He must have been referring to computer programs. Bjoern, i know you sons, you like to show up playing with the toys and signalling loyalty to the ones, who will later on grant you the serious stuff. Your humble mutt
I am not getting, what you are trying to say. Einstein is reffering to computer programs an Bjoern is a little dog, you also know his sons??? Confusion...
Let´s get to topic. This is one of the best threads on the web, I always loved the respectful high level of diskussion here, combined with so much knowledge, effort, passion and taking things seriously. Let´s go back to this kind of style and concentrate on the thread title. Please.
Let´s get to topic. This is one of the best threads on the web, I always loved the respectful high level of diskussion here, combined with so much knowledge, effort, passion and taking things seriously. Let´s go back to this kind of style and concentrate on the thread title. Please.
I have a question that is partly interesting.
I understand that hornresp will compute directivity for a single segment horn. And I like and sue this feature quite a bit.
What is the reasoning behind the choice to not compute directivity in a multiple segment horn?
Can directivity be calculated for a multiple entry conic like the synergy horn?
How about a multiple entry LeCLeach?
That I have been fooling around with for a while.
The ability to simulate it would be slightly easier than the cut and paste method!
I understand that hornresp will compute directivity for a single segment horn. And I like and sue this feature quite a bit.
What is the reasoning behind the choice to not compute directivity in a multiple segment horn?
Can directivity be calculated for a multiple entry conic like the synergy horn?
How about a multiple entry LeCLeach?
That I have been fooling around with for a while.
The ability to simulate it would be slightly easier than the cut and paste method!
David already told me its orders of magnitude more difficult to do a general multisegment horn.
I don't believe that where sound enters a horn affects its directivity. I've been studying the directivity of my conical, multi-entry (synergy) horn by leaving out the downstream entries from the model, faking a driver at the apex that has the bass response and then looking at the normalized directivity.
But unless you are building an axi-symmetric horn, you still have to do some handwaving to apply the results to what you plan to build. I'd actually like some advice on that. It seems if you want to see the horizontal directivity of a rectangular horn, you should model a conical whose diameter is equal to its width. Is that right?
The useful part of simulating directivity of a single segment conical horn was that it predicted significant midband narrowing. Well, it would have been useful, except that I had already built the horn and found out the hard way. Unfortunately, as you point out, I can't turn to HornResp to predict how much improvment I'd get from a second segment ala Keele. What made me reluctant to do a 2nd segment initially is that the HR sims of the single segment conical were remarkably free of mouth reflections. OTOH, adding a 2nd segment resulted in horrendous reflections from the point of change of slope. No doubt these don't show up in the real world or that 2nd segment ala Keele wouldn't be so common.
I think I can agree that being able to simulate a design or a design change is very much preferred to producing and measuring real world articles.
And sometimes even a simulation in the best of programs misses important hicups in the design's response.
Please don't take my comments as being critical of HR. To use a tool effectively, one has to know its limitations and learn to work around them and within them. You only really there with experience. I'm still on my first horn and enjoyed describing some of that experience in what I intended as an ironical fashion.
Hi Mark,
The reason is given in Post #6381.
http://www.diyaudio.com/forums/subwoofers/119854-hornresp-639.html#post4755776
Kind regards,
David
That's because calculating directivity is not a trivial task. Analysing multiple segment horns really requires the use of a true finite-element model, which in the case of Hornresp would complicate things greatly and significantly slow down the calculation of results. I experimented with a boundary element model some time ago, but it just took too long (several hours) to generate the desired frequency response curve, so the project was abandoned.
Thanks David.
I did indeed read this post. A few hours after you originally made it actually.
I can add a simple point that decent FEA of a curved or multiple segment conic horn in most any FEA program takes a bit of time to generate.
I for one would be willing to wait for the computation time if it produced some meaningful results.
David if I could assist in any way you know my contact info.
Backwards!
Instead of trying to solve the problem of determining the radiation pattern of a specific horn geometry, why not try to determine the horn geometry that delivers the desired radiation pattern instead?
The technology to do this is called Shape Optimization and it continues to be ignored on this website because it destroys all the myths about the superiority of any one particular horn shape over another.
Regards,
WHG
Instead of trying to solve the problem of determining the radiation pattern of a specific horn geometry, why not try to determine the horn geometry that delivers the desired radiation pattern instead?
The technology to do this is called Shape Optimization and it continues to be ignored on this website because it destroys all the myths about the superiority of any one particular horn shape over another.
Regards,
WHG
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That is very true Bill.
Doing your homework first off avoids many pitfalls.
Studying what has been done previously is some of the best ways to really advance. The old saying of there's nothing new under the sun most certainly applies to audio. The more I have read and learned about past work, the greater my appreciation for the work of those generations previous.
Some of it really was empirical cut and paste methods. But reading works by Olson for example show how much calculation was actually possible in times past.
Horn Shape Optimization (2)
A lot of study is a prerequisite to rational horn design.
Applying shape optimization to horn design is covered by a U.S. Patent [1] issued to a firm in Southern Australia.
A lot of work has been published [2] by students and faculty members of Uppsala University, Sweden
Regards,
WHG
Reference URLs
[1] U.S. Patent
https://www.google.ch/patents/US8494815
[2] Recent Example
https://www.researchgate.net/publication/222547823_Shape_optimization_of_an_acoustic_horn
A lot of study is a prerequisite to rational horn design.
Applying shape optimization to horn design is covered by a U.S. Patent [1] issued to a firm in Southern Australia.
A lot of work has been published [2] by students and faculty members of Uppsala University, Sweden
Regards,
WHG
Reference URLs
[1] U.S. Patent
https://www.google.ch/patents/US8494815
[2] Recent Example
https://www.researchgate.net/publication/222547823_Shape_optimization_of_an_acoustic_horn