(Comments by me (Tom))
1. "The Function and Design of Horns for Loudspeakers" C.R. Hanna and J. Slepian, 13 pp. (JAES reprint, original article first presented in 1924 by AIEE) comment: Thorough treatment of conical, exponential and hyperbolical horns with lots of math, including some analogies/models from the electronic world. 2. "Discussion: The Function and Design of Horns for Loudspeakers" H. Fletcher, V. Karapetoff, S. Boyajian, A. Nyman, E.W. Kellogg, L.P. Rundle, J. Minton, J. Slepian, 9 pp. (JAES reprint, original article first presented in 1924 by AIEE) comment: Comments, discussion and critique of the preceding paper. Given the age of these papers, some will be old news, but they are of great historical interest and of general interest to any horn builder. 3. "A High-Efficiency Receiver for a Horn-Type Loudspeaker of Large< Power capacity" E.C. Wente and A.L Thuras, 6 pp. (JAES reprint, original article from Bell System Technical Journal, 1928) comment: Witness the invention of the compression horn driver as we know it. These guys designed the Western Electric 555 and 594 drivers! Describes first generation of compression drivers, with field coils, phase plug, edge wound aluminum ribbon voice coils and aluminum diaphragms. Great stuff! 4. Bunch of Celestion and Electro-Voice PA bass horn drawings, 11 pp. comment: Big beasts, get a new house if you plan to use any of these at home. Some could possibly be shrunk a little and adapted for other uses than big scale PA. Cool designs, though. 5. "A Back-Loaded Wall-Horn Speaker" Rick Steiner, 12 pp. (Speaker Builder 4/91) comment: Kind of interesting, with a clever horn mouth that takes advantage of the floor, but not a very flexible design, as midrange and tweeter are mounted into the front of the bass horn enclosure. Uses Speakerlab mid and tweet horns and Oaktron 15" woofer. Big speakers that appear to play reasonably deep bass. 6. "The Show Horn" Bruce Edgar, 12 pp. (Speaker Builder, 2/90) comment: Big, 50 Hz hypex bass horn with folding inspired by old University design. Probably great if you have the space. Uses EV EVM12L driver. 7. "Solving the Klipschorn Throat Riddle" Bruce Edgar, 4pp. (Speaker Builder 4/90) comment: Theoretical analysis of the constricted throat geometry used in the Klipschorn. Gives clues as to how the technique can be used to accomodate for a wider choice of woofers to be used in a bass horn. 8. "Vintage Designs: University Classic" Courtesy of B.Edgar, 1 page. (Speaker Builder 2/90) comment: Large bass horn...the folding used in this horn inspired Edgar when he designed the Show Horn. Horn has room to fit midrange and tweeter horns inside the bass horn mouth. 9. "A Low Frequency Horn of Small Dimensions" Paul W. Klipsch, 8 pp. (JASA, Vol. 13 October 1941) comment: The first paper on the classical Klipschorn (corner bass horn). Some curves and a lot of enthusiastic talk about how good the horns sound. 10. "Improved Low-Frequency Horn" Paul W. Klipsch, 4 pp. (JASA, Vol. 14 January 1943) comment: Followup to previous article, better measurements and some improvements in the design of the horn. 11. "A High Quality Loudspeaker of Small Dimensions" Paul W. Klipsch, 6 pp. (JASA, Vol. 17 No.3 January 1946) comment: Complete system using the corner bass horn and HF horn using WE 555W driver is described, along with evaluations. If you own a KHorn, all these articles should be useful. 12. "Generalized Plane Wave Horn Theory" Vincent Salmon, 13 pp. (JASA, Vol. 17 No.3 January 1946) comment: A theoretical treatment of horns, with mathematical and electrical models/analogies. Lotsa math, not a lot of immediate practical interest. 13. "A New Family of Horns" Vincent Salmon, 7 pp. (JASA, Vol. 17 No.3 January 1946) comment: Introduction of the (then) new hyperbolic-exponential horns, along with a number of graphs and mathematical explanations. 14. "Horn Loudspeaker Design" Parts 1-3 Jack Dinsdale, 17 pp. (Wireless World, March, May and June 1974) comment: Essential horn basics written by a horn enthusiast with a practical approach to things, meant to inspire the amateur builder. Great, great article that covers different horn flares, including the tractrix. The last article finishes off with two practical designs, one of which is a huge tractrix bass horn. Excellent, lots of useful curves, tables and explanations that normal people can understand. Many good literature references worth checking out (many are on my list already). 15. "Low-cost Horn Loudspeaker System" "Toneburst", 4 pp. (Wireless World, May 1970) comment: Large, Klipsch-style split bass horn with HF horn on top. Pictures and drawings seem frustratingly cryptical to be followed directly by a builder, but the design seems interesting nevertheless. If nothing else, at least for inspiration. 16. "Tractrix Horn Theory" Andy Grove, 2 pp. (HiFi World Supplement, November 1994) comment: It Stinks! I could have done better myself! Forget it! 17. Chapter 7 - "Horn Loudspeakers" from "Elements of Acoustical Engineering" Harry F. Olson, 17 pp. (34 pages in original book) - 1957 comment: Nice treatment of general horn theory with many graphs, drawings and even practical considerations and examples. Nice!! 18. Catalog of Lowther Club Danmark (Denmark) H.J. Loenborg, 12 pp. comment: Short summary of Voigt's work on horns and driver design along with practical application details. Many interesting pictures. Specs and prices of the whole range of Lowther drive units and a short overview of different folded horn designs, complete plans of which can be ordered from the club. Whole thing in Danish... 19. Chapter 9 - "Horn Loudspeakers" from "Acoustics" L.L. Beranek 1954, 14 pp. (27 pages in original book) comment: A lot like Olson's treatment of horn speakers, essential basic theory with some drawings, graphs and other nice things. Some practical examples here as well. 20. Sections 5.17 through 5.30 from "Elements of Acoustical Engineering" H.F. Olson, 8 pp. (16 pages in original book) comment: Mathematical treatment of impedance and other characteristics of different horn flare types, also shows effect of truncating horns on impedance plot and some other interesting things. 21. Sections 2.19-2.20 from "Elements of Acoustical Engineering" H.F. Olson, 4 pp. (7 pages in original book) comment: Great, VERY useful polar diagrams that show dispersion/directivity patterns of many different horns for fixed or varying flare rate or mouth size. Nice. 22. "Loudspeaker Performance" Paul W. Klipsch, 3 pp. (Wireless World, February 1970) comment: Enthusiastic horn propaganda from Klipsch himself. If there's any doubt, this article tells you why horns are it! Fun to read. Makes most modern speakers seem crude and awkward. Interesting and important comparison of distortion in horn vs. direct radiator speaker. 23. "Design For A Folded Corner Horn" H.J.F. Crabbe (Wireless World, February 1958) comment: A very strange and exotic looking corner horn said to have a response down to 40 Hz. Looks like a nightmare to build, but the complete unit looks like something out of a 1950s sci-fi movie, pretty cool. Appears to utilize some sort of Lowther driver. has midrange horn on front of driver and rear loaded bass horn on the other side. 24. Plan: "Lowther Acousta 124" Lowther Loudspeaker Co. comment: Folded rear loaded horn for two 8" drivers (can't tell which) for full range no xover operation. 25. Plan: "Lowther Classic 400" Lowther Loudspeaker Co. comment: Another folded rear loaded horn (full range) for one 8" driver (I think). 26. Plan: "Lowther Acousta 109" Lowther Loudspeaker Co. comment: Yet another rear loaded folded full range horn for one 8" driver. 27. Plan: "Lowther Acousta 115" Lowther Loudspeaker Co. comment: Still one more rear loaded folded horn, like the Acousta 109, only bigger. 28. Chapter 11 - "Horn-Type Enclosures" from "Hi-Fi Loudspeakers and Enclosures" 2nd. edition. A. Cohen, 14 pp. (28 pages in original book) comment: Great explanation and intro to horns with little math and down to earth approaches. Many examples and an enthusiastic tone (pro horns!). Get the entire book if you can. 29. "Horns" from "High Quality Sound Reproduction" James Moir, 12 pp (23 pages in original book) comment: Nice general, reasonably light explanation of horns with some cool pictures and drawings of practical designs. The rest of the book is excellent, too. Look for it at the library. 30. Chapter 12 - "Combined Enclosure-Horn System" from "Hi-Fi Loudspeakers and Enclosures" 2nd. edition. A. Cohen, 5 pp (was 10 pages in original book). comment: Brief explanations of how it's possible to horn load reflex ports and build VOT style cabinets that combine horn loading and reflex loading. Not really crucial. 31. "Hoeyjttaler-selvbyg bogen" Audioscan, 1982. comment: Essentially a catalog of Coral full range and horn/compression drivers along with general speaker theory and many designs using Coral drivers, a couple of VOT-style brutes, too. Read it and cry 'cause Coral is no longer in business. Some theory, too. Only interesting to scandinavians I guess, since it's all in Danish. Has specs for all the Coral drivers available back then. (High efficiency full range & horn drivers). 32. "1st Book of Hi-Fi Loudspeaker Enclosures" B.B. Babani, 48 pp. (96 pages original book) comment: A collection of speaker enclosure designs, some worthless but some interesting ones, including a few Altec designs and the old Karlson bass speaker. Very sparse details and descriptions, but lots of inspirational drawings. 33. "Ton-and-a-Quarter of Sound" Walter Wysoczanski, 5 pp. (8 pages orig. article) (Audio, January 1964) comment: WOW!!! Huge, cast concrete full range horn system with front loaded bass horns that use two 15" woofers each. Concrete HF horn for Altec 288 compression driver. 34. "Wide-Angle Dispersion of High-Frequency Sound" A.B.Cohen, 5 pp. (Audio Engineering, December 1952) comment: Excellent discussion of dispersion in HF horns of different types and how it can be optimized. With curves, sketches and Cohen's comprehensive way to explain things. Great! 35. "A New Loudspeaker of Advanced Design" Daniel J. Plach and Philip B. Williams, 4 pp. (Audio Engineering, October 1950) comment: Description and evaluation of the Jensen G-610 Triaxial loudspeaker that has horn loaded midrange and tweeter. Extremely cool looking driver. Very enthusiastically written by two of the co-developers of the speaker. Interesting. 36. "A Loudspeaker for the Range from 5 to 20 kc" B.H. Smith and W.T. Selsted (Audio Engineering, January 1950) comment: Interesting article describing a HF horn system with two horn loaded drivers. These horns are of the flat, "circle sector" type, good descriptions of which are seldom found in horn literature. These have some interesting properties worth looking into, particularly dispersion. Another plus is that they're very easy to build compared to most other horn types. 37. Section 4.4. - "Horns" Rossi, 7 pp. (12 pages in original book) ("Acoustics and Electroacoustics") comment: Presents the different main families of horns, in a mathematical way, with lots of differential equations and other apalling stuff. Might still be useful. 38. Section 7.4 - "Horn Loudspeakers" Rossi, 7pp. (12 pages in original book) (Acoustics and Electroacoustics) comment: Brief intro to horn loudspeakers, with discussion of efficiency, frequency response, distortion. Theoretical, with some analogies (electrical equivalents). Nothing major. 39. "The Edgar Midrange Horn" Bruce C. Edgar, 11 pp. (Speaker Builder, 1/86) comment: The original article about the Edgar midrange tractrix horn, of general interest to anyone building midrange horns, but has very detailed costruction details - a must if you plan to build the standard midrange horn. Great! 40. "The Klipschorn Throat Revisited: Or, Oooops" Bruce C. Edgar, 2 pp. (Speaker Builder, 6/90) comment: Corrections and additions to the article called "Solving The Klipschorn< Throat Riddle" (SB 4/90). Don't read one without reading the other. 41. "Round The Horn" Philip Newell and Keith Holland, 8pp. (Speaker Builder, 8/94) comment: Very interesting article on midrange horns, particularly circular horns. Many measurements and references to a very thorough 5-year study. Should be of interest to any horn builder. 42. "The Monolith Horn" Bruce C. Edgar, 7 pp. (Speaker Builder, 6/93) comment: Edgar's imposing 40 Hz bass horn, complete with measurements, drawings, photos of construction details. Cool stuff! 43. "Chapter Five: Theory of Horns" J. Merhaut, 13 pp. (26 pp. in book) ("Theory of Electroacoustics") comment: Basic theory on wave propagation, dense math. Covers exponential, conical and hyperbolical horns. Not very pragmatic, but theoretically thorough. 44. "Prediction and Measurement of the One-Parameter Behavior of Horns" K.R. Holland, F.J Fahy, and C.L. Morfey, 23 pp. (JAES, Vol. 39, No. 5, May 1991) comment: (from the header of the paper): "It is investigated to what extent aspects of the performance of horns can be modeled using Webster's one-parameter horn equation. A computer model, based on Webster's equation, is described. Its results are compared to measurements. It is shown that a one- parameter horn model can accurately predict throat impedance provided that the shapes of the wavefronts are taken into account." 45. "Chapter 4 - Radiation of Sound" L.L. Beranek, 13 pp. (26 pp. in book) ("Acoustics") comment: Good treatment of dispersion of sound from different sources, including examples of different horn types, with polar diagrams. 46. "On the Specification of Moving-Coil Drivers for Low-Frequency Horn-Loaded Loudspeakers" W. Marshall Leach, jr., 6 pp (12 pp in journal) (JAES, Vol. 27, No. 12, December 1979) comment: (from header of the paper): "A procedure is described for the design from specifications of moving-coil drivers for low-frequency horn-loaded loudspeakers. The method permits specification of the upper and lower cutoff frequencies, the volume of the cavity behind the driver, the driver area, the horn throat area, and the desired system electrical impedance. From these specifications, the required Thiele-Small small-signal parameters of the driver are determined under the condition of a maximum-sensitivity constraint on the system. The procedure can be easily modified for a maximum-efficiency constraint." 47. "Design Factors in Horn-Type Speakers" Daniel J. Plach, 3 pp (6 pp in journal) (JAES, Vol. 1, No. 4, October 1953) comment: The paper mainly deals with the improvement of low frequency cutoff characteristics made possible by using reactance annulling in hypex (hyperbolical-exponential) horns. Of special interest with regard to bass horn design. 48. "Sound Translating Device" E.C. Wente, 5 pp. (US Patent No. 2,037,187. April 14, 1936) comment: This is the patent for the compression driver that came to be manufactured under the name "Western Electric 594A", and basically this driver has all the ingredients of compression drivers made today, the only difference being the magnetic circuit. In modern drivers permanent magnets are used instead of field coil magnets, but apart from that the 594A driver is as "modern" as any. Compare to a JBL 2445 and see how refined this 60+ year old driver was! 49. "Dem Bass auf die Sprunge geholfen (Hornlautsprecher fuer den Tieftonbereich Teil 2)" Bernd Timmermans, 2 pp. (Klang & Ton 4/91) comment: Very brief and basic horn theory (how much can one cover on 2 pages?). In German. 50. "Reconsider, baby - The promise of horns in the contemporary situation" Joe Roberts, 4 pp. (Sound Practices, Fall 1994) comment: Discussion of the horn and triode amplifier reneissance, in a context of tradition, history and trends. Written by Joe Roberts, enjoyable as always. 51. "Casual Reactions" Herb Reichert, 5 pp (Sound Practices, Spring 1994) comment: Description of Edgar Horn systems, and the BLISS (Blue Island Sound System) with photos and sketches. Enthusiastic and insightful as always with Herb's articles. 52. "What About Horns?" Greg Boynton, 4 pp. (Sound Practices #1, Vol. 1, Summer 1992) comment: Good advice, dos and don'ts for anyone trying to collect parts for a home horn system with special attention paid to Altec VOT speakers. Good, healthy horn propaganda. 53. "The Manta-Ray Horns" Clifford A. Henricksen and Mark S. Ureda (JAES, Vol. 26, No. 9, September 1978) comment: The paper deals with the theoretical basis for Altec Lansing's Manta-Ray type of constant directivity horns. 54. "A Study of Theatre Loud Speakers and the Resultant Development of the Shearer Two-Way Horn System" John K. Hilliard, 8 pp. and "Dividing Networks for Loud Speaker Systems" John K. Hilliard, H.R. Kimball, 6 pp. (JAES, Vol. 26, No. 11, November 1978 - reprinted from Academy Research Council Technical Bulletin, 1936 Volume, March 3, 1936 pp. 1-28) comment: Historically and technically very interesting paper about this big Shearer/MGM theatre horn system whose development involved greats like Harry F. Olson and James B. Lansing. Great! 55. "Acoustical Studies of the Tractrix Horn. I" and "Acoustical Studies of the Tractrix Horn,. II" Robert F. Lambert, 10 pp. (JASA, Vol. 26, No. 6, November 1954) comment: Early and significant work in the prediction of throat impedance characteristics is presented, what makes this paper even more interesting is that the horn is a large axisymmetrical tractrix, in experiments driven by a WE 555W driver. Interesting, hard to find information about tractrix horns. 56. "The Tractrix Horn Contour" Bruce Edgar, 6 pp. (Speaker Builder, 2/81) comment: Very good introduction to tractrix horns, with interesting historical information about Voigt's work. Useful graphs and charts for tractrix design. Many further references given.