First do no harm. The responsible preservation and conservation of heritage master tapes.
One might assume that master tapes are best played back on the same equipment that originally recorded them. Yet the science strongly suggests otherwise. There are many reasons why legacy tape recorders should never be used to play back heritage master tapes.
All tapes are slowly deteriorating from age-related chemical degradation. Huge numbers of Mylar (polyethylene terephthalate) film based tapes now exhibit varying degrees of an oxide binder chemical degradation (called soft binder syndrome) that in some cases renders them un-playable without special treatment. Acetate film based tapes can suffer from another age-related degradation that makes them brittle and fragile. Using studio analog recorders having forced-guidance tape paths, fixed-pin lifters, or unnecessary path elements such as erase and record heads for playback can permanently damage or even destroy irreplaceable masters.
Amplitude versus time, minimizing the playback distortions.
Revealing the true sound quality hidden in a master tape requires a playback hardware platform that contributes no additional distortion.
There are two predominate distortions introduced in analog audio tape playback. The first is time base degradation, observed as unwanted frequency modulation and shift known as wow and flutter and pitch change.
Mylar-based tapes stretch (change in length) under tension. This makes recording and reproducing analog audio signals on these tapes challenging if you want to preserve the recording's time base accuracy. An obvious solution is the servoed constant tension transport. Further reduction of time base corruption can be accomplished by improving the mechanical quality of the tape transport mechanism. This approach is costly but the results are audible. Consider for example that flutter doesn't only contribute unwanted frequency modulation, it also introduces unwanted amplitude modulation.
The second distortion type is amplitude response error, observed as a non-linearity of signal magnitude plotted across the frequency spectrum. It turns out that perfecting the mechanics of how the tape travels over the face of the reproducing head is fundamental to controlling this distortion.
Fortunately, both of these distortion types are readily measured with suitable instrumentation and both are easily detected by trained listeners.
Meet the reproducer, a reference-quality tape transport mechanism optimized for playback.
We manufacture state-of-the-art reproducers (analog tape playback systems) for sound recordings archives. Some of the design objectives for our products are outlined here.
We know that achieving the lowest time base corruption requires a servo constant-tension, servo capstan, precision guidance transport design fitted with high precision headblocks employing no forced guidance. Our reproducers make the headblocks rapidly interchangeable and also offer easily adjustable tape tensions and capstan speed trim.
Proof of performance.
FFT spectral analysis can quantify the time base accuracy of any analog audio tape transport. As suggested by Dale Manquen, a 12.5 kHz carrier signal that is four times higher in frequency than the historic wow and flutter measurement standards is used. This permits wide-band flutter analysis that includes scrape flutter, once erroneously believed inconsequential to the perceived sound quality of recorded music.
Reference-quality playback electronics.
With a reference-quality transport contributing near-perfect tape guidance with exceedingly low scrape flutter generation and high dynamic azimuth stability, optimal playback can be realized through low-noise, low-distortion playback electronics that accurately follow the established equalization curves.
Audition our state of the art solutions.
We began our work designing and building state-of-the-art analog magnetic tape reproducers back in 1987, making 2019 our thirty-second year. Please get in touch to learn more about our Model One and Two reproducer systems (use the form below).
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