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In Reply to: Re: From Wayne Parham - Re: Patentable claim posted by tomservo on July 6, 2002 at 16:55:53:
Hello again Tom!You wrote:
> > I have been looking at a lot of old posts today, it seems that
> > you have made dozens and dozens if not more posts about the Unity
> > horn in the last year or so, you had made this a personal crusade
> > "to stomp this out".Actually, there have only been two times I've given the Unity device a second thought. The first was a year ago, when Mark Seaton wrote remarks comparing the Unity with my Professional Series four π loudspeaker system. The second time was this week, when I was surprised to find that you had worked on patenting the thing.
I have written a lot of things in general about loudspeaker performance in the time domain; This is not necessarily about the Unity, and my opinions in this matter are first documented in the 70's.
Maybe you feel I've been a "big meanie." Maybe my approach has been rude, and I'm sorry for that. I don't honestly like "product bashing," and find it distasteful. So I don't like that this thread has taken this tone, and for my part in it, I'm sorry.
But I think the technical debate we've entered into has merit. I'd like to see it continue until it reaches a point of conclusion, if that's possible.
> > In the end it is exactly the kind people I had wanted to Unitys to
> > go to that you have harmed, how many that were thinking about it
> > didn't get it because of your tirades.You have yet to convince me that your claims have merit. My opinion stands, and with good technical grounds.
> > Those tirades driven because you felt threatened or something
> > and based on your misunderstanding of how things work and lack
> > of test equipment to find out for yourself.Your explaination of your device doesn't square with existing theory. You have the extra burden of proof. I do not misunderstand - I disbelieve.
> > Just as bad, you harmed Nick's business, he is a nice guy and one
> > of relatively few places a DIY'r can get cool stuff, these are the
> > people that need support, not someone crusading against them,
> > especially someone who is wrong to boot.And in an earlier post, you wrote:
> > You must imagine the world revolves around you I guess and that no
> > one has ever given any of this though before you.See, Tom, now you're showing your arrogance. You see in others what is most evident within yourself. It is you that appears to imagine the world revolving around you and "needing" your "revolutionary new explaination" of horn theory to replace our existing ones. You appear to actually believe that you have broken all the rules and hit new ground. So it is you that is predatory with your claims.
I'm not the only one that is building horn loudspeakers, and neither are you. You are not the only horn builder that caters to the DIY market.
But you and your associates are the only ones saying that you have a single horn flare that is capable of providing acoustic loading from 200Hz to 20Khz. You say that it is a perfect point source. Since the rest of us discuss our systems using traditional horn theory, that puts us at a distinct disadvantage. We speak in terms of mass loading and upper frequency cutoff, while you and your associates speak of ultrasonics from physically large horns. Quite a difference, and shocking since your device is based on a Salmon family horn, same as most of the rest of us. These are all fairly narrow bandwidth devices, limited to a few octaves or so. Certainly nothing like two decades. So when you claim that yours is capable of doing this, you are potentially hurting the business of everyone else.
...and you are wrong to boot.
> > You insist that the Unity doesn't work but will not or cannot
> > answer any of my questions related to getting you to explain on
> > what grounds you base your insistence.I have made my grounds very plain. I'l reiterate them here:
1. I do not believe that the Unity device acts as an acoustic transformer, i.e. provide horn loading over the two-decade bandwidth claimed.
2. I do not believe the Unity device manages to correct the movement in time over the span of frequencies delivered by its subsystems in this two-decade bandwidth, such that it acts as a point source. You have said, "generally a first or second order crossover gives the best results" in this design. This very statement means that you had not figured out how to make this thing work when you wrote it. Not only that, but the midrange drivers have wavelength-scale distances between them and across their diaphragms, and they enter a common chamber.> > I suspect you are feeling like you took a good long Whiz into a
> > campfire and now are finding having to stand in the "steam"
> > unpleasant.Touche! That's so funny!
But you appear to have become unbalanced and defensive. If your argument has merit, then it should be easier to explain than this. One would think you would have quantified it better by now.
> > An array of sources that are small acoustically (less than 1/4 wl
> > in size) can combine totally and coherently IF they are less than
> > 1/4 wl (1/3wl if some directivity is acceptable) apart, center to
> > center. In the range they operate in, the mid driver exit holes
> > and horn dimension are less than 1/4 WL and load the horn as a
> > pressure (being too small acoustically to make a beam).If that were true, I could accept this. But at high and middle audio frequencies, 1/4 wavelength is pretty small. How are you managing to get multiple midrange drivers packed within the space of less than 4 inches? A quarter wavelength at 1Khz is only 3.4 inches, and I expect you are running the midrange diaphragms even higher than this. If they are crossed over with a low order filter, then the regions of interest are pretty wide and wavelength scale gets very small.
So what are your dimensions and frequencies, exactly? Please quantify the scale instead of speaking in generalities and put this issue to rest.
We've discussed the time alignment issue quite a bit. So let's move to another issue that is perhaps even more telling. I've read your claims about wideband loading by putting diaphragms in the walls of your conical horn. It's always left me scratching my head. The rest of the world puts their diaphragms in the apex, and often with a compression chamber. This is always done to increase efficiency, and having constant cross section area is required to satisfy the conditions of the Webster equation. Failure to do this has been shown to reduce the effectiveness of the horn, and is what I sometimes refer to as a "mal-formed horn."
Most of your peers feel pretty good when we can get linear response from a horn over three octaves. Please don't simply show what you do, or discuss the phenomenon with the analogy of the "changing flare rate." Another way to describe this is a "large discontinuity" in the throat for the drivers mounted closer to the mouth. Some of my designs have this too, but I've always called it a mal-formed horn - a compromise - 'cause that's really what it is. In those designs, it's better than nothing, but it is used for economy of size and complexity, and not for performance.
So please expand on the mathematical model you've used to derive the wideband performance of your horn. Maybe you can discuss how it relates to the Webster equation.
I'm still laughing about the "steam." Nice shot, man!
Wayne
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Follow Ups
- Re: From Wayne Parham - Re: Patentable claim - Wayne Parham 07/7/0202:46:26 07/7/02 (0)
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