: (1)64 bit host (2)upsampling 44.1 -> 48kHz (3)WaveRT polling mode.

Fix output audio glitches in 64 bit version when upsampling by integral factor.

Fix a4apanel64 crash on exit (not that anyone would have noticed)

Stuart

 

Denon 4311 with XT32 and Audyssey Pro

Oppo 93 and 103

Panasonic VT50

Sherwood R-972 with its version of the Trinnov Optimizer

MiniDSP 10x10 HD

PSB Imagine T2, Center, and Surrounds (as of 5/2014); HSU ULS-15 subs (2)

 

The Audyssey FAQ Guide can be found here:

http://www.avsforum.com/...

sdrucker is offline  
post #4709 of 12042 Old 09-24-2013, 06:13 AM
AVS Addicted Member
 
kbarnes701's Avatar
 
Join Date: Jan 2008
Location: Main Listening Positon
Posts: 18,691
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 1901 Post(s)
Liked: 1988
Quote:
Originally Posted by sdrucker View Post
 
Quote:
Originally Posted by kbarnes701 View Post

Given that we all agree that moving the mic by even one inch or less will have a visible impact on the graphs, it seems to me, Stuart, that the only way to ensure repeatability from one month to another is to never move the mic in between times. But this is not practical, so - in my case - I live with the small variations I see when comparing a current graph with an older one where nothing has changed in the room. I know it has to be the mic that has moved.  But, as I have said many times, I also know that I move my head way more than one inch in any direction during the course of a movie, so why worry about the mic having been moved a little bit anyway?  The only way to be sure to hear what the mic measured is to clamp your head in a vise at the exact mic position - and even Jerry has rejected that as an idea!!  LOL.

See my last post on the 23rd: I've declared victory by getting 'close enough'. And no vise for me either....

BTW I don't know if anyone's noticed, but there's a newer ASIO4ALL beta (2.11 Beta 2) than the one many of us download last winter. The beta supposedly:

Make an effort to take back control over blocked ("unavailable") audio devices.

Fix minor resource leak.

Fix regression in 2.11 Beta 1: Function of the "Always Resample" checkbox was inverted.

Remove excess outputlatency under the followingconditions: (1)64 bit host (2)upsampling 44.1 -> 48kHz (3)WaveRT polling mode.

Fix output audio glitches in 64 bit version when upsampling by integral factor.

Fix a4apanel64 crash on exit (not that anyone would have noticed)

 

Where do we download ASIO4ALL?   OK - don't answer that - unless it's to call me a lazy sod** and to tell me to use google LOL. I'll google it right now... and here it is:

 

http://www.asio4all.com/

 

I'll give it a try when I re-measure later this week.

 

**Limey slang word. Mild pejorative. Not sure what the American equivalent is. 

kbarnes701 is offline  
post #4710 of 12042 Old 09-24-2013, 01:16 PM
AVS Club Gold
 
sdrucker's Avatar
 
Join Date: Feb 2006
Location: Chicago, IL
Posts: 2,211
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 140 Post(s)
Liked: 145
Quote:
Originally Posted by kbarnes701 View Post

Where do we download ASIO4ALL?   OK - don't answer that - unless it's to call me a lazy sod** and to tell me to use google LOL. I'll google it right now... and here it is:

http://www.asio4all.com/

I'll give it a try when I re-measure later this week.

**Limey slang word. Mild pejorative. Not sure what the American equivalent is. 

The limey equivalent is more printable and mildly more polite than the American equivalent IMO....

Only reason I didn't mention the ASIO4ALL website is because I figured that anyone who's reading it already has ASIO4ALL or has looked at Jerry's guide. I'm downloading it tonight and doing one last set of measurements, then moving onto the Trinnov box later this week.

Unrelated: the "crackle"/occasional static issue with REW/HDMI that some of us are noticing is really getting annoying. I've done the replace inputs, unplug/plug cables, and cycle in/out of REW game, but once the static/crackle wash starts, it doesn't completely go away unless I reboot the laptop, and I'm scared that someday I'll bottom out my sub or blow a tweeter or something with enough cancel/rinse and repeat cycles. The issue seems to be most evident at the beginning and end of sweeps, but it's not consistently happening.

I've read on some forums (gearslutz, for example) that sometimes playing with the laptop battery setting to be always on or "best performance" helps, or increasing the latency, but both are "hit or miss" solutions. Apparently ASIO4ALL crackle issues are normal with other software plug-ins as well, such as pro audio gear and PC-based recording.

Switching HDMI cables helped with that one bitstream/PCM problem I had with using the Oppo as my conduit between the laptop and an AVR (I find it refreshingly more stable than the direct Denon connection, at least as far as not needing to play the connection/input game to get my AVR recognize the laptop HDMI connection), but I'm referring the older problem with REW/HDMI.

I hope the new ASIO beta does better.

Stuart

 

Denon 4311 with XT32 and Audyssey Pro

Oppo 93 and 103

Panasonic VT50

Sherwood R-972 with its version of the Trinnov Optimizer

MiniDSP 10x10 HD

PSB Imagine T2, Center, and Surrounds (as of 5/2014); HSU ULS-15 subs (2)

 

The Audyssey FAQ Guide can be found here:

http://www.avsforum.com/...

sdrucker is offline  
Reply Audio theory, Setup and Chat

Tags
Dayton , Dayton Audio , Room Equilizer Wizard Rew

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off