All Indiana Line cabinets are filled with polyester – a synthetic non-woven fabric of high purity, known for its excellent damping of the internal resonances of the speaker cabinets. What's more, polyester is also extremely resistant to stretching, drying and moisture.
In order to emphasize the exceptionally clear and natural sound of our loudspeakers, we decided to get rid of the troublesome components from the crossover where it was necessary – in the tweeter filter. In all loudspeaker models in which this filter is used, we use only air coils and foil capacitors. These elements do not introduce harmful distortions to the filtered signal, as is the case with ferrite core coils and electrolytic capacitors.
The short-circuit ring is made of pure, perfectly electrically conductive aluminum (1010). It has been placed inside the magnetic system of the mid-woofer. By linearizing the impedance of the loudspeaker, it positively influences the sound of the low and medium frequencies of the acoustic band, significantly reducing non-linear distortions. The ring also absorbs the heat emitted from the speaker coil, increasing its thermal load capacity.
The use of numerical calculations allowed for obtaining a balanced frequency response and low level of distortion, as well as reducing power losses. The obtained sound results were verified by many hours of listening tests. The tweeter filter circuit uses only air coils and foil capacitors. This allowed to avoid distortions that often appear in the case of electrolytic capacitors or coils with a ferrite core. Core coils, when present in a crossover, have a laminated high-silicon iron core, which minimizes distortion from the iron cores.
Curv is a combination of special fibers with high stiffness and high internal damping. It is a material that is thermally formed into a cone profile, which ensures very good directional characteristics of the sound. The Curv cone combines the advantages of membranes made of natural materials (warm and pleasant sound) with the advantages of stiff membranes (high dynamics, precision and a wide, even frequency response). The membranes made of Curv material are also moisture-resistant and are characterized by high durability. The Curv cone has been used in the mid-woofers.
DomHorn is a specially shaped front of the tweeter, which appropriately directs the energy generated by the treble transducer, while increasing their efficiency. Thanks to this solution, the tweeter can play clearer and stronger, easily keeping pace with specialized midrange units and high-efficiency and large-diameter woofers, even with louder music reproduction in larger spaces.
The Dual-Wave upper spring is an original, precisely designed membrane suspension that expands the range of linear operation of the loudspeaker. It reduces distortion, especially in the low bass registers, and improves the articulation of the midrange of the acoustic band. This translates into improved sound of instruments, especially percussion, string and acoustic ones. Thanks to the Dual-Wave solution, unevenness of the frequency response, which results from the resonance of the membrane edge, is also reduced, without the need to varnish it. Dual-Wave suspension drivers also have an eye-pleasing appearance that refers to professional designs used, among others, on stages and equipped with the so-called accordion springs.
The tweeter is mounted in the cabinet with a rubber insulating pad. This solution is to limit the vibrations transmitted from the front wall of the column cabinet to this sensitive component. The use of a floating mount in the case of a tweeter increases the spatiality of the sound, improves the stereo and clarity of the treble.
Indiana Line loudspeakers cabinets are made of MDF panels. They are made using the latest production techniques, which ensures high precision of workmanship, great repeatability and excellent performance parameters for many years. MDF is a moisture-resistant material, it is massive and it suppresses all resonances very well. To completely remove unwanted vibrations, we used transverse reinforcements of the cabinet. They take the form of horizontal rings that are located at key points along the entire height of the loudspeaker cabinet.
Universal and extremely popular polypropylene is a valued material, often used for speaker membranes. However, in order to ensure the most faithful transmission of micro-details, we decided to further increase the stiffness of the cone. We achieved this by doping polypropylene with a mineral called mica. This shiny, hard material significantly improves the parameters of the membrane, guaranteeing the transducer a long and reliable operation, and at the same time giving it an attractive appearance.
A radial damping chamber that prevents harmful reflections under the tweeter dome while allowing it to achieve a low resonance frequency. The small, but at the same time strong, neodymium magnet of the tweeter is surrounded by a space in which – due to its shape – standing waves cannot be generated, which is the case with classic radial chambers located in the axis of the dome.
Original design of the tweeter's frontplate. It is cast from aluminum and has a rubber surface (instead of the commonly used plastic). Ensures proper treble dispersion. It helps to widen the sound stage and better fill the room with high frequencies.
The front panel of the column is placed in the box in a unique way – it is slightly tilted back because it is embedded in the box – shallower at the bottom and deeper at the top. This solution is not used by other manufacturers in models offered in a similar price segment. The front panel also has a constant thickness, which varies depending on the Indiana Line loudspeaker model, up to 30 mm, which increases the mechanical stability of the loudspeaker and prevents unwanted vibrations, and also contributes to obtaining a transparent sound.