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From Munich to Buren
In the beginning there was the horn, first formed by cupped hands to make a shout carry farther. The same principle was used for sound reproduction eons later. Amplifiers in the roaring twenties of the previous century were limited in power and transducers were handicapped in performance. Fitting a horn to such drivers enhanced the capabilities of the amplifier-speaker combination. As technology progressed amplifiers grew more power whilst improved dynamic drivers lost sensitivity. Hornspeakers remained the providence of theaters where huge systems were an integral part of the stage.

Music playback at home in those times could be accomplished without them. GE engineers Rice and Kellogg invented a wideband direct-radiating driver based on the moving iron principle. RCA licensed the design to market the driver in their Radiola. This 1-watt amplifier/speaker combination was to be used with a separate radio receiver. RCA cleverly set up the NBC radio network to provide content and thus sales for their Radiola.

While the world was in turmoil during the first half of the ‘40’s, Paul Klipsch worked on his hornspeaker ideas culminating in the famous Klipschorn which used the room’s corners to amplify sound quality and quantity so that the package would fit in a normal post-war living room. The Klipschorn reintroduced the horn to playback in the home.

Cessaro at Munich HighEnd 2011

All trends are cyclic. They come and they go. In audio horn popularity came and went as other loudspeaker designs gained and lost popularity in the market. With the coming of age of solid-state amplifiers, speaker efficiency stopped being an issue and the need for hornloaded systems to generate acoustic gain diminished. Though not completely forgotten—diehardcore lovers survive for anything—horns were relegated to obscurity after their heydays were over.

Acapella horns at Munich HighEnd 2011
  It wasn’t until the late ‘70s when Jean Hiraga, then editor of French audio magazine L’Audiophile, refocused the audio world’s attention on the virtues of hornloaded speakers especially in combination with flea-power SET amplifiers. Jean’s Japanese/French background made him the ultimate evangelist. Many Japanese audiophiles had never abandoned the old horn/SET concept and raised it up to a loving cult. It was to be Jean Hiraga who translated this cult into and for the modern West literally and figuratively. The basic perquisite is a love of music. This is the vital core around which all other audio regalia are grouped.

Of course horns are necessary just as are SET diagrams, silver wire and a fine soldering iron. The original Japanese cult grew out of a DIY community that was born from necessity as the sound quality the members sought was no longer commercially available. Hiraga was and remains a driving force not only for DIY projects but more commercial endeavors catering to those who want to acquire a ready-built piece of equipment that still offers some tweaking and tuning.

Another promoter of simple high-quality amplifiers designed in combination with hornloaded speakers was the late Harvey ‘Gizmo’ Rosenberg. With a completely different background in brand forging and public relations, Harvey stimulated many to commence the “search for musical ecstasy” as he would describe the goal. The success of Jean, Harvey and related efforts to return horns to the public eye was  apparent at this year’s Munich High End show where many companies had either added one or two hornloaded models to their product range or built their whole existence around them.

Some were successful, others failed dramatically and many more were still in transition. In Munich Italian Diesis Audio showed their 3.5-way Caput Mundi which sports a coaxial horn combined with a woofer duo in an open baffle. The compression driver in the horn throat is said to cover 600Hz to 25KHz. The speakers were set up in a pavilion with many exhibitors in a virtually static display. In the looks department the Caput Mundi—capital of the world, i.e. Rome to some—scored well, in the aural arena the verdict remained blank.

Ditto for Blumenhofer. Interested visitors were invited to join Blumenhofer at their factory for a listening session including catering but the show proper provided mere visual entertainment. Next to a huge 4-meter long folded bass horn sat the more salonfähige Gran Gioia, a two-way that can be fitted with field-coil compression drivers and field coil woofers built by Wolf von Langa. Too bad a working demo involved a 3-hour round trip from the show.

More blanks were fired at the Auto-Tech booth. This Polish company produces a real wealth of horns for DIY projects or ready-to-go assemblies. We counted at least 12 different types of horns—they prefer wave guide—with many of them in various size options. You want bi-radial, elliptical, elliptical with a lip, spherical, tractrix or any other shape? Auto-Tech can help. Unfortunately the open booth in the ‘zoo’ section of the event was static once again so we walked off without an impression of the Mummy or the large Universum with Sub1.

Meanwhile active demos are a cornerstone of Avantgarde Acoustic. It was this German company which burnt the image of a horn on the retina of anyone interested in audio today. With looks and sound you may fancy or not, Avantgarde at shows is always talked about. We like their signature sound though show demos can be a little hard to stomach. These horns can play loud without breaking a sweat but sometimes too much really is too much. Powered by their own electronics the Trio with double Basshorn was kept well under (volume) control when we visited the large room in one of the Atriums. The signature sound is a bit in your face and you need some distance before all drivers cohere as a fluid entity. On the downside we can say that the system played in the room but did not play the room.