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Old 3rd July 2010, 07:24 PM   #4471
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Back to topic. Isn't 1D polar directivity graph showing a very limited view of the generated soundfield - or only I can't interpret it? Why not show the generated 'soundfield' with a polar map?
Even big players in the pro prefer showing data with the 2D polar map.

Last edited by daniel; 3rd July 2010 at 07:51 PM.
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Old 3rd July 2010, 08:50 PM   #4472
gedlee is offline gedlee  United States
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Originally Posted by mac View Post
That's good to hear especially since your data has now onto the bottom of JohnK's page...
The problem is that they are normalized to the axial response, which I have said over and over again is not a good thing to do and is especially wrong in the case where the listening axis IS NOT the normal axis. Further. showing only limited data, which I DO NOT do, is always prone to misleading interpretations (like here).

I still contend that I have no problems posting John's (or anyone elses's) data in its entirity and with his approval of its correctness (full disclosure of measurement conditions, etc. would be required of course, such as electronic EQ, etc. One could easily re-EQ every angle producing a beautiful set of polar curves. This should be disclosed). I would noramlly not make this later offer, but given the errors that have occured, when I have no way of detecting them myself, I would rely on his determination.

I am interested only in being fair and honest, and I get very annoyed when I see fairness being shunned by others.
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Old 3rd July 2010, 08:58 PM   #4473
gedlee is offline gedlee  United States
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Quote:
Originally Posted by daniel View Post
Back to topic. Isn't 1D polar directivity graph showing a very limited view of the generated soundfield - or only I can't interpret it? Why not show the generated 'soundfield' with a polar map?
Even big players in the pro prefer showing data with the 2D polar map.
I'm a little confused, because what you suggest is exactly what I am saying as well (or maybe you are agreeing with me, its not clear). Angular polar plots are a very limited way of viewing the sound field, just as single axis curves, and can be very misleading. You are quite correct that the Pros have all gone over to polar maps, a trend that I completely agree with. Many are too course a resolution for my taste and there is a point of contention with polar maps regarding to "normalize or not". I do not agree with "normalization" because this does NOT show the sound field as it actually is. I want to see what is radiated - period - as clearly as possible, without normalization, with as little smoothing as is feasible, etc. Such plots are not readily available, which is why I wrote my own.
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Old 3rd July 2010, 09:59 PM   #4474
ScottG is offline ScottG  United States
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Originally Posted by gedlee View Post
The problem is that they are normalized to the axial response, which I have said over and over again is not a good thing to do and is especially wrong in the case where the listening axis IS NOT the normal axis. Further. showing only limited data, which I DO NOT do, is always prone to misleading interpretations (like here)..


I am interested only in being fair and honest, and I get very annoyed when I see fairness being shunned by others.

Presumably the data is not limited, but it is a different view. John's provided the view that most closely matches his own.. is that not fair?

..and speaking of fair..

This is your representation:

Nathan

Is it fair to use a 6db color gradation?

While you do have those areas that are problematic "circled" in white on the sonogram, does it really show the degree of difference from the average (for any axis)?

Looking at the accompany single axis freq. response (on your preferred axis), suggests a decent (neither good or bad) +/- 3 db across the average. BUT is that really what it is?




IMO you have purposefully chosen a sonogram "view" to highlight HIGHER losses in pressure to emphasize the design's most notable character/feature.

Further, the single axis freq. response doesn't adequately represent the average because:

1. The deviation*S* are *broad* - effectively spanning an octave.
2. It doesn't show that just 7.5 degrees off-axis that there is a fairly substantial change in sound pressure throughout the response. (..and as mentioned, this isn't obvious in the sonogram.)



Is any of that fair or honest?

It depends on your perspective.
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Old 3rd July 2010, 10:09 PM   #4475
gedlee is offline gedlee  United States
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One more thing - I've made my position on using DIY as an advertising vehicle for my products clear in the past, but I can see that it needs to be refreshed.

That I use DIY to advertise my products is absolutely the case. All one has to do is look at the banner ads, I'm right there. I think that this is a good thing because, as Jason will tell you, without advertisers, this site is in trouble. It isn't free and advertiseres are a requirement. I do not advertise on any other sites (not directly that is).

Do I unfairly use threads to advertise my products? Not intentionally. I try to be careful about direct reference to them in the threads, except in my own GedLee forum. Do they come up? Absolutely. In this recent episode John brought them up, not me. A better place for his comments would have been the GedLee forum.

While I am a manufacturer, that is a very recent event in my career and one mostly foirced on me by the economy. All loudspeaker work has gone overseas,and unless I moved there (which I could do at any time I wanted to) I had to find some way to stay in the US and still work in audio. The only way that this is possible in this environment is to become your own manufacturer. But the fact remains that audio is all that I have ever done and I see no reason why I should avoid DIY because I am now a manufacturer. I'm not really even a DIY guy, never have been. I come here, because many people here are truely interested in sound quality - what I have spent my life studying - and I am happy to relay what I know about the subject.

Everyone is free to avoid my posts, if you don't like what I have to say.
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Old 3rd July 2010, 10:23 PM   #4476
ScottG is offline ScottG  United States
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One more thing - I've made my position on using DIY as an advertising vehicle for my products clear in the past, but I can see that it needs to be refreshed.

That I use DIY to advertise my products is absolutely the case. All one has to do is look at the banner ads, I'm right there. I think that this is a good thing because, as Jason will tell you, without advertisers, this site is in trouble. It isn't free and advertiseres are a requirement. I do not advertise on any other sites (not directly that is).

Do I unfairly use threads to advertise my products? Not intentionally. I try to be careful about direct reference to them in the threads, except in my own GedLee forum. Do they come up? Absolutely. In this recent episode John brought them up, not me. A better place for his comments would have been the GedLee forum.

While I am a manufacturer, that is a very recent event in my career and one mostly foirced on me by the economy. All loudspeaker work has gone overseas,and unless I moved there (which I could do at any time I wanted to) I had to find some way to stay in the US and still work in audio. The only way that this is possible in this environment is to become your own manufacturer. But the fact remains that audio is all that I have ever done and I see no reason why I should avoid DIY because I am now a manufacturer. I'm not really even a DIY guy, never have been. I come here, because many people here are truely interested in sound quality - what I have spent my life studying - and I am happy to relay what I know about the subject.

Everyone is free to avoid my posts, if you don't like what I have to say.


I absolutely agree.


I personally think that your commercial website post is fair.


I ALSO think Johnk's is fair as well - and is ALSO commercial in nature.


.the PROBLEM is objecting to John's website without taking a closer examination at your own.

It's also an even *bigger* problem to suggest dishonesty.
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Old 3rd July 2010, 10:29 PM   #4477
mac is offline mac  United States
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Earl, I noticed that you posted rear-wave data for (only) the Orion. Do you believe this is an important metric? Regardless, I think it would be interesting to see the rear polar patterns of your loudspeakers displayed in your application.

Also, going back to your published Orion data... You previously mentioned that the data below 200Hz should be ignored (due to dipole interactions, I think). If this is the case, can you tell me why the LF data for the reverse side seems to be relatively flat down to 20Hz?
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Old 3rd July 2010, 10:57 PM   #4478
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LspCAD does polar plots and polar maps, either as simulations or using real measurements. You can choose no normalization, normalize to the on-axis response or normalize to the strongest response. The angle spacing and frequency spacing can be whatever you have. LspCAD will figure it out and interpolate. The free demo version does everything except save files.

Edit: I like normalized plots so you you can see directivity directly. But to be fair to Earl's speakers where the design axis is ~22 degrees, I'd build a data file where the nominal 0 degrees in the file is really the ~22 degree measurement.
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Old 3rd July 2010, 11:09 PM   #4479
gedlee is offline gedlee  United States
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Earl, I noticed that you posted rear-wave data for (only) the Orion. Do you believe this is an important metric? Regardless, I think it would be interesting to see the rear polar patterns of your loudspeakers displayed in your application.

Also, going back to your published Orion data... You previously mentioned that the data below 200Hz should be ignored (due to dipole interactions, I think). If this is the case, can you tell me why the LF data for the reverse side seems to be relatively flat down to 20Hz?
I will post some rear data at some point just to prove what I am about to say. There is nothing there. Above about 200 - 300 Hz, it's just all black, pretty uninteresting - once youv'e seen one youv'e seen them all. That's not at all the case of the Orion, which justifies the display of its rear radiation. It would also not be the case for a lot of other speakers, but it is certainly true of mine.

There is a technical reason for measuring the rear radiation (too technical for discussion here, but the bottom line is that the rear data can be used to better refine the forward data), so from now on I will most likely measure the full 180 degrees, but only in exceptional cases will I bother to show it - those cases where it is anything but totally predictable and uninteresting.

The data for the Orion below 200 Hz "could be good", but it "could be bad" as well. I just do not have any data or experince to know how well a near field patching works for a dipole. I have every reason to suspect that its wrong, but that doesn't mean that it is. In my data, I use nearffield data to refine a monopole model that fits that data set. Obviously this won't work for a dipole. But I did do a dipole fit on the model, but I wasn't happy with the results in that it was too sensitive. In general you have a good model when it is fairly insenitive to small changes in the parameters. That is the case with the monopole model. But the dipole proved to be more difficult.

So perhaps the rear LF response is accurate, and the front bad, or then again maybe its the other way arround.

I'd love it if someone would measure the Orion that has a better free field setup than I do. What I have works fine for what I do, but clearly it was inadequite for a dipole at LF. I'd post someone elses data that was better than what I have done if they would just send me what I need. I was asked to measure the Orion and my only requirement to do that was to be allowed to post the data, but that doesn't mean that better data could not be obtained, only that I can't do it.

I think that it is time to begin to see real data in a manner that allows comparisons. Audio has become far too sophisticated to continue to hide behind limited data showing only what the manufacturer wants to show. I have always appluaded Floyd Toole and Harman in this regard, but I think that my data presentation is more complete than theres in many ways. (They have a better chamber than mine!!)
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Old 3rd July 2010, 11:29 PM   #4480
ScottG is offline ScottG  United States
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..I have always appluaded Floyd Toole and Harman in this regard, but I think that my data presentation is more complete than theres in many ways. (They have a better chamber than mine!!)
They have "released their speakers in the wild" however:

Stereophile: Revel Ultima Studio2 loudspeaker

I have an easier time with the waterfall plot (over the basic polar and sonogram view). On the other hand the lack of color in JA's horizontal waterfall is a pretty serious problem.. it makes it *very* difficult to better determine where pressure losses are with respect to degree, especially with uniform responses like this speaker has.
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