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In Reply to: Re: From Wayne Parham - Re: Patentable claim posted by Wayne Parham on July 5, 2002 at 01:34:40:
Wayne wrote:
"Perhaps you're right. Certainly in the case of concentric devices containing multiple horns, what you say is true. I'm not sure this would be true of products that have a woofer cone that doubles as a flare for a compression device; While not mentioned in the claims, Figure 3 as well as most of the early implementations of the Unity device were two-way systems. But you may be right, nonetheless."Dan's examination is correct. A concentric driver would not form a discrete loading point on a common horn with the compression driver in conventional use. Even in the case where the cone forms the horn for the compression driver there would be no subsequent loading of the midrange in a segmented horn. The design is scalable to any number of drivers and horn segments. Obviously to get lower in frequency the horn must have a larger mouth.
Wayne then wrote:
"But what do you think about the technical merits of the described system? The device described is said to acoustically horn-load three separate driver subsystems and remain phase-accurate across the spectrum. This kind of wide-band loading is not possible according to horn theory and being simultaneously frequency-linear and time-linear is not possible according to filter theory."Ok, so let's first address the loading issue separately from the time/space/phase issue. Tom's realization of this means for wide band loading of a variable flare rate horn is the basis of the design working. Looking at a large, variable flare rate horn, in this case a conical horn, it is found that for a given throat size and wall angle, the bandwidth of loading from a driver at the throat is limited, regardless of how far the flare is extended or how large the mouth is. This is nothing new. What Tom made the realization of is that if we look at this same horn in segments, we find that the horn can be segmented such that each segment can provide loading for a given bandwidth, where each segment further from the throat loads a lower frequency band. As such, the more segments which are added by extending the flare, the lower in frequency, and the wider the bandwidth which can be loaded. From what I recall, you can model each section of the horn as a discrete horn with the throat area equal to that of the flare's cross-section at the loading point. The problem with implementing such a design is that discrete horns would by definition be separated in space, and the coverage pattern would be intersecting rather than being one in the same. With the Unity Summation Aperture, we are able to get around this large separation in space, and our coverage pattern is now one in the same, not the intersection of two patterns.
I hope this clears up any confusion with the ability to load the the horn over a wide bandwidth. If this was directly possible according to conventional horn theory, the design would be nothing to speak of. I guess the best way to explain it would be to consider that conventional horn theory (and there are a few different perspectives) suggest this performance is not possible from a single drive unit. We fully agree with this fact, and the Unity Summation Aperture solves this problem using multiple drivers in a new, and unique manner. If you look past the rules of thumb and look at the math behind the horn models, the Unity design does not violate the theories when properly applied to this implementation. I believe Marshal Leach's papers and models co-incide with the design and modeling Tom performed. Realize we also have some proprietary acoustics software which was originally developed for some of the work done with NASA, and is the same software which Tom used to predict the response of the LAB Bass Horn which thus far appears to be matching the predictions rather well.
Now onto this whole time-domain mess...
Maybe the best way to explain this is by posing some questions. First, let us consider a hypothetical, multi-way, single origin driver. Think of a true co-axial driver in the ideal of size. Now, we still need a crossover do divide up the frequency bands between the multiple portions of this multi-way driver. Now, my question to you is this: What happens in the time domain when you introduce a low pass filter?
Answering this question explains the nature of how the horn allows a Time Correct operation. (FYI - "time aligned" is trademarked by some other manufacturer)
Mark Seaton
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Follow Ups
- Re: From Wayne Parham - Re: Patentable claim - Mark Seaton 12:08:51 07/05/02 (1)
- Re: From Wayne Parham - Re: Patentable claim - Wayne Parham 16:59:24 07/05/02 (0)
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