The Subjective and Objective Evaluation of Room Correction Products - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #1 of 582 Old 11-01-2009, 05:33 PM - Thread Starter
Senior Member
 
Tonmeister2008's Avatar
 
Join Date: Dec 2008
Location: Westlake Village, CA, USA
Posts: 291
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 25
For people interested in room correction: recently, we did some controlled listening tests and objective measurements on different room correction products, and presented the results at the recent 127th AES convention in NYC.

I've summarized the results in my recent blog posting entitled, "The Subjective and Objective Evaluation of Room Correction Products". Make sure you look at the AES presentation that accompanies the blog posting.

Cheers,
Sean Olive
My Audio Blog
Tonmeister2008 is offline  
Sponsored Links
Advertisement
 
post #2 of 582 Old 11-01-2009, 07:59 PM
Member
 
byrne's Avatar
 
Join Date: Apr 2009
Posts: 34
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Interesting.

Can you put names to 1 - 6? Didn't see it anywhere.





Full presentation is here:
Presentation
byrne is offline  
post #3 of 582 Old 11-01-2009, 08:15 PM - Thread Starter
Senior Member
 
Tonmeister2008's Avatar
 
Join Date: Dec 2008
Location: Westlake Village, CA, USA
Posts: 291
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 25
The products I tested are listed in slide 7 in alphabetical order:
  • Anthem Statement D2
  • Audyssey Room Equalizer
  • Harman (6 seat average)
  • Harman (optimized for primary seat)
  • Lyngdorf DPA-1
  • No Equalization
In the subjective and objective test results that follow, I have hidden the identities of the products and simply used the codes RC1 through RC6 - assigned to the products in descending order of preference. For the purposes of the paper, the product identities are not relevant. Sorry.

Cheers,
Sean Olive
My Audio Blog
Tonmeister2008 is offline  
post #4 of 582 Old 11-01-2009, 11:43 PM
AVS Special Member
 
Roger Dressler's Avatar
 
Join Date: Jul 2000
Location: Oregon
Posts: 8,283
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 186 Post(s)
Liked: 178
Hi Sean,

Quote:


Looking at slide 24, the most preferred room corrections produced the smoothest, most extended amplitude responses measured at the primary listening seat. The largest measured differences among the different room corrections occur below 100 Hz and around 2 kHz where the loudspeaker had a significant hole in its sound power response. The room corrections that were able to fill in this sound power dip received higher preference and spectral balance ratings.

Looking at Slide 26, if you ignore RC4 (naked speakers) and RC6, the other 4 RCs all look very similar from 300Hz-20kHz. In other words, they did a good job fixing the speaker's 2 kHz hole. Darned uniform, in fact.

So the preference for RC1/2 comes down to their extended bass performance and spectral rise into the bass. It makes me wonder how these RCs would compare if that element were removed from the equation. How well do these RCs compare wrt small response errors, or phase--if that's an issue, or multi-seat coverage, or room modes? Maybe they all do pretty much the same there (ignoring RC6), and thus would all sound pretty much the same once the consumer could dial in his preferred house curve.

The test certainly shows the value in getting the house curve right. Did it mask the other more subtle performance aspects where room correctors might more importantly distinguish themselves, areas that can only be addressed by the RC algorithm, and not a tone control or EQ?
Roger Dressler is offline  
post #5 of 582 Old 11-02-2009, 07:25 AM - Thread Starter
Senior Member
 
Tonmeister2008's Avatar
 
Join Date: Dec 2008
Location: Westlake Village, CA, USA
Posts: 291
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 25
Quote:
Originally Posted by Roger Dressler View Post

Hi Sean,



Looking at Slide 26, if you ignore RC4 (naked speakers) and RC6, the other 4 RCs all look very similar from 300Hz-20kHz. In other words, they did a good job fixing the speaker's 2 kHz hole. Darned uniform, in fact.

So the preference for RC1/2 comes down to their extended bass performance and spectral rise into the bass. It makes me wonder how these RCs would compare if that element were removed from the equation. How well do these RCs compare wrt small response errors, or phase--if that's an issue, or multi-seat coverage, or room modes? Maybe they all do pretty much the same there (ignoring RC6), and thus would all sound pretty much the same once the consumer could dial in his preferred house curve.

The test certainly shows the value in getting the house curve right. Did it mask the other more subtle performance aspects where room correctors might more importantly distinguish themselves, areas that can only be addressed by the RC algorithm, and not a tone control or EQ?

Hi Roger,
I would generally agree that in these particularly tests (ignoring RC6 and RC4) the main differences among the room corrections was related to choice of LF cutoff and target curve.

However, there is another huge factor which I didn't talk about in the paper, and that has to do with how much work was required to coax some of these room correction products to even work this well. One of the products chose a subwoofer crossover of 800 Hz, before we manually intervened, and told it 80 Hz. Some of them have problems integrating the subwoofer with the satellite without manual override from the engineer. Another didn't think the room had any gain so we had to manually intervene again. The usability of some of these products has a lot to be desired, and the manuals are often vague and misleading. To make these products work even this well, takes patience and someone who knows what they are doing.

In my view, a room correction process should be nearly 100% automated, and not require the user to dial in a target curve or select one from 25 choices (that just tells me the manufacturer doesn't really know what the real target should be). The user shouldn't have to choose a subwoofer crossover or know what the LF limits are for their system. The more manual and labor-intensive the room correction calibration process becomes the more likely users will abuse it, or not use it at all. That gets us further away from the goal of having good sound everywhere.

Cheers,
Sean Olive
My Audio Blog
Tonmeister2008 is offline  
post #6 of 582 Old 11-02-2009, 08:16 AM
AVS Addicted Member
 
penngray's Avatar
 
Join Date: Feb 2006
Location: Florida
Posts: 26,779
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 29
Awesome,

Another bookmarked link!

Thanks Sean!!

It is not "open-minded" to reject knowledge - Bob Lee
penngray is offline  
post #7 of 582 Old 11-02-2009, 09:47 AM
AVS Special Member
 
Roger Dressler's Avatar
 
Join Date: Jul 2000
Location: Oregon
Posts: 8,283
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 186 Post(s)
Liked: 178
Quote:
Originally Posted by Tonmeister2008 View Post

However, there is another huge factor which I didn't talk about in the paper, and that has to do with how much work was required to coax some of these room correction products to even work this well. ... The usability of some of these products has a lot to be desired, and the manuals are often vague and misleading. To make these products work even this well, takes patience and someone who knows what they are doing.

Hi Sean,

Thanks much for your reply. That sheds very new light on the matter. Here I was thinking, wow, isn't it amazing that all their respective mics and procedures gave such high uniformity >300 Hz, since your slides merely mentioned that each was set up per their instructions. That this was not the case is important information.

Quote:
In my view, a room correction process should be nearly 100% automated, and not require the user to dial in a target curve or select one from 25 choices (that just tells me the manufacturer doesn't really know what the real target should be). The user shouldn't have to choose a subwoofer crossover or know what the LF limits are for their system. The more manual and labor-intensive room correction becomes the more likely users will abuse it, or not use it at all. That gets us further away from the goal of having good sound everywhere.

Lofty goals, and I totally agree with them in principle.

Having never heard a perfectly tuned room, I'm not sure what that actually sounds like, nor if it would it satisfy me over the long haul at my usual playback volume, with my usual content as afflicted by "circle of confusion" EQ design.

If I listen 20 dB below ref, as is common, I need some extra bass lift, for example. Maybe one of the newangled Dolby, THX, or Audyssey auto-loudness gizmos would handle that, but maybe not--or introduce other unwanted side effects. So I like having some manual EQ not only for the loudness offset, but also to compensate for certain recordings where bass is all over the shop relative to others. No one setting seems right thus far.

To me, a final consumer AV processor, with comprehensive facilities, needs a hands-off RC as you advocate, but also some manual means to select or alter the house curve to the tastes of the master of the house. Purists may leave it off, of course. But there's no accounting for taste in the game of making consumers happy. The Reference vs Preference debate is not over, nor is the need to play at other than reference level (whatever that is for music recordings).

I also like the idea that the user has a button that can switch between sweet spot and several seat optimizations. No other RC has that--and it's a major oversight IMHO. Marry this up with BassQ (which has done miracles in my room) and the world is yours!
Roger Dressler is offline  
post #8 of 582 Old 11-02-2009, 10:49 AM - Thread Starter
Senior Member
 
Tonmeister2008's Avatar
 
Join Date: Dec 2008
Location: Westlake Village, CA, USA
Posts: 291
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 25
Hi Roger,
Agreed. There is no doubt that until the "circle of confusion" is broken, and every recording is mixed/mastered over a standard calibrated monitoring environment, recordings will continue to be the weak link in our dream of having good sound everywhere.

As I pointed out in the conclusion section of the AES preprint, until the recording industry gets its act together, the preferred in-room target curve will continue be a moving one.

Cheers,
Sean Olive
My Audio Blog
Tonmeister2008 is offline  
post #9 of 582 Old 11-02-2009, 12:16 PM
Advanced Member
 
jmichaelf's Avatar
 
Join Date: Aug 2005
Posts: 988
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 13
This is good work at the right time to be doing it. The sample is relatively small, but it's a very good start. You may have already thought of this, but I'll just throw it out there: How about a test with heights and widths processors? DSX, Yamaha & Dolby compared to none.
jmichaelf is offline  
post #10 of 582 Old 11-02-2009, 09:21 PM - Thread Starter
Senior Member
 
Tonmeister2008's Avatar
 
Join Date: Dec 2008
Location: Westlake Village, CA, USA
Posts: 291
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 25
Quote:
Originally Posted by jmichaelf View Post

This is good work at the right time to be doing it. The sample is relatively small, but it's a very good start. You may have already thought of this, but I'll just throw it out there: How about a test with heights and widths processors? DSX, Yamaha & Dolby compared to none.

Funny you mention that, as I am in the process of doing some competitive benchmarking tests on different commercial up-mixers including the ones you mentioned. Stay tuned.

Cheers,
Sean Olive
My Audio Blog
Tonmeister2008 is offline  
post #11 of 582 Old 11-03-2009, 12:17 PM
 
BigZippyBongHits's Avatar
 
Join Date: Nov 2009
Posts: 79
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Tonmeister2008 View Post


In my view, a room correction process should be nearly 100% automated, and not require the user to dial in a target curve or select one from 25 choices (that just tells me the manufacturer doesn't really know what the real target should be). The user shouldn't have to choose a subwoofer crossover or know what the LF limits are for their system. The more manual and labor-intensive the room correction calibration process becomes the more likely users will abuse it, or not use it at all. That gets us further away from the goal of having good sound everywhere.

To some of the people who want a quick set and forget setup, I kind of agree. But to those of us who want to really dial in their HT and music setups, the last thing I would want is an "auto" room EQ system. At least as it stands now, they are just too primitive and past doing a decent "ballpark" job, they still leave alot to be desired.

I have a couple of HT setups including one with an Onkyo NR 906 for the bedroom. The Audessy EQ setup it comes with left ALOT to be desired. Using an Audio Control RTA 3505 and a 20hz-20khz pink noise test cd it showed a +/- db level of almost 11db over the audio spectrum from the listening position. Using the RTA I was able to smooth the audio curve to within +/- 3db with a naturally sloping curve with the bass region being roughly 2-3db higher than the treble range(human ears naturally are more sensitive to higher frequencies, and less sensitive to bass frequencies, thus a more "natural" sound audio curve is to have a slight emphasis in the bass regions). As it stands right now, auto room EQs just cant do this in proficient manner.
BigZippyBongHits is offline  
post #12 of 582 Old 11-03-2009, 12:23 PM
Senior Member
 
InPhase's Avatar
 
Join Date: Oct 2005
Location: West Sacramento, CA
Posts: 289
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Sean,
Thanks so much for your research and for participating on this forum. I highly recommend that everyone bookmark his blog. I have lots of questions about your findings in relation to room eq systems. Thanks for your time.

If you are using well behaved speakers with a flat power response, is there any reason to eq above around 500Hz? Disregarding dynamic eqs, have you found that you can actually "improve" the sound in room?

If you are going to eq a "well-behaved" speaker with room eq, how would you measure this in order to not degrade the sound well above the transition frequency? Should the eq systems allow a way to do a close-mic'ed measurement of each speaker with a short time-window (pseudo anechoic)? And in general, if you are going to eq a room with any speakers above around 500Hz, over what time interval do you integrate the measurement? Have we identified this yet? Isn't this a main part of the problem with room eq systems?

I am highly interested in the new Harman eq. Do you have an expected release date and/or price? Do any of the Harman eq solutions give more weight to the primary listening position's measurement (better yet, can the user adjust the weighting?) or is this accomplished the same way as everyone else by measuring multiple locations close to the primary listeners head? Also, can we expect the new Harman eq to have the equivalent of the Bassq built-in? Also, will the Harman eq solution provide a way to adjust the loudness curve on the fly for poorly mastered sound (TV mostly)?

Thanks!
InPhase is offline  
post #13 of 582 Old 11-03-2009, 12:30 PM
Member
 
Anomad's Avatar
 
Join Date: Nov 2009
Posts: 33
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I am thankful for this info, as I'm just getting ready to buy an auto EQ, but was disappointed the neptune unit wasn't evaluated. My friend swears by it, but I wanted to know if it's better or worse than audyssey.
Anomad is offline  
post #14 of 582 Old 11-03-2009, 12:39 PM
Advanced Member
 
jmichaelf's Avatar
 
Join Date: Aug 2005
Posts: 988
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 13
InPhase, the test indicates that beyond 500hz rooms can still get in the way, though not with the consistency of the sub 500hz region. Another important observation suggests that the testers perceived the RC induced high frequency roll-off as a flat response. I'd suggest that the they would find the 1.5k-6k hole in Harman's uncorrected room a bother even with a sweetened bass EQ.

A different way of attacking the >500hz problem is through directivity. If treble were sent in a beam as opposed to a cone, you might be able to take care of that hole in measurements. Sean, get us some 800 project array measurements in your test room stat! We have to compare them to your B&Ws between 1 and 8khz.
jmichaelf is offline  
post #15 of 582 Old 11-03-2009, 01:18 PM
AVS Addicted Member
 
noah katz's Avatar
 
Join Date: Apr 1999
Location: Mountain View, CA USA
Posts: 20,380
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 105 Post(s)
Liked: 138
"I am highly interested in the new Harman eq."

First I've heard of this; can you point me to any more info? Googling just turned up old products.

Noah
noah katz is offline  
post #16 of 582 Old 11-03-2009, 01:41 PM
Member
 
Anomad's Avatar
 
Join Date: Nov 2009
Posts: 33
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Actually, without knowing which unit is which, this information is only useful for entertainment purposes. It's interesting, but only serves to cast more doubt on the subject.
Anomad is offline  
post #17 of 582 Old 11-03-2009, 01:49 PM
AVS Addicted Member
 
sdurani's Avatar
 
Join Date: Oct 2001
Location: Monterey Park, CA
Posts: 18,818
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 551 Post(s)
Liked: 633
Quote:
Originally Posted by noah katz View Post

First I've heard of this; can you point me to any more info?

I wonder if it's the "SFM" that Sean refers to in this blog post:

http://seanolive.blogspot.com/2009/0...81552717575967

Sanjay

Sanjay
sdurani is offline  
post #18 of 582 Old 11-03-2009, 01:51 PM
AVS Special Member
 
apodaca's Avatar
 
Join Date: Jul 2005
Posts: 1,173
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Nice read. I myself would seem to 'be in agreement' with these results. Of all of the room corrections I have tried which were limited to Audessey Flat, Front as well as Yamaha YPAO Flat, Front and Natural - I much prefer the Natural setting which provides a slight rolloff of high frequencies.I also cant stand subwoofers that dont go down to 20hz which does make the sound thin in my opinion.

Having said all of this though I believe that the recordings used for evaluation should be disclosed and the study needs to show it was independent of these.
apodaca is offline  
post #19 of 582 Old 11-03-2009, 02:08 PM
Senior Member
 
InPhase's Avatar
 
Join Date: Oct 2005
Location: West Sacramento, CA
Posts: 289
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Sound Field Management is the technology used in the Bassq. I don't know if this is usable above the transition frequency. Toole only refers to SFM in his book in reference to bass. It seems that Sean is referring to a new Harman eq that no information has been released on yet.
InPhase is offline  
post #20 of 582 Old 11-03-2009, 02:16 PM
Senior Member
 
InPhase's Avatar
 
Join Date: Oct 2005
Location: West Sacramento, CA
Posts: 289
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by jmichaelf View Post

InPhase, the test indicates that beyond 500hz rooms can still get in the way, though not with the consistency of the sub 500hz region.

I don't see this as a conclusion of the test. Can you elaborate more?

Quote:


I'd suggest that the they would find the 1.5k-6k hole in Harman's uncorrected room a bother even with a sweetened bass EQ.

Do you mean the dip in the power response of the speakers?

Quote:


A different way of attacking the >500hz problem is through directivity.

Yep, that is why I use Danley synergy horns.
InPhase is offline  
post #21 of 582 Old 11-03-2009, 02:47 PM - Thread Starter
Senior Member
 
Tonmeister2008's Avatar
 
Join Date: Dec 2008
Location: Westlake Village, CA, USA
Posts: 291
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 25
Quote:
Originally Posted by noah katz View Post

"I am highly interested in the new Harman eq."

First I've heard of this; can you point me to any more info? Googling just turned up old products.

Here is what I can tell you: the Harman room correction algorithms tested in this paper (RC1 and RC2) are the same ones available in the new JBL Synthesis HATS/SDEC systems. The HATS/SDEC system will also be available for Revel loudspeaker systems with room correction available up to the point where the room modal/boundary effects are no longer an issue (400-500 Hz). Beyond that frequency, you are equalizing the loudspeaker, which is not necessary with these loudspeakers.

The same room correction technology will find its way into other Harman products in the near future.

Cheers,
Sean Olive
My Audio Blog
Tonmeister2008 is offline  
post #22 of 582 Old 11-03-2009, 03:02 PM - Thread Starter
Senior Member
 
Tonmeister2008's Avatar
 
Join Date: Dec 2008
Location: Westlake Village, CA, USA
Posts: 291
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 25
Quote:
Originally Posted by Anomad View Post

Actually, without knowing which unit is which, this information is only useful for entertainment purposes. It's interesting, but only serves to cast more doubt on the subject.

I just revealed which products were ours in the test.

Sorry, but if you've read any of my AES papers or Floyd's we never reveal the identities of the competitors' products we test, since it's bad manners, and not usually relevant to the research questions being addressed in the experiment.

Isn't it the task of the audio reviewer to tell you which room correction product is good, and which one is not?

What I have shown you is that there is a pretty good correlation between what listeners like and the in-room measurements taken at the primary listening seat. If your room correction isn't producing the sort of curves I've shown, then you might want to consider returning the product, and getting one that does.

Cheers,
Sean Olive
My Audio Blog
Tonmeister2008 is offline  
post #23 of 582 Old 11-03-2009, 03:22 PM - Thread Starter
Senior Member
 
Tonmeister2008's Avatar
 
Join Date: Dec 2008
Location: Westlake Village, CA, USA
Posts: 291
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 25
Quote:
Originally Posted by InPhase View Post

Sound Field Management is the technology used in the Bassq. I don't know if this is usable above the transition frequency. Toole only refers to SFM in his book in reference to bass. It seems that Sean is referring to a new Harman eq that no information has been released on yet.

SFM takes advantage of multiple subwoofers to lower the seat-to-seat spatial variance by taking advantage of acoustical interference to tame room modes. So it only works over the upper operating range of the subwoofers which is typically 80-120 Hz. We used a single subwoofer in these room correction experiments, and therefore, SFM wasn't employed.

I suppose SFM could work at a higher frequencies in a really small room (i.e. car), but then you have the potential issue of localizing the subs.

Cheers,
Sean Olive
My Audio Blog
Tonmeister2008 is offline  
post #24 of 582 Old 11-03-2009, 03:46 PM
AVS Special Member
 
Frank D's Avatar
 
Join Date: Sep 2001
Posts: 1,308
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 21
Quote:
Originally Posted by Tonmeister2008 View Post

The products I tested are listed in slide 7 in alphabetical order:
  • Anthem Statement D2
  • Audyssey Room Equalizer
  • Harman (6 seat average)
  • Harman (optimized for primary seat)
  • Lyngdorf DPA-1
  • No Equalization
In the subjective and objective test results that follow, I have hidden the identities of the products and simply used the codes RC1 through RC6 - assigned to the products in descending order of preference. For the purposes of the paper, the product identities are not relevant. Sorry.

So RC4 is No Equalization. Which ones are the others?

Thanks
Frank D is offline  
post #25 of 582 Old 11-03-2009, 03:52 PM
AVS Addicted Member
 
sdurani's Avatar
 
Join Date: Oct 2001
Location: Monterey Park, CA
Posts: 18,818
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 551 Post(s)
Liked: 633
Quote:
Originally Posted by Anomad View Post

Actually, without knowing which unit is which, this information is only useful for entertainment purposes.

You can kinda guess which is which by looking at the slides.

When averaged over 6 seats, one room correction results in a straight line (slide 23). When measured from the primary listening seat, another room correction becomes a fairly straight line (slide 24). Which 2 RCs does that remind you of in Sean's alphabetical listing? Since all the tests subjects were in the primary listening seat, you can guess which of the two was most preferred.

Of the three remaining RCs, only one incorporates room gain, and it looks like that was the third most preferred (slide 24). Number four is no RC (dotted line). The remaining two RCs not only look like they don't incorporate room gain, but actually seem to start rolling off the low frequencies, which could possibly lead to complaints of anemic bass (sound familiar?).

The identities/order really isn't important, since the most popular may not end up being your personal favourite, any more than the most popular song on radio these days will be your current favourite too. Sure it's likely you'll prefer it, but not guaranteed. Better to listen for yourself (with your system, in your room) than rely on mass preference.

Besides, the study seems more interested in correlating subjective preference to objective measurements (like Harman/Sean had done previously with loudspeakers) rather than creating some sort of ranking for consumer room correction products.

As such, it was more than mere "entertainment" for me. I picked up a couple of things: hadn't realized how similar the various RCs were above 3-500Hz), didn't know how important room gain would turn out to be, etc. It also confirmed something I think we all knew: correction in the lower frequencies is what really separates the various RCs.

One thing I wish Sean had mentioned in his paper is how much manual work they had to go through to get these 'automated' systems to give decent results. Now there's a differentiator that a consumer like me would be interested in. Or course, that might mean naming names, which may not be worth the trouble. Still, I'd like to find out which RC set the crossover to 800Hz.

Sanjay
sdurani is offline  
post #26 of 582 Old 11-03-2009, 04:04 PM - Thread Starter
Senior Member
 
Tonmeister2008's Avatar
 
Join Date: Dec 2008
Location: Westlake Village, CA, USA
Posts: 291
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 25
Quote:
Originally Posted by InPhase View Post

Sean,
Thanks so much for your research and for participating on this forum. I highly recommend that everyone bookmark his blog. I have lots of questions about your findings in relation to room eq systems. Thanks for your time.

If you are using well behaved speakers with a flat power response, is there any reason to eq above around 500Hz? Disregarding dynamic eqs, have you found that you can actually "improve" the sound in room?

If you are going to eq a "well-behaved" speaker with room eq, how would you measure this in order to not degrade the sound well above the transition frequency? Should the eq systems allow a way to do a close-mic'ed measurement of each speaker with a short time-window (pseudo anechoic)? And in general, if you are going to eq a room with any speakers above around 500Hz, over what time interval do you integrate the measurement? Have we identified this yet? Isn't this a main part of the problem with room eq systems?

I am highly interested in the new Harman eq. Do you have an expected release date and/or price? Do any of the Harman eq solutions give more weight to the primary listening position's measurement (better yet, can the user adjust the weighting?) or is this accomplished the same way as everyone else by measuring multiple locations close to the primary listeners head? Also, can we expect the new Harman eq to have the equivalent of the Bassq built-in? Also, will the Harman eq solution provide a way to adjust the loudness curve on the fly for poorly mastered sound (TV mostly)?

Thanks!

Hi InPhase,

Lots of questions: Are you developing a room correction product?

If you buy decent loudspeakers with a flat on-axis response and smooth sound power response, then there is little need to equalize them above the room transition frequency (300-500 Hz). In our experiments, this particular loudspeaker did not have a good sound power response (i.e large dip at 2 kHz due to mismatch in DI between mid and tweeter), and extending the equalization improved the overall sound quality, as the subjective ratings indicate.

I think you've identified some of the problems in doing so-called "blind" room equalizations where you don't know in advance the on and off-axis behavior of the loudspeaker, and its directivity. With a constant DI loudspeaker you can equalize blindly, but with a loudspeaker with non-constant DI you risk improving the quality of sound power at the expensive of the direct sound. You can try to characterize the direct sound separately in a near-field or time-gated measurement but that also has some problems associated with it: as you move the microphone closer to the loudspeaker, you get large variations in measured response with small positional changes in the microphone, which makes it difficult to get a good match between channels..

If the room is acoustically non-reflective then perhaps there is less risk of poorly equalizing a bad loudspeaker, but reflections are generally a good thing from the perspective of spacious sound, timbre richness, loudness, better intelligibility, saving amplifier power, eliminating unnecessary acoustical treatment, reducing your audio carbon footprint.

Buying a good loudspeaker will solve all of these problems, lower your electrical bills, and save the environment, at the same time.

SFM will be an integral part of our room correction systems for multi-seat setups, since using multiple subs to do the brunt of the hard work has a lot of inherent benefits. I think I answered most of your other questions in a previous posting I made.

Cheers,
Sean Olive
My Audio Blog
Tonmeister2008 is offline  
post #27 of 582 Old 11-03-2009, 04:17 PM
AVS Special Member
 
filecat13's Avatar
 
Join Date: Jul 2003
Location: SoCal
Posts: 4,485
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
Liked: 86
Quote:
Originally Posted by Tonmeister2008 View Post

Here is what I can tell you: the Harman room correction algorithms tested in this paper (RC1 and RC2) are the same ones available in the new JBL Synthesis HATS/SDEC systems. The HATS/SDEC system will also be available for Revel loudspeaker systems with room correction available up to the point where the room modal/boundary effects are no longer an issue (400-500 Hz). Beyond that frequency, you are equalizing the loudspeaker, which is not necessary with these loudspeakers.

The same room correction technology will find its way into other Harman products in the near future.

Okay, about five months ago, Chris Neumann used the DACS 4 on my then new Synthesis® One Array set up with the SDEC4000. Am I correct in inferring that it's now last year's news? or

I won't run out right now and get it done ($$$$ you know), but should I be thinking about a re-cal?

What I can afford, when I can afford it...
filecat13 is offline  
post #28 of 582 Old 11-03-2009, 04:19 PM
AVS Addicted Member
 
noah katz's Avatar
 
Join Date: Apr 1999
Location: Mountain View, CA USA
Posts: 20,380
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 105 Post(s)
Liked: 138
Sean,

"The same room correction technology will find its way into other Harman products in the near future."

Can you be more specific about what type(s) of products (receivers, standalone EQ, etc) and when they will actually be available?

"SFM takes advantage of multiple subwoofers to lower the seat-to-seat spatial variance by taking advantage of acoustical interference to tame room modes. So it only works over the upper operating range of the subwoofers which is typically 80-120 Hz."

Why doesn't it work below 80 Hz?

Per the Harman paper on multiple sub placement, I was planning on two subs on opposite mid walls to cancel/not excite the odd-order modes.

Noah
noah katz is offline  
post #29 of 582 Old 11-03-2009, 04:23 PM - Thread Starter
Senior Member
 
Tonmeister2008's Avatar
 
Join Date: Dec 2008
Location: Westlake Village, CA, USA
Posts: 291
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 25
Quote:
Originally Posted by Frank D View Post

So RC4 is No Equalization. Which ones are the others?

Thanks

RC1 and RC2 are the Harman room corrections, and RC4 is no EQ. The others you have to guess, or do some clever detective work and deductive reasoning.

Cheers,
Sean Olive
My Audio Blog
Tonmeister2008 is offline  
post #30 of 582 Old 11-03-2009, 04:37 PM - Thread Starter
Senior Member
 
Tonmeister2008's Avatar
 
Join Date: Dec 2008
Location: Westlake Village, CA, USA
Posts: 291
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 25
Quote:
Originally Posted by noah katz View Post

Sean,

"The same room correction technology will find its way into other Harman products in the near future."

Can you be more specific about what type(s) of products (receivers, standalone EQ, etc) and when they will actually be available?

"SFM takes advantage of multiple subwoofers to lower the seat-to-seat spatial variance by taking advantage of acoustical interference to tame room modes. So it only works over the upper operating range of the subwoofers which is typically 80-120 Hz."

Why doesn't it work below 80 Hz?

Per the Harman paper on multiple sub placement, I was planning on two subs on opposite mid walls to cancel/not excite the odd-order modes.

<,Why doesn't it work below 80 Hz?>>

Sorry, I wasn't more clear: SFM works below 80-120 Hz, which is the upper operating range of the subwoofer. Putting the subs on opposite walls should cancel odd-order modes along that dimension

Besides current JBL Synthesis and Revel systems equipped with HATS/SDEC, I can't be any more specific regarding products and release dates at this point in time.

Cheers,
Sean Olive
My Audio Blog
Tonmeister2008 is offline  
Reply Receivers, Amps, and Processors

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