JBL S3900 Floor standing speakers
What is JBL S3900? It is a three-way floor speaker system, structurally repeating the classical speaker systems. Low-frequency range operates two parallel affiliate 10 inch 100FE-12 speakers. Their diffusers are made from cellulose with reinforcement threads of fiberglass; such material seems to be covered with penny villus by touch. Movable system is built on ceramic magnet; it has a spider, made from Conex, coils are wound by aluminum wire with copper plating, laid on edge. The suspensions of JBL low-frequency speakers are always be famous not only for its linear features and lightning response, but for its comparative short life: in classical studio monitors they need to be changed in 1-2 years. In new home models more wear-resistant composition was used, in order to make the suspensions work for long years, keeping its sound properties.
Loaded on biradial horn, 175ND-3 compressive driver traditionally synchronizes the main and the most important of spectrum. It has a titanium diaphragm with Aquaplas damping coating, setting in motion by powerful neodymium magnet and kapton voice coil.
The band from 850 to 12000 Hz is given to the mentioned driver, witch means a deficiency of separating filters exactly in that place, where all musical information is concentrated. This provides minimizing of phase and intermodulation distortion, which greatly effects on space characteristics and sound "truthiness". The horn, placed at S3900, is made of composite material Sonoglass and doesn't respond to any knocking at all; accordingly, it won't make any additional hues in sound, like other classical JBL and Altec horns made and often were need in extra damping. The throat is covered by fine metal grating, which protects the diaphragm from encroachment of too many curious guests. However, if you are sure, that nobody attempts your audio system, I would recommend taking the grating off. The experience of using very different models of classical and modern drivers tells that such gratings, actually, influence negatively the brightness and openness of the sound, even when it appears only while comparative listening the acoustic with and without grating.
A tiny super-high-frequency speaker 139ND, also having a titanium diaphragm and magnet system, based on neodymium alloy, comes into play on 12 kHz and is responsible for extra air and the volume in the sound. Unlike studio brothers with same construction, in this model crossover doesn't give a possibility to regulate a feedback in MF/HF ranges. To tell the truth, despite of the utility of such regulators, I never use them out of the optimal position, corresponding to lineal AFC. If you urgently need to use them for damping the feedback on HF, there is a sense to think about a change of previous speaker's system elements. As for the rest, the separating filter JBL S3900 meets expectations from acoustic of this type: coils with air mandrel and qualitative polypropylene condensers on HF/MF, coils on transformer iron in low-frequency section. The crossover provides a separate connection of sections by passive "bi-amping" scheme, for which there are two terminals on the back board. A round input port of phase inverter is situated near them; the pipe of witch is made of stratified pressboard with full accordance with the custom. The body of JBL S3900 is covered with mahogany veneer; you can never find fault with quality of the finishing. The speakers systems, like most of JBL models in the last time, are assembled at the plant of the company in Mexico.
I know well the script of both classical JBL speakers and new versions, that's why, from first seconds of the listening, I understood, there was no necessary to expect any unpleasant surprises from S3900. Everything is in the best customs of the company: explosive dynamics, rich and legible middle-frequency range and absence of power limits make the sound of rock compositions be tasty and exciting. Whether it is old kind rock or modern metallic groups, the sound always stays clear and open; at the same time, good recorded compositions sound gorgeous and middling recordings - just well. There is no any discomfort even at ultra high volume level, and, despite of declared high and actual sensitivity of acoustic, the hand stretches to the volume control on purpose to put a jerk in it. But if you do it with some today low-frequency models for trying to awake them or to squeeze any emotions, you will just get an extra doze of adrenalin. In classical repertoire JBL appropriate wall of sound is keeping, symphonic orchestra is completely turning around to the listener, and, at the same time, all groups of instruments and soloists are neatly taking their places in space. There are no any claims to the timbre intensity, chorus instruments and voices are accurately discernible in tonalities. On the whole, the performance is turned out to be very truly and alive, witch needs a bit more "air" and lightness of flying at portrayal of single instruments; but I am inclined to blame for this other elements of system, not the speakers. One should think, a powerful two-bar valve amplifiers will be the best suitable partners for S3900. What about placing the speakers, they unlock their low-frequency potential in full measure by distance from back and side walls for 1 meter at minimum. Thus, correct scene is formed by directions of the oscillator's axes exactly to the place of listening - all the same, to escape completely from narrowed diagram of directness in horn system is impossible. It will be better, if the distance between the speakers equals the distance of the point, where the listener is: in other words, it is desirable to build the equilateral triangle.
If we compare the sound of JBL S3900 with classical monitors of 43** series, you can find definite differences among similar features. For the most part, they concern a bit more "romantic" of middle-frequency in old models contrary to higher accuracy of novelty. As for the rest, the script is very similar.
