Audio that delivers hammer blows to the opposition?

With the ability to reach infrasonic frequencies as low as 18Hz, the Thor subwoofer from MAG Cinema deploys innovative technology to deliver an immersive bass experience. Peter Knight listens in.

 

When you give your product the name ‘Thor’, you need to be pretty confident its performance lives up to its name — especially if the product is a professional-grade subwoofer whose purpose in life is to deliver a new type of bass and exceptional sound pressure.

Launched two years ago, the Thor subwoofer is from MAG Cinema, a Ukrainian-based audio specialist with a wide range of solutions for exhibitors. Incorporated into the Thor subwoofer is M-Force technology which includes a patented moving magnet linear motor structure from the Italian pro-audio amplifier manufacturer Powersoft. Instead of having a lightweight coil moving in a fixed magnetic field, it has a lightweight magnet in the middle of two huge fixed coils. The manufacturers say this delivers a strength factor 20x higher than conventional designs, and allows it to drive a huge diaphragm with unprecedented control.

A collaborative effort

For a number of years, MAG Cinema has worked alongside Powersoft to deliver a variety of different products for professional audio. So it was clear who MAG Cinema should turn to when it came to the development of breakthrough equipment for premium experience cinema installations.

The goal of the Thor subwoofer design was to achieve ultimate precision in the reproduction of the low-frequency effect track, which provides the basis for the immersive cinema experience. In the eyes of the team at MAG Cinema, traditional cinema subwoofers — based on wound voice coil transducers — are limited in their performance in the infra-low spectrum, lacking in terms of sound pressure levels (SPL), have a lower frequency threshold, and generate a great amount of distortion. Looking for an alternative approach, MAG Cinema’s engineers turned to the M-Force technology from Powersoft. M-Force is a unique transducer that uses a moving magnet linear motor structure to generate sound frequency oscillations. This solution has a power output capacity that exceeds that of a traditional transducer, allowing the use of a bigger reinforced diffusor (30in in diameter) to create unparalleled SPL figures.

Another prominent feature of M-Force technology is the use of acoustical feedback to adjust for moving system non-linearities and exterenal environmental influence. Implemented by DPC (differential pressure sensor) and extremely low-latency processing of the digital signal, this technology helps to ensure precision in  the reproduction of the input signal.

The external cabinet of the Thor subwoofer was created specifically to add to the benefits of the M-Force system. Based around a transmission line design, the system’s frequency range has been extended down to 18Hz (-3dB), while being capable of attaining a peak SPL of 145dB — 2dB below the level of a Formula 1 car drive-by at full throttle, which should satisfy most audiences. The cabinet is heavily reinforced to withstand the enormous pressures generated by M-Force, while at the same time being made slim enough to fit into tight behind-screen spaces.

The low-frequency reproduction is a matter of how big the volume of air is that can be moved. The M- Force product allows for high efficiency in a smaller footprint together with a reduction in distortions and minimisation of power compression effects. With a nominal power of 5000W, Thor is a self-powered system with Powersoft’s M-Drive amplifier providing all the controls, monitoring, and protection needed to drive a highly advanced transducer.

In testing, the results achieved by the Thor design were impressive. As stated previously a low frequency of 18Hz was achieved, rising to 125Hz, with a total distortion level so low it allowed perception of subtle cinema track features not typically revealed by traditional cinema subwoofers.

Announced at CinemaCon in 2017, the Thor subwoofer has proven to be a popular product with 25+ screens across 10 countries already installed. This technology does not just have an application in cinema or other similar situations, it has been used in other applications too. The nature of the vibrations that the subwoofer creates, mean it is the perfect system to reproduce the experience of an earthquake — as used in a visitor centre in Iceland. The experience uses the bass drivers to agitate concrete parts of the floor, similar to the way an earthquake would. Given the speaker’s ability to reach these depths, it is likely that the technology will have practical uses elsewhere, too.

 

At the practical end of Thor’s hammer?

To test the theory in practice for Cinema Technology, Peter Knight hopped on the Eurostar for a trip to Paris to experience the Thor subwoofer. The system has been installed in a brand new seven-screen cinema, Les 7 Batignolles complex in the 17th arrondissement, an area of Paris significantly redeveloped in the past decade, thanks in part of the city’s bid to host the 2012 Olympics, writes Peter. Opened in December, the site includes one 352-seat PLF auditorium into which the Thor subwoofer has been installed as a fundamental element of the entire sound system supplied by MAG Cinema. It sits to the screen’s left, and — displaying its intentions clearly — is fully visible to the auditorium (i.e. the black screen skirt is deliberately not covering it). Consequently, during the demonstration it was possible to see clearly the activated vibration of the cone. The cinema played some trailers and Dolby Atmos content to illustrate the system’s capabilities, and to allow us to experience the full quality of the sound.

 

The bass this system produces is quite different to what you might ordinarily experience when in a cinema or a similar audio-driven environment. Obviously it is a challenge to describe something so physical in words, but it was notable that there is a lack of harshness in the way you experience the bass in comparison to what you might hear and feel with traditional subwoofers. This is smoother — almost velvety in its feeling. The best way to describe it would be to compare it to something like drinking a smooth, perfectly formed cup of coffee instead of instant coffee. The two are quite different. You feel the bass in your body, but not in a harsh way. It is both effective and settled at the same time. Watching a movie is an engaging experience that can only be its best if all the audio effects can be heard in the way they were originally created. In my view, for its low-frequency audio and infrasonic elements in particular, the M-Force system has been successfully incorporated to give better results than a number of conventional low-frequency effects subwoofers.

 

About Powersoft
Established in 1995, Powersoft is an Italian company with over 100 staff. Its roots were in the development of energy-efficient, high-powered amplifiers . The group boasts a worldwide sales network and service centres in over 80 countries. www.powersoft.it

 

About  MAG Cinema
MAG Cinema is a Ukrainian company offering cost-effective sound solutions. It has existed for over 20 years. Many of its cinema products were created in collaboration with installation providers to be  reliable and competitive.  www.mag-cinema.com

 

Avatar

About Peter Knight

Peter Knight is the Commissioning Editor for the Cinema Technology Magazine, along with the Managing Editor for the Mad Cornish Projectionist website. He is still a working projectionist and AV technician with an interest in all things projected both in traditional cinema and elsewhere too. Peter has been running his own business since 2017.

View all posts by Peter Knight →