JBL K2 S9800 Floor standing speakers
JBL K2 S9800 is the result of the ambitious project of the company, which in 2000 wanted to regain its reputation of the best manufacturer of speaker systems. The upper part is given for a horn section - a small horn of super-tweeter perched on sloping top panel and the main horn, serving the lion's share of frequency range, takes all width of the body. However, the speakers are the main feature of JBL K2 S9800 - all of them were specially developed for the flagship model. Super tweeter, picking up the baton at 10 kHz, is equipped with extremely light and rigid 25mm beryllium dome, which is loaded on the small horn with cone angle of 60 degrees in vertical and of 30 degrees in horizontal plane. A 76mm mid-frequency dome is also made of beryllium and the horn, at the same time, has a cone angle of 90 degrees in horizontal and of 50 degrees in vertical plane. MF-rung covers the range from 800 to 10000 Hz - so, the frequencies, which a human ear is the most sensitive to, are sounded by one speaker and this gives the possibility to avoid phase distortion.
Bass speaker in JBL K2 S9800 is also extraordinary - this is a 15-inch paper cone, driven by a powerful magnet from Alnico alloy (aluminum-Nickel-cobalt). This material was popular in 1960's - 70's as it allowed to achieve a very energetic sound with good attack in lower part of the range. However it had one significant disadvantage - at high power the magnets, made of it, tended to demagnetization. Therefore, the alloy practically was ceased to be used in the late 1970's. This problem was successfully solved due to new developments of the JBL specialists and now Alnico is experiencing its rebirth. Sound coil of LF-speaker is spooled by flat aluminum cable and the double symmetric spool from Nomex reduces distortion, associated with nonlinear displacement of the diffusor. Bass link is loaded on bass reflex, the dual port of which is placed on the back panel at the bottom of the speaker system.
The construction of the crossover is very interesting too. Firstly, it is located in the separate body at the bottom of the speaker in order to eliminate the effect from the side of backscattered radiation of LF-speaker. Secondly, crossover's board is located in the horizontal pull-out box, which facilitates the access to it. Thirdly, in order to avoid distortions in the crossover at zero potentialthe JBL engineers fell back on such an original way as precharge of capacities over 9-volt battery.
In addition, the crossover allows you to adjust back-blow on high frequencies with the step of +/-0,75 dB and three-position switch is located next to acoustic terminals for this reason. Another rare but very useful technique is the presence of a chain allowing the connection of amplifiers directly to the speakers, passing the crossovers. Thus the user can organize multiband amplification with active filtering, which is carried out by the external crossover.
If you are used to listen to music on simple acoustics, being equipped by the speakers with long-throw diffusers, the sounding of JBL K2 S9800 can become a shaped revelation for you. First of all, a true concert dynamics strikes you - for example, at playing "Physical Graffiti" of Led Zeppelin the illusion of presence in the live performance of legendary group appears. The attack in the bottom part of the range is especially good: the bass is quick and sharp and it doesn't kin to that, which is played by LF-speakers with long throw. There is no any drone, although the test room can hardly be called big. Vocal is localized exclusively correct and because of the fact that it isn't always released exactly in the middle between the speaker systems, not all systems are able to transmit its position in space so correctly.
Mid-frequency range really impresses too - amazing openness and clarity of sound convert the listening of Vivaldi compositions into almost a drug from which you can hardly refuse. Tonal richness of strings is saved brilliantly, all dynamic contrasts and intonations, as well as the interaction of instrumental groups in the orchestra, are transmitted perfectly. A curious observation: due to open character of the sound of JBL K2 S9800 you forget about formal "audiophile" parameters (such as depth of stage, separation of instruments and so on) and just enjoy the music. And if JBL K2 S9800 demonstrates excellent dynamics even with digital signal source, it will be hard to imagine what it can show with good vinyl turntable. By the way, although the listening was held with powerful transistor amplifier (at the same time it was impossible to make a complaint to the sound), horn construction and high sensitivity of JBL K2 S9800 make the use of tube amplifiers be very temping - it would be very interesting to know how JBL K2 S9800 will approve itself in combination with a good single ended tube amplifier.
