Tractrix Getting it right

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Does anyone have access to the patents and any writings by P.G.A. Voight on the tractrix horn, the only thing that seems downloadable at this time from the varous sites maybe differnt from what Voight had layed out, possibly to compensate for the problem of not loading all of the way down to the design Fc. Or do we just take the Fc that we want and lower it by about 25% to reach our target freq.?:confused:
 
I've got Voigt's 1926 patent application ('Improvements in Horns for Acoustic Instruments') re the tractrix contour on my computer at the moment. It's a bit of a pain to read as it's in 4 separate pdf files. If you PM me, I'll send you over a copy.

FWIW, I don't like the tractrix contour for bass horns. Give me a good hyperbolic or hypex any day. It's fine for the midrange etc of course, and to be fair, a friend of mine built a superb pair of tractrix bass horns for his EX4s, so YMMV as ever.

Scott
 
Greets!

Well, when I did it was closer to a half octave (0.707*Fc), but the problem is that the low throat distortion you use the tractrix for is now worse than if you'd used an expo with a tractrix-like mouth end correction. Then there's the much increased beaming issue..... Not many 'free lunches' in audio design.

GM
 

GM

Member
Joined 2003
Re: 1/2 Octave lower

David R. Carlso said:
......."P.G.A. Voight can be claimed to calculate: Fc=c/(4*r)."

Interesting, never seen this before and according to it the horn I built should have been another ~5.83" long, which I know isn't true, so I have to wonder if it's just an approximation for patent/whatever purposes.
 
I think it's more of an assumption on the part of the the author of the HornCalc software, although Voigt clearly generalised -reading p.2 of his patent, he didn't make quite such a specific claim; only that "...such that the sound is expanding as if the source was at the fixed distance which is at least a quarter wavelength of the lowest frequency at which full efficiency is required, away."
 
attn.: Scottmoose, Low frequency directivity

Hello Scott,

A Tractrix, or other, short shape, to build a Horn sub-woofer, or, depending on size, maybe, 2 bass units, might increase low frequency dispersion/directivity, sufficiently, for example, to reduce my neighbors, being harassed by my rumblebumbling, when enjoying, for instance, a film.

So, in order to study the feasibility, of this idea, I to, would very much like to have a copy of: Voigt's 1926 patent application ('Improvements in Horns for Acoustic Instruments').

Could you also let me know, how to obtain a 'Tractrix, contour calc., program', for my (Ubuntu) computer?

I've been playing with this idea for a quiet a while, so it's time to start making such horns, or breaking these thoughts.

Before, I tried, time-aligned bass-units, placed close up, to the listening position, but I couldn't get that right.

So, if you could help me with this, I would be very grateful,

Erik van Andel
257-3
1053PN Amsterdam
The Netherlands

E-mail: e.r.vanandel@gmail.com

Phone: 0031 6 11353881

I've got Voigt's 1926 patent application ('Improvements in Horns for Acoustic Instruments') re the tractrix contour on my computer at the moment. It's a bit of a pain to read as it's in 4 separate pdf files. If you PM me, I'll send you over a copy.

FWIW, I don't like the tractrix contour for bass horns. Give me a good hyperbolic or hypex any day. It's fine for the midrange etc of course, and to be fair, a friend of mine built a superb pair of tractrix bass horns for his EX4s, so YMMV as ever.

Scott
 
Does anyone have access to the patents and any writings by P.G.A. Voight on the tractrix horn, the only thing that seems downloadable at this time from the varous sites maybe differnt from what Voight had layed out, possibly to compensate for the problem of not loading all of the way down to the design Fc. Or do we just take the Fc that we want and lower it by about 25% to reach our target freq.?:confused:

Try here:
http://www.diyaudio.com/forums/full-range/212257-paul-voigt-interview-bruce-edgar.html

and here:
http://p10hifi.net/forum/voigt_interview.pdf
 
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