Tag Archives: SWH

++ Announcement (23.09.2025) ++ Revoke of permission for the free use of my Calculators and Designs and IP

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Unfortunately, I no longer see any way to continue making my intellectual property available free of charge. After more than five years of giving so much to the community, my own benefit is not even close to zero, but far into the negative.

For this reason, I hereby revoke permission for the free use of all spreadsheet horn calculators and designs provided by me anywhere and, overall, the use of my intellectual property with immediate effect as of 23.09.2025!

For those who have already downloaded my calculators in the past (there have been thousands of downloads already!), I expect at least that you make a donation if you want to continue using them to support my work and to keep this blog alive. Otherwise, please delete all the corresponding files that are related to my intellectual property. Keeping any copies is not permitted. Please contact me by email if you would like to continue using my work to discuss conditions.

If you would like to use my calculators and designs in the future to build your own horns, please feel free to contact me by email. A license must now be purchased in order to manufacture any horn loudspeakers based on my intellectual property. In this case, please contact me by email and just shortly describe your project, and we can discuss conditions.

If you have already built any horn speakers based on my work, I would really appreciate it if you consider making a donation. Please also contact me by email in this case.

If you simply enjoy reading my blog and would like to support my work, please consider supporting me with a donation by contacting me via email to discuss the details.

Any commercial use of my intellectual property for the software, results, designs, CAD files, or documentation provided here remain strictly prohibited! But I am open for discussion about special conditions.

Progressive Expansion T-Factor Horns

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In this post I would like to describe a method that I have been using since some time to get more flexibility with regard to different horn profile slopes. The fact that slow expansion profiles like the exponential or spherical wave horn provide very good loading but suffer somewhat with respect to directivity control inspired me to look for an algorithm that influences the given specific horn expansion function. I ended up with a modification of the well known wave front surface area expansion formula for hyperbolic (hypex) horns which is given by:

\tag{1a}S_z = S_0\cdot \left( cosh(\frac{m}{2}\cdot z) + T \cdot sinh(\frac{m}{2}\cdot z) \right)^2
\tag{1b}m=\frac{4\pi \cdot f_c}{c_s}

I will not go into more detail but with T=1 we get exactly the well known exponential horn for a two dimensional surface area expansion. This formula can also be used for the spherical wave horn with it’s assumed spherical wave fronts and will put out the same SWH profile already described on this site. Equation (1) is extremely flexible because when  T \lt 1 an hyperbolic profile is the result and when T \to \infty the horn profile becomes conical. This is the reason why I switched to this formula as it gives me the flexibility to produce horn shapes with different slopes only by changing one parameter. Up to here nothing new but what if we make T a variable function that depends on a reference point somewhere on the horn axis z_{off} and the distance from or to this offset?

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