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 Post subject: Re: Horn question
PostPosted: November 30th, 2017, 10:12 pm 
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Joined: February 28th, 2013, 10:38 am
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J-ROB wrote:
Tom,

Here's one JMLC lecture: https://pearl-hifi.com/06_Lit_Archive/1 ... TF2010.pdf

I'll try to find a link for another good one. I have it on my computer as a pdf somewhere...


This one? http://www.rintelen.ch/download/JMMLC_h ... _etf10.pdf

Roscoe


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 Post subject: Re: Horn question
PostPosted: November 30th, 2017, 10:52 pm 
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Joined: April 20th, 2014, 5:21 pm
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yeah, worth a read.

I forgot that was archived on Christian's site.

There is a lot going on with horns that makes it very hard to generalize. Or predict sonics from pictures and looks.

At ETF, Bjorn Kolbrek gave a lecture with animated simulations of what is happening in the modeled horn during frequency sweeps, using software that he wrote for his PhD dissertation. He gave a paper on this project at AES last year or the year before... Maybe AES members can get that. It was paper of the year.

Anyway, at certain frequencies interference patterns get real complex and can lead to a breakdown of loading, i.e. beaming...when the horn doesn't act like a horn any more. No horn it seems is perfect. All have frequency dependent impedance anomalies, with greater or lesser measurable effects.

The notion of time anomalies arising from reflections due to diffraction, pressure boundaries, and mouth terminations is a key performance factor, and where JMLC focused his work, hinted at in the attached papers.

25 years or so ago, my bud Arthur Loesch used some zillion dollar meteorological forecasting software he was working on at the University to model horns. He said the system is incredibly complex and basically fell into the realm of Chaos Theory. Things were probabilistic rather than deterministic, and detailed modeling of the conditions at the mouth of a horn with complex input signals was an absurdly intensive task.

Both JMLC and Arthur were math professors doing this on the side. There isn't much money in horn theory. Bjorn is probably one of the few recent grads in this field. He had a job offer from KEF/Celestion before he graduated and he is working there now desgning horns and drivers.


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