A physicist uses X-rays to rescue old new music recordings

Rescuing music with X-rays
Sebastian Gliga winding a tape on a Studer A80: The tape device is on financial loan from Idee und Klang in Basel, the studio of audio engineer and composer Daniel Dettwiler. The analog device, which was made in Regensdorf in the 1970s, serves to produce reference recordings that can be directly as opposed with the benefits of the synchrotron measurements. Credit score: Paul Scherrer Institute/Mahir Dzambegovic

Scientists are establishing a approach that utilizes the exclusive synchrotron X-ray light from the Swiss Light Source SLS to non-destructively digitize recordings from significant-worth historic audio tapes—including treasures from the Montreux Jazz Festival archive, this kind of as a exceptional recording of the King of the Blues, B.B. King.

Magnetic tapes have virtually wholly disappeared from our life and now only love a nostalgic specialized niche existence. On the other hand, substantial quantities of these analog magnetic media are continue to stored in the archives of sound studios, radio and Television stations, museums, and personal collections around the world. Digitizing these tapes is an ongoing problem as very well as a race against time, as the tapes degrade and sooner or later turn out to be unplayable.

Sebastian Gliga, physicist at PSI and skilled in nanomagnetism, and his workforce are creating a strategy to non-destructively digitize degraded audio tapes in the optimum high-quality employing X-ray light. To reach this goal, they have been collaborating with the Swiss Countrywide Seem Archives, which has manufactured tailor made-manufactured reference recordings and furnished audio engineering know-how. Now, a partnership with the Montreux Jazz Electronic Venture will assistance to further more build and examination the process.

Preserving audio tapes from decay

The remaining users of the well known rock band Queen just lately faced a big obstacle. In their studio, the musicians discovered a tape from 1988 made up of a song with the voice of their famous singer Freddie Mercury, who died in 1991. Even so, the tape was badly ruined. At initial, no a single considered they would be in a position to conserve this exclusive piece. With terrific energy, the sound engineers managed to be successful following all.

“It can be like stitching pieces collectively,” guitarist Brian May well instructed the BBC. On 13 October 2022, the song “Facial area It Alone” was ultimately launched and stormed the all over the world charts, extra than 30 many years following its authentic creation.

“This case in point exhibits that tapes are not created to last for good,” describes Gliga. “The material decays above time and can no for a longer time be played again.” Although it is achievable to painstakingly reassemble and restore such tapes, Gliga and his workforce are pursuing a totally new method. They use synchrotron radiation: “With X-ray gentle from a synchrotron, we can reconstruct even seriously damaged tape fragments without having even touching them.”

A exceptional live performance recording of famous blues guitarist B.B. King is presently sitting down on Gliga’s lab bench. In 1980, the King of the Blues performed his second live performance at the Montreux Jazz Festival—a 48-moment spectacle that was captured on tape by Swiss sound engineer Philippe Zumbrunn. Nowadays, having said that, only about 10 seconds of this recording can be performed back at a time. The chemical composition of the tape has previously decayed to these kinds of an extent that any playback on a traditional unit will only even further damage the tape.

“We ended up not only interested in the musical content of this B.B. King recording, but also in using on the obstacle its state of decay provides,” states Gliga. “Synchrotron radiation may well overcome the limits of standard restoration solutions.”

Looking at the magnetic states

Audio tapes retail outlet information in a layer of small magnetic particles—like tiny compass needles pointing either north or south. When the tape is recorded, their magnetic orientation is changed—the tape will become magnetized, and the audio information and facts is now bodily saved in the orientation pattern. To participate in back again this sample, the tape is moved earlier a perform head. As the magnetic subject frequently adjustments by the sample, a voltage is induced in the enjoy head and an electrical sign is produced. This sign is amplified and transformed into an acoustic signal.

With his X-ray process, Gliga does not depend on the magnetic field, but on the person compass needles that create this area. “The magnetization states of these very small particles, whose dimension is scaled-down than a tenth of the diameter of a human hair, can be study out virtually individually making use of the X-ray gentle of the SLS and transformed into a large-excellent audio sign,” he says.

The most correct copy

“Digitization is a continual course of action,” describes the physicist. The so-called sampling price is important. The phrase refers to the frequency at which an analog signal is sampled for conversion into a digital sign. The continuous seem wave is divided into segments of a selected time interval and saved digitally. A better sampling amount implies a greater resolution in the digitization of the authentic sign.

Since the synchrotron light-weight can evaluate practically each single magnetic compass needle on the tape, it can obtain unparalleled resolution. “We accomplish anything like the most accurate copy,” Gliga clarifies.

Nostalgia satisfies high-tech

A lot of the audio world is physics and can be expressed in formulation and figures. Having said that, when it will come to ideas such as audio and the excellent generated, the subjective aural encounter is paramount. That is why Gliga will work with specialists like the Basel sound engineer and composer Daniel Dettwiler. Dettwiler is renowned for analog music processing. His studio is also house to a Studer A80, a tape equipment that information and plays back magnetic audio tapes with large precision.

“What we reconstruct with X-rays is the raw audio sign as it is stored on the tape,” explains Gliga. Even so, if you play the exact same tape on the Studer, you get a a little distinctive signal. “This is thanks to the electronics inside of the machine, which additionally system and manipulate the sound.” Gliga and his team thus use this analog system from the 1970s to review the appears extracted at the synchrotron with the conventionally digitized parts.

At the minute, nonetheless, the synchrotron mild continues to be off—it is “dark time” at the SLS. The substantial exploration facility is going through a thorough enhance involving now and the beginning of 2025. The goal is to make improvements to the brilliance of the synchrotron beam by a element of 40.

“Our process will gain significantly from the up grade, and it will allow even more efficient measurements,” describes the physicist.

Offered by
Paul Scherrer Institute


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A physicist uses X-rays to rescue outdated music recordings (2024, April 8)
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