Jennifer's childhood on Magnabelt

Being a long-time follower of CuriousMarc's YouTube channel - where he and his team document vintage electronics, space hardware and much exquisite gear - in 2022 I came across a video of him recovering a recording made on a 4" IBM Magnabelt magnetic tape. The video offers a beautiful insight into a beautiful piece of engineering: Marc restores his own IBM Executary 214 dictation machine in order to recover a recording made in 1965 by Jennifer Bell's father, when she was four years old.

Upon watching the results, I couldn't resist offering Marc some extra help with the post-processing of the recovered audio. I got in touch and he promptly sent me the audio file. I figured some processing could remove unwanted blemishes and improve the overall intelligibility of the recording.

The process involved correcting pitch for variations in the machine's transport mechanism, flutter, noise reduction, corrective EQ to compensate for the system's frequency response, and a couple of other things, such as attenuating the "thumps" caused by the periodic pass of two tape creases, a result of the way the belt was stored.

When dealing with artifacts like these, one can take advantage of what would in most cases be purely a technical issue. Here, the mains hum on the recording was quite helpful in establishing the correct tape speed: it fingerprints the original recording with a pilot tone that can be used to correct variations in playback speed, including wobble, flutter and the baseline speed.

You can hear the difference below.

Marc and you both have done a beautiful job restoring this tape, it really is very clear. I am very grateful and in awe that you can get this sound all these years later. Many, many thanks! I now know what my dad is saying at the very end, although I'm sure it must sound mysterious to you. Dad was singing Stanley Holloway's The Elephant Alphabet: "A-nut and B-nut and C-nut and D-nut." That alphabet song was a favourite of mine at the time.