Tesi 6

Indiana Line Tesi 6 floorstanding loudspeaker column features a bass reflex tunnel construction in its base, allowing for dynamic reproduction of sound. The interior of the enclosure hides robust reinforcements, and the components used help reduce the impact of unwanted resonances on the sound. This three-way model from the Tesi series, inspired by the Tesi 661 speaker column, is primarily intended for larger rooms.


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Indiana Line Tesi 6

The new version of the Indiana Line Tesi series, represented by the floorstanding Tesi 6 model, is characterized by an exceptionally attractive ratio of quality to price. Its distinguishing features are the rational use of selected, already proven components from the Diva line and a simple yet universal form. The new models from the Tesi series are primarily aimed at users who want to achieve attractive, modern sound in their audio system – balanced, yet clean and dynamic. They are available in three colour variants: black oak, white, and mocha.

Stylish and solid enclosure

The Tesi 6 loudspeaker has an enclosure made of MDF, reinforced with dense bracing, appropriate for Indiana Line’s top floorstanding designs. The bass reflex port placed in the base reduces the audibility of resonances emanating from it, which at the same time allows the speaker to be placed closer to the wall without worrying about excessive bass boost. Aesthetic rings masking the mounts of the speaker baskets give the enclosure an elegant look. Furthermore, the column also has a magnetic grille. The slightly rounded upper edges of the enclosure emphasize the universal character of the Tesi 6 model. Compared to its predecessor, the Tesi 661 model, the dimensions of the enclosure have changed slightly – the newer design is approximately 1 cm taller.

High-frequency transducer with a new front panel

The Tesi 6 model features a 26 mm high-frequency dome with the Indiana Line’s special feature: Radial Venting Chamber. The tweeter’s magnetic system uses a powerful neodymium magnet. However, the front of the high-frequency speaker has been modified compared to the Tesi series models previously available. Its rectangular shape is inspired by the latest speakers from the Diva series, although it is made using a simpler mounting technique. This new design allows the high-frequency transducer to better blend with the appearance of the rings of the other electroacoustic transducers, with all speaker screws hidden from the view, significantly improving the speaker’s appearance.

New electroacoustic transducers

In addition to the tweeter, the Tesi 6 model uses three other transducers – a 160 mm midrange and a pair of 160 mm low-frequency transducers with large linear excursion. They have membranes made of polypropylene with a mixture of mica, providing them with the necessary rigidity for exceptionally precise reproduction of even the finest sound details. The phase plug used in the midrange transducer of the Tesi 661 model has been replaced with a dust cap in the new Tesi 6, and the transducer itself operates in a compact sealed enclosure, completely separated from the resonant cavity of the bass reflex system of the pair of woofers operating below. All this results in exceptional, among others, open and clear sound of the midrange and deep, unconstrained bass, because it comes from a noble three-way system.

Optimization of used components

Indiana Line Tesi 6 is equipped with a total of four perfectly designed electroacoustic transducers. The low and midrange frequency transducers have magnetic circuits optimized using modern design techniques, all equipped with inductance linearization rings. Significantly increased magnets have reduced distortion, improved linearity, and low-frequency reproduction. The diameter of the low-frequency and midrange transducers, like in the older generation of the Tesi series, is 16 cm, thus larger than in the new Diva series models (Diva 3 and Diva 5). The solutions used in them make the sound clear and precise even at high volume levels, regardless of the genre of music being played.

Upper suspension

The Tesi 6 model uses a new Dual-Wave suspension for low-midrange speakers. This solution resembles professional, stage speakers with so-called accordion springs in its appearance. For the first time, the Dual-Wave technology has been implemented in new models from the Diva series by Indiana Line. In practice, we have here a precisely designed upper suspension that effectively extends the linear operation range of the speaker while reducing intermodulation distortion (especially in low, bass range), which in turn improves the articulation of the midrange. The positive impact of this solution is particularly noticeable in percussion, string, and acoustic instruments sound.

Optimized crossover

Indiana Line Tesi 6 floorstanding loudspeaker has a new, highly optimized speaker crossover. It has been developed using the latest design methods and specialized measurement systems. The topology and component quality are retained from the new Diva models. The crossover ensures a smooth impedance characteristic, high efficiency, low distortion, and proper sound dispersion. As a result, the Tesi 6 loudspeaker can cooperate practically with any amplifier.

The most important features of the Tesi 6 model:

  • 3-way acoustical design
  • Magnetically attached grille
  • Highly optimized crossover design
  • Crossover frequency: 300 Hz and 3 kHz
  • MDF enclosure with dense internal reinforcement matrix
  • 2 x 160 mm low-frequency transducer
  • 160 mm midrange transducer in a separate sealed chamber
  • Enlarged and improved magnetic circuits, with impedance linearizing rings
  • Dual-Wave – proprietary upper suspension design for woofer and midwoofer membrane
  • 26 mm tweeter with Radial Venting Chamber technology
  • Bass reflex enclosure with down-firing port in the base
  • Frequency response: from 35 Hz to 22 kHz
  • Available colours: white, black oak or mocha
  • Recommended amplifier power: 30 – 160 W
  • Sensitivity: 92 dB (2.8 V/1 m)
  • Dimensions (H x W x D): 942 x 180 x 300 mm
  • Weight: 15.6 kg

Technical data

Speaker alignment / type

3-way / floorstanding

Box aligment / port placement

bass-reflex / bottom

Driver diameter

tweeter: 26 mm, textile dome, midrange: 1 x 160 mm, mica-polypropylene cone, woofer: 2 x 160 mm, mica-polypropylene cone

Frequency response

35 – 22000 Hz

Sensitivity (2,8 V/1 m)

92 dB


300 / 3000 Hz

Bi-wiring / bi-amping


Amplifier loading impedance

4 – 8 ohm

Suggested amplifier power

30 – 160 W

Dimensions (H x W x D)

942 × 180 × 300


black, white, mocha


15,6 kg

Air coils and film capacitors

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.

Air coils and film 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.


Computer-optimized crossover design

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.

Computer-optimized crossover design

Dual-Wave suspension

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.

Dual-Wave suspension

Mica-poly cone

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.

Mica-poly cone


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.


Indiana Line New Tesi – owner's manual