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Old 11th December 2009, 11:41 PM   #6511
Pano is offline Pano  United States
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Yes we have. It's going to depend on the driver. But without a horn, it's pretty far down in level. Have never heard one with a horn in the back.
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Old 12th December 2009, 03:43 AM   #6512
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Neither usual (ancient) CD concepts nor Earls oblate sheroide actually do that for us and Jean-Michel's contours actually having "smooth and consistent" sound field sadly ain't any close to CD.
Hello Michael

What is wrong with Earls waveguide?? What's wrong with the PT Waveguides JBL uses?? I don't understand the importance you are putting on minimum phase?? Either Earls waveguide or the PT's are a step in the right direction. The only experience I have are with the PT Waveguides. There is no question they sound better than the average 80's vintage diffraction horns. I would hazard to guess Earls waveguides sound better as well.

CD horns are not an Ancient concept and compared to compression drivers are actually new kids on the block. That all started at EV in the late 70's early 80's.

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Yeah – but what *if* we finally come to a "min phase horn" contour that combines CD with a "smooth and consistent" sound field over a useful bandwidth?
What is a minimum phase contour?? If I look at the PT's I use they look fine as far as minimum phase is concerned. So does the Exponential 2307 Horn I posted previously. The real audible differences between the two is that one is CD and the other is not. I don't see where MP comes into this.

Rob
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Old 12th December 2009, 12:58 PM   #6513
mige0 is offline mige0  Austria
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Hi Rob,
Regarding my naming of "Min Phase" horn contour I can't explain any better as already did – its putting emphasis on the benefits we can have from the concept of "min phase" in audio – when understood and done right – meaning we have to be after a smooth and consistent sound field that tracks in frequency response over an as wide as possible bandwidth and room angle.

I can't put JBL's PT horns into perspective as I have no experience whatsoever with these – I only could guess that there are strong mouth reflections going on as its basically a cut conical at this point. (probably you can point me to polar measurements?)

Some pretty enlightening simus for this case I've shown some pages back in Earl's thread – accurately confirming what people have measured ~ 100 years ago.

As for Earl's attempts, I'd like to outline that to a great degree its been his preaching of the importance of directivity control that made me aware of how important this topic actually is.
So – as much as we seem to be in conflict with each other – there *is* a basis where we are in full accordance and I'm even thankfully that he called my attention there.

What exactly is wrong with oblate spheroid contour (besides "lowest diffraction" theory behind )?
Actually IMO it's pretty well performing in the CD context but there is a severe dis-consistency in the sound field it produces (on-axis somewhere at ~4kHz IIRC).
I have show simus in Earls thread that are confirmed by his own measurements he courtesy sent me for CSD analysis – also shown by me some pages back .
The issue here (and possibly in my Manazita quasi min phase dipole horn) is the same as I've outlined for the PT horn – just less pronounced as Earl tries to minime mouth reflection by a arbitrary round over (I've shown simus how much different round over's help in his thread also some pages back).

Sadly we have not seen yet measurements of the huge Min Phase horn of the DIY show in Gelsenkirchen – nor have we seen measurements yet from what I found to be even more promising Min Phase horn simus from soongsc.

Hey soongsc ! – any news on that ones?

Michael

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Old 12th December 2009, 02:37 PM   #6514
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Michael,

The problem I have with all this discussion is that I have yet to see any data that shows any deviation form MP in other horns. So when you say MP horn, it doesn't mean anything to me at all. It doesn't separate it form the rest of the pack.
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Old 12th December 2009, 02:55 PM   #6515
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Quote:
Originally Posted by mige0 View Post
...
Sadly we have not seen yet measurements of the huge Min Phase horn of the DIY show in Gelsenkirchen nor have we seen measurements yet from what I found to be even more promising Min Phase horn simus from soongsc.

Hey soongsc ! any news on that ones?

Michael
I'm not sure which you are talking about. I have already posted data on four designs, and do not intend to post any more until someone else matches that number. Quoting data from others don't count.
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Originally Posted by john k... View Post
Michael,

The problem I have with all this discussion is that I have yet to see any data that shows any deviation form MP in other horns. So when you say MP horn, it doesn't mean anything to me at all. It doesn't separate it form the rest of the pack.
I second that.
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Old 12th December 2009, 03:28 PM   #6516
mige0 is offline mige0  Austria
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Originally Posted by soongsc View Post
I'm not sure which you are talking about. I have already posted data on four designs, and do not intend to post any more until someone else matches that number. Quoting data from others don't count.

Click the image to open in full size.
taken from:
Geddes on Waveguides

Have you posted measurements for the upper one? - I must have missed it - could you please point me there ?

Showing simus only "does not count"

###################

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Originally Posted by john k... View Post
Michael,

The problem I have with all this discussion is that I have yet to see any data that shows any deviation form MP in other horns. So when you say MP horn, it doesn't mean anything to me at all. It doesn't separate it form the rest of the pack.

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Originally Posted by soongsc View Post
I second that.

I give up on trying to explain / justify that one - gonna take some English lessons ....

Michael

Last edited by mige0; 12th December 2009 at 03:33 PM.
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Old 12th December 2009, 04:12 PM   #6517
soongsc is offline soongsc  Taiwan
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Quote:
Originally Posted by mige0 View Post
Click the image to open in full size.
taken from:
Geddes on Waveguides

Have you posted measurements for the upper one? - I must have missed it - could you please point me there ?

Showing simus only "does not count"

###################
Those are just part of analysis of a new design, which also depends on a new driver. There is no firm date for that driver yet.
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Old 12th December 2009, 04:43 PM   #6518
mige0 is offline mige0  Austria
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Originally Posted by soongsc View Post
Those are just part of analysis of a new design, which also depends on a new driver. There is no firm date for that driver yet.
So - which measurements do you mean then?

Michael
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Old 12th December 2009, 05:06 PM   #6519
soongsc is offline soongsc  Taiwan
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Originally Posted by mige0 View Post
So - which measurements do you mean then?

Michael
Summary is here, but you would have to dig through the thread to recall the details.
Geddes on Waveguides
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Old 12th December 2009, 05:55 PM   #6520
mige0 is offline mige0  Austria
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Originally Posted by soongsc View Post
Summary is here, but you would have to dig through the thread to recall the details.
Geddes on Waveguides
Kidding - eh ?
Don't think I would have missed *any* measurements form you in this thread connected to the topic at hand


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