AFI

AFI (Audio Fidelity Improvement) & HiFi-Studio Wittmann, the discoverers of the sound improvement of vinyl records by means of thermal relaxation, also known as tempering.
The idea and the technical know-how for the record flattener came from Dr. Ullrich Kathe - a passionate hi-fi fan, analog lover and long-time customer of HiFi Studio Wittmann. One day, Ulli Kathe brought his vision of a record flattener into the studio, motivated by the knowledge that wavy records directly influence the essential settings of a high-quality pickup, such as the horizontal alignment of the turntable, tracking force, VTA, azimuth and anti-skating. Depending on the shaft position, the needle dips to different depths, which changes the previously carefully set parameters during scanning. Oliver Wittmann, the owner of the studio, was immediately enthusiastic about the idea. He offered to take care of marketing and sales as well as the sonic evaluation of the flattening processes. That was the start of the joint project: 'The record flattener', Made in Germany.
During the two years of development, we experimented, tinkered and ironed with passion. Countless test records were put through processes with different temperatures and varying warm-up, holding and cooling times. Oliver Wittmann regularly checked the sound of the ironing results on his reference system. It was of central importance not only to achieve a perfectly flat record, but also to ensure that the sound quality remained undiminished. It was during this research process that the decisive "aha" moment occurred: "Wait a minute, that sounds better than before!" This is how the innovative idea of tempering vinyl records was born. Another year of development work was devoted to determining the optimum temperature curves and holding times. The goal: to achieve the best possible tempering of vinyl records and thus maximum sound improvement.
In 2016, the time had finally come: the world's first record flattener, the AFI flat, with a special tempering/relaxation program to improve the sound of vinyl records was launched on the market.
Tempering, a form of heat treatment, has been used in the industry for a long time. The basic principles of tempering were already known in ancient times, particularly in the processing of metals. However, the systematic application of these techniques in modern industry only began with the industrial revolution in the late 18th and early 19th centuries. For example, the tempering of steel was a decisive step in the production of high-quality tools and components. The industrial application of tempering to materials such as glass and plastics started in the 20th century, aided by improved chemical and physical knowledge and new manufacturing methods.
Records are pressed at around 150 degrees Celsius, with the pressing process taking around 30 seconds. After a short cooling phase, during which the matrices are cooled with water, the record is removed and stacked on a spindle, weighted down with metal plates, for further cooling. Due to the uneven and rapid cooling - much faster on the outside than on the inside - and the toughness of the material, the long molecular chains of PVC and polyvinyl acetate have little chance of aligning themselves in a relaxed manner. This production method leads to material stresses that are "frozen" in the material and are audible.
During tempering, the vinyl record is slowly and evenly heated up to plateau temperature, held at this temperature for a while and then cooled down very slowly and in a controlled manner - a process that can take up to four hours. Slow and even cooling is more important than heating. This allows the molecules to align themselves naturally and without stress. This process significantly reduces tension, making the material harder, more robust and more homogeneous.