It’s been a while since I wrote an article for my blog. As far as I was able to do in time, many other horn profiles have been investigated and programmed with help of my DrBA spread sheet calculator. The blog is therefore clearly behind the current stage of development. Now it is time to reduce the gap somewhat.
When I was working on the True Expansion Tractrix horn, during the research I found something that gave me the base idea of a whole range of new horn profiles. It was a reference to the hyperbolic spiral, which was something like this: if you unroll a hyperbolic spiral on a line and place a virtual pen in the center of the spiral, you get a Tractrix curve. What? A Tractrix curve? If the Tractrix curve is known to be suitable as a horn profile, is this also the case for the hyperbolic spiral?
DonVK’s second article deals with the verification of the DrBA spherical wave horn calculator and BEM simulation model construction. Only the round mouth spherical wave horn was initially used for comparison to published works. Additionally, the effect of adding a roll-back section or even more a merge of the roll-back section with the inner horn wall will be discussed. As already mentioned in the original patents, the continuation of the horn profile beyond the mouth plane has positive effects and leads to more even results.
After I had finished my first horn profiles as 3D models, the question arose whether it is possible to perform a proof of concept by simulation. Doing some research on the web, I soon discovered the simulation software ABEC3 (http://www.randteam.de/ABEC3/Index.html). Fortunately, by a lucky coincidence, I was able to make two contacts through a DIY forum, which were far ahead of me in this area and have supported me with discussions and simulations. In particular, I would like to thank Don for his tireless support in creating and visualizing the respective ABEC3 scripts for the further development of respective horn profiles. Without Don’s involvement in my projects and the encouraging results, I would hardly have pushed the programming and, of course, the creation of this website with this commitment. I was able to motivate Don to summarize his findings in a few articles and I am pleased to present them in this context.
In particular, I would also like to thank Joerg Panzer, who has provided us with free non-commercial ABEC3 licenses. Thus, it was possible that we could easily exchange the results and work much more efficiently.
The challenge was from the beginning that the horn profiles should work especially as free-standing horns. This requires the simulation of specific measures and configurations. Don wrote an article that I would like to publish here.
The BEM simulations shown in this article took several hours to solve on our workstations which are on a quite actual performance level. It should be mentioned that especially the high frequency part beyond 10 kHz is a special challenge and the results still show some artifacts which are clearly related to the underlying model.