I wish I still had the measurements to show, but I actually borrowed one of these when I first saw it. I got really excited about the idea, as I thought it might be a decent automatic room correction device for not that much money. I took it back and told the store owner, thanks but no thanks. He was nice enough to lend it to me, but I think he assumed it was a guaranteed sale.
Here is what I found, after taking tons of measurements at various locations in the room, as suggested, it was able to smooth response about the same any of the various eq's do. I also took phase measurements, and it appeared to have absolutely no impact on the phase response of the room. The bass was smoother at one location, the primary location of measurements. If I introduced more and more varied location measurements, the response became more and more rough and complex, with more and more anomalies due to phase cancellation (Phase change correlated with bass dip). There appeared to be very little improvement from this magic black box in and of itself.
It didn't compare with the level of improvement garnered from multiple subs and room treatment, and I don't consider it a replacement for these two things. It might have valuable advantages if used in conjunction with these other two more important issues, it might make for an incremental improvement, but I feel the 600 dollars was better spent on other things. I think the technology, as implemented by Lyngdorf, would be more useful as they have processors with multiple outputs, allowing you to fix phase anomalies of multiple subs as well as add precise parametric eq to peaks not smoothed out by the rest of the treatment. It also can act as a complete surround processor source, which makes a lot more sense than adding a bunch of devices.
In the case of movies, the delay added by these devices is significant, and not all processors can correct for this. It causes lip sync problems that need to be addressed, which is why I prefer one device that can account for all of this, and minimize the delay. I'm sure this is a non issue on bass, but as I recall, the Ergo works over a broad range of frequencies, not just bass.
Here is what I found, after taking tons of measurements at various locations in the room, as suggested, it was able to smooth response about the same any of the various eq's do. I also took phase measurements, and it appeared to have absolutely no impact on the phase response of the room. The bass was smoother at one location, the primary location of measurements. If I introduced more and more varied location measurements, the response became more and more rough and complex, with more and more anomalies due to phase cancellation (Phase change correlated with bass dip). There appeared to be very little improvement from this magic black box in and of itself.
It didn't compare with the level of improvement garnered from multiple subs and room treatment, and I don't consider it a replacement for these two things. It might have valuable advantages if used in conjunction with these other two more important issues, it might make for an incremental improvement, but I feel the 600 dollars was better spent on other things. I think the technology, as implemented by Lyngdorf, would be more useful as they have processors with multiple outputs, allowing you to fix phase anomalies of multiple subs as well as add precise parametric eq to peaks not smoothed out by the rest of the treatment. It also can act as a complete surround processor source, which makes a lot more sense than adding a bunch of devices.
In the case of movies, the delay added by these devices is significant, and not all processors can correct for this. It causes lip sync problems that need to be addressed, which is why I prefer one device that can account for all of this, and minimize the delay. I'm sure this is a non issue on bass, but as I recall, the Ergo works over a broad range of frequencies, not just bass.
I think to determine whether a device like that really works as well or not, first we need to look at the room and speaker performance individually. If the speaker is lacking in the low very low frequencies at the desired listening level, I don't think that kind of device can correct for it. It would be just physically limiting. A device like that should allow user to set the range of it's application if it has capability to handle quite wide audio range.
I'm not really sure what you are getting at, but my subwoofer, on it's own, has a pretty smooth response. I've shown it's individual response before. Both of my subs have a response that is more than smooth enough. The anomalies in the response are largely due to the room, not the speaker. They are of very good quality too, so again, I don't see that as an issue.
Isn't the room the whole issue here? I thought the point of the Ergo was to correct for room problems? Regardless of how bad my room is, shouldn't this device, according to it's claims, correct for the deficiencies? In my case, from a value stand point, other options were more effective at fixing bass problems. I found that tuned bass traps such as so called "spring traps" spring trap worked better than this device at fixing bass problems. Even greater yet, though the cost was great that 600, was multiple bass sources. At the time of using that device I had two, now I have more in that my main speakers act as bass sources. At the time, the bass response in my room was most smoothed over the range of listening positions via two subwoofers at opposite ends of the room and with two home made spring traps. It wasn't/isn't perfect, but those worked better. In my measurements of my room, the Ergo didn't seem to add enough after those devices to justify the cost of the item, so I took it back.
Isn't the room the whole issue here? I thought the point of the Ergo was to correct for room problems? Regardless of how bad my room is, shouldn't this device, according to it's claims, correct for the deficiencies? In my case, from a value stand point, other options were more effective at fixing bass problems. I found that tuned bass traps such as so called "spring traps" spring trap worked better than this device at fixing bass problems. Even greater yet, though the cost was great that 600, was multiple bass sources. At the time of using that device I had two, now I have more in that my main speakers act as bass sources. At the time, the bass response in my room was most smoothed over the range of listening positions via two subwoofers at opposite ends of the room and with two home made spring traps. It wasn't/isn't perfect, but those worked better. In my measurements of my room, the Ergo didn't seem to add enough after those devices to justify the cost of the item, so I took it back.
I modified my simulation code to handle 8 sources and started simulating DBAs. Very uniform response below 100 Hz in the room I am considering. Basically void of peaks though there are some cancellations which are fairly narrow band. And the response is matches the minimum phase from the amplitude below 100 Hz in all cases. Additionally, since the DBA does not cancel the DC mode the response has a nice linear boost as the frequency drops.
This is by far the best response I have seen over a wide area. I think a DBA with a little eq based on multi-position measurement would be a killer setup.
As I said a few posts ago. I think the DBA make room response a done deal. 4 woofers on front and 4 on back walls, wired in series/parallel, a delay/Eq (My Beringer DEQ2496 should do nicely) and a stereo amp.
This is by far the best response I have seen over a wide area. I think a DBA with a little eq based on multi-position measurement would be a killer setup.
As I said a few posts ago. I think the DBA make room response a done deal. 4 woofers on front and 4 on back walls, wired in series/parallel, a delay/Eq (My Beringer DEQ2496 should do nicely) and a stereo amp.
gedlee said:
Yes, the marketing is pretty laughable. i like the room with the splashes of different color in it - totally meaningless, but pretty.
At low frequencies, at least if you read Pedersen's AES paper, it really amounts to deriving a target curve from an IEC standard room and equalizing to that curve. At least Jan understands the physics involved. I dont believe there is multisub processing, and I'm not sure what they do at high frequencies. From the demo I heard, it wasn't doing much at high freqs (not necessarily a bad thing if the speaker is good to start with).
Hi Dr Geddes, do you feel that bass trapping is beneficial if one uses multiple subwoofers, or do you feel that your approach completely obviates the need for bass absorption? My impression is the former, but at least one fan of your approach remembers the latter. If bass trapping would indeed be helpful but one is working with an already constructed room where the boundaries cannot be re-mounted in such a way as to flex as much as possible, do you tend to look kindly upon diaphragmatic absorbers or Helmholtz absorbers because they tend to avoid absorption at mid- and high frequencies? Thanks for clarifying.
gedlee said:
Yes, if done correctly. But you need to figure out what correctly is.
Yes, other configurations can be found with 8 woofers. For example you can take Todd's 4 woofer floor array, 1/4 wave length from walls and lift it 1/4 wave length off the floor. Then add a second 4 woofer array 1/4 wave length off the ceiling. This will give pretty smooth response as long as you are near the center of the 1/4 wave boundaries. Thew first excited modes are (4,0,0), (0,4,0), (0,0,4), (4,4,0), (0,4,4) and (4,0,4). And the response follows the MP response at low frequency too! But don't sit too far off center. However, the DBA seems to give pretty good response just about independently of listening position and all the woofer are mounted in places which are out of the way.
Yes the real world counts, but I have my doubts that is something simulated bad it will be good in the real world. The question is more that if it simulates good, how well will it really work in the real world.
markus76 said:John, fixing everything below 100Hz is good but how will you fix the higher frequencies up to the Schroeder frequency? Applying porous absorbers will affect performance of the DBA. I can't quantify that effect so I guess we will have to wait until you show some measurements
Best, Markus
I do hope to set up a DBA but it won't be tomorrow. But in terms of consistency of response with changes in listening position I have yet to simulate anything that comes close. See the thing is I have no vested interest in what works or doesn't work. Heck, the DBA isn't my idea. If I could get a 2, 3 or 4 woofer result that appeared to work as well I'll try it.
youngho said:
I really believe that some LF absorption is essential to good bass. The combination of good LF absorption and multiple subs creates, IMO, and ideal bass situation. If you can do one and not the other then do multiple subs, but absorption adds a lot to the modal interactions and smoothness of the response.
Some "bass traps" are more absorptive at mid to HFs than they are at LFs, these must be avoided. What I have found works well is very heavy drapes behind the speaks, since in that location even HF absorption is positive. But HF absorption anywhere forward of the speakers should be avoided.
gedlee said:
Eight woofers mounted in the wall of a perfect rectangle is not very practical only to those who don't have rectangular rooms. As lot of people do have such rooms. It may be more convenient to mount the woofer out of the way in a wall. And by who's definition are the optimum positions of a 3 woofer system convenient? If I give you the dimension of my rectangular room can you tell me where to put those 3 woofers?
But the question is, "Is there an audible advantage?" You don't know unless you try it. To dismiss it out of hand is unreasonable. Unless the woofer low frequency output is MP then looking only at the amplitude response is only 1/2 the story. It says nothing about the decay. If the response is MP then we know about the decay. If I know I have the same MP response at a listening position in two different rooms then I know I will have the same decay and if I apply MP eq to one system I know that the same eq applied to the second system will yield the same result. You can't say that with a non-MP system.
Now if you will excuse me I'm going to listen to a little music in a nonrectangular room with 2 cardioid woofers and dipole panels.
A) Why should I, or anyone except your declaration of good enough? A Kia may be good enough for you. I might feel a BMW or Lexus is required to be good enough for me. Is it wrong to strive for something better than good enough? How about better yet? I think "better yet" might be superior to "good enough".
B) On one hand you talk about science. What is the science behind good enough?
C) You don't have any idea what I have or have not done, or will or will not do in my listening environment, so please don't assume.
D) I don't have to do it to show that scientifically something is potentially better than something else.
E) I haven't dismissed anything. I have presented the results of my simulations. When I get around to testing for sure I'll look and listen to a 3 woofer system in the same room.
F) If I want to set up a 3 woofer system in a 14' L x 12'W x 7' 8" H room, where should I place them? Ok, one is a corner, then what? I know exactly where to start with a 4 woofer Welti set up and for an 8 woofer DBA from the science. What does the science say about the placement of a 3 woofer system?
Back to the music. Brahms ND is so soothing.
B) On one hand you talk about science. What is the science behind good enough?
C) You don't have any idea what I have or have not done, or will or will not do in my listening environment, so please don't assume.
D) I don't have to do it to show that scientifically something is potentially better than something else.
E) I haven't dismissed anything. I have presented the results of my simulations. When I get around to testing for sure I'll look and listen to a 3 woofer system in the same room.
F) If I want to set up a 3 woofer system in a 14' L x 12'W x 7' 8" H room, where should I place them? Ok, one is a corner, then what? I know exactly where to start with a 4 woofer Welti set up and for an 8 woofer DBA from the science. What does the science say about the placement of a 3 woofer system?
Back to the music. Brahms ND is so soothing.