# Reading Tapes Backwards: A Legitimate Approach to Saving Time and Money in Digitization Projects?
## 3 Experimental Setup: Signal Flow and Data Set  
The experiment presented in this paper is intended as an investigation that, if verified, could become a practice within the complex process of digitizing audio documents on open reel magnetic tapes, in other words, establishing the correct method for reading magnetic tapes, even if part of the content was written backwards (in the opposite sense of the first-choice reading). By proposing this experiment as part of the investigation of the complex digitalization process, we could not evade all those rules and good practices that also govern the choice of the analogue-to-digital transfer system. The choice of this system becomes, in this occurrence, an integral part of the experimental setup. According to the ethics and principles of preservation strategy, as it is described in [27], the selected experimental setup reflects what is stated in [28] regarding the reproduction of analogue magnetic tapes in chapter 5.4 [29]. As a professional reel machine usually used for audio master recording, the Studer A810 (2-tracks, 1/4 inch), owned by the Centro di Sonologia Computazionale laboratory of the University of Padua, was picked for the experiment (CSC--[[http://csc.dei.unipd.it](http://csc.dei.unipd.it)]([http://csc.dei.unipd.it](http://csc.dei.unipd.it)) (accessed on 20 June 2021)--has been a leading research center in the field of computer music, creation and preservation over the last 50 years [25]). For the occasion, the machine was suitably overhauled with regards to both the electrical components and the mechanical ones, depending on the type of magnetic tape used for the experiment, a 1/4 inch RTM SM911. The Studer A810 has four recording and reading speeds, but only the speed of 15 ips (inch-per-second) was used for the experiment. It is well known, as reported in [29], that the higher the writing speed, the higher the frequency response of the machine and the higher the quality of the audio recorded. Consequently, the speed of 15 ips was preferred, although the highest is 30 ips, as a compromise for all those open reel tape audio documents, which are mostly at speeds of 7 1/2 ips, if not lower. For some estimates, [18] shows an analysis of the last seven years of work at the CSC laboratory of the University of Padua on national and international archival materials and, specifically, on the ratio of the number of tapes for each replay speed used to the total amount of tapes. The attention paid to the choice of the replay speed is due to the fact that the experiment involved both writing operations on tape to prepare the test material and reading, subject to the actual experiment in this paper. For completeness of information, CCIR equalization was set on the reel machine. The samples recorded on the magnetic test tape were the result of a selection between different audio materials, lasting about 15 s each. Regarding the characteristics of the chosen ones, these firstly had to cover the entire frequency response spectrum of the Studer A810. Then, they had to present peculiarities useful for subsequent computer analysis, for example, having very evident transients, as in the case of a snare drum, and coming from heterogeneous sources for timbre and other sound qualities. For completeness of information, the samples used by the authors for the experiment were born-digital audio files, stereo interleaved, normalized to an average RMS around \(-18\) dB, with.wav extension and 24-bit 48 kHz resolution.