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In the Forum: Horn-Loaded Speakers
In the Thread: The European Triode Festival’s horns
Post Subject: Bass horn and crossoverPosted by Marc HENRY on: 12/19/2007

Hi Romy and all,

first of all, my name is Henry, with a "Y". due to an Irish grand-grand-grand father called "O'Henry". the O' was deleted when my grand-grand father was born, due to a silly servant of registry office. :-) all my horns uses the calculation formulas developped by my friend Jean Michel Le Cleac'h.
my colleagues at work are Dominique Mafrand (
Hugues Borsarello and Olivier Roblin from Borsaudio (
and Anaël Rousseau from nAr Cables (

i met André Klein for the first time during this triode festival and never heard about him before. he built the big "steamer", an incredible audio sculpture which won the thoriated tungsten amplifier contest.

i do not love too much classical bass horn like Jbl 4550. the bass reflex low end do not match the over-100Hz horn bass.

i have made several bass horn prototypes, straits or curved, for 10" and 15" drivers, with several cutoff from 100 to 40Hz. some with closed cabinet or with open baffle.

For this Musique-Concrete horn system called "Grande Castine" (it was developped in Saint Cast Le Guildo, Britanny, France, from were females inhabitants are called "Castines" ) i prefered a modified 60Hz Le Cleac'h cylindrical horn, with a "decompression" ratio of 1/1,4.
the goal is : no cabinet sound, no bass reflex sound, high efficiency, a cutoff low enough to use an active infra-bass cabinet for the first octave, and a resonable size (1m*1m*80cm)
it is fully usable from 60 to 250Hz.
actual drivers are ALtec 515-16G 

the mid is a 220Hz 2", with modified Radian 950Pb high-mid-treeble is a modified BMS 4540

crossover : active 18db, 250Hz for the bass
passive, 300Hz 6db for mid
passive, 4000Hz, 6db for high.

The problem with this bass horn is a great sensitivity to room acoustic.  not very surprising for an open baffle ! if there is any resonance in the room, bass become less "slamy", and fusion with other register is less good.

several evolutions are coming : custom made drivers, an "open-cabinet" for the bass horn, a quite heavy all passive-all symetrical crossover...and an active bass cabinet for the 25-60Hz area.

 i am quite proud of this system : very good fusion, no sweet spot problem, usable at high sound levels with a single watt, light-weight and beautiful for a horn system...any audio anthousiast can come home with his own cd's. Saint Cast le Guildo is near "Le mont Saint Michel", west of France :

the system at home :  (the double 18" infra-bass is not in use actually)

best regards,
Marco ---------------------------------

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