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Old 17th February 2011, 07:44 AM   #521
tinitus is offline tinitus  Europe
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you guys have to get a better grip of yourself


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Old 17th February 2011, 01:05 PM   #522
dlr is offline dlr  United States
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you guys have to get a better grip of yourself


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No problem, my points (and those of John's re-stated) stand on their own. I'm simply looking for direct responses to direct comments and questions.

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Old 17th February 2011, 01:07 PM   #523
dlr is offline dlr  United States
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This is true. So when we do equalization like used in UE, we have to measure various locations to help identify how to equalize to provide optimum performance. This is much faster than trying to do a full scale non-linear analysis. Equalizing to a simple standard location does not seem to obtain optimum results. Additionally, the noise level during measurement is also going to play a significant role in effecting equalization.
None of this is any different for the UE than it is for any other type of crossover. It's a basic issue of design. What sets the UE or any other DSP apart? Nothing, other than the ability to also equalize phase response.

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Old 17th February 2011, 02:01 PM   #524
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although it was a VERY non-linear case, but we got the idea.
That is exactly the point. It takes a lot of nonlinearity to get an audible effect, just as Klippel does. But it ius easy to get these nonlinearities below audibility, but then he does get to sell his measurement gear. The whole test is setup to show an effect that is a non-issue in the real world.
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Old 17th February 2011, 02:19 PM   #525
gedlee is offline gedlee  United States
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I think that the correctness of both Dave and John's points has been well established. I see no errors in them. I can't follow what "fntn" is actually saying, it appears to change, but what does seem clear is not correct. Loudspeakers are very nearly perfectly linear devices (with massive amounts of linear distortions). There deviations from nonlinearity, within their "intended" operating range of output, are extremely small for the most part. If they weren't then the sound would be almost unrecognizable (and yes, I have heard speakers do this when broken or driven too hard, but that should be the exception not the norm). In virtually all of my work I just design conservatively for signal level capability and simply ignore the non-linearities. Perception of nonlinear distortion is grossely over-estimated.
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Old 17th February 2011, 02:31 PM   #526
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Confusion over the presence of linear conditions or lack thereof seems to be very prevalent - even among folks who fancy themselves as "experts". As Linkwitz seems to do, I maintain that a vigilant attention to detail as to the physical cause of any particular observed distortion is warranted before we assume it can be readily dealt with with simple tools like equalization. When in doubt, the standard tests establishing the properties of additivity and homogeneity should be applied. Linkwitz's warning about conducting tests for the presence of non linear distortion is in my view warranted and correct. The assumption (as appears to be the case with others in this thread) that the bulk of measured distortion is linear and can be corrected with tools like EQ is not grounded in reality. Moreover, most simple forms of distortion testing do not adequately reveal non linearities that are very much a part of the systems we work with on a daily basis. The results we hang our hat on are indeed very much skewed by our particular perspective and focus.
There is no confusion here at all. No one has suggested that these system are perfectly linear. No one has suggested that the bulk of the distortion is linear. However, since the goal of any system design is generally that it perform as a linear system over its intended operating range, it would be negligent to start with components in which nonlinearity was a dominant factor in that range. If you go to Mark k's or Zaph's web sites and look over the measurements they provide, the evidence is clear that for any quality driver linear distortion is the dominant problem. Choose any driver, define the bandwidth over which nonlinear distortion is reasonable and what you have left is the linear distortion. With todays technology designing a driver with low nonlinear distortion over some intended useful range is not the difficult task.

If it is intended to design a speaker than can play at 120 dB then it would be wise, to say the least, to start with components which behave linearly over the require frequency range at those levels. No one is suggesting that the design should start with drivers than exhibit 30% nonlinear distortion and expect anything other than crap.

What has been stated is that these system have linear and nonlinear aspects of their response to an input. And it has been stated and demonstrated that the linear aspects of the system can be corrected by a linear correction without affecting the nonlinearity adversely. It can be called equalization, response shaping, designing a crossover network, or what ever you like. But the idea of bringing the amplitude response into closer agreement with some desired target response using some type of filter between the source and the driver, active, passive, digital or analog, is applying a linear correction. It has never been suggested that such a correction does anything but addresses the linear aspects of the response. It has never been suggested that this is the end all to be all. What has been suggested is that with DSP the degree of accuracy with which this linear correction can be achieve is far superior to that which can be done with analog filter.

Making such a linear correction will not change the way the driver responses to a specific input because the driver has not been changed. Now if I do a 1 V RMS sine sweep on a raw driver and I can get an amplitude vs frequency and some crude measure of distortion such as THD. If I place some response shaping network in the signal path and do another 1 V RMS sweep I will get a different distortion measurement as well as a different amplitude. That is not indicative of a change in the nonlinearity of the driver, it is indicative of the change in the input just as the amplitude response reflects this change.

If you want to say that it is appropriate to measure the nonlinear distortion with the filter in place, I have no argument there. I have said for years I see little uses of distortion measurement made on raw drivers other than that they are informative of the raw materials going into a speaker.

The problem here is not the assertion that linear distortion is dominant but rather your continued implication that nonlinear distortion is. You seem to continue to imply that all the problems are in the nonlinear domain and the linear aspects are of little significance.

In any event, I have turned my attention to designing my own version of a ZDL system. I can assure you it will have both low nonlinear and low linear distortion.
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Old 17th February 2011, 02:40 PM   #527
soongsc is offline soongsc  Taiwan
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None of this is any different for the UE than it is for any other type of crossover. It's a basic issue of design. What sets the UE or any other DSP apart? Nothing, other than the ability to also equalize phase response.

Dave
I think if you tried yourself, you will find that phase is important. But I know of no other way to change configurations and test as fast as UE, so I really haven't tried. What other packages do is of no interest to me unless the basic method is described clearly enough for me to make a judgement whether I wish to try or not. Perhaps you have something particular in mind?
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Old 17th February 2011, 02:46 PM   #528
soongsc is offline soongsc  Taiwan
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That is exactly the point. It takes a lot of nonlinearity to get an audible effect, just as Klippel does. But it ius easy to get these nonlinearities below audibility, but then he does get to sell his measurement gear. The whole test is setup to show an effect that is a non-issue in the real world.
I have not compared or analyzed this, so I cannot comment. Klippel demonstration was just to explain what it would sound like, I don't think I'd ever select a driver like that. It's getting close to the point where I have to consider it more carefully though.
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Old 17th February 2011, 03:07 PM   #529
dlr is offline dlr  United States
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I think if you tried yourself, you will find that phase is important. But I know of no other way to change configurations and test as fast as UE, so I really haven't tried. What other packages do is of no interest to me unless the basic method is described clearly enough for me to make a judgement whether I wish to try or not. Perhaps you have something particular in mind?
If you're referring to phase EQ, you're forgetting my early input wherein I showed the measured response of my new dipoles. This was simply to suggest an alternative EQ method and tool to Joachim back then. I surely had no idea it would cause someone to go viral.

In addition, I used the UE built into SE v17 back in the fall of last year in my primary 3-way passive system at the time, created the same crossover for Fc and slope to approximate the passive version and EQ'd the phase as well. Alternating between flat phase and minimum-phase I couldn't hear a difference. I'm not convinced at all that it's audible in a speaker system. But I always figure it's prudent to optimize as many aspects as possible. I can do it, so I do.

Of course I'm using that fully UE EQ'd dipole system now. I've tried it minimum-phase as well and have a lot more experimentation planned.

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Old 17th February 2011, 03:26 PM   #530
soongsc is offline soongsc  Taiwan
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My experience between flat phase and minimum phase is that the difference is the preferred polarity I listen to each album. I also need to do more experiments to see what is optimal. One of the reasons I have not used open baffle designs is that the wave front is just to complicated, and introduces coloration to sound, also slightly smearing the focus. As learned in physics, waves just pass through each other, and there is no way in reality to perfectly combine multiple sources into a simple source wavefront. I do realize that others have different design tradeoff considerations.

Has a visitor a few days ago, we just setup a pair of speakers in our living room which had no special treatment to absorb reflections. I just flipped the polarity around and asked what he heard different. He just pointed out that one polarity seemed to be better focused, which was also my perferred polarity (I did not tell him though).

I think there's some sort of demo version of UE available one the SE web site to test sound card compatibility, not sure what it actually does.
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Last edited by soongsc; 17th February 2011 at 03:28 PM.
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