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Tractrix Horn Loading [message #41816] Sun, 06 July 2003 19:38 Go to next message
Adrian Mack is currently offline  Adrian Mack
Messages: 568
Registered: May 2009
Illuminati (1st Degree)

Hi everyone,

So many people say tractrix horns dont load properly down to their flare frequency, and that they only start properly from about an octave above the horns flare frequency. I've done some modeling in Hornresp, and found this statement to be not always the case. I've had some times where indeed it showed on the SPL curve that it doesn't go flat down to its flare frequnecy at all. But I've also found some tractrix horns that DO load right down to their flare frequency, according to hornresp.

The Eminence Alpha 6 in a tractrix horn with flare freq of 242Hz, 26cm^2 throat and 1600cm^2 mouth (40cm long horn) does show it flat all the way down to 242Hz, which is its flare frequnecy. So would it be able to be used down to its flare frequnecy because its flat all the way down to that? Or should I still follow the "rule" about tractrix horns not loading down to their flare frequency?

Thanks!
Adrian

Re: Tractrix Horn Loading [message #41819 is a reply to message #41816] Sun, 06 July 2003 19:52 Go to previous messageGo to next message
Bill Martinelli is currently offline  Bill Martinelli
Messages: 677
Registered: May 2009
Illuminati (1st Degree)

You might find that even if the tractrix horn loads the driver down to cutoff that the throat distortion will increase at near cutoff frequencies. If this happens you will be unhappy. Every style horn will work better with different drivers but you wont know for sure until you build it and test it.

Bill

Peaking in the bottom octave [message #41821 is a reply to message #41816] Sun, 06 July 2003 20:21 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 18757
Registered: January 2001
Illuminati (33rd Degree)
You undoubtedly have some peaking in the horn design you are talking about that has increased output near the cutoff frequency. I often build conical horns with this same sort of response, so I'm not against this practice. But the fact is that the acoustic loading of tractrix and conical horns becomes less resistive at the flare frequency than it is further up, and this translates to lowered efficiency. A bump in the bottom octave from resonant peaking can be used to raise output instead.
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