THE FOG HORNS

It was year 1879 and in the full bloom of Industrial revolution the steam ship Auredes was launched from the Newhaven, UK manufacture.
It was loaded and continued on it`s maiden voyage to Kristiansand, NO. After departing from Hanstholm, DK, the steam ship encountered an unexpected North Sea storm that surprised the skeleton crew at 3.25 AM. Massive waves caused a breach of the hull and the ship began slowly taking on water.
After hours of struggling with the water pumps it was inevitably filling up. The storm subsided and thick fog engulfed Auredes. The Captain Ambjørn Digulsen ordered the evacuation and stayed on the ship alone, sounding the fog horns into the night. The horns stopped at 6.55 and the wail of a breaking vessel was heard by the crew. From that time the people of Hanstholm heard unaccountable phantom fog horns from the sea. Every year, on the day, people gather and listen for the ghastly sounds that end abruptly at 06.55 PM
In October 2013, a project was started, that would put the captains tormented spirit to rest. With the help of a professional salvage team, the wreck was finally located and the divers retrieved the ship`s fog horns, anchor, parts of the engine and the captain`s mortal remains.
Captain Ambjørn Digulsen was given a burial by the Lighthouse in Flekkerøy, NO.
​The artifacts from the Steam Ship Auredes now reside in the Naval Museum, Kristiansand, NO.
The museum night guards say they can still hear the sound of the old fog horns on the Cursed Day,
but now it became easier to hear it, with all the speakers installed.
The Horn / Open Baffle Hybrid idea came to life as a modification of a 150Hz Tractrix Horn. The system was designed as a two way. The big bass horn would sit on the floor or hang from the ceiling and project at an angle while the smaller tweeter horn  placed on an adjustable speaker stand or mounted to the bass horn.
The curve of the bass horn is based on heavily modified Tractrix curve (150Hz). The mouth opens up faster than Tractrix and is fairly shallow, so it functions like a Waveguide / Baffle. I decided on 12 segment Horn for bass and 8 segment 350 Hz modified Tractrix for the upper range. The simulations were made with HornResp, sketches and blueprints with SketchUp. The plans were then printed out and transferred to wood. Cutting the plywood proved to be quite difficult. The ply would break off and splinter.  The stability wasn't affected but inaccuracies are -+1 mm along the diameter. Plywood fibers were aligned parallel to the curve profile, so the Ply structure itself provides additional rigidity. After all the segments were cut out I used the Stitch and Glue method to put it together. The Ply for the smaller 8 sided Horn had to be Steam bent before stitching and finished with epoxy wood filler.
The throat of the bass horn was cut out of MDF and attached to Plywood segments ; The bitumen stripes were then glued between segments and the driver was attached to test the resonances. Next, a few layers of polyurethane weave were applied and tightly compressed to the Waveguide. The artificial rust effect was chosen for the whole Project to imitate a rusty ship`s horn.The texture of old rusted metal was made with sculpting paste and  detailing. The horns were covered with a protective finish before applying the Acryl base and many layers of artificial rust, The design uses structural integrity rather than mass to minimize reverberation, so the weight of this Prototype was kept as low as possible; in fact the horn itself weights less then the Bass driver (Eminence Alpha 15).  The tweeter horns are made with 3 mm Plywood, reinforced with Epoxy / Polypropylene weave and have Monacor MRD-44PA compression drivers installed. Compression drivers were modified  for hi-fi use and used as a dipole. 
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