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Hörerlebnis 25


Loudspeaker: Jupiter of CD-Konzertmöbel

ONCE FOR EVER

from Marco Kolks

For me, loudspeaker are generally simple, rectangular, not very sensational cabinets, apart from some completely exceptional designs. Lately, however, there is an omnidirectional radiator on the market from Bissendorf near Osnabrück, which I associate with african sculptures. (By the way, the design is a debatabel point. Especially in this case there may be different points of views.) The name of the product suggests furthermore that the engaged designers of CD Konzertmöbel have got a healthy self - awareness: JUPITER. This roman god was without any doubts regarded as the most powerful and mightiest among all representatives of the superhuman host as well as the highest guarantor of the cosmic order. Such a naming raises expectations in me, particularly as such an ordering hand would already satisfy me concerning complex music. This about 65 kg weighting loudspeaker, with a height of 130 cm - this may already be mention here - has satisfied them all.

JUPITER is an omnidirectional 2-way-complete range horn and is therefore completely different from usual construction, basing on direct emittance. The idea of this principlet is, to emit the sound into the room about a spectrum of 360 degrees as homogeneous as possible. Because of that, the share of indirect sound, the sound which reaches the ear about reflections, is much higher than with conventional sound transmitters. The efficiency is indicated with 92 dB and turns comparatively high. A downwards emitting mid-range-treble loudspeaker, which is beared by four bars is situated at the top of the box. The titanium membrane which cannot be seen from the outside is measuring 100 mm and is controlled by an extremely strong ferrite magnet. The bass is produced by a loudspeaker which is turned by 180 degrees and directed upwards (nearly 10 kgs in weight). Between the two chassis a soundleading horn which is tapered very much to the borders takes over the distributing function of this classic omnidirectional sound source.

The bass-cabinet is based on the Helmholtz resonator principle with different, but exactly definated tunnels. The cleverly thought-out inner bracing and interlockings prevent from any standing and therefore distorted waves in the corpus which is made by highly condensed laminated birch-wood combinated with medium-condensed fibre-plate. (Helmholtz resonators are widely spread among manufacturers of loudspeakers who are offering vented boxes and who include the bass-supporting advantages of such a construction. By the way, Helmholtz resonators are working very narrow-band and have therefore be calculated exactly.)

To the principles of omnidirectional sound sources: Nearly all developers are striving for the ideal of the point shaped sound source. But scarecely anyone is offering such a system which is very advantageous in its theoretical conception. At the same time it is a well known fact, that conventional dynamical loudspeakers, especially on higher frequencies have got a strong directive efficiency. This effect is very strong, when you put yourself behind the box. From the treble tweeter nothing is emitted there and from the mid-range loudspeaker also only a few arrives there. Nevertheless, high and mid-range frequencies are very important for the ear concerning the stereophonic and spatial hearing.

In this connection one has to considerate the effect of natural sound fields of instruments. A piano i.e. has got an extremely large sound radiation field without a straight directive effect. It therefore doesn`t matter whether you are standing at the left, at the right, in front or behind the piano. If there are, neverless differents in sound, these are, according to my experiences first and foremost due to spatial influences like reflections. Even in the range of milliseconds our brain registers differences in transmitting time and is therefore able to determine precisely the direction of a signal. All further signals, following shortly after a first sound (i.e. reflections) will automatically be related to the firmer acoustical information and will probably be assigned to it. The opinion of design engineer Markus Duevel is, that we are able to detected in real time the room size and its attenuation by the minimally delayed sound reflections. Spatial reflections would therefore be essential for the acoustical orientation. But it has to be said, that our ear is not able to analyse reflections coming from the same direction like the direct sound.

To transmitt the spatial information of the sound carrier into our living room, we need an acoustical projection field, a hearing room. According to Duevel a well-balanced sound field is the condition to reproduce the recording room virtually in the hearing room. Directly emitting and extremely focussing loudspeakers therefore project unnatural sound events because the indirect sound of the record can not be detected because of temporal masking effects and as a result a shallow sound pattern is arising. The better the beamwidth the better the depth stepping. When constructing omnidirectional loudspeakers it has to be taken care very precisely that a time- and phase constant radiation is guaranteed, not to smear the spatial information. Only when a homogenuous ratio between sound signal and sound field is given, says Duevel, a natural music reproduction would be possible.

Believers in measuring techniques will yell out at the latest in the laboratory. In a room which is lacking in reflections only distorted result can arise when determing the sound pressure. The conventional measuring only registers a part of the really given off acoustical power. As a result the sound pressure is much to low, because the whole sound which is radiated back is absorbed by the room. Even unpleasant interference phenomenous can occur, when sound radiated to the sides reaches the recording area of the measuring microphone.

Through the years unfortunately the conventional constructional style with large sound wall as "industrial standard" has succeded. Thereby very interesting alternatives like JUPITER or dipole radiators have been relegated to the wrongly scarcely noticed exotic status. The part of the sound engineers is partly to blame for this. They take the view that each sound recording always is preserves frontal information, which should be reproduced mirror-inverted, that means directly. In this respect, they regard dipol- or omnidirectional radiators as a mistake in the logic, because to their opinion, they disreflect the reproduction.

Position: The best condition for the loudspeaker is in my listening room a distance to the back wall of 75cm. The loudspeaker should also have quite a distance to the sides. An angles position, as I usually practice it, is not necessary because of the transmitter principle. The base really should have a decoupling effect, but acoustical advantages are clearly recognizable by using spikes. (Acoustic Balance in this case)

Comment:

JUPITER makes no secret of the fact that it prefers tubes. The Burmester-Equipment surely sounds acceptable, but it doesn`t get out the full capacity of the loudspeaker: the well known problem of interaction. I had to accept this painfully when a good friend of my family plugged-in an old japanese full-range amplifier and a cheap CD-player to test-hear. The differences between these two teams are so small that the solution which is much more expensive simply must be regarded as a bad investment. The exchange against a tube amplifier has been the right decision. I would only partially follow the recommendation of Manfred Claas of CD-Konzertmöbel to consult triodes. Two times 5 Watt are enough to achieve high room-loudness. The treble and mid-range area will be reproduced three-dimensional and completely free, at the same time the deep frequences are suffering. They are missing the pressure which this transmitter is easily able to produce. Jupiter and the pre-final amplifier combination of Beck are a good team. They go together the middle course between all extremes. At least I gain one positive result: With DM 28.000 the JUPITER is anything else but a cheap loudspeaker. Who has decided to make such an investment has not to invest much money in the electronic afterwards. First class results can already be achieved with ordinary amplifiers. Of course, the better the frontend, the better the final result.

This loudspeaker reacts very sensible to cables, it goes together with Acoustic Balance or pure-silver-connections of Dope Sounds. To become open to this kind of music reproduction, several hours of listening are necessary. It took several weeks until I understood this kind of music reproduction. However, then it was all up with me. With the JUPITER the produce was very difficult because again and again I lost myself in the music, so that the scratching of the blank groove remembered me to my duties. In the evening I forget all around me I admit that I fall in love with the lightness of the performance.

Spatial effect and lightness are incomparably. Who sets great store by these characteristics cannot escape this omnidirectional radiator. In the price range of the JUPITER I know no other loudspeaker which could be compared with it concerning these points. And the reproduction is unusual at the first moment. Usual systems - possibly angled to the ideal sitting position (sweet spot) - are more directly and supposed to be more gripping. Compared with the original, however, the omnidirectional radiator from Bissendorf offen plays more honestly. The question is anyhow, how far the actual Hifi feels itself obliged to the natural reproduction and has not become a toy to satisfy the play instinct of men. Concerning this, costumers have got different opinions. Not all of them will prepared to leave old well-loved habits in favour of new experiences.

For the market, however, obvios advantages will arise. With the JUPITER it will be possible to gain a new clientele. Furthermore, this loudspeaker is a worthwhile alternative to the existing range of products. At the same time the success seems to be predetermined in the long term. Who makes the decision for such a sound transmitter will stay a satisfied customer for many years. By the way, the JUPITER manages excellent each style of music. The more komplex the music is, the clearer it sets itself off against the competitors by its bewitching spatial effect. Furthermore it shows clearly the differences between digital and analogue reproduction.

Lori Liebermann plays ballads very sensibly ("gone is the girl", pope music offered by good buy - Tel.: 0711-241155), which are furthermore recorded in first class quality. The voice of the singer ("all over again") lingers, detaches itself completely from restricting electronics. At the same time an unusual silence is coming in my listening room. This impression is difficultly to describe. One has to make this experience on one`s own to be able to judge or it. Very sensible music-lovers complain about a light pressure on the ears of the listener created by directly radiating loudspeakers. By the omnidirectional principle the reproduction appears more light, although it is a little bit more reserved, what has not be seen in contrast to natural music. With the JUPITER it is, for constructive reasons, simply not possible to produce the precision of my other transmitters which I carried to extremes by bending them extremely. With regard to the sum of its capabilities it is, however, no disadvantage. The sound colours are always pleasant warm, without blowing up. The intrumentalists take over firm and unshakeable positions what constributes to the silence within the sound pattern.

These realizations apply to "Back to Back" of Duke Ellington and Johnny Hodges, an excellent record from 1959 and now remastered version (Verve). The two-chanel-recording technology of this epoch can not be pushed up, but the light Blues-Swing-Style mix gains a lot from this rare aura which is able to fill the listener with enthusiasm. The saxophone of Johnny Hodges keeps during all recordings ans pitches its natural timbre. That is the more important, than the long-standing partnerof Duke Ellington takes over the leading of the melody.

For me, the irish singer Mary Black (Circus,Arcade LC 5896) is an important measure to evaluate Hifi-components. Her songs are living by her charismatic voice. Even very small tonal changings in the reproduction become unpleasantly noticeable as inacceptable interventions in an entirety in music which is carefully in time with each other. It seems that the JUPITER likes to leave such "misinterpretations" to others. Even now this surprising spatial effect combined with absolute precision is emerging. This loudspeaker helps to an absolutely stress-free listening.

On the turntable of the Piano Forte LA 4 "Just friends" is turning. In the last months I came to appreciate the solid running gear combined with the SME V and the Rohmann of Ortofon. In that moment I noticed, but for the first time, that I prefer a little bit more pressure in the deep regions. Who, however, has not always to listen for small shades, will surely not miss anything.

Within many weeks I couldn´t find any weakness, they appeared to me because of my present habit of listening, which has to be reconsidered in some points. I am therefore pleased to admit: I am enthusiastic about this transmitter.

On balance: Those, who go together the way with the JUPITER into a rich sound future consider the subject loudspeaker closed. You buy once for ever. And you will surely close with conventional solutions.