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Dynaudio Image 4 2-way loudspeakers The Dynaudio Image 4 is a large tower speaker with just two drivers, a 28mm tweeter & a 20cm woofer with bass reflex loading. It is rated to handle amplifiers up to 180 watts per channel & has a very smooth frequency response. By LEO SIMPSON Large 2-way loudspeakers are relatively unusual. The trend is for larger speakers to have three, four or even more drivers. This is sometimes done deliberately so that buyers feel that they are getting more value for their money but it does not necessarily result in better sound. The design philosophy behind the Dynaudio Image 4s is that more is not better. Many loudspeaker systems on the market do not have any useful bass response below 50Hz so these Dynaudio Image 4 loudpeakers are unusual in this respect too. They have a very smooth response which extends down to below 30Hz - almost a full octave below 50Hz. The difference that can make is sensational. But why go to a tower loudspeaker. The overwhelming fashion among loudspeaker designers today is to produce small 2-way systems which have to be mounted on stands if they are to give the best performance. The stand brings the tweeter up to about the ear level of the seated listener and thereby ensures that he or she is sitting almost "on axis" with the tweeter. Thus, the listener gets to hear ·every little nu- This cross-section of the Dynaudio 24-W-100 shows its unusual construction. The voice coil is 100mm in diameter and the circular magnet is ventilated to prevent pressure build-up under the large dust cap. The inside-out construction of the magnet means that flux leakage is low & the speakers can be used close to TV monitors. 4 SILICON CHIP ance produced by the tweeter. Although small loudspeakers can also conveniently sit on a bookshelf, they usually don't give the best results in this position because they are too close to the walls or corners of the room. This tends to muddy the bass and lower midrange. So it is back to having stands for the best results. Now while having small speakers on stands is necessary if they are to produce their best, it also means that they occupy more floor space than their small size would indicate. The stands inevitably must be quite heavy and their "foot print" is quite large to avoid having them easily tipped over. Thus, the typical loudspeaker stand has a footprint which is 25 to 30cm wide and 30 to 35cm deep. With the above factors in mind, a tower loudspeaker starts to make a great deal of sense. It doesn't occupy a lot of floor space and it doesn't need a stand since it is already tall. The tower concept also means that the designer can settle for a much larger enclosure and thus obtain a much better bass response than would be possible - all other things being equal. The trouble is, some tower speakers don't look attractive at all. However, by any normal standards, the Dynaudio Image 4s are impressive to look at. The designers have managed to design a large loudspeaker without producing one that dominates a room. As a tower speaker, it is quite tall at 950mm high but its width of 270mm and its depth of 325mm means that it occupies no more floor-space than typical bookshelf sty le speakers mounted on stands·. A contributing factor to its grace rather than gross is that the grille cloth frame does not cover entire front of the cabinet, leaving more than a third of the veneered panel visible. I should state at the outset that the Image 4s are available in two genuine timber veneer finishes: black Ash and Mahogany. This reddish timber is somewhat lighter than the Rosewood which used to be a popular furniture finish many years ago. In this reviewer's opinion, the Mahogany finish is a delightful contrast to the dreary black of today's speakers. Removing the grille cloth frame reveals that the Image 4s are simply a 2way bass reflex design with a 28mm soft dome tweeter and 200mm (8-inch) woofer with a polypropylene cone and foam rubber roll surround. -However, there is far more to it than that because both drivers turn out to be "specials", produced to meet the requirements of the Australian design team, Glen Leembruggen and David Connor. The immediately noticeable feature of the woofer is its very large dust cap. That conceals a voice coil which is 100mm in diameter. This must be a record for virtually any loudspeaker driver. The upshot is that the voice coil can dissipate very large amounts of power without becoming excessively hot and this means that "dynamic compression" is greatly reduced. In conventional loud~peakers, high power dissipation causes the voice coil resistance to rise and thus the speakers do not respond linearly to loud signals - they are compressed. Dynaudio claim that the 24-W-100 woofer used in the Image 4s will faithfully reproduce a 1000 watt 10 millisecond transient. If that sounds remarkable, they make the same claim for the matching D-28-AF tweeter! On the rear panel, the Image 4 has a recessed terminal panel with large gold-plated binding posts which can take really massive loudspeaker cables or banana plugs. Furthermore, there are two pairs of terminals which are normally connected in parallel with gold plated straps. With the straps removed, you have the option of bi-wiring or bi-amping. Personally, I cannot see the point of bi-wiring. In. effect, you use separate pairs of leads to power the tweeter and woofer and thereby supposedly reduce any interaction between high and low frequency signals as they pass along the cable. To anyone with a knowledge of AC circuit theory, and Pictured are two units in the Dynaudio Image range: the large Image 4s (right), subject of this review, & the Image 3 which uses the same D-28-AF tweeter. more particularly the Superposition theorem, this is rubbish. Note that whether you elect to "biwire" or "bi-amp" your loudspeakers, the normal crossover components remain in place. In addition, a bi-amp system (ie, two separate power amplifiers in each channel) requires an electronic crossover and its inevitable phase shifts at the crossover frequency will be added to those already produced by the loudspeaker's own filter network. These additional variances cannot be allowed for by the designers and therefore the results will not be as good as if the speaker was used in the conventional fashion. Some reviewers have argued that bi-wiring means less voltage drop for the signals to the tweeter and woofer but even that is not true, although it would take rriore space than can be spared to prove this argument. To me, the only reason for includ- ing the bi-wiring facility is to satisfy the hifi faddists, those golden eared types who hear an improvement after every fiddle and tweak. Whether or not you agree with the idea of bi-wiring, bi-amping or other gimmicks, the connecting terminals for these Image 4s are beauties and they should be a feature of any loudspeaker that claims high performance -you really do need them if you are to use heavy speaker cables and thereby obtain the best sound quality. Lest any reader think that I am against heavy speaker cables, let me reassure you on that score. I believe that the lower the resistance of the speaker cables, the better. Again, I don't have space to go into the reasons why and nor are they the ones necessarily espoused in hifi magazines. The highest quality components have also been used in the crossover filters (air-cored inductors, etc). The MAY 1993 5 These scope photos show the enormous power handling capability & dynamic range that these speakers have. They can reproduce a 1000 watt transient with no dynamic compression. crossover network is a third order Chebyshev filter for the tweeter and a 6dB/octave filter for the woofer. The crossover frequency is 2.5kHz. By the way, the Image 4 is specified as having a nominal impedance of 6 ohms. The minimum impedance is 4 ohms and occurs at just under 3kHz. On a practical note, the Image 4s are unwieldy to lift and move about. While they are not particularly heavy at around 27kg, there is nowhere to grasp them. The baffle is completely flush when the grille is removed. In facr, I resorted to lifting them by putting one hand inside the port there is no other practical hand hold. Listening tests As noted above , relatively few loudspeakers have a response extending below 50Hz and those that go below 30Hz are rare indeed. The Image 4s have a frequency response quoted at 36Hz to 25kHz within ±3dB. That is exceptional enough in itself but it also means that the usable bass in a typical living room can be expected to be below 30Hz. Our listening tests on constant sinewaves indicate that the Image 4s do have a very smooth and extended frequency response right up to the limit of audibility and yes, it really is usable down to below 30Hz, with very little tendency to frequency doubling (ie, tending to second harmonic distortion) at moderate power levels. In other words, the bass is very clean and when compared to many other largish speakers, quite restrained. For its part, the tweeter is exceptionally smooth and the crossover does its work well, with little sign of "suckouf' or phasing problems. The cabi6 SILICON CHIP net is also commendably "dead" and panel resonances are well muted. So how do they sound on music. To some ears, on orchestral music, the treble may sound a little bright but extended listening indicates that it is more a matter of clarity of reproduction than a matter of a bright response. Stringed instruments are very well produced and the stereo imaging from a pair of these speakers is very sharp (hence the name "Image"?) On normal instrumental music it cannot be said that the bass response of the Image 4s seems notable. As noted above, it is quite restrained, a sign that there is little bass distortion. It is only when you play classical organ or piano pieces that it really shows its stuff. The dynamics of a concert grand piano are rarely reproduced by any hifi system regardless of its cost. Consider that the lowest note on a piano is A, four octaves below A 440Hz. That means its fundamental frequency is 27.5I-Iz. Consider also that the piano has the largest dynamic range of any instrument in the orchestra and you begin to get some idea of how difficult it is to reproduce. In fact, the full bottom octave of the piano is not reproduced at all, on fundamentals, by many bookshelf speakers which have a bass cut-off at 70Hz or higher. Hence, on paper the Image 4s should be well suited to piano works and indeed they are. As one who is exposed to a great deal of piano music (from a Yamaha U1A) played by my daughters, I can state that I have never heard a loudspeaker give a more realistic rendition of the piano. The growl of those bass strings together with the big sounding board is really there. You can hear the damper action clearly and even the squeak of pedals or the pianist's stool on some tracks - very impressive. On drums, whether played in an orchestra or a jazz combo, the Image 4s are startling - ·you will not hear deeper bass unless it is from the real thing. These speakers are what some hifi enthusiasts call "fast". Their attack on transients is what makes their reproduction of piano, drums and percussion instruments so good. It almost goes without saying that the rendition of classical organ pieces is a delight to hear, and feel. Again, they can seem quite subdued in the bass when compared with other large loudspeakers but when they "speak" they are clearly heard. For a speaker with such an extended bass, you might expect it to be a little "chesty" on male voice but it is quite natural. No problems on that score at all. Efficiency of the Image 4s is about average at 90dB/1 W/lm and to get the best out of them you need an amplifier capable of at least 100 watts per channel into 4-ohm loads. The manufacturer specifies their power handling at up to 180 watts but I would go further and state that they should comfortably handle the output of a 200 to · 250 watt per channel amplifier on normal program material. Conclusion By any normal standard, this must be rated as a rave review. In my listening room which has cement rendered walls, slate over a concrete floor with rugs and plenty of bookshelves to give a room sound which is about right (not too bright), these speakers gave an exceptional account of themselves - I have not heard better, even from speakers costing many times more. There, I've really gone and said it. But the Dynaudio Image 4s are not cheap and are well out of the range of most enthusiasts. Their recommended retail price is $2.490 a pair and they have a 5-year warranty. However, if you can afford them they will give far more satisfaction than other speakers costing many times the price. If you cannot afford them, have a listen to the lower priced units in the range which start from $690 a pair. For further information, contact Scan Audio Pty Ltd, 52 Crown St, Richmond, Vic 3121. Phone (03) 429 2199. SC