JBL Aquarius

JBL Aquarius II S106

The product line shown above is one of the most striking ever developed by JBL. The Aquarius series was groundbreaking in technology and style. But with one exception, their existence was short-lived. It came onto the market after a storm of development activity, but was to disappear again within two years. What follows is an insight into the risks and challenges associated with advancing the state of the art. Unfortunately, most of the documentation for this project has been lost. However, the description of the events described below is based on the best information currently available.

DESIGN PRINCIPLE

The Aquarius series was all based on a common design principle – slot-loaded bass cabinets combined with a widely dispersed high frequency range. The intention was to develop a series of loudspeakers that would have few restrictions on room placement and a stereo sound field that is largely independent of the listener’s position. The idea of a wide dispersion stereo soundstage had been developed by JBL with the revolutionary Ranger designs (i.e. Paragon, Metregon and Minigon). However, these designs required a large, curved dispersion panel with unique housing size and geometry requirements that limited their application. There was a need for a more flexible and cost-effective approach. This was accompanied by a brief fad for omnidirectional speakers that developed in the mid-sixties. Such designs were marketed by Harman Kardon and Stewart Hegeman and were particularly well received by the audiophile market in New York. After all, JBL was interested in revitalizing sales with radically new products that would break new ground in form and function. All these factors led to the development of a new loudspeaker series in the late sixties, which became known as Aquarius.

The principle of slotted enclosures was invented by Ed May, Head of Product Development at JBL. Before joining JBL in 1959, Ed May had been a partner with Jack Frazier in the Frazier May loudspeaker company, which introduced the concept in the mid-fifties. The illustration on the left shows a cross-section of this design. The woofer was actually a front-firing speaker, and the loading cap and panel were the front of the speaker (i.e. the sketch is not meant to illustrate a top-firing speaker).

Ed had tried to interest JBL in this concept shortly after joining the company. However, it took until the fad of dispersed sound field loudspeakers in the mid-sixties for JBL to see an application. In 1968, Ed was authorized to start developing a prototype. The original prototype was a two-sided stacked, coaxial design with the drivers firing forward into a circular front plate that provided the slot loading. This design was promising, but marketing preferred a rear-facing woofer with a rear-mounted slotted plate. This would allow greater flexibility in the housing design and probably also enable more effective coupling with a rear panel.

AQUARIUS 2, 2A

Design changes led to a second prototype, which was eventually developed into the Aquarius 2 and 2A. These would be the first products developed, even if the model names are somewhat misleading. The sketch on the right illustrates the rear slot loading that was to be used for the Aquarius 2 and later for the Aquarius 3. The Aquarius 2 had a 12? 123A driver mounted at the rear in the center of the housing. Spacers were placed radially around this driver, and a flat plate was attached to the spacers to ensure slot occupancy. Two 5? LE5 midrange drivers were also mounted on the back near the top of the cabinet. They had their own charging plugs, which were attached to the diffraction plate. As the diffraction panel limited the frequency response above 5,000 Hz, the high frequencies were reproduced by a single LE20 direct radiating tweeter mounted on the front panel.

Ed’s original Aquarius 2 prototype was considered a sonic success. It provided a wide, deep sound image, as the slotted drivers created a dense comb filter that maintained a relatively flat performance at almost any listening position. The front-mounted LE20s provided a certain degree of image localization. However, developing the prototype into a production system proved to be extremely difficult. The system was known to be sensitive to minor production deviations in the transducer and housing tolerances. Such deviations could change the sound character from expansive and balanced to thin and nasal. After all, the drivers had to be selected by hand and tuned to extremely tight tolerances, which drove up production costs considerably.

AQUARIUS 1

The development of Aquarius 1 took place at the same time as that of 2 and 2A. The Aquarius 1 was modeled on the successful 4310 monitor and the subsequent L100. The midrange and tweeter drivers were the same LE5 and LE 20, with the woofer 10? LE10 instead of the 12? 123A was used.

The drivers were all front mounted, and individual diffraction panels were designed for the bass and midrange. The design of these panels developed empirically and resulted in elliptical shapes, which are shown in the sketch on the left. It is interesting to note that this design proved to be the least susceptible to production variations and was arguably the best sounding of the series.

AQUARIUS 4

The development of the Aquarius 1, 2 and 2A was practically complete when Ed May left JBL in 1970. The refinement of the partially completed Aquarius 4 fell on the shoulders of George Augspurger, who was JBL’s Technical Director at the time.

Aquarius 4 Geometry
© and Courtesy George Augspurger
The original concept for this speaker was a very compact, columnar design on which an LE8T was mounted. This driver worked across the entire range and fired into a conical diffuser that provided 360-degree dispersion. This concept was not new and is revived every few years. However, it proved difficult to adapt to the selected driver.

The LE8T was not suitable for slot loading. The design had to be modified so that the loading functions more like a radial horn. It also turned out that the system had to be redirected above and below the muzzle, so that an empty upper chamber was added to the housing. Even with this additional baffle, the short horn produced a pronounced resonance at around 1000 Hz. This was eventually mitigated by drilling out the center of the conical charging plug to create a quarter-wave stub. However, this solution brought with it a new problem. The quarter-wave trap dissipated frequencies above 5000 Hz, so that high-frequency amplification was required. This was achieved by an LE20, which fired from the rear and had its own circular slit charge to direct it in one direction.

An equally big challenge was to design the system in such a way that a reasonable low-frequency response could be developed. Originally, the column below the driver was designed as a simple ventilated housing. However, this room had the geometry of an organ pipe and sounded like one. It took a long time to develop a solution that consisted of a filled chamber open to a ventilated space below. This enabled a usable low-frequency extension to 40 Hz.

AQUARIUS 3

© Harman International, courtesy of John Edwards
The last speaker to be developed in this series was the Aquarius 3, which would be the sole responsibility of George Augspurger and would be the most ambitious design of all. The desire was to develop a non-directional speaker for the high-end market segment. A large bass speaker should be used in combination with a compression driver, which is typical for such modern systems as the Olympus. However, all chassis would use a form of indirect radiation.

The starting point was an enlarged version of Ed May’s prototype for the Aquarius 2. The same configuration of woofers and midrange drivers was used, only the 12? woofer was replaced by the 14? LE14A replaced. An LE85 compression driver would be mounted on the front in combination with a radial horn specially developed for this system. The new horn would be designed for the widest possible radiation pattern and would require groundbreaking research and development.

George’s experiments with horn design began inauspiciously with teak serving trays with a diameter of about 18? from a local DIY store. The first horn worked pretty well, but the response was noticeably different on and off axis. George responded by cutting tapered radial slits into the bowl to create a more diffuse sound source. This idea was inspired by Karlson’s concept of radial slots, which was popular in the 1950s. The slotted horn was much closer to a hemispherical source, with very little loss in overall efficiency.

Attaching the horn to the front panel, as Ed May had originally intended for the Aquarius 2, worked pretty well, but there was a noticeable change in response directly on the axle. Mounting the horn on the top plate, as one would expect from a radially aligned horn, smoothed the radiation pattern but did not sound as good. The best results were achieved when the horn was tilted at 45 degrees, which explains the characteristic letterbox shape of the housing.

Modifying the rear panel to accommodate the larger LE14A driver was relatively straightforward. However, George soon discovered that the slot store posed a number of unique problems. This load effectively added significant mass to the cone at low frequencies. Since the bass reflex ports were located in the slot, there was additional mutual coupling between the woofer and the ports. As a result, the woofer cone had to be lighter and the suspension stiffer than a standard JBL LE14A. Despite this, the bass response was much more extended than conventional JBL systems of similar size, and the diffraction panel naturally attenuated the midrange response to allow easier matching between drivers.

According to its designer, the Aquarius 3 was a very good sounding speaker that could keep up with contemporary JBL systems. In particular, its solid and extended bass response was arguably superior to most JBL speakers. To this day, George Augspurger regrets not having bought a pair for personal use.

MARKET IMPACT

The Aquarius 1, 2, 2A and 4 were introduced in 1970. Her unique styling and technique caused quite a stir in the industry. However, this was not reflected in sales. The Aquarius 2 and 2A were a particular disappointment. It quickly became clear that their relatively high costs, both in development and in production, could not be recouped. They were canceled before the end of the year. The failure of these speakers led to the Aquarius 3 being canceled before production could even begin. Only four development pairs were ever produced before the program was discontinued. The Aquarius 1 and 4 were to continue in service until the production year 1971. The Aquarius 1 was manufactured in a limited production series and was discontinued after this series was sold out. Only the Aquarius 4 was to remain in production for the next five years.

L120 Aquarius Q
© Harman International, courtesy of Ed Lacinski
The relative success of the Aquarius 4 was interesting given the fact that it arguably had the most uncompromising performance of the range. However, a compact form factor and the timing spoke in its favor. The extremely small footprint of the columnar design allowed for great flexibility in placement in any number of living environments. In the early seventies, there was a short-lived technological development that underlined this advantage. This was the introduction of the quadraphonic sound. The need to accommodate four speakers for quadraphonic playback made the small footprint of the Aquarius 4 even more desirable. In fact, the relative success of this design led to a later, larger version that was introduced in 1975. It was the L120 Aquarius Q three-way loudspeaker. By the mid-seventies, however, the quadraphonic phenomenon was on the wane due to market segmentation caused by a lack of standards. All Aquarius series were to be discontinued by 1977.

Nevertheless, the legacy of the Aquarius series was to continue into the 1990s. The Aquarius 4 was redesigned and relaunched as the S2 in the mid-1980s. The single LE20 in its original design has been replaced by four 1? tweeters, which were placed in the corners of the woofer slot. The LE8T was replaced by the 108H woofer. The housing design and dimensions were practically identical to the original. The S2 was launched with an accompanying subwoofer called the S1. This accommodated a further 108H woofer in a similarly dimensioned column housing. The last incarnation of the Aquarius concept was developed in 1990 as the S119 exclusively for the Asian market. This was virtually identical to the S2, but used shielded drivers and was produced in a high-gloss finish.

ANALYSIS OF THE MARKET FAILURE

The disappointing sales figures for the Aquarius series were due to three main factors. Firstly, the design concept was undoubtedly a technological step backwards. Rather than raising the level of sound accuracy, it was intended to address shortcomings in the recording process that would eventually be remedied as the industry matured. It should not be forgotten that this was the era of “ping-pong” stereo recordings. Instead of trying to capture a three-dimensional sound field, mixes were routinely created by simply placing separate instrument tracks on separate channels. In these recordings, a diffuse sound field could artificially create a sense of space.

Secondly, there was not enough time for development. Added to this was the desire to launch a whole family of unusual speakers on the market without having enough time to thoroughly develop and test the systems. In another six months, the sound quality of the Aquarius 2 and 4 could have been significantly improved.

Finally, there was a problem with the radical difference in sound compared to previous JBL products. JBL was a successful high-end manufacturer with a reputation for distinctive sound character. The Aquarius series was seen by many as too great a departure from this character. It therefore did not find immediate acceptance in its existing market niche. In addition, it was difficult to set up the diffuse sound concept in a typical listening room and almost impossible to demonstrate effectively in a dealer’s showroom. This made it difficult to address a new market niche.

The lack of market acceptance was disappointing, but not catastrophic for the company. At the time. JBL was a small, high-caliber company that operated without marketing studies or focus groups. A new design was sent to retailers, and it either succeeded or failed. The fact that the Aquarius concept failed was regrettable, but it was implemented with ease. In fact, the launch of the Aquarius series coincided with the launch of the L100.