The Bass & Midrange speakers

On most of the ACT speakers, BC Acoustique chose to use SEAS drivers for the bass and midrange. All of them were conceived in cooperation by BC Acoustique and the renowned Norwegian drivers’ manufacturer under their high quality standard. The drivers were carefully designed to be perfectly adapted to the need of each speaker. Polypropylene was chosen for its high qualities, particularly its lightness, rigidity and neutrality. With such transducers, the performances obtained are remarkable. The midrange is rich, expressive and detailed while the bass is deep, warm with an astonishing clarity.


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- Cone profile and suspension specifically designed for a steady frequency response with no accidents. This allows the use of slow slope crossover for higher phase coherence.
- The use of a Polypropylene diaphragm with variable thickness makes an excellent compromise between lightness and rigidity. Damping has been particularly studied to guarantee the neutrality of sound.
- Spider was specifically studied to offer a perfectly symmetrical movement.
- Large size magnet improves power, sensitivity and transient response.
- Moving coil naturally ventilated and cooled. It can reach high acoustic pressure with very low distortion rate.
- Rigid basket with a very open rear side to reduce the disturbing primary reflections.


Bass & Medium: On most models ACT, the transcript of bass and medium is provided by original SEAS speakers. They are designed to specifications according to BC Acoustique quality standards of the Norwegian manufacturer. All speakers have been very careful and tailored to each speaker design. Polypropylene was chosen for its qualities of lightness, rigidity and neutrality. With such transducers, the performance is remarkable. The medium is rich and expressive, warm and detailed. Bass is deep, articulate, and still very readable.

The Tweeter

For the treble of the ACT line, BC Acoustique chose to develop the BC100 horn tweeter. A common model to all ACT speakers, this tweeter is the result of an important collaboration with Fostex, one of the most prestigious High End drivers’ manufacturers.

Compared to a classic dome tweeter, the BC100 brings a remarkable definition of higher frequencies, an incredible clarity, efficiency and good transience.

Its frequency response chart is regular up to 50 kHz for an ideal transcription of high definition sources (SACD or DVD-Audio) without the inconveniences that can be found with super tweeters.

The BC100 can also reproduce all the dynamic that you can find in music or movies without any loss or distortion.


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- A Ferrofluidated moving coil lowers the resonance frequency and increases power handling.
- A large double magnet gives the motor power and speed.
- Titanium Dome, rigid and light for a fast step response.
- The compression chamber optimises the acoustic impedance of the sound wave.
- Aluminium horn with a profile developed to improve frequency response linearity, ease the phase coherency and limit directivity.


The Woodwork

The woodwork is made out of high density 30 to 40mm thick MDF. All wood panels are veneered on both sides to avoid any risk of bending of the wood on the long term.

The internal architecture is quite complex, using diffusors and resonators, inclined panels and stiffening pieces for the cabinet.

These solutions eliminate all sound coloration and resonances. The speaker gains in neutrality and clarity.

The ACT line uses a bass reflex solution. The tuned vent, whose position in the cabinet was carefully studied, is used to increase the energy level but also to get rid of one of the resonating frequency inside the cabinet. Damping material is used in strategic places to absorb internal waves without affecting micro information.

The drivers are mounted in a very specific way to conciliate acoustic and mechanical benefits while giving the speaker a unique design.

No screw is seen from the outside of the speaker as the drivers are held from the inside. The outer aluminium ring allows a very tight and homogenous fixing of the basket. It facilitates the flow of unwanted vibrations and its curved profile limits the creation of reflections on the outer rim of the basket.

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They break the sound waves to avoid any echoing inside the cabinet. These do not affect all micro information.

Inclined panels
Limit the stationary waves.

Stiffening pieces
Bring more rigidity to the cabinet and suppress stationary waves. Thorough studies were done to find the best setting in the speaker for these elements.

These independent compartments were designed to absorb unwanted frequencies.


The Crossover

The crossover of the ACT line was designed with components selected for their top quality. The state of the art connectors come from WBT renowned for their mechanical and electrical performances. Internal cables all come from Tara Labs, a leader in cable technology. Even if its architecture is complex, the crossovers are using only a fairly slow first order slope of 6dB/Octave. This solution preserves the phase of the drivers and the coherence of sound. To make the ACT line easy to adapt to a room, the use of a number of specific resistors allow the auditor to change the level of the tweeter. 5 positions are available to increase or reduce the tweeter level by up to 3dB. It will be simpler to adapt the speakers to the listening conditions of the room and to the other components of the Hifi/AV system.

To improve integration and fixing, the new A3 has now a 2 parts crossover. The first part is fixed on the side panel of the cabinet, opposed to the woofer. The second part remains on the back of the terminal but its integration has been improved: damping foam is used between the terminal plate and the crossover to cancel any vibration or resonance.

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Polypropylene Capacitors
High power ceramic resistors
Unsaturated coils