Klipschorn® Corner Horn Loudspeaker System

Three matched horns

THE BASS HORN, of folded corner horn design, has an air column sufficient to reproduce, without distortion, the lowest note on most pipe organs and it maintains flat response up to the top of its assigned range, about G above middle "C" in the music scale. No other bass speaker of comparable size has ever been able to achieve this. Miniaturized bass speakers have been attempted, but so far no one has in-vented a miniature 32-foot wave length. In design the bass horn is substanti-ally exponential in expansion, actually comprising a series of wedge-shaped spaces which approximate the exponential expansion to a very close degree.

ACOUSTIC DATA Nominal exponential flare rate, 40 Hz, deviation from exponential rate less than 0.01 wave length; lower and up-per effective cutoffs with proper drive unit, 28 and 550 Hz, upper crossover used, 400 Hz; peak conversion effi-ciency is over 800/o, trough efficiency over 500/0; available acoustic power from qualified 10 watt amplifier is over 3 watts. A very important design consideration is the short radii of bends in the horn, permitting propagation of wave lengths as short as 18 inches corresponding to frequencies as high as 750 Hz, making the recom-mended crossover of 400 Hz conservative. Only by twin passages can this be accomplished. Attempts in 1940 to achieve the results by a single sound path proved futile. The throat is the upper limiting design element.

CONSTRUCTION Rigidly braced plywood, grade A-B (marine grade in marine models), is assembled with nearly 2 gross of screws, plus other fastenings, with high grade adhesives on all structural joints. The system is free from air leaks, a mandatory requirement for peak-free response, and extremely solid, more than fulfilling the basic requirements that a horn be "a reasonably rigid boundary for an air column" (A. G. Webster, inventor of the exponential horn).

THE MEDIUM RANGE K-400 HORN, successor to the KLIPSCH sectoral-type K-s Series horn (first of its type; U.S. Pat. 2,537,141 and widely copied) offers a wider frequency range, lower peak-trough ratio and better polar response. Its use has permitted lowering the first crossover from 500 Hz to 400 and raising the upper crossover from 5,000 to 6,000 Hz. With the K-55-V driver the peak-trough limits are easily held to 6 db (reference level plus or minus 3db). No other mid-range system type tested here has exhibited less than 10 db peak-trough ratio.

THE HIGH FREQUENCY SPEAKER K-77 is a horn-type tweeter carefully selected for type and quality, mounted and ensemble-tested by the manufacturer. It gives natural rendering of tones from high "G" to beyond the limits of hearing, without artificial exaggeration or peaking of the ultra high frequencies. Tweeters in general involve such small dimensions and correspondingly small tolerances that variations in output, between units of the same production lot, will exceed 10 dB. After selecting a type for average performance, power capacity, polar pattern, acceptance is based on testing the entire delivered lot. Response of finished assemblies must lie between bracketed limits in final test or be fitted with a different driver in the appropriate range. The Research and Development Laboratory is charged with selection of driver types: curves of response from 15 to 25,000 Hz and modulation distortion measurements are made on equipment accurate to a fraction of one decibel and with dynamic range sensitivity of over 80 decibels.

ACOUSTIC DATA The tweeter driver and horn K-77 exhibit an overall measured pressure variation of only 8 decibels from 5 kHz to 19 kHz, exhibiting less pressure variation and lower distortion than any other tweeter tested.

CREATED FOR THOSE WHO APPRECIATE THE FINEST, the KLIPSCHORN system has been produced without regard for expense to offer the closest possible identity with original sound. In it we use three carefully matched horns which complement each other. We have settled on the use of these three horns with their individual driver units because tests show that this combination affords the smoothest response of any combination tested. And we have tested practically every principal make of driver, foreign as well as domestic. If the addition of more speakers would improve reproduction, we would add them. If driver units were available which are superior to the ones we use, we would readily substitute them. If the insertion of controls would increase fidelity, we would insert them. But we have found that these extras do not contribute to the fidelity of reproduction - they merely create artificial "hi-fi"" effects which are distortions of the original. The purchase of a KLIPSCHORN is a final one. Of the thousands in the world, the used market is nil.There is no way to improve the fundamental design of these speakers so people keep them.

THE HORN PRINCIPLE is most simply explained by comparison with a piston pump. A piston, sloshing up and down in the middle of a lake by itself, fails as an effective pump. An open-cone speaker, sloshing the air in a room, fails as a sound generator especially at wave lengths larger than the diameter of the cone. But put a cylinder around the piston and it becomes effective as a pump; properly match a horn to the vibrating diaphragm and it becomes an effective speaker. The resulting increase in efficiency minimizes distortion. The advantage of utilizing a corner as part of the horn is that it provides a large radiating area to propagate long wave lengths.

CORNER HORN DESIGN employs reflection of sounds from the walls and floor (or ceiling) of a corner. Reflections produced by two walls double the wave length capability, adding an octave to the bass range. And reflections from the floor or ceiling increase the range by still another half octave.

KLIPSCHORN SYSTEMS ARE DESIGNED AND TESTED FOR UNIFORM RESPONSE UNDER TYPICAL CONDITIONS. The three horns in each are properly balanced in the Klipsch laboratory, requiring no adjustment by the owner. Where unusual room acoustics present a problem, it is recommended that the room be corrected with the addition of draperies, carpeting or other absorbent material. In occasional instances, changing the speaker from one corner to another is advantageous. Any attempt to insert 'presence" controls, pads, or attenuators in a loudspeaker system would merely introduce distortion. Their use would be comparable to asking the recording artists to play extra loud or extra soft within a specified range of notes.

KLIPSCHORN is a Registered Trade Mark of Klipsch & Associate5 Inc. Klipschorn response is more extended, more uniform - and less distorted - than the response of any other speaker.

FULL FREQUENCY RANGE Overall response of system: less than 10 decibels down at 32.7 Hz; less than 8 decibels extreme variation to 19 kHz. Fundamental tones radiated down to 25 Hz. Output approximately 10 decibels higher than the best direct radiator and 20 decibels higher than some typical systems.

INDIVIDUALLY TESTED The listening test, especially involving comparison with original sound, is accepted as final, although sound pressure curves are relied on as a research aid. Critical listeners are asked not merely, "Does it sound good?;' but are asked to compare recorded sound, played through a Klipsch loudspeaker system, with the original sound, ranging from solo violin to full symphony orchestra. Usually, from one half to three quarters of the audience is not able to distinguish the difference. Each speaker is individually tested under the personal supervision of Paul W. Klipsch.

ADAPTABLE TO MANY USES The KLIPSCHORN speaker system, while designed primarily for home use, is also ideal for public halls, schools, churches, libraries, studios, audition
rooms, and laboratories

RECOMMENDED ASSOCIATED EQUIPMENT The KLIPSCHORN reproduces everything fed into it by the amplifier and sound source. This makes it imperative that equipment of the highest quality be used. Freedom from distortion and actual power output (undistorted) at 30 Hz is more important than published power rating. We have heard superior sound from both tube and transistor-type equipment The manufacturer's design, skill, and integrity contribute more to amplifier quality than the particular types of components used in construction.

LOW OBSOLECENCE The basic structure of the KLIPSCHORN sound reproducer is fundamentally correct; improvements in detail will undoubtedly occur, but the basic system need never be changed. With possible future changes in drive units, the KLIPSCHORN system may be kept up to date for a lifetime. Conversion kits are available to afford modern performance from early models of serial num-ber 14 and higher.

PLACE IN BEST AVAILABLE CORNER For best results, install your Klipschorn loudspeaker in a corner affording the most unobstructed wall space. Keep the corner of the top pushed into the corner of the room wall. Flanking draperies are entirely permissible as long as they leave sound passageways clear. It is recommended that nothing be set on top of the system such as vases, bric-a-brac, ash-trays, etc. because they may rattle. An artificial corner may be built to accommodate the KLIPSCHORN, and the problems of difficult rooms have often been solved with carefully designed artificial corners. These can frequently be constructed using a room divider or bookshelf against a wall so as to reflect the rear wave from the other side of the bass horn. Natural comers always provide maximum effi-ciency, but temporary problems can be solved with ingenuity.

NO KITS OR DRAWINGS. KLIPSCHORN speakers are available as complete systems and also as components. Kits and drawings are not available.
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