Active Field Control
Active Sound Field Control System
For more than 125 years, the skilled craftsmen of Yamaha have been creating the best musical instruments in the world. The driving force of the company has always been the achievement of excellent sound quality. Whether it’s making instruments, developing state-of-the-art sound reproduction technologies, or creating audio equipment for theaters and concert halls, Yamaha is always looking for new ways to ensure the greatest possible listening experience.
First used by Yamaha in 1985, Active Field Control (AFC) technology is an acoustic processing system designed to correct and improve the architectural and acoustic characteristics of cultural centers, temples, theaters and concert halls, while carefully preserving the natural sound characteristics of the premises.
The AFC3 is the third generation of innovative Active Field Control (AFC) systems from Yamaha, the most well-known brand in the audio industry.
There is a growing trend that requires buildings for cultural, scenic and public purposes to become more versatile, easily adapted to various tasks. Designed with this trend in mind, the AFC3 system is a cost-effective alternative to mechanical means of modifying room acoustics. Providing a scalable solution that can be used in a wide variety of rooms, AFC3 allows, for example, to arrange classical music concerts in a very large hall without the use of sound amplifying equipment, to use an organ in a small church, or to optimize the acoustic conditions of musicians in the pavilion of a recording studio. By pressing the button, you can change the reverb parameters, almost instantly correcting the acoustic environment of the presentation. In addition, the AFC3 is capable of delivering equally high-quality audio experiences to both performers and the public.
More than 80 cultural and public buildings in the United States and Japan are now equipped with Yamaha AFC systems. In Russia, 4 installations have already been completed. The AFC3 model is a state-of-the-art system for improving the acoustic characteristics of the room and is available for a large number of stage venues and recording studios.
What is AFC?
Active Field Control is an acoustic amplification system used to improve the architectural and acoustic characteristics of a room and optimize reverberation while maintaining the natural acoustic “tonality” of the room. Yamaha’s digital signal processing technology allows you to implement this system in a specific room with a small number of basic devices.
The AFC corrects the acoustic conditions using an acoustic feedback system. This distinguishes AFC from other technologies that use digital reverbs to simulate the characteristics of a room.
AFC3 Main unit
The AF C3 main unit is based on the well-known Yamaha DME64N digital processor. The advanced version of this processor for AFC 3 includes matrix mixers, delay lines, parametric equalizers and routing functions, as well as specialized digital signal processing tools designed for AFC applications. An AFC-FIR card is inserted into one or two slots of the AFC3 processor, which supports the functions of” rotating ” Electronic Microphone Rotator (EMR) microphones and processing data with a filter with a FIR.
AFC System FIR Board
The AFC system FIR card (AFC-FIR card) is used to provide data processing by the FIR filter with a higher order that was previously unattainable. Thanks to the AFC-FIR board, AFC3 systems are able to work with the order of the FIR filters, 125 times more than in the previous generation of AFC systems. This increase in the order of the FIR filters allows you to achieve a much longer natural reverberation in the room without a distorted and unnatural-sounding signal.
By correcting the gain in the links of the FIR filter, the system adjusts the signal in the feedback loop, and as a result, the energy additionally brought back into the room, changing the effective absorption in the room and the resulting reverberation time.
Efficiency that does not depend on the location of the source and receiver of the signal in the room.
The system is effective for controlling both early reflections and diffuse sound fields.
At the present stage of development of digital technologies of active control of the sound field, fundamentally new opportunities have appeared, which have opened up new perspectives in the work of musicians, composers and sound engineers, including the following:
— the ability to correct the acoustic shortcomings of the sound field of a real room in the conditions of a rehearsal, concert and sound recording;
— the ability to change the acoustics of halls, rehearsal rooms and studios, optimizing them for a specific genre of musical material;
— the ability to optimize the acoustics of a real room for a specific work, the selected genre of musical material.
— the ability to quickly change the acoustic parameters of the sound field for each piece in the intervals between works in one concert.
— creating conditions for authentic recordings of symphonic music and modern acoustic music in stereo, surround sound, 3D sound, etc. in studios with insufficient volume according to the standards of architectural acoustics.
— the ability to create and perform new acoustic music in a simulated acoustic environment, invented by a composer or musician-interpreter or sound engineer.