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Old 26th January 2009, 02:51 AM   #991
gedlee is offline gedlee  United States
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Noah

My idea is this. Based on experience, the foam in my designs makes the sources very hard to localize, the speakers disappear. Anyone who has heard them will attest to that. So, perhaps, the Harpers may just be the right thing. Direct radiating surrounds that aren't localized. Thats my hope.

Coaxs would always be localizable because of the poor waveguides that they are forced to use.
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Old 26th January 2009, 03:05 AM   #992
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"the foam in my designs makes the sources very hard to localize"

They don't disappear w/o the foam?

My experience is that lots of good speakers disappear if they're located w/enough distance from the back and side walls.

This isn't possible w/most surrounds, which are wall mounted, so other means must be used.

BTW, those polar plots for the Harper's look amazingly good.

When will you get to try them as surrounds?
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Old 26th January 2009, 12:14 PM   #993
gedlee is offline gedlee  United States
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In my experience any horn or waveguide (except mine) are localizable and this has been one of my issues about them. With the foam they aren't. The foam takes away whatever it is that we localize to. I suspect that it is the HOM, but thats just a hypothesis. Without the foam the OS waveguide tend to disappear much better than most, but with it they are gone. Diffraction horns are always obvious where they are - you could never fool me with that type of device.

Some piston loudspeakers can disappear, but few. Most dome tweeters can be easily localized. So, to me, any dome tweeter system would not be a good choice for a surround if pointed at you.
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Old 26th January 2009, 12:45 PM   #994
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Quote:
Originally posted by gedlee
In my experience any horn or waveguide (except mine) are localizable and this has been one of my issues about them. With the foam they aren't. The foam takes away whatever it is that we localize to. I suspect that it is the HOM, but thats just a hypothesis. Without the foam the OS waveguide tend to disappear much better than most, but with it they are gone. Diffraction horns are always obvious where they are - you could never fool me with that type of device.

Some piston loudspeakers can disappear, but few. Most dome tweeters can be easily localized. So, to me, any dome tweeter system would not be a good choice for a surround if pointed at you.
Earl,

Does how intimately the foam is in contact with the waveguide have an effect? The reason I ask is that in order to attach the foam to the waveguide the former is sprayed with glue - I have found that this is never evenly spread on the foam.

So is the random nature of the glue breaking up the HOMs or is it the body of the foam that is de-localizing the sound?

Regards

Alan
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Old 26th January 2009, 12:46 PM   #995
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Quote:
I don't see how dipoles are feasible if one wants bass down to below 100 Hz, so that leaves bipoles or monopoles facing upward; I've read many times that they work very well and would be the simplest/cheapest to implement.
I think it can be feasible. I did a quick test of dipoles against a side wall and found they went flat down to 80 Hz without eq. Not a very rigorous test, but enough to suggest it just might work if I try it in the future. I'm not sure if dipoles make much sense with waveguide-based speakers like the summa.
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Old 26th January 2009, 12:57 PM   #996
gedlee is offline gedlee  United States
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Quote:
Originally posted by AlanElsdon


Earl,

Does how intimately the foam is in contact with the waveguide have an effect? The reason I ask is that in order to attach the foam to the waveguide the former is sprayed with glue - I have found that this is never evenly spread on the foam.

So is the random nature of the glue breaking up the HOMs or is it the body of the foam that is de-localizing the sound?

Regards

Alan

I've wondered about this myself. If the glue gets very thick, as it does if the foam is reused many times, then a clear effect can be noted. But I cannot tell anything is effected by the thin layer of the first application. There will be some effect, but I think that it is small if the glue layer is small.
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Old 26th January 2009, 01:45 PM   #997
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Quote:
Originally posted by gedlee
The evidence is from Floyd Tooles book and lecture. He claims that monopoles facing the listeners were found to be more appealing, but that the tembre of the speakers had to be the same as that of the mains.

Thomason Holman was the one who said that dipoles are the better choice, but that was quite a while ago. I'm not sure if thats still his position. I'm going to try the monopoles now that I have a speaker that suites me.

How to point the monopoles when one uses a fairly directive speaker is a different question and one that I want to look into. By default the surrounds in a small room have to be at a junction of two walls. One should take this into consideration in placing and pointing them, but the answer is not obviuos to me at this point.
I actually talked with him maybe a month ago about this. I was asking about the THM speaker system, and what the surrounds were like. He was a little vague, I think intentionally, but I think eh was suggesting that he still prefers dipoles. He seemed to feel it was very room dependent, and suggested it was whatever makes the user happy. I think he felt that most rooms were of poor shape and size for a good theater setup, and that the surround were a key speaker to modify in order to fit the room, and best develop the desired experience. However, he seemed to indicate that with his new 10.2 system, or even the modern 7.1's to a point, that monopoles might be a better option in the right room. His requirement for monopoles to work correctly seems to be beyond any room I've ever had, but I'm sure is common enough in custom home theaters. The listener needs to be a fair distance from each surround speaker, relatively equidistant. My room is far too small for all but one person to be in that position. Additionally, my living room is open to my kitchen, so I don't have a side wall to mount those speakers on. He also mentioned liking the sound of a surround with mostly direct radiating sound, and some diffused dipole. I would suggest that this is very similar to what I developed for my surrounds using those M&K tripole enclosures I picked up.

Oh wait I forgot a key part of his 10.2 and suggestions. He said that systems should have both. The primary surrounds should be monopole while the other effects channels should be dipole. I believe he said that is how his system is to be arranged.
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Old 26th January 2009, 01:59 PM   #998
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Matt

I had longtalks with Floyd at ALMA and he is not in favor of dipoles at all. But he did agree that there probably is no one correct solution for surrounds as there tends to be for the mains in stereo. I'm going to try the Harpers as surrounds and I'll let you know.
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Old 26th January 2009, 02:02 PM   #999
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So who do we believe, Floyd or Thom? Hasn't that been the issue all along, people who basically invented these concepts or were influential in the standards, argue over which is best.

I don't have enough amplifier channels or surround speakers, but I am interested in testing Thom's idea of lot's of surrounds with a mix. He suggested a way to use the 7.1 to create the effect he was looking for with discrete 10.2. He felt that more monopoles helped reduce localization a lot, while improving the rear stage.
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Old 26th January 2009, 02:24 PM   #1000
gedlee is offline gedlee  United States
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There is no fixed belief in surrounds, its too new for the "best practice" to have settled out yet.
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