Tractrix (or other) horns for Altec drivers?

[taudo]

The German folks selling tractrix horns for Altec drivers on eBay are on summer holiday. Does anyone know of a source of something similar to play with? I've come up dry in a couple of days of googling. Thanks!

taudo

[GM]

Yeah, it's called DIY.

GM

[taudo]

GM,

Care to expand on that? I came across about a half dozen different DIY methods and really don't care to try them all. [Frankly, I'd rather buy a pair, if anyone knows of a source]

taudo

[taudo]

GM,

Thanks for those links! It appears that Sierra-Brooks has already done the experiment I wanted to try and made a commercial product out of it. I love the look of those 32" horns - but suspect that if I drop $3500 on pair of them for an experiment, I'll be exiled to the barn!

Given that Avantgarde, Galix, Acapella and others are all advertising speaker systems with similar looking plastic horns, I'll bet there is some OEM turning them out by the boatload.

taudo

[GM]

What's to elaborate on? I mean all you need to know is on the net. This site is just one of many: http://www.volvotreter.de/ so if you need further clarification on something, you will have to ask specific questions.

WRT different ways to make them, either carving them from a solid block of wood on a lathe or casting them in concrete is the ideal, but two flat sides and two curved sides made from 3/4" 13 ply BB or Appleply works well also. FWIW, I prefer conical over tractix for loading compression drivers, but the tradeoff for the lowest distortion/better off axis response is an increase in size for the same usable BW.

http://www.sierra-brooks.com/

GM

[taudo]

Mike,

Thanks for that input - it appears to be just what I found with the exception of the above mentioned German folks who _were_ selling inexpensive plastic or resin tractrix horns specifically for Altec drivers. I hope they decide to sell 'em again after the "summer break".

If worst comes to worst, I may try building one up using the "concentric rings of wood" method.

Thanks!

taudo

[GM]

I guess I wasn't clear enough the first time, the sonic difference between a round and square version using a 800 series CD is so minor that I can't justify the extra work required to make it round unless you just want it round for round's sake. The only caveat is that the square throat must be smoothed/tapered to a round termination, which is easily done with Bondo or similar and the mouth be a square equivalent to the round horn's diameter instead of the 1WL circumference rule.

If you want to further reduce any possibly perceived difference, then shape a small Bondo applicator to make a rounded corner and fill/round off the internal joints. This has the advantage of covering up the gaps when simple joinery is used by lazy woodworkers like me.

A point rarely mentioned is the need for a non-porous, slick surface to ensure good performance since wave propogation is moving back n' forth at ~13,560"/sec, so using a good sealer and waxing it with racer's wax or similar polymer is required if made from wood, though the 511/811s benefit from it also, especially so if all the usual tweaks are done.

GM

[MikeInNH]

I looked into this a couple of years ago when I rebuilt my Model-15's. I wasn't DIS-satisfied with the horn on the Model-15, but I had heard so much about the tractrix horns that I looked into them.

Most if not ALL the production tractrix horns that you can buy are made of these exotic hand carved woods that I just couldn't justify the experiement. Companies like Klipsch use Tractrix horns which are made of some polymer or resin. But as far as I know they don't have one for the Altec 800 or 900 series compression drivers.

[MikeInNH]

taudo

I saw those horns also on Ebay. Do you remember which models you were looking at??? They seem to offer a few different models for the 800 series. I didn't know what the differences are between the different models.

Let me know if you do end up getting them. I'd be very curious as to what the sound expereince would be like. Maybe I'll rebuild my 15's AGAIN...Oh my wife will really love that.

[sunnysal]

they basically have three models one with a >1000 cut off one with a >400 cut off and another with a >180 cut off, you can order with different driver sizes 1"-2"...you can see them on ebay now; http://cgi.ebay.com/ws/eBayISAPI.dll...sPageName=WDVW

or visit the web site;
http://www.stereo-lab.de/

I have no relation with the sellers nor have tried these horns,
best of luck, tony