Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 82 - AVS Forum
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post #2431 of 11702 Old 04-06-2013, 10:25 AM
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Quote:
Originally Posted by Selden Ball View Post

Amir,

Why do you claim that the graph should slope down from low to high frequencies and that "flat" is not good?
For a few reasons:

1. The research and consensus seems to be that. Here is a sampling.

AES Paper: FULLY AUTOMATIC LOUDSPEAKER-ROOM ADAPTATION – the RoomPerfect system
JAN ABILDGAARD PEDERSEN1 AND KASPER THOMSEN2

"Reproduction of sound in a room always results in an increased sound pressure level towards lower frequencies. This is partly a consequence of the lower absorption found in typical rooms at low frequencies. However this is natural to the human ear as this provides the sense of being in a room. Consequently a room correction system cannot be allowed to remove this smooth increase in level at low frequencies, also referred to as the room gain [32, 33]."

AES Paper: ADJUSTING A LOUDSPEAKER TO ITS ACOUSTIC ENVIRONMENT - the ABC system
Jan Abildgaard Pedersen
Acoustics Research, Bang & Olufsen, Struer, DK-7600, Denmark, e-mail: jgp@bang-olufsen.dk

"Another problem of such systems is the choice of a suitable target function, e.g. a constant amplitude characteristic has been found not to be optimal. "

Presentation by Earl Geddes: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDwQFjAB&url=http%3A%2F%2Fwww.gedlee.com%2Fdownloads%2FOptimalBassPlaybackinSmallRooms.pptx&ei=rUxgUYfzBeftiQKnqoCoDw&usg=AFQjCNGFlHGd1VRRrHGVd9pchJBd_ZIRbg&sig2=D460C5iYDq9R9e-f_Uhptw

[*] Good bass, in the context of this report, and my personal preference, is a frequency response that has a subtle rise to the lowest frequencies, but which is otherwise very smooth in both frequency and space
[*] Why the “subtle rise”? Why not just flat?
[*] The reason is that the bass in small rooms is always “dead” when compared o larger spaces
[*] Hence a flat response will sound lacking in bass because there is a tradeoff between the sensation of level and the duration of a signal – the shorter signal will sound softer
[*] How much “bass enhancement”?
[*] I have found that between 3 and 6 dB of bass boost from about 200 Hz down to about 20 Hz is what I judge to be “neutral”
[*] There are those who judge bass by its level despite the fact that this level is not at all natural or neutral
[*] This is not what this discussion is about
[*] This discussion is about “neutral, but adequate bass reproduction in a small room”


Here is a graph showing target curve from B&K (the gods of measurement mics and such) showing the target curve should be, dating back many decades:

900x900px-LL-1a8f9b04_bkroomcorrectionpreferredresponse.jpeg

Here is a less formal reference but with a nice picture: http://www.hifizine.com/2011/06/bass-integration-guide-part-1/

Figure-1-Target-curve-where-the-bass-response-is-shelved-up-by-6-dB.png

2. Formal listening tests say so as I quoted. These were performed double blind. The listener heard some tracks and was asked to judge is performance in various areas including bass. Here is a sampling from this AES report: The Subjective and Objective Evaluation of Room Correction Products
Sean E. Olive, John Jackson, Allan Devantier, David Hunt and Sean M. Hess, Harman International,

"The more preferred room corrections (RC1-RC3) produced smoother curves with more extended output below 60 Hz. The slope of the curve also seems to be an important indicator of preference: The more preferred room corrections had more downward sloped curves, whereas the least preferred room corrections (RC5 and RC6,) tended to have flatter slopes, probably related to the manufacturer’s choice of target curve."


As to the FUD campaign against this research, the only thing that matters is if you can specify an actual fault on how human subjects were all gamed in a double blind test to say they like more bass. The mere implication doesn't amount to anything I am afraid especially when the listening tests confirmed what is known as proper target curve per above references. Note that another competing non-Harman did well by using the same technique as did doing no EQ at all! The correlation was very high across all the systems in this area as evidenced by consensus across 6 expert listeners.

3. The science indicates so. When the wavelength of sound becomes large with respect to the source and distance to barriers, the sound power accumulates with respect to each barrier presented (so called "room gain."). This only happens in low frequencies. Now add to this the fact that in our typical living environments we have many furnishings that absorb mid to high frequencies but almost nothing that absorbs sub frequencies. Put succinctly, what we think is "real," that is, how everything sounds to us in everyday life, is subjected to room gain. Taking it out would mean presenting a situation that is not natural. So not surprising that both industry/research consensus and listening tests confirm the same.

4. My own testing. I have had the pleasure of owning programmable/customization EQ systems for a decade now. Using these systems, one can easily play with a single domain like low frequency optimization down to even a single filter/mode correction. Try as I have, I cannot make myself like a flat bass response. Yes, qualitatively it sounds proper flat. But I am always compelled to boost the level post equalization. I suggested a set of tests for people to run to confirm the same. While Audyssey is an all or nothing proposition making such test harder, you can get there by only listening to the sub.
Quote:
Is this slope supposed to be the equivalent of the THX equalization recommended for movie audio tracks when played back in home environments?
If you mean the X-curve, I will say it bluntly by borrowing a line from the movie, Rain Man, "X-curve sucks." biggrin.gif See my post here: http://www.avsforum.com/t/1439769/any-suggestions-for-cables/180
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What document are you getting the plots from?
As posted, they are from a presentation based on the AES report from Harman in my references above.
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I would have expected that appropriate adjustments of the relative sound levels would already have been made by the person doing the audio mixing for a movie, A flat trace is supposed to indicate that the audio system will accurately reproduce what the person doing the audio mix intended. (Reference instead of personal preference.) A downward slope indicates that higher frequencies are being progressively more attenuated relative to the lower frequencies.
See this post of mine here: http://www.avsforum.com/t/1439769/any-suggestions-for-cables/150#post_22723642

And this graph from that post in survey of professional recording/mixing rooms:

i-9ZbrrbF.png

Net, net, what you are saying is a dream. There is no such reference in audio. Never has been and never will be. And further, professionals are no better situated than you and I are in determining "what is right." So they fiddle with their rooms just the same per above graph.

So the only plan is to close your eyes and test your own systems and determine your preferences. If you can't do that, then the starting point should be what all of the above evidence says, not just some gut feeling that flat is right backed by IMHO a mistaken target curve in mass market AVRs.

Amir
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post #2432 of 11702 Old 04-07-2013, 02:40 PM
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OK, that makes sense: it's music vs movie / preference vs reference.

Optimum movie audio essentially requires a "dead" listening room and flat audio response so that the acoustics of the movie's soundtrack dominates the experience. In contrast, when listening to music, people prefer the instruments to seem to be in one's own room, so the listening room's acoustics should dominate the experience. Also, it seems to me that since the music's playback sound level tends to be significantly lower than what one would experience in person at a live concert, the raised bass level provides an approximation to loudness contour processing without requiring dynamic processing. Since music recording normally does not involve the equivalent to the references used by movie audio mixers, applying movie references to music playback can't be optimal. Ideally, the settings would have to be different for every music recording that one plays back. frown.gif

Does anybody know if any of the multichannel Blu-ray video concert recordings have been created using the equivalent of movie reference audio mixing?

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post #2433 of 11702 Old 04-07-2013, 02:41 PM
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Quote:
Originally Posted by jkasanic View Post

@Selden Ball:  Call me a skeptic, but I think this answers your question...
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Originally Posted by kbarnes701 View Post

Again, call me sceptical or cynical, but I am also very wary of tests conducted by anyone with a vested interest in the outcome...
Lobbing skepticism towards the messenger doesn't invalidate the message. That's called argument from incredulity. Olive's comparison pointed out two things: the smoother the frequency response (fewer peaks & dips), the more it was preferred; perceptually flat was preferred over measured flat. If you can point to research/evidence which refutes those findings, then that would be more useful than simply informing readers that you're skeptical.

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post #2434 of 11702 Old 04-07-2013, 03:19 PM
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Quote:
Originally Posted by sdurani View Post

Quote:
Originally Posted by jkasanic View Post

@Selden Ball:  Call me a skeptic, but I think this answers your question...
Quote:
Originally Posted by kbarnes701 View Post

Again, call me sceptical or cynical, but I am also very wary of tests conducted by anyone with a vested interest in the outcome...
Lobbing skepticism towards the messenger doesn't invalidate the message. That's called argument from incredulity. Olive's comparison pointed out two things: the smoother the frequency response (fewer peaks & dips), the more it was preferred; perceptually flat was preferred over measured flat. If you can point to research/evidence which refutes those findings, then that would be more useful than simply informing readers that you're skeptical.

 

Point taken.  If I understand correctly, this correlation applies more to music where there is no reference standard?  I guess my question really is if I want to hear a movie's audio track reproduced as closely to the original mixer's intent as possible, should I be working to achieve a response with a boost in the bass region (4-8dB?) that gradually slopes downward (presumably resulting in a +/-3dB variance over the +150Hz-20kHz range or try to achieve an even response over the entire range (again +/-3dB with EQ)?

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post #2435 of 11702 Old 04-07-2013, 09:12 PM
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Quote:
Originally Posted by jkasanic View Post

If I understand correctly, this correlation applies more to music where there is no reference standard?
It can apply to either. Unless you don't think that movie playback can benefit from unmasking details that would otherwise be swamped by loud peaks and hearing sounds that would otherwise be buried in nulls. As you pointed out, the difference is that there is no reference standard in music production the way there is within the film industry. With no reference to be accurate to, all you can rely on is personal preference.  And even where there is a reference standard, if you were to measure several different movie dubbing stages (been done), they wouldn't measure as close to each other as one might think.
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Originally Posted by jkasanic View Post

I guess my question really is if I want to hear a movie's audio track reproduced as closely to the original mixer's intent as possible, should I be working to achieve a response with a boost in the bass region (4-8dB?) that gradually slopes downward (presumably resulting in a +/-3dB variance over the +150Hz-20kHz range or try to achieve an even response over the entire range (again +/-3dB with EQ)?
If you want to hear what the recoding engineer intended, then get your frequency response as close as possible to their reference. If it turns out by coincidence that you like that sound, then that's great. If it turns out you don't, well that's to bad for you, because "what Joe likes" is not part of the reference spec. Doesn't matter if you're enjoying the results or not. That's irrelevant. What matters is that you're hearing what "they" heard. Reference.

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post #2436 of 11702 Old 04-07-2013, 10:26 PM
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OK, that makes sense: it's music vs movie / preference vs reference.
I don't know how many more ways I can explain that there is no real reference for movies. Maybe I should quote what I said in the other thread:
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I suggest reading AES paper, " A New Draught Proposal for the Calibration of Sound in Cinema Rooms (21/4/12)" by Newell and Holland. In there, they show measurements of 11 Dolby certified Mixing Rooms ("dubbing theaters") and real theaters both of which are calibrated according to X-curve. The graph to the left shows this and on the right is the same for theaters which supposed to match it:

i-T8JTZmn.png

Still think these rooms all sound the same and stick to some standard that makes them so? If so, here is the authors of the paper:

"Figure 1 shows a set of response curves from the calibration positions of 20 different rooms, most of which are considered to sound noticeably different from each other."

What is being followed are 1970s concepts of acoustics which include such antiquated concepts as 1/3 octave measurement/equalization, and response curves that no one can explain the reasoning behind them. There is an initiative to re-evaluate what is being done but for now, there is no real concept of "reference." If you sit down with the people who are doing this re-evaluation as I have you will get an earful how broken it all is. And we can judge ourselves by looking at objective results such as above.

So again, there is no reference. What there is, is what sounds good to you. And that is most likely a smooth response that slopes down from low to high frequencies.

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post #2437 of 11702 Old 04-08-2013, 12:50 AM
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If I divide the speed of sound by the frequency of your dip, I will get the wavelength of that frequency. 1130 ÷ 300 = 4 feet. In order to produce a cancellation dip at that frequency, the direct sound from your speaker would have to combine with a copy of the sound (reflection) that is out of phase.

If the reflected path off a wall is 4 feet longer than the direct path from your speaker, the reflection will be in phase with the original 4-foot wave, albeit delayed once cycle (4 feet later). But if the reflected path is only 2 feet longer than direct path, then they will combine with the reflection mid-wave (180° out of phase with the direct sound). Cancellation.

How would the reflected path be 2 feet longer than the path of the direct sound from your speaker? It makes a 1 foot trip to the wall and a 1 foot trip back to the speaker plane to combine with the direct sound. So there must be a boundry 1 foot away, for that 2-foot round trip. 2 feet of extra travel is a half of the 4-foot wavelength. When combined, they'll cancel at that frequency (300Hz).

If you suspect a dip in the frequency response might be due to speaker/boundry interference (rather than modal), look for a wall a quarter wavelength away: ¼ of 4 feet is 1 foot. Easy to remember?
If you pull the speaker far enough out, say 4 feet from the wall, then there are some interesting benefits. Since 4 feet would be the quarter wavelength, the full wavelength would be 16 feet. 1130 ÷ 16 = 70Hz. Pulling the speaker out that far into the room will not only reduce the energy of the reflection (smaller dip) but will lower the frequency of the cancellation (below the crossover point). Pretty neat.

By comparison, moving a subwoofer closer to a boundry (aside from the ususal benefits) will slide its boundry cancellation dip higher up the frequency range, hopefully well above its crossover point. Convenient how that works out.

Since I have no intention, let alone space, to place my L/C/R speakers 4 feet into the room, I instead loaded up my front wall with absorbtion. No reflections = no boundry cancellation. There's more than one way to skin a cat.

Excellent read! After reading this, I simply moved the smaller of my two subs a mere six inches toward the wall and dramastically reduced the ugly 60hz null in my room. I cannot believe how much of a difference this made! I was busy scooting them left and right, but that did not help as much as making sure the reflection off the back wall was not directly meeting at my MLP.

Thank you!


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post #2438 of 11702 Old 04-08-2013, 05:42 AM
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Quote:
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Originally Posted by jkasanic View Post

@Selden Ball:  Call me a skeptic, but I think this answers your question...
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Originally Posted by kbarnes701 View Post

Again, call me sceptical or cynical, but I am also very wary of tests conducted by anyone with a vested interest in the outcome...
Lobbing skepticism towards the messenger doesn't invalidate the message. That's called argument from incredulity. Olive's comparison pointed out two things: the smoother the frequency response (fewer peaks & dips), the more it was preferred; perceptually flat was preferred over measured flat. If you can point to research/evidence which refutes those findings, then that would be more useful than simply informing readers that you're skeptical.

 

A fair comment, and I have no evidence to refute the claims. Nonetheless, I remain sceptical when anyone with a vested interest in something makes a claim. I am extremely sceptical, for example, when someone who sells so-called 'high end' equipment claims that it makes an audible difference to SQ (although that is fairly easy to refute I grant you). 

 

Being sceptical doesn’t mean I don't believe what is being said, of course - it means that I am of a mind to question what is being said. AFAIK that is what 'sceptical' means.

 

FWIW I personally much prefer a perceptually flat response to a flat response (which I believe I said) and as a consequence run a 'house curve' which rises from roughly the XO point (100Hz in my case) to about 30Hz, from where it falls gently. I've managed to achieve that through a combination of luck and effort I think - using what limited placement options are open to me in my awkward room and Audyssey and some post-Audyssey measuring and tweaking. I have yet to use PEQ to see if I can improve things, but this is my next step when I feel like taking up the mic again.

 

Our Brit spelling of sceptical never looks right to me - I type it with a K and my auto-correct changes it to a C.



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post #2439 of 11702 Old 04-08-2013, 07:00 AM
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post #2440 of 11702 Old 04-08-2013, 07:59 AM
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Ok, so I did some more measuring/tweaking this weekend as I didn't take into consideration the negative impact the sub distance tweak could have on my L+R+Sub response as I was optimizing for C+Sub response.  Audyssey initially set my sub distance to 30' and I tweaked the setting to 17.6' in my first attempt.  This left a dip at 80Hz on the L+R+Sub response.  The center is crossing at 80Hz and the L and R at 90Hz.

 

C+Sub at 17.6' (teal) and 22.4' (red) with an 80Hz crossover and 1/6 smoothing:

 

L+R+Sub at 17.6' (gold) and 22.4' (light blue) with a 90Hz crossover and 1/6 smoothing:

 

Honestly, I couldn't subjectively say if I made things better or worse as I couldn't hear much of a difference when playing back multi ch movie tracks.  I'm also wondering if some of the higher frequency response changes are a result of minor variances in the mic location more than anything else?  In any case, I'd be interested in others observations.

 

On a slightly different note, I've noticed something with REW and legacy RCA connections that I wonder if others have experienced?  When I measure my combined L+R+Sub in stereo or C+Sub using L+R RCA connections and PLIIx setting on my prepro, the output is approx. 7dB higher than taking L or R measurements separately.  Here are some plots of L+R+Sub, C+Sub, L+Sub and R+Sub without Audyssey:

 

 

I have been offsetting the curves for comparison purposes but just wanted to confirm that when I connect my Y-splitter to both the L and R channels the additional gain is reasonably explained?  I guess I wasn't expecting 7dB.

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post #2441 of 11702 Old 04-08-2013, 08:36 AM
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Quote:
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Quote:
Originally Posted by AustinJerry View Post

Amir, so you are saying the red curve "should" sound worse then the green curve.  Interesting, I never would have come to this conclusion by looking at the graphs.  Of course, the real test is in listening, and unfortunately I can't do that.

 

Edit:  That is your graph, jkasanic.  Which sounds better to you, the red or the green?

 

Seriously though, I plan to do some A/B listening this weekend with some known content if only in an attempt to quantify subjectively the improvement Audyssey creates.

 

As mentioned previously, I plan to experiment more with my XO setting to improve the dip from 70-150Hz.

 

Well, I did do some listening over the weekend and I can safely say that my system with Audyssey is night and day better than without.  I will admit though that this could be a result of the significantly improved bass response and the implied negative effects from other comments regarding Audyssey induced peaks at higher frequencies could be there but at least for me, the improvements in the bass far outweigh the latter.

 

Here's 4 plots of my L+R+Sub response with 1/6 smoothing:

 

Purple:  No Audyssey

Blue:  Audyssey at recommended 30' sub distance

Gold:  Audyssey at first sub distance tweak of 17.6'

Red:  Audyssey at last sub distance tweak of 22.4'

 

 

The dip from 120-160Hz (bottom at 135Hz) is the only real blemish I can see when comparing to the other Audyssey corrected plots.  I also experimented with the crossovers but that didn't seem to help the response at all...quite the opposite.

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post #2442 of 11702 Old 04-08-2013, 08:41 AM
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^ Regarding the higher level when measuring L+R, versus measuring the individual speakers, my experience is the same, although I am using HDMI.  I don't think there is any cause for concern.

 

Just curious, have you considered setting the crossover for all three speakers at the same value?  What caused you to choose 80 for the center and 90 for the L&R?  I don't know if it would make any difference in the smoothness of the splice, but it may be worth trying.

 

Perhaps I missed something, but how did you come up with the 22.4' distance?

 

Suggestion when presenting results of sub distance tweak measurements:  always include the original response before tweaking so we can see the improvement (Edit:  OK, I see it in the bottom set of measurements, sorry), and limit the graph horizontal axis to 15-300Hz.  The sub tweak certainly has no impact on the frequencies above 1kHz, so the difference in your measurements in the high frequencies is likely due to normal variances between measurements.  When I am determining the sub distances, I place the mic in the MLP and don't move or touch it until all measurements are completed.

 

So, which distance did you decide to go with?  In my setup, when I optimize the distance using Center+subs, I rarely get a different optimized setting for L+R+subs (with all crossovers at 80Hz).


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post #2443 of 11702 Old 04-08-2013, 09:57 AM
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^ Regarding the higher level when measuring L+R, versus measuring the individual speakers, my experience is the same, although I am using HDMI.  I don't think there is any cause for concern.

 

 

Same here. I assumed it was because two speakers are playing and not one. 

 

Quote:
So, which distance did you decide to go with?  In my setup, when I optimize the distance using Center+subs, I rarely get a different optimized setting for L+R+subs (with all crossovers at 80Hz).

 

I find the same as Joe - if I optimise the splice for C+subs, I get a different result than if I optimise for L+R + Subs. All XOs at 100Hz. I just compromised between the two to get a result that was OK for both.



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post #2444 of 11702 Old 04-08-2013, 10:07 AM
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Being sceptical doesn’t mean I don't believe what is being said, of course - it means that I am of a mind to question what is being said.
What question were you asking? Rather than saying you don't believe what is being said, you've basically been saying you don't believe who is saying it. Like not believing a math textbook salesman when he says 2+2=4, because he sells math textbooks. That's not skepticism, that's ad hominem; hence my earlier comment about "lobbing skepticism at the messenger".
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I personally much prefer a perceptually flat response to a flat response (which I believe I said) and as a consequence run a 'house curve' which rises from roughly the XO point (100Hz in my case) to about 30Hz, from where it falls gently.
Then, even as an Audyssey user, it shouldn't surprise you that perceptually-flat target curves would be preferred to measured-flat target curves in a comparison of room correction systems. Why would you be skeptical of those results?

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post #2445 of 11702 Old 04-08-2013, 10:14 AM
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Originally Posted by jkasanic View Post

When I measure my combined L+R+Sub in stereo or C+Sub using L+R RCA connections and PLIIx setting on my prepro, the output is approx. 7dB higher than taking L or R measurements separately.
I'm not 100% sure but that might be a case of the subwoofer output being normalized for the number of channels, which some receivers do automatically. When you engage PLIIx, the system might be adjusting the subwoofer level to be the bottom portion of 7 speakers. That would make the subwoofer level much louder than when it is being the bottom portion of a single speaker. Again, not sure that's what happening, just a guess.

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post #2446 of 11702 Old 04-08-2013, 10:17 AM
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Originally Posted by AustinJerry View Post

^ Regarding the higher level when measuring L+R, versus measuring the individual speakers, my experience is the same, although I am using HDMI.  I don't think there is any cause for concern.

 Thanks for confirming this.

 

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Just curious, have you considered setting the crossover for all three speakers at the same value?  What caused you to choose 80 for the center and 90 for the L&R?  I don't know if it would make any difference in the smoothness of the splice, but it may be worth trying.

I did try 90Hz as well as 100Hz for LCR (satellites were raised from 40Hz to 100Hz).  I must've deleted the measurements before I saved the .mdat file.  Going from memory, increasing the XO caused strange behavior below the orignial XO in the case of increasing the center from 80Hz to 90Hz and 100Hz as well as increasing the L and R from 90Hz to 100Hz.

 

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Perhaps I missed something, but how did you come up with the 22.4' distance?

Trial and error through the iterative process described in the sub distance tweak procedure.  I used the C and sub channel to see if an improvement was possible (it was) and then from there I kept checking my L+R response to find a good compromise since the responses did vary (see below).  If there's a better way, let me know!

 

C+Sub at 30' (purple), 17.6' (red) and 22.4' (gold):

 

 

L+R+Sub at 30' (green), 17.6' (blue) and 22.4' (red):

 

 

I went with 22.4' as I thought the L+R+Sub transition in the XO was much better but after reviewing these two plots again, perhaps 17.6' was a better result for both?!  Graphitis Nervosa setting in...wink.gif

 

EDIT:  Here are the same graphs with no smoothing and 15-300Hz (per the guidelines):

 

C+Sub at 30' (purple), 17.6' (red) and 22.4' (gold):

L+R+Sub at 30' (green), 17.6' (blue) and 22.4' (red):

 

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post #2447 of 11702 Old 04-08-2013, 10:25 AM
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Quote:
Originally Posted by sdurani View Post

Quote:
Originally Posted by jkasanic View Post

When I measure my combined L+R+Sub in stereo or C+Sub using L+R RCA connections and PLIIx setting on my prepro, the output is approx. 7dB higher than taking L or R measurements separately.
I'm not 100% sure but that might be a case of the subwoofer output being normalized for the number of channels, which some receivers do automatically. When you engage PLIIx, the system might be adjusting the subwoofer level to be the bottom portion of 7 speakers. That would make the subwoofer level much louder than when it is being the bottom portion of a single speaker. Again, not sure that's what happening, just a guess.

 

Interesting thought.  It definitely has something to do with the prepro as I find the same result when I turn off my LCR external amps and measure only the sub response.  One thing I will check next time I'm measuring is how the response varies if I'm in stereo (L, R and L+R RCA connected) or in PLIIx (L+R RCA connected).  FWIW, I'm using an Integra DHC-80.3.  I believe Keith has the same model in an Onkyo (5509) which might explain why he also sees the same phenomenon.  Would be interesting to hear from others with different receivers/prepros.

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Quote:
Originally Posted by sdurani View Post

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Originally Posted by kbarnes701 View Post

Being sceptical doesn’t mean I don't believe what is being said, of course - it means that I am of a mind to question what is being said.
What question were you asking? Rather than saying you don't believe what is being said, you've basically been saying you don't believe who is saying it. Like not believing a math textbook salesman when he says 2+2=4, because he sells math textbooks.

 

Yes, that is a very fair summation of my position in this particular instance. I wasn't actually asking a question. I can question something to myself without voicing it.

 

Quote:
 That's not skepticism, that's ad hominem; hence my earlier comment about "lobbing skepticism at the messenger".

 

Again, a fair summation.

 

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I personally much prefer a perceptually flat response to a flat response (which I believe I said) and as a consequence run a 'house curve' which rises from roughly the XO point (100Hz in my case) to about 30Hz, from where it falls gently.
Then, even as an Audyssey user, it shouldn't surprise you that perceptually-flat target curves would be preferred to measured-flat target curves in a comparison of room correction systems. Why would you be skeptical of those results?
 
I didn’t say I was IIRC. What I am/was sceptical about is the testing of the different RC systems from a company with a vested interest. Basically I agree with RUR who said "Keith, by now anyone who's familiar with the many discussions of the test knows which RC is which. The fact that Harmon has leaked UUT identities (and not only for this test) has, rightly or wrongly, fueled a certain amount of cynicism regarding their objectivity."
 
I'm not inclined to start an argument with you over this, Sanjay, so it is probably best to let it rest. It's OT anyway. 


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post #2449 of 11702 Old 04-08-2013, 08:10 PM
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Quote:
Originally Posted by AustinJerry View Post

^ Regarding the higher level when measuring L+R, versus measuring the individual speakers, my experience is the same, although I am using HDMI.  I don't think there is any cause for concern.

Just curious, have you considered setting the crossover for all three speakers at the same value?  What caused you to choose 80 for the center and 90 for the L&R?  I don't know if it would make any difference in the smoothness of the splice, but it may be worth trying.

Perhaps I missed something, but how did you come up with the 22.4' distance?

Suggestion when presenting results of sub distance tweak measurements:  always include the original response before tweaking so we can see the improvement (Edit:  OK, I see it in the bottom set of measurements, sorry), and limit the graph horizontal axis to 15-300Hz.  The sub tweak certainly has no impact on the frequencies above 1kHz, so the difference in your measurements in the high frequencies is likely due to normal variances between measurements.  When I am determining the sub distances, I place the mic in the MLP and don't move or touch it until all measurements are completed.

So, which distance did you decide to go with?  In my setup, when I optimize the distance using Center+subs, I rarely get a different optimized setting for L+R+subs (with all crossovers at 80Hz).

1) My subs will be here tomorrow. Yippee!!!

2) That's 15-300 Hz and NO SMOOTHING, correct? Also, when posting full graphs, are we using 1/3 or 1/6 smoothing? Does it matter?

3) WRT sub distance tweak guide, is ProLogic II required for REW non-legacy setup?
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1 - Great news!

2 - 15-300Hz, no smoothing.  Full range, 1/6 smoothing.

3 - If you can output a discrete signal to the center channel using HDMI, then PLII is not required. 


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post #2451 of 11702 Old 04-08-2013, 09:15 PM
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Thanks, Jerry. Here's a pic of my humble space with sound panels. I've been looking at treating the ceiling next. What do you think about these foam tiles in the image below? I believe each tile is 24x24" and 2" thick.



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With regards to ceiling treatments, you only need to treat the point of first reflection. No need to cover a large section of the ceiling. Stand on a ladder and hold a mirror against the ceiling while someone sits in the MLP. Move the mirror around until the front speaker is visible. That's where the treatment should be placed. I have been toying with placing two 24x24 panels on the ceiling, one for each reflection (left and right front speaker). Unfortunately, I can't treat for the center channel reflection because a ceiling fan is in the way.

What brand are those tiles? A 2" thickness doesn't provide much absorption.

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post #2453 of 11702 Old 04-08-2013, 10:03 PM
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Yeah, I was thinking of treating a small area directly above the speakers. The tiles come 12 in a pack which should be more than enough. The name of the site is Foamforyou.com. This particular style comes with either a 1/4 or 1/2" gap, but I don't think they come any thicker. I'd have to call to find out. I might give them a try. I prefer the foam tiles to hanging the panels from the ceiling.
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Quote:
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Yeah, I was thinking of treating a small area directly above the speakers. The tiles come 12 in a pack which should be more than enough. The name of the site is Foamforyou.com. This particular style comes with either a 1/4 or 1/2" gap, but I don't think they come any thicker. I'd have to call to find out. I might give them a try. I prefer the foam tiles to hanging the panels from the ceiling.

 

Do they give any coefficient of absorption for those foam panels? If not, I’d steer clear of them personally. The GIK panels look OK when ceiling mounted. I fix four hooks into the ceiling at the appropriate places and then use long cable ties to go through those hooks and the eyes on the panel. You can then pull the cable ties tight to get the panel to whatever distance you want it from the ceiling. Beware: do not pull them so tight that the panel touches the ceiling or you will never be able to remove them without destroying them - leave a sufficient gap to get a knife in to cut the cable tie if required. Cinch each cable tie a little at a time so the panel is evenly spaced all round. Looks pretty good IMO. Choose GIK panels to match the colour of the ceiling and they blend in better than you'd think.



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post #2455 of 11702 Old 04-09-2013, 05:59 AM
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Yeah, I was thinking of treating a small area directly above the speakers.

Directly above the speakers won't do anything. The treatments must be at the first point of reflection.

Keith, is that what you did? We're you able to hear/measure a difference? Did you use GIK 242's?

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post #2456 of 11702 Old 04-09-2013, 06:24 AM
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Quote:
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Yeah, I was thinking of treating a small area directly above the speakers. /quote]

Directly above the speakers won't do anything. The treatments must be at the first point of reflection.

Keith, is that what you did? We're you able to hear/measure a difference? Did you use GIK 242's?

Yeah - 242s on the ceiling. It measured a little differently but it's difficult to say if it was audible. I think I hit the diminishing return thing by the time I did the ceiling TBH. The worst reflection point is right where a glass light fitting is located and I can neither remove it (WAF) nor, obviously, cover it so I was a little stymied in my efforts anyway. 

 

I think that the really big gain comes from the first treatments you install. I heard a huge and immediate difference then in terms of imaging. The later treatments made more subtle changes and the final treatments, well, it's difficult to say.

 

Overall though, treatments have brought me bigger SQ gains than anything else.



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post #2457 of 11702 Old 04-09-2013, 06:47 AM
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Yeah - 242s on the ceiling. It measured a little differently but it's difficult to say if it was audible. I think I hit the diminishing return thing by the time I did the ceiling TBH. The worst reflection point is right where a glass light fitting is located and I can neither remove it (WAF) nor, obviously, cover it so I was a little stymied in my efforts anyway. 

 

I think that the really big gain comes from the first treatments you install. I heard a huge and immediate difference then in terms of imaging. The later treatments made more subtle changes and the final treatments, well, it's difficult to say.

 

Overall though, treatments have brought me bigger SQ gains than anything else.

 

Jerry already commented but I was curious about your thoughts regarding treatments for my room?

 

Tricorner traps in the 3 main corners.  The top two behind the screen would need to be custom height due to the soffit.  I'm actually researching DIY for these corner traps behind the screen since they aren't visible.

 

 

Then I was thinking GIK 242's but not really sure between those and the 244's (although 5.5" is pretty thick hanging on the wall!).  Maybe 244's behind the screen and 242's in the living space?

 

 

Was it Glenn Kuras or someone else at GIK you worked with on your room?

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post #2458 of 11702 Old 04-09-2013, 07:04 AM
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Yeah - 242s on the ceiling. It measured a little differently but it's difficult to say if it was audible. I think I hit the diminishing return thing by the time I did the ceiling TBH. The worst reflection point is right where a glass light fitting is located and I can neither remove it (WAF) nor, obviously, cover it so I was a little stymied in my efforts anyway. 

 

I think that the really big gain comes from the first treatments you install. I heard a huge and immediate difference then in terms of imaging. The later treatments made more subtle changes and the final treatments, well, it's difficult to say.

 

Overall though, treatments have brought me bigger SQ gains than anything else.

 

Jerry already commented but I was curious about your thoughts regarding treatments for my room?

 

Tricorner traps in the 3 main corners.  The top two behind the screen would need to be custom height due to the soffit.  I'm actually researching DIY for these corner traps behind the screen since they aren't visible.

 

 

Then I was thinking GIK 242's but not really sure between those and the 244's (although 5.5" is pretty thick hanging on the wall!).  Maybe 244's behind the screen and 242's in the living space?

 

 

Was it Glenn Kuras or someone else at GIK you worked with on your room?

 

Hey Joe!

 

It was Bryan Pape who worked with me - a very patient guy. We did it all via email. I sent him a 3D model of my room and he used that as the starting point.

 

I wouldn't neglect all those other corners - you have the ceiling/wall corners and the floor/wall corners too. AIUI the more corners you can do the better the result.  Also don't forget the ceiling reflections.

 

I think the 244s are the best choice for angling across the corners - that is how I use them anyway. I then use 242s on the wall/ceiling for taming the reflections shown in my ETCs. I used string and mirrors in combination.

 

Can you use any  244s on the floor in front of the screen?  I assume you have thick drapes over that window on the back wall?

 

I am far from an expert on room treatments but AIUI the more corners you treat, the better, using measurements and your ears as guides for both the 244s and the 242s. At some stage you reach diminishing returns and after that it's more Graphitis Nervosa setting in than significant benefits. But it's surprising how much treatment you can get into a room if you try!



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post #2459 of 11702 Old 04-09-2013, 07:32 AM
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Joe,

 

I agree with everything Keith said.  Things I have learned:

 

- Bass traps (e.g. 244's) work considerably better when mounted at a 45-degree angle in a corner.  Don't forget that the intersection of a side wall and the ceiling is a great place to mount the bass traps, if it passes WAF.

 

- For normal full-spectrum treatments (e.g. 242's), install at 1st reflection points to start with, and then locate other reflection points using ETC/String Technique.  Don't just throw up panels anywhere--you run the risk of deadening the room (for music in particular, maybe not so important for cinema).

 

- If you are going to treat the ceiling, make sure you use a mirror to find the 1st reflection points (as I recommended to pres2play).

 

Edit:  I dealt with Bryan Pape as well.  Glen is the owner/founder (Glen I Kuras).


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post #2460 of 11702 Old 04-09-2013, 07:39 AM
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Will someone quickly remind me how to gate measurements in REW?

I want to limit the acquisition window for outdoor DIY speaker measurements.

Thanks
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