how to make spherical ( tractrix ) wood horns, step by step

[angeloitacare]

hi

here you can learn how to make spherical wooden horns, explained step by step ( thanks for John Haskin for his precious informations ) :http://www.flickr.com/photos/7808268@N07/
if you decide to make a pair, i can email you corel graph's for tractrix horns with 88cm diameter ( 150hz ) and 58cm ( 250hz ) horns.
John Hasquin does not recommend to make them bigger than with 88cm diameter :
" I would advise you not to make a horn any bigger than 88cm mouth. The 95cm mouth horn is too big and you will not be able to get good high frequency out of it. A 95cm mouth horn with 10cm throat will be about 92cm deep. For a horn that is between 80cm to 73cm deep, you will need a very efficient speaker like the Fane Studio 8M or the Ciare 8.5 Nd MR " .
If you do not have a lathe, you can use a file, and make them manually, as explained at vincent.brient site: http://vincent.brient.free.fr/pav_ronds.htm
angelo

[murray johnson]

Hi Angelo,

This is interesting stuff. The tractrix geometry defines itself but what characteristics (TS or otherwise) are you looking for in a driver to match to such a horn?

Other people I have spoken to suggest that the Tractrix might not be the best profile for lower frequency horns and that the Hypex or Salmon family of horns works better. Any views on this?

[angeloitacare]

hi Murray

i do base exclusively on experience of others, as i never built a mid-bass horn before. I know the exponential flare is good too, but size to put such a beauty into a livingroom has to be taken in consideration too. Do you have any experience ? Salmon family, i've never heard abought that. Do u have any link ore info's ?

Angelo

[Markus]

.

[murray johnson]

The Salmon Family of horns are basically also known as the Hypex (Hyperbolic exponential)type which typically have a M factor (flare rate) of between 0.5 and 1.0. This makes them longer than a standard exponential but with supposedly much better LF loading. Hornresp allows you to calculate them. I do have some fairly heavy duty AES papers somewhere about these.

I was more interested in how you would choose a driver to fit one of these tractrix horns. There will be more to it than just high sensitivity. You need to take note of the driver's natural resonance frequency, excursion, Qts etc before fitting one to a horn. You wouldn't want to put in a high Q driver suited for OB use or indeed a dedicated, long throw but inefficient subwoofer driver intended for use in a relex cabinet.

[Purite Audio]

Markus Sauer wrote:

.

Short and to the point, Markus!

[Markus]

That's me!

[angeloitacare]

hi Murray

exponential horn is big, that's the problem. Otherwise, shure, if size doesn't matter, it would be certainly interesting to use this flare.
Like Steve Shell of cogent, or japanese Ale ore Goto use.

Drivers. again. i base myself on experience of others. Here
John Hasquin's recomendation :

I would advise you not to make a horn any bigger than 88cm mouth. The 95cm mouth horn is too big and you will not be able to get good high frequency out of it. A 95cm mouth horn with 10cm throat will be about 92cm deep. For a horn that is between 80cm to 73cm deep, you will need a very efficient speaker like the Fane Studio 8M or the Ciare 8.5 Nd MR. For horns that are 73cm to 67cm deep, and then you can use more normal woofers like the B&C Speaker 8PE21.

i bought a fane crescendo 8M to use with it, but John says its not so good. do you have any experience with these drivers ?

The Fane Studio series have been discontinued some time ago. The Crescendo series are a cheaper replacement for the Studio, and are not the same. They have weaker magnets and cheaper voice coil materials. The next best woofer would be the Ciare 8.5 Nd MR. The B&C Speakers 8PE21 can be used, but if you want any high frequncy out of it, you need to keep the horn shorter than 73cm.

rds Angelo

[murray johnson]

How high a high frequency are you thinking of? You'd presumably want your mid driver to be coming in at 800-1KHz

I also don't really understand why you can't use a 12" driver (with maybe a 6-8" throat) & thus keep the horn a bit shorter. I am thinking of a 4 way system. I'd barely have room for that never mind 5 ways!

[angeloitacare]

certainly there are many ways to do things. but start to experiment around, does cost time and money. so i prefere to go the road others have gone already. I want to cross at 600hz with a Radian 950Pb ( do u know that driver? ) in a 53cm tractrix horn, and use a Fostex T500a MKII in the high frequency region, at 8khz and above. Some time i would like to try out Vitavox S2 and AK woofers. They seem to belong to the very best , but are rare on the aftermarket.

[murray johnson]

Even a 53 cm horn represents an Fc of just over 200 Hz and may be a little bigger (& longer) than you really need if you are crossing over at 600 Hz. It'll be interesting to learn how well it all behaves up and around 8KHz (nearly 4 octaves)

[Purite Audio]

Listening to and measuring drivers, experimentation with horn profiles and materials is absolutely essential and it does take a great deal of time and money,

[angeloitacare]

yes, your are right. well, i do not know all the theories and have no practical experience for a racional answer . I am just in the beginning of my journey. I heard the Edgar Horn at CES this year. he uses a smaller, i guess 30cm diameter horn , for the mid frequency channel. The size of the instruments was too small, and stereo image was not good too. I do not know if the hornsize was a reason. If you observe Avantgardes, Cessaros, Martion, Acappella etc., they all use a size this large for the mid frequency channel, even if it is not needed, when they us a mid-bass horn , too. There is a reason for that. Of course, it would be best to go 5 channels for the highest refinement. I will make the enclosures in a way, so that i can still add a mid-high channel, if i wish to.

what setup to you have now ? i bought last year a orphean horn from bd-design. But as more i listen to it, more i get convinced that it is too compromised for me, specially in the high frequency region. Image is not good, and dispertion is quit narrow. So i guess better than 100% phase coherence and point source, is to use a right size horn for each frequency range.