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Multi-Way Conventional loudspeakers with crossovers

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Old 19th August 2008, 07:23 PM   #511
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Earl, but maybe electroforming is a way to produce your waveguide in the intended cost/quantity ratio? *Dreaming of getting rid of filler*

Patrick, would love to see some pictures of your Summas.

Best, Markus
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Old 19th August 2008, 07:26 PM   #512
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Quote:
Originally posted by Patrick Bateman ...
#3 - now that the whole room has been rotated, reflections off the walls won't happen simultaneously in *time.*
...
Yes, it's known that decorrelation helps in localization. But how much and how is it measured?

Best, Markus
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Old 19th August 2008, 07:27 PM   #513
gedlee is offline gedlee  United States
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Quote:
Originally posted by markus76

Earl, are there any papers in JAES or similar publications? I have easy access to that and always love to learn something new.

And yes, there'll be definitely a new thread called "Placing the Nathan 10" Why is there no room acoustics section in this board??

Best, Markus
Markus

Lidia and my paper was never submitted for publication, but I think that its on my web site.

The data in AES is sparse and not directly applicable, but you can glean some important information from the works of Brian Moore in the audibility of group delay. Pay particular attention to the point he makes about how this form of signal distortion would be absolute level dependent. This is a key point, but one that he only mentions in passing and doesn't seem to put together the relavence. Because virtually all of the subjective work in loudspeakers is done at fairly low SPL levels, the diffraction, which is a group delayed signal, might never show up at those levels. But at some level it will and at even higher levels it will be the limiting factor in sound quality. John Vanommen has posted several times, and many others have noted, how loud the Summas play without fatigue, compression or coloration. I attribute this to two things; the thermal perfomance, which is virtually never considered in hih-fi speakers, and diffraction which is virtually never considered at all.

The hard data is sparse, but all available data points to exactly what I am saying.
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Old 19th August 2008, 07:33 PM   #514
gedlee is offline gedlee  United States
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Quote:
Originally posted by markus76
Earl, but maybe electroforming is a way to produce your waveguide in the intended cost/quantity ratio? *Dreaming of getting rid of filler*

Patrick, would love to see some pictures of your Summas.

Best, Markus
Personally, electroforming is a dead end.

I've built more of these devices than you could possibly imagine and I am perfectly comfortable with my approach. When others quote costs they are only quoting materials, not tooling, time, etc. OK, the material cost for one of my baffles is about $15. The rest is labor, tooling amoritization and IP. When are these costs going to be factored into these outrageous claims?
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Old 19th August 2008, 07:35 PM   #515
gedlee is offline gedlee  United States
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Quote:
Originally posted by markus76


Yes, it's known that decorrelation helps in localization. But how much and how is it measured?

Best, Markus


Markus

I'm not sure what you mean here, but as a blanket statement it is incorrect. If you were to decorrelate the two stereo signals the imaging would disappear. The correlation of the left and right signals is precisely what the ear uses to localize.
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Old 19th August 2008, 07:52 PM   #516
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Earl,

I'm not talking about summing localization but reflections (see papers from Ando 1977, Toole 2006, Walker 1994).

Best, Markus
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Old 19th August 2008, 08:46 PM   #517
gedlee is offline gedlee  United States
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And I'm not talking about refections but diffraction.

Or are you refering to the decorrelation comment? If so, then yes a decorrelated reflection would be an advantage to imaging, just as elliminating the early reflections would be even better. But such things are not possible, reflections are coherent and ever present. Decorrelation only occurs after multiple reflections, many ms. after the initial arrival and the early reflections.
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Old 19th August 2008, 09:47 PM   #518
Salas is offline Salas  Greece
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Is it what we commonly call ''reverberation''?
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Old 19th August 2008, 10:00 PM   #519
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Originally posted by gedlee
And I'm not talking about refections but diffraction.

Or are you refering to the decorrelation comment? If so, then yes a decorrelated reflection would be an advantage to imaging, just as elliminating the early reflections would be even better. But such things are not possible, reflections are coherent and ever present. Decorrelation only occurs after multiple reflections, many ms. after the initial arrival and the early reflections.
Isn't diffraction like a decorrelated reflection when the diffracted sound arrives at the listening position?
Is there a way to measure or calculate the point when a reflection becomes decorrelated enought to have a positive impact?
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Old 19th August 2008, 10:10 PM   #520
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Quote:
Originally posted by Patrick Bateman


Dr Geddes could make a hell of a lot more money doing audio work as a full time employee. As DIY'ers, we're VERY LUCKY that guys like Geddes and Danley post on here. Some of the old timers might remember guys like Dan Wiggins, who was also very generous with his time.

Sooner or later they all lose a ton of money on the DIY market, throw in the towel, and get a day job.
Supplying quality product and a business failing in a limited market are two different things. I don't see a correlation. Supplying a poor product and a business failing are definitely related though.

Businesses go under everyday and yes its horrible for those involved. However I think it goes without saying that if the product isn't up to standard then this will only become an inevitability and that company won't be missed. Harsh but true.

Regardless of how generous folks are with their time, the minute they sell something, there's a certain level of quality to be reached - enough to satisfy the customer.

You see I could setup a shop front with a humble OAP at the desk dealing with customers. Folks would never be rude to that guy, well reasonable folks wouldn't. My point? I could supply substandard product and should anyone shout down to the old man on the desk, others would rightly flock to save him. Does it make it right though? Depends at who and what your looking at.

The moral of the story here? Geddes is an OAP

BTW Wiggins failed not because of the DIY market but because some of his partners ran off with a load of money and he made a bad call switching production to overseas. He also, at times, provided shoddy aftersales service.

Folks were and still are screaming out for his drivers so the demand is and was there.

Behind every failed business there's usually either bad decisions involved or bad products.
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