JBL Hartsfield
Theree is no doubt that the JBL Hartsfield was one of the most beautiful speakers ever made. The build was amzingly complex. As I understand there were two versions. I have the plans for the 1959 version but was there another bass horn design? I believe we would like to test this at the Klipsch Museum some day. A period correct Hartsfield versus period Klipschorn. There is of course only one is still in production today and only one is still made by hand in the USA.
Here are plans for the 1959 Hartsfield download here.
In a 1955 article on the hi-fi industry, Life magazine called the Hartsfield "the ultimate dream speaker". High Fidelity magazine stated in another 1955 article, "of all of the Klipsch derived family, one speaker, in my estimation, is noticeably superior - the Lansing Hartsfield."
The development of the Hartsfield was intrinsically tied to the success of the previously introduced Klipschorn. Paul Klipsch had developed his namesake speaker in 1949. It was an ingenious design that used a complex folded horn to front load a 15" bass driver and then used a corner placement that allowed the walls of a room to act as an extension of the horn. This increased the effective horn length to allow bass extension to 35hz.
That speaker was a stunning success due to its combination of unparalleled efficiency and full bandwidth response. Almost every home speaker manufacturer rushed to develop a version of the corner horn. JBL was not immune to this pressure. JBL's dealers were clamoring for a product to compete in this market. Enter William L. Hartsfield.
The design of the Hartsfield was not terribly innovative. Instead, it was an example of refining a proven concept with an uncompromised approach to design and build quality. (Nonetheless, the Hartsfield design was considered unique enough that a patent was issued in 1957) While there had been some criticism of the Klipschorn in its use of mass market drive units and an insufficiently rigid cabinet, there would be no such compromises with the Hartsfield.
he Hartsfield would incorporate the highest quality drivers in JBL's inventory - the 085 kit consisting of the 150-4C bass driver and the 375 high frequency compression driver. Both units had been originally designed for professional use in theatre speakers. The 150-4C used the same magnet and basket as the earlier D130 and 130A but added an extension to the outer rim. This allowed the installation of a steep-angled, straight-sided cone compared to the curvilinear cone in the earlier units. This cone design provided added strength to accommodate horn loading of the driver.
The 375 had just been introduced and was developing a reputation as the finest high frequency driver available. It was unique in its use of a 4" diaphragm and 2" throat exit. The 4" diaphragm and voice coil allowed for unparalleled output and the large throat resulted in minimal distortion. This driver was combined with a brand new H-5039 exponential horn and "Koustical Lens" developed by Bart Locanthi. It was crossed over at 500hz using the N-500 dividing network.
The cabinet for the Hartsfield used inordinately heavy stock for its construction. It was comprehensively braced to result in an extremely solid and rigid enclosure. A single speaker weighed over 250 pounds. The final system was a sonic and visual powerhouse.
The Hartsfield was introduced in 1954 to near universal acclaim that reached a pinnacle with the publication of the previously mentioned Life magazine article. The publicity generated by that article resulted in an immediate jump in name recognition and sales for JBL. JBL's Los Angeles location, in the center of the movie and recording industry, resulted in the sale of a number of Hartsfield systems to local celebrities. This fact was played up in subsequent marketing campaigns to great success.
In 1959, there was a significant redesign of the bass horn in the Hartsfield. The stated purpose was to simplify the horn path to result in a smoother response. However, it was likely that the greater motivation was monetary since the redesign resulted in a simplified construction that significantly reduced manufacturing costs.
In 1964, the driver configuration was changed to add the 075 ring radiator to make a three-way system. This addressed a long standing limitation of the Hartsfield -- a restricted high frequency bandwidth. The 375 driver never did extend much beyond 10Khz. In the 1950's, this was not that significant since most recordings were also restricted in high end response. However, by the 1960's it was common for recordings to contain information that reached into the highest octaves. The new 085 configuration, consisting of the 150-4C bass driver, 375 midrange, 537-509 horn, 075 tweeter, N400(or N500H) and N7000 cross-overs, could now boast a bandwidth that would extend beyond the limits of human hearing.
Unfortunately, 1964 was also the last year of production for the Hartsfield. Its discontinuance was related to the success of stereo reproduction. The requirement for a corner placement was not a significant issue when only one speaker had to be located in a monaural system. However, a stereo system required two, unobstructed, adjacent corners that were reasonably spaced. Not every home could accommodate this requirement and thus the available market was restricted.
Nonetheless, the success and impact of the Hartsfield to JBL cannot be overstated. According to Margaret Thomas, the wife of Bill Thomas and a long time JBL employee, the Hartsfield "made" JBL. It was that speaker that gave the company national recognition. It was in large part responsible for sales increases that would average over 50% a year for the next three years.
Hartsfield history by Don McRitchie
Here are plans for the 1959 Hartsfield download here.
