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Analog tape recording Transfer Tips
Analog tape recording was developed in Germany sometime in the early 1940's. This technology was brought to the United States sometime after the end of WW-II. Ultimately, tape recording replaced other methods of audio recording, such as direct to disc mastering, acetate and wire recording. Early recorders held the recording media (ferrous oxide) on paper tape backing. The grainy texture of paper produced discontinuities with the contact with the recording and playback heads, producing numerous analog artifacts. Later, more sophisticated backings were employed to get around that problem, but new problems were introduced that only showed up in subsequent years. Some of the problems that were introduced are of concern to the audio restoration engineer or archivist, since the effects of age on the tape backing may have degraded the oxide material. Care in handling and pre-processing the tape should be considered when transferring old tape recordings to your hard drive for restoration. The following pre-processing and handling precautions should be taken depending on the tape medium.
Analog tape recording was developed in Germany sometime in the early 1940's. This technology was brought to the United States sometime after the end of WW-II. Ultimately, tape recording replaced other methods of audio recording, such as direct to disc mastering, acetate and wire recording. Early recorders held the recording media (ferrous oxide) on paper tape backing. The grainy texture of paper produced discontinuities with the contact with the recording and playback heads, producing numerous analog artifacts. Later, more sophisticated backings were employed to get around that problem, but new problems were introduced that only showed up in subsequent years. Some of the problems that were introduced are of concern to the audio restoration engineer or archivist, since the effects of age on the tape backing may have degraded the oxide material. Care in handling and pre-processing the tape should be considered when transferring old tape recordings to your hard drive for restoration. The following pre-processing and handling precautions should be taken depending on the tape medium.
- Paper Backed Tape: This type of tape was recorded monophonically. The signal is located in the center of the tape. Therefore, a full track playback head is optimal for the best reproduction. If this is not available, use the two inner tracks of a 4-track playback machine transferred binaurally. Later, you can decide which track is the cleanest or make a decision whether or not the two tracks should be summed to mono. If a 4-track machine is not available, re-adjust the height (if you have the mechanical inclination to do so) of the playback-head on whatever reel-to-reel machine that you have access to until the tape players output signal is maximized. Also, adjust the azimuth for the best reproduction of the upper registers of the audio spectrum.
- Acetate Backed Tape: Acetate tape was used through the 1950's and halfway through the 1960's. If it is uncertain whether or not you are dealing with acetate-backed tape, hold the reel up to a light bulb looking through the layers of tape. If the view appears to be translucent, the tape is very likely to be acetate. This tape backing deteriorates over time, often giving off the odor of acetic acid (vinegar). This deterioration can cause playback problems, because the tape changes dimension, and often bows, not allowing it to pass over the playback heads of the tape deck evenly. This produces dropouts if not properly dealt with. The only way to deal with this problem is to increase the tape take up reel tension. Some sophisticated machines (3 motor tape decks) have electrical controls or internal adjustments to facilitate this. Three motor tape decks use the reel motors to establish the tape tension by applying low levels of DC to the motor field winding(s). Simpler machines will require more imagination on your own part. Another alternative is to install felt pressure pads on your machine's playback head. In either case, realize that the increased tension required to force the tape to pass evenly and flatly across the playback head will increase head-wear. But that may be a worthwhile price to pay if you are transferring a priceless tape for restoration and digital archiving.