Axiolab - KIT008

  DataSheet KIT KORRIBAN

Korriban; three-way loudspeaker composed of excellent loudspeakers, taking shape in all its sonic and structural grandeur. Judging from the images proposed, the diffuser looks more like a mini tower, this is camouflaged by the narrow front baffle of only 21cm and its relatively normal height for a diffuser of this type (120 cm). Having displaced the sub-woofers and passive 26cm on the side wall has obviously allowed the front baffle to be narrowed down, giving unquestionable improvements in terms of design and sonic rendering. We will see in detail the article how this diffuser was designed and developed, which has been able to give different satisfactions in different areas. At the end of the games it is always the same story that is difficult and reach simplicity in its different forms, starting from the name. The most attentive of you will have noticed the "simple" name attributed to this speaker: Korriban. Planet of the famous Star Wars saga, with aggressive, warlike and desert connotations. From the "raw" and poor color content, it gives Korriban (the diffuser) a "bad" and "aggressive" appearance, which is only gladdened by the sonic component if you do not overdo it with the volume knob.

The R2904 / 700000 is a tweeter from the revelator series of the Danish company Scan Speak. Unequivocal feature for this northern European tweeter is the presence of the ring radiator placed on the front of the dome. The magnetic assembly is neodymium. The shape of the latter is a large donut where absorbent material is inserted in the center of the hole to dampen possible resonances. The construction and technological features developed on this tweeter mean that harmonic distortion and dynamic compression have been optimized to the maximum. Leathery and gritty tweeter, which if not tamed properly could give some problems especially on sibilants. It expresses a good frequency response even if in the neighborhood of 20-40kHz it shows a ripple of the response that is around 3dB above the average of 92dB, which is less in the off-axis response at 45 °.

The TBW5-2143 was chosen for its mechanical characteristics and the material composition of the membrane, in order to guarantee the response to the medium frequencies as natural as possible. The materials that make up the membrane are: paper and bamboo fiber. The loudspeaker has an excellent constructive realization in terms of materials and mechanical tolerances. The basket is of good thickness, in die-cast aluminum, with a fairly careful dimensioning of the spokes. The suspension is made of santoprene. The latter is a thermoplastic compound that is processed in the same way as normal plastic. The difference lies in the degree of flexibility and durability clearly in favor of santoprene compared to normal plastic. The declared parameters of Thiele & Small differ from those measured by a certain quantity. Looking at the table opposite, we note that the compliance and mass parameters are slightly different from the manufacturer datasheet, obviously these differences will affect the relative merit factors that must be taken into account when simulating the loading of the transducer at the cash desk.

The Scan Speak 26w / 4558t00 is a Discovery sub woofer, with good mechanical / electrical characteristics and a generous range (+/- 12.5mm). Taking a closer look, you can see the large magnetic complex formed by two 147mm diameter ferrite magnets with a thickness of 18 mm. The composition of the magnetic complex is typically called a sandwich, that is: the die magnets have been arranged to form a whole with the front and back polar plates that short-circuit the magnetic field. Structurally, the large sub wooofer has a die-cast aluminum basket with quite thick and wide spokes, just enough to guarantee good rigidity to the entire structure. For a good ventilation of the moving coil, from 51 * 33 mm developed on four layers, eight "openings" (of the basket) of 35 * 20 mm have been provided immediately below the spider, guaranteeing a good air circulation on the whole complex . The cone of the loudspeaker is made of anodized aluminum, guaranteeing a good seal and non-deformability, the dust cover is made of fiberglass and paper. Finally the NBR rubber suspension (Nitrile rubber, also known as Buna-N, Perbunan or simply NBR, is a synthetic rubber, an acrylonitrile (ACN) and butadiene copolymer) and the NOMEX spider give life to this 26 cm all muscle and character.

The proportion of the piece of furniture (Figure 4) has been taken care of in order to optimize the phenomenon of stationary waves that are triggered inside the cabinet. The sub-woofer is housed in a net volume of about 40l without considering the sound absorbing. The recommended thickness for the structure of this type of diffuser is a minimum of 3 cm to a maximum of 5 cm. The wood used is marine birch plywood but the classic MDF can also be used as long as the optimal thickness is respected.

The diffuser, developed for the greatest height (120cm), has a narrow and long frontal baffle and a predisposition to rounded corners. These precautions are to be considered in the key, decrease of the physical phenomenon called diffraction. The diffraction occurs whenever the acoustic wave concerned encounters a sudden change in the radiation impedance due to an obstacle. This obstacle must have such dimensions that it can be "seen" by the acoustic wave. Reducing the horizontal dimension of the front panel reduces the difference between the arrival times of the direct signals and those diffracted at the edges, obtaining a decrease in the perception of this phenomenon.

Another expedient prepared on the design of the cabinet, are the two millings on the sides of the loudspeakers. By sizing the width of these "channels" it is possible to decrease the effect of localized diffraction at a frequency comparable to the wavelength equal to the width of the channel itself. At each milling, a part of the energy of the main wave is diffracted in all directions, effectively subtracting from that of the wave that continues its path along the panel towards the furthest edge, thus obtaining an attenuation of the intensity of the signals diffracted by the most distant edges.

The sound-absorbing material used is a mix of density and thickness which, in addition to increasing the net volume, absorbs and subtracts energy from the internal resonances that are created, easily calculable thanks to the use of environmental acoustic formulas for axial modes. Note the use of high density absorbent material in the sub-woofer chamber with an overall thickness of about 12 cm. Clearly this thickness is not comparable to the wavelengths involved, but it is however of good effectiveness in order to dampen the internal resonances that are triggered. The duct used is the PTD68L220 (6.8 cm * 22 cm) which for obvious reasons must be slightly altered bringing the length of the latter to 18.5cm. It is recommended to check the dimensions from the datasheet of the supplier. The post binds drawn are purely indicative, BP08 is recommended for this application. Also in this case check the dimensions of the specific datasheet. In order to optimize the cutting process it is advisable to check the dimensions of the holes from the respective loudspeaker datasheets: SS 26W / 4558T00 and SS 26W / 0-00-00.

A speaker that does not pay attention to subtleties and artifacts of circumstance. Elegant in its proportions, a little less in the finish, but this is a factor of secondary importance since it can be finished in countless different ways and with one own taste. For those who need a non-invasive solution in medium / large environments, with a fair amount of space from the back wall (at least 50cm), to whom an imposing and telluric speaker is needed, Korriban is ready to implement these and other characteristics of sure interest even for the most demanding user. Obviously not all roses, the placement of the sub and the duct on the side and rear walls respectively complicates the positioning in the environment. It will be necessary to take into due account the space to be dedicated to this diffuser in order to provide for half a meter (in reality it can even reach 40-35cm from the back wall with a good yield) from the back wall and about 40 cm per side. By getting too close to the back wall and the side walls, in addition to a swelling of the low range, there will be a sensation of flattening the sound and a decrease in the vertical and horizontal soundstage which in a single word translates into a decrease in the scene reproduced.

All the Kits present in this session of the site, have been realized by the engineers of our company department "Axiolab" which mainly deals with consulting, design and realization of customized and unusual systems. For more information on this product and other KITs that have already been carefully made, consult the Axiolab website by clicking on the link below.

- KIT KORRIBAN -